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Posted: 3/3/2016 10:50:16 PM EDT
[Last Edit: jaqufrost]
I have two Bobro mounts. A 30mm single lever mount and a 34mm double lever mount. Last year I had the 30mm quit holding zero after about 400 rounds (estimated). My groups went to 3+ MOA and I could easily move the scope mount back and forth on every AR15 upper I had. I sent it to Bobro and they said a part was out of spec, repaired it and sent it back.
A couple days ago there was a thread discussing AR optics and I started examining my Bobro mounts because of it. I checked my 30mm mount and it is again moving when "locked" down. It is not as easy to move as the time it failed, but I can move it back and forth with hand strength. I then pulled out my 34mm double lever mount and checked it. It too moves back and forth with some pressure. Both of these mounts hold zero to around 1 MOA, unless your rifle is very good, you will probably never see it. I've been trying to get consistent .5 MOA groups for awhile, and having difficulty - which I have blamed mostly on ammo and reloads (and maybe it is the ammo and reloads). But a mount that will shift under hand pressure is out. I made a short clip of it moving for those who wouldn't believe my story.  Update #1 I found part of my problem this morning. I pulled out my calipers to measure the recoil lugs. I found two problems on the 34mm mount. The lug appears to be undersized, only measuring .206 across. It also has one broken screw. All my uppers have a distance between slots of .210 to .212. My 30mm mount has a lug that measures .210 across, I believe that's why it barely moves on most my uppers.  Update #2 I just got off the phone with Andrew (owner of Bobro). The 34mm is going back for repair. He said they will have to replace the base since the screw broke off and said it was their fault the screw broke and it was probably over torqued at the factory. The 30mm won't go back. He indicated the way Bobro's are designed they will all move if pushed hard enough, but should auto center to the front based on the lug. Update #3 Here is a picture of the disassembled mount, you can see the stud that broke off with just a couple inch pounds of pressure.  I got it mailed back today, hopefully they will have it fixed before too long. Update #4 I received my replacement mount from Bobro yesterday. The good news is it's a brand new mount with their weight saving cuts. It has a recoil lug with a width of .212, so I can't feel it move on my regular AR upper. I pulled out rifle that doesn't have a full recoil lugs and unsurprisingly the spring clamps were not enough to hold it in place. Here is a quick video of it moving on that rail.   |
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Posted: 3/3/2016 11:02:16 PM EDT
[#1]
Originally Posted By jaqufrost:
I have two Bobro mounts. A 30mm single lever mount and a 34mm double lever mount. Last year I had the 30mm quit holding zero after about 400 rounds (estimated). My groups went to 3+ MOA and I could easily move the scope mount back and forth on every AR15 upper I had. I sent it to Bobro and they said a part was out of spec, repaired it and sent it back. A couple days ago there was a thread discussing AR optics and I started examining my Bobro mounts because of it. I checked my 30mm mount and it is again moving when "locked" down. It is not as easy to move as the time it failed, but I can move it back and forth with hand strength. I then pulled out my 34mm double lever mount and checked it. It too moves back and forth with some pressure. Both of these mounts hold zero to around 1 MOA, unless your rifle is very good, you will probably never see it. I've been trying to get consistent .5 MOA groups for awhile, and having difficulty - which I have blamed mostly on ammo and reloads (and maybe it is the ammo and reloads). But a mount that will shift under hand pressure is out. I made a short clip of it moving for those who wouldn't believe my story.  https://youtu.be/V3TnMeqNjXo
Have you contacted bobro? |
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Posted: 3/3/2016 11:16:36 PM EDT
[#2]
No. The likelihood of receiving three bad levers - one being returned to bobro and sent back as good, is extremely low.
Any single lever should be strong enough to prevent that movement, especially since the majority of their mounts are a single lever design. |
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Posted: 3/3/2016 11:21:53 PM EDT
[#3]
Quote HistoryOriginally Posted By jaqufrost:
No. The likelihood of receiving three bad levers - one being returned to bobro and sent back as good, is extremely low. Any single lever should be strong enough to prevent that movement, especially since the majority of their mounts are a single lever design. So what's your plan? Stick them in a drawer and never use them again? At least if you contact them they will warranty them for you. |
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Posted: 3/3/2016 11:30:48 PM EDT
[#4]
I may let them warranty them. Then they will go on the EE.
For now a G mount is on the way to replace the 34mm Bobro. |
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Posted: 3/3/2016 11:37:07 PM EDT
[#5]
I don't like bobro for large heavy optics. Red dots and smaller scopes seem to work fine.
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USA
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Posted: 3/4/2016 3:22:02 AM EDT
[#6]
That sucks! I'm sure the frustration on the range makes it worse. I hope your next mount works out and makes range time better.
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Posted: 3/4/2016 8:58:20 AM EDT
[#7]
Updated OP.
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Posted: 3/4/2016 12:51:53 PM EDT
[#8]
I just got off the phone with Andrew (owner of Bobro). The 34mm is going back for repair. He said they will have to replace the base since the screw broke off and said it was their fault the screw broke and it was probably over torqued at the factory.
The 30mm won't go back. He indicated the way Bobro's are designed they will all move if pushed hard enough, but should auto center to the front based on the lug. |
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MI, USA
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Posted: 3/5/2016 10:17:31 AM EDT
[#9]
It's a soft mount design . . . like the ARMS.
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Posted: 3/5/2016 10:21:42 AM EDT
[#10]
Quote HistoryOriginally Posted By glock24: It's a soft mount design . . . like the ARMS. |
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Posted: 3/5/2016 10:29:55 AM EDT
[#11]
For the cost of the mount & being the 2nd time with a problem, I would ship a replacement mount to you with a return tag if I was the boss!
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Posted: 3/5/2016 10:48:56 AM EDT
[#12]
I have an ACOG on a Bobro mount, but that's as heavy as I would go with the single lever design.
I'm pretty sure Bobro came out with dual lever mounts to address issues with heavier scopes. However, the complexity of the mounting system (required tolerances, etc) has always given me pause. |
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Posted: 3/5/2016 12:04:46 PM EDT
[#13]
One of the lugs was broken and barely holding on. It snapped as soon as I put a couple inch pounds of torque on it to remove the fastener.
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MS, USA
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Posted: 3/6/2016 11:46:29 AM EDT
[Last Edit: MS556]
[#14]
Screwed on recoil lugs seem a design flaw. Small screws in a high impact and stress area. Why can't they machine the lug into the base as do others? Why does the lever not close sufficently to prevent fore and aft movement? I can understand that some mounts need to be pushed forward bringing the lug into tight contact with the front edge of the rail slot before locking the levers, but it should not move once the levers are engaged.
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Posted: 3/6/2016 5:05:12 PM EDT
[Last Edit: jaqufrost]
[#15]
I think the recoil lug is press fit and screwed in place. Andrew said they would toss the bottom part because the screw broke.
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Posted: 3/22/2016 10:25:33 PM EDT
[#16]
I mailed it back on the 8th, it's the 22nd. Hopefully they will get it fixed soon.
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Posted: 4/1/2016 11:58:03 PM EDT
[#17]
I called Bobro today, apparently they forgot about my mount and it was sitting on a shelf. Thankfully they are mailing me a new replacement mount today.
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Posted: 4/2/2016 12:23:04 AM EDT
[Last Edit: brodband8]
[#18]
All of my larue mounts do this also.
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Posted: 4/2/2016 12:28:21 AM EDT
[#19]
Quote HistoryOriginally Posted By brodband8: All of my larue mounts do this also. My new G mount passes this test as long as the cross bolts are over 7.5 in lb. |
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MS, USA
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Posted: 4/3/2016 9:51:26 AM EDT
[#20]
Quote HistoryOriginally Posted By jaqufrost:
I would tighten them then. IMO it normally won't make much difference with rifles that won't shoot under an inch anyways. My new G mount passes this test as long as the cross bolts are over 7.5 in lb. http://www.ar15.com/forums/t_16_5/3707_First_look_at_a_Geissele_Super_Precision_mount_.html Quote HistoryOriginally Posted By jaqufrost:
Originally Posted By brodband8:
All of my larue mounts do this also. My new G mount passes this test as long as the cross bolts are over 7.5 in lb. http://www.ar15.com/forums/t_16_5/3707_First_look_at_a_Geissele_Super_Precision_mount_.html Agree, neither Larue nor ADM mounts can be moved within the slots if you do the lever tension adjustment properly. |
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Posted: 4/3/2016 10:10:54 AM EDT
[#21]
Thank you for saving me some money..!
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Posted: 4/8/2016 8:06:13 AM EDT
[#22]
I received my replacement mount from Bobro yesterday. The good news is it's a brand new mount with their weight saving cuts. It has a recoil lug with a width of .212, so I can't feel it move on my regular AR upper. I pulled out rifle that doesn't have a full recoil lugs and unsurprisingly the spring clamps were not enough to hold it in place. Here is a quick video of it moving on that rail.
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Posted: 4/8/2016 11:50:06 AM EDT
[#23]
That is kind of sad actually.
I used to be a big fan of Bobro until I was deceived about the compatibility of their BCO mount as it relates to working with the TA31 as well  Considering I called directly to ask the question of Andrew himself and then the story was changed after it arrived and I wanted to sell the mount it soured me on them as a company and I will no longer buy their products.
Say what you want about Mark but I think that situation would have been handled much, much differently if it was a Larue mount instead that I had ordered. |
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IN, USA
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Posted: 4/8/2016 12:02:51 PM EDT
[Last Edit: ARgonot]
[#24]
Originally Posted By jaqufrost:
Update #4 I received my replacement mount from Bobro yesterday. The good news is it's a brand new mount with their weight saving cuts. It has a recoil lug with a width of .212, so I can't feel it move on my regular AR upper. I pulled out rifle that doesn't have a full recoil lugs and unsurprisingly the spring clamps were not enough to hold it in place. Here is a quick video of it moving on that rail. https://youtu.be/O1JCadv8IuA
So your replacement Bobro mount works perfectly and exactly as advertised on a proper picatinny rail. |
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Posted: 4/8/2016 12:52:12 PM EDT
[#25]
Yes, the replacement appears to work fine. But I don't trust any of their mounts for precision work. I also understand there are limitations to their design that prevent them from working on many rails and they cannot be adjusted to compensate.
YMMV, I'll be happy to sell you a 34mm Bobro mount if you want one. |
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IN, USA
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Posted: 4/8/2016 1:41:28 PM EDT
[Last Edit: ARgonot]
[#26]
Quote HistoryOriginally Posted By jaqufrost:
Yes, the replacement appears to work fine. But I don't trust any of their mounts for precision work. I also understand there are limitations to their design that prevent them from working on many rails and they cannot be adjusted to compensate. YMMV, I'll be happy to sell you a 34mm Bobro mount if you want one. Quote HistoryOriginally Posted By jaqufrost:
Yes, the replacement appears to work fine. But I don't trust any of their mounts for precision work. I also understand there are limitations to their design that prevent them from working on many rails and they cannot be adjusted to compensate. YMMV, I'll be happy to sell you a 34mm Bobro mount if you want one. What kind of rails do they not work on? If you mean the type of rail you most recently tested your new mount on, that is not a legitimate test at all. LaRue does not recommend their mount be used on that type of rail either because it is grossly out of spec. I would love to buy that mount for reasonably less than retail because I would have to purchase a set of 1" rings. Bobro does clearly state the following: Must be compatible with any 1913 Specification Rail, to include systems that are out of specification (within reason) and this includes Weaver rails. A picatinny rail with a full depth center groove running the length of the rail is definitely not 1913 spec, not even 'reasonably'. I saw the photo below in the Benelli forum and the movement & damage was deemed by LaRue to be the out of spec rail. LaRue recommended to not put their mount on that rail again. The topic is on this page. 
This is the type of rail that mangled that LaRue mount. Notice it looks just like the one you tested your new Bobro with: 
If Bobro mounts had a seriously flawed design then we wouldn't be just hearing about it now. They have been long proven to be good to go. Bobro honored their warranty, replaced it, it works as advertised on a proper rail. Good for Bobro! I bought a LaRue FUG and it absolutely would not tighten to my spec rails (or any other rail) no matter how much it was tightened. They honored their warranty, replaced it, it worked as advertised on my proper rail. Good for LaRue! I understand that you may have used that grossly out of spec rail to demonstrate that Bobro's 'auto-centering lug' is a required part of a Bobro mount's performance, but as I've shown ... LaRue evidently doesn't recommend their mounts on that rail either and certainly would NOT recommend you overly tighten their mount to compensate. I wouldn't trust that out of spec rail for precision work. That's really where the weakness is. |
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MS, USA
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Posted: 4/8/2016 7:25:17 PM EDT
[Last Edit: MS556]
[#27]
Quote HistoryOriginally Posted By ARgonot:
What kind of rails do they not work on? If you mean the type of rail you most recently tested your new mount on, that is not a legitimate test at all. LaRue does not recommend their mount be used on that type of rail either because it is grossly out of spec. I would love to buy that mount for reasonably less than retail because I would have to purchase a set of 1" rings. Bobro does clearly state the following: A picatinny rail with a full depth center groove running the length of the rail is definitely not 1913 spec, not even 'reasonably'. I saw the photo below in the Benelli forum and the movement & damage was deemed by LaRue to be the out of spec rail. LaRue recommended to not put their mount on that rail again. The topic is on this page. <a href="http://s1084.photobucket.com/user/ARgonot7/media/MISC/Benelli%20M4%20LaRue_zpseeyv9g9l.jpg.html" target="_blank">http://i1084.photobucket.com/albums/j416/ARgonot7/MISC/Benelli%20M4%20LaRue_zpseeyv9g9l.jpg</a> This is the type of rail that mangled that LaRue mount. Notice it looks just like the one you tested your new Bobro with: <a href="http://s1084.photobucket.com/user/ARgonot7/media/MISC/Benelli%20M4%20Stock%20Rail_zpsmsrvwnql.jpg.html" target="_blank">http://i1084.photobucket.com/albums/j416/ARgonot7/MISC/Benelli%20M4%20Stock%20Rail_zpsmsrvwnql.jpg</a> If Bobro mounts had a seriously flawed design then we wouldn't be just hearing about it now. They have been long proven to be good to go. Bobro honored their warranty, replaced it, it works as advertised on a proper rail. Good for Bobro! I bought a LaRue FUG and it absolutely would not tighten to my spec rails (or any other rail) no matter how much it was tightened. They honored their warranty, replaced it, it worked as advertised on my proper rail. Good for LaRue! I understand that you may have used that grossly out of spec rail to demonstrate that Bobro's 'auto-centering lug' is a required part of a Bobro mount's performance, but as I've shown ... LaRue evidently doesn't recommend their mounts on that rail either and certainly would NOT recommend you overly tighten their mount to compensate. I wouldn't trust that out of spec rail for precision work. That's really where the weakness is. Quote HistoryOriginally Posted By ARgonot:
Originally Posted By jaqufrost:
Yes, the replacement appears to work fine. But I don't trust any of their mounts for precision work. I also understand there are limitations to their design that prevent them from working on many rails and they cannot be adjusted to compensate. YMMV, I'll be happy to sell you a 34mm Bobro mount if you want one. What kind of rails do they not work on? If you mean the type of rail you most recently tested your new mount on, that is not a legitimate test at all. LaRue does not recommend their mount be used on that type of rail either because it is grossly out of spec. I would love to buy that mount for reasonably less than retail because I would have to purchase a set of 1" rings. Bobro does clearly state the following: Must be compatible with any 1913 Specification Rail, to include systems that are out of specification (within reason) and this includes Weaver rails. A picatinny rail with a full depth center groove running the length of the rail is definitely not 1913 spec, not even 'reasonably'. I saw the photo below in the Benelli forum and the movement & damage was deemed by LaRue to be the out of spec rail. LaRue recommended to not put their mount on that rail again. The topic is on this page. <a href="http://s1084.photobucket.com/user/ARgonot7/media/MISC/Benelli%20M4%20LaRue_zpseeyv9g9l.jpg.html" target="_blank">http://i1084.photobucket.com/albums/j416/ARgonot7/MISC/Benelli%20M4%20LaRue_zpseeyv9g9l.jpg</a> This is the type of rail that mangled that LaRue mount. Notice it looks just like the one you tested your new Bobro with: <a href="http://s1084.photobucket.com/user/ARgonot7/media/MISC/Benelli%20M4%20Stock%20Rail_zpsmsrvwnql.jpg.html" target="_blank">http://i1084.photobucket.com/albums/j416/ARgonot7/MISC/Benelli%20M4%20Stock%20Rail_zpsmsrvwnql.jpg</a> If Bobro mounts had a seriously flawed design then we wouldn't be just hearing about it now. They have been long proven to be good to go. Bobro honored their warranty, replaced it, it works as advertised on a proper rail. Good for Bobro! I bought a LaRue FUG and it absolutely would not tighten to my spec rails (or any other rail) no matter how much it was tightened. They honored their warranty, replaced it, it worked as advertised on my proper rail. Good for LaRue! I understand that you may have used that grossly out of spec rail to demonstrate that Bobro's 'auto-centering lug' is a required part of a Bobro mount's performance, but as I've shown ... LaRue evidently doesn't recommend their mounts on that rail either and certainly would NOT recommend you overly tighten their mount to compensate. I wouldn't trust that out of spec rail for precision work. That's really where the weakness is. . Do you perhaps have a Weaver rail, not a Picatinny. Not the same. Many Picatinny mounts will not work on Weaver rails because the slots are wider, among other things (slot spacing can vary sometimes).. Perhaps I'm mistaken. Hard to tell from the photos. |
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Posted: 4/8/2016 9:44:55 PM EDT
[#28]
Here is a video of the Bobro mount with a PRI rail.
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IN, USA
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Posted: 4/8/2016 11:13:05 PM EDT
[#29]
Quote HistoryOriginally Posted By jaqufrost:
Here is a video of the Bobro mount with a PRI rail. https://youtu.be/B6_03F8fdEw
Are you trying to say that PRI rail is a 1913 Specification Rail and include systems that are out of specification (within reason)? I do not yet fully understand what your scheme is, but I have observed that you are specifically choosing grossly out of spec rails in order to promote said scheme. |
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IN, USA
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Posted: 4/8/2016 11:21:01 PM EDT
[Last Edit: ARgonot]
[#30]
Quote HistoryOriginally Posted By MS556:
. Do you perhaps have a Weaver rail, not a Picatinny. Not the same. Many Picatinny mounts will not work on Weaver rails because the slots are wider, among other things (slot spacing can vary sometimes).. Perhaps I'm mistaken. Hard to tell from the photos. Quote HistoryOriginally Posted By MS556:
Originally Posted By ARgonot:
Originally Posted By jaqufrost:
Yes, the replacement appears to work fine. But I don't trust any of their mounts for precision work. I also understand there are limitations to their design that prevent them from working on many rails and they cannot be adjusted to compensate. YMMV, I'll be happy to sell you a 34mm Bobro mount if you want one. What kind of rails do they not work on? If you mean the type of rail you most recently tested your new mount on, that is not a legitimate test at all. LaRue does not recommend their mount be used on that type of rail either because it is grossly out of spec. I would love to buy that mount for reasonably less than retail because I would have to purchase a set of 1" rings. Bobro does clearly state the following: Must be compatible with any 1913 Specification Rail, to include systems that are out of specification (within reason) and this includes Weaver rails. A picatinny rail with a full depth center groove running the length of the rail is definitely not 1913 spec, not even 'reasonably'. I saw the photo below in the Benelli forum and the movement & damage was deemed by LaRue to be the out of spec rail. LaRue recommended to not put their mount on that rail again. The topic is on this page. <a href="http://s1084.photobucket.com/user/ARgonot7/media/MISC/Benelli%20M4%20LaRue_zpseeyv9g9l.jpg.html" target="_blank">http://i1084.photobucket.com/albums/j416/ARgonot7/MISC/Benelli%20M4%20LaRue_zpseeyv9g9l.jpg</a> This is the type of rail that mangled that LaRue mount. Notice it looks just like the one you tested your new Bobro with: <a href="http://s1084.photobucket.com/user/ARgonot7/media/MISC/Benelli%20M4%20Stock%20Rail_zpsmsrvwnql.jpg.html" target="_blank">http://i1084.photobucket.com/albums/j416/ARgonot7/MISC/Benelli%20M4%20Stock%20Rail_zpsmsrvwnql.jpg</a> If Bobro mounts had a seriously flawed design then we wouldn't be just hearing about it now. They have been long proven to be good to go. Bobro honored their warranty, replaced it, it works as advertised on a proper rail. Good for Bobro! I bought a LaRue FUG and it absolutely would not tighten to my spec rails (or any other rail) no matter how much it was tightened. They honored their warranty, replaced it, it worked as advertised on my proper rail. Good for LaRue! I understand that you may have used that grossly out of spec rail to demonstrate that Bobro's 'auto-centering lug' is a required part of a Bobro mount's performance, but as I've shown ... LaRue evidently doesn't recommend their mounts on that rail either and certainly would NOT recommend you overly tighten their mount to compensate. I wouldn't trust that out of spec rail for precision work. That's really where the weakness is. . Do you perhaps have a Weaver rail, not a Picatinny. Not the same. Many Picatinny mounts will not work on Weaver rails because the slots are wider, among other things (slot spacing can vary sometimes).. Perhaps I'm mistaken. Hard to tell from the photos. I do not understand your question. The pic I previously posted of the rail with the full length groove is what comes stock on a Benelli M4 in a US gun shop. This is known to be a POS needing replaced in order to use high quality QD mounts due to being grossly out of spec. The MESA Tactical ShotShell carrier works wonderfully with the Bobro mount I have and any other QD mounts available. Compare the pic of the stock Benelli rail with the pic of the MESA Tactical rail. Much more material where it needs to be for both LaRue and Borbo QD mounts to function as designed & recommended. There are MANY rails that are not 100% spec that has been designed to work specifically for high quality QD mounts that are available. |
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Posted: 4/8/2016 11:22:39 PM EDT
[#31]
Quote HistoryOriginally Posted By ARgonot:
Are you trying to say that PRI rail is a 1913 Specification Rail and include systems that are out of specification (within reason)? I do not yet fully understand what your scheme is, but I have observed that you are specifically choosing grossly out of spec rails in order to promote said scheme. Quote HistoryOriginally Posted By ARgonot:
Originally Posted By jaqufrost:
Here is a video of the Bobro mount with a PRI rail. https://youtu.be/B6_03F8fdEw
Are you trying to say that PRI rail is a 1913 Specification Rail and include systems that are out of specification (within reason)? I do not yet fully understand what your scheme is, but I have observed that you are specifically choosing grossly out of spec rails in order to promote said scheme. Mount designers need to take the interrupted (nothing in the center of the rail) design style fact into account as it is a standard practice as shown here and here by two major suppliers of scope bases to the military and law enforcement. They are definately "in-spec" according to the MIL-1913 standard or they wouldn't be in use by the military I wouldn't think. I highly doubt that the PRI rail he has is out of spec. |
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IN, USA
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Posted: 4/8/2016 11:37:00 PM EDT
[Last Edit: ARgonot]
[#32]
Quote HistoryOriginally Posted By jlficken:
Mount designers need to take the interrupted (nothing in the center of the rail) design style fact into account as it is a standard practice as shown here and here by two major suppliers of scope bases to the military and law enforcement. They are definately "in-spec" according to the MIL-1913 standard or they wouldn't be in use by the military I wouldn't think. I highly doubt that the PRI rail he has is out of spec. Quote HistoryOriginally Posted By jlficken:
Originally Posted By ARgonot:
Originally Posted By jaqufrost:
Here is a video of the Bobro mount with a PRI rail. https://youtu.be/B6_03F8fdEw
Are you trying to say that PRI rail is a 1913 Specification Rail and include systems that are out of specification (within reason)? I do not yet fully understand what your scheme is, but I have observed that you are specifically choosing grossly out of spec rails in order to promote said scheme. Mount designers need to take the interrupted (nothing in the center of the rail) design style fact into account as it is a standard practice as shown here and here by two major suppliers of scope bases to the military and law enforcement. They are definately "in-spec" according to the MIL-1913 standard or they wouldn't be in use by the military I wouldn't think. I highly doubt that the PRI rail he has is out of spec. Great ... now specifically ask LaRue if they recommend their mounts on those rails AS WELL AS the pic of the stock Benelli M4 mount that they previously said was NOT recommended and is out of spec. If they reverse their decision merely to satisfy this forum topic then that would be disappointing if not transparent. |
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Posted: 4/8/2016 11:37:24 PM EDT
[#33]
The video is just showing that Bobro's mount design is fully dependent on the recoil lug to hold zero. I took video of the PRI rail because it meets picitanny specs in every way except the center of the rail is cut out.
I don't remember who made the rail on the video I shot this morning. I think it came with the savage .22 when I bought it. The video is very up front about the missing center of the rail. Several people on this forum have stated the recoil lug wasn't even needed on Bobro mounts. They claimed that Andrew at Bobro said his mount has more clamping force than Larue or ADM. It doesn't, at least not if the Larue or ADM mount is adjusted right. When I first bought a Bobro mount I thought the clamps were strong enough to keep the mount from moving under recoil. They're not. Bobro mounts will hold zero fine as long as their spring based recoil lug is thicker than the recess it drops into. If your rail is gapped a few thousandths over or your mount's recoil lug shrinks after a few hundred cycles, it will start having zero issues. It won't be horribly off for most applications though. Were talking about the scope being able to float back and forth about .001 to .006.
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Posted: 4/9/2016 12:29:40 AM EDT
[#34]
After reading this I went and checked my Bobro extended mount. Surprisingly it moves with not a lot of pressure.
The movement is a very small amount. It's on a blaster not a sharpshooter so I'm definately not going to change it. Kinda disappointing though. |
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Posted: 4/9/2016 8:52:19 AM EDT
[#35]
Quote HistoryOriginally Posted By ARgonot:
Great ... now specifically ask LaRue if they recommend their mounts on those rails AS WELL AS the pic of the stock Benelli M4 mount that they previously said was NOT recommended and is out of spec. If they reverse their decision merely to satisfy this forum topic then that would be disappointing if not transparent. Quote HistoryOriginally Posted By ARgonot:
Originally Posted By jlficken:
Originally Posted By ARgonot:
Originally Posted By jaqufrost:
Here is a video of the Bobro mount with a PRI rail. https://youtu.be/B6_03F8fdEw
Are you trying to say that PRI rail is a 1913 Specification Rail and include systems that are out of specification (within reason)? I do not yet fully understand what your scheme is, but I have observed that you are specifically choosing grossly out of spec rails in order to promote said scheme. Mount designers need to take the interrupted (nothing in the center of the rail) design style fact into account as it is a standard practice as shown here and here by two major suppliers of scope bases to the military and law enforcement. They are definately "in-spec" according to the MIL-1913 standard or they wouldn't be in use by the military I wouldn't think. I highly doubt that the PRI rail he has is out of spec. Great ... now specifically ask LaRue if they recommend their mounts on those rails AS WELL AS the pic of the stock Benelli M4 mount that they previously said was NOT recommended and is out of spec. If they reverse their decision merely to satisfy this forum topic then that would be disappointing if not transparent. The mounts that Bobro and Larue designed are made for AR's with non-interrupted rails while a lot of precision rifle stuff isn't made that way. ADM, GDI, Spuhr, Badger, Nightforce, TPS, and on will work because they use a cross bolt instead of a machined lug like basically all rings. I don't really care what Mark or Andrew say about their mounts being in-spec as they fail to work properly on numerous picatinny rail designs (not AR15) in use by the military and law enforcement today. I have no dog in this fight as I only own an AIAT that has a non-interrupted rail, however, it isn't the norm for precision rifles. |
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MS, USA
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Posted: 4/10/2016 8:52:56 AM EDT
[Last Edit: MS556]
[#36]
Forgive the diversion, but what is the history behind the interrupted 1913 rail? Why was the decision made to remove the center part of the slot? Is this to permit use of lower iron sights when an optic is removed? Some other reason? Pardon my poor knowledge in the subject. School me up.
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Posted: 4/10/2016 11:13:00 AM EDT
[#37]
I think it's primarily removed as a weight saving measure. Most mounts don't need the center, especially if they use a full cross bolt.
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Posted: 4/12/2016 9:09:40 PM EDT
[#38]
Just tried sliding my Bobro T-1 mount on my SR15.
I'll be damned, I could see the fucker moving ever so slightly. This is actually the exact reason I sold off my Larue mounts, because if I tightened them to the point they *didn't* do that, they were no longer QD. Makes me wonder how much this impacts precision shooting. I have these mounts on a few rifles, all of which shoot *very* well. Makes me wonder what other mounts I could move if I really tried.... |
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Posted: 6/29/2018 4:56:33 PM EDT
[#39]
I noticed the other day that Trijicon's mounts no longer have the spring lug. Instead they have a solid machined lug like most other designs.
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Posted: 7/5/2018 12:39:53 AM EDT
[#40]
Interesting thread here. Our scope mounts incorporate a 6 Lug design for increased rail engagement and also because there are always slight variations from slot to slot on picatinny Rails as well.
Also important, durin* the drop testing as we were designing the mounts for the Trijicon MRO (we are the OEM Maker for all MRO Mounts) we learned that Rails such as the one pictured above, with a perpendicular Machined line down the picatinny (to save weight?) lost zero 100% of the time when drop tested versus traditional picatinny Rails which under the same conditions did not lose zero. Full disclosure: I’m one of the dudes at ZRODELTA Try a ZRODELTA Mount - and if it doesn’t hold zero we’ll refund your money. |
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Posted: 7/15/2018 10:49:01 PM EDT
[#41]
Quote HistoryOriginally Posted By TheClintWalker:
Interesting thread here. Our scope mounts incorporate a 6 Lug design for increased rail engagement and also because there are always slight variations from slot to slot on picatinny Rails as well. Also important, durin* the drop testing as we were designing the mounts for the Trijicon MRO (we are the OEM Maker for all MRO Mounts) we learned that Rails such as the one pictured above, with a perpendicular Machined line down the picatinny (to save weight?) lost zero 100% of the time when drop tested versus traditional picatinny Rails which under the same conditions did not lose zero. Full disclosure: I'm one of the dudes at ZRODELTA Try a ZRODELTA Mount - and if it doesn't hold zero we'll refund your money. |
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Posted: 9/11/2018 9:09:54 AM EDT
[#42]
@Sheddy You asked about why I don't like Bobro anymore in my GD thread that got locked. This thread pretty well details it.
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Posted: 9/15/2018 10:33:25 PM EDT
[#43]
Quote HistoryOriginally Posted By glock24:
It's a soft mount design . . . like the ARMS. |
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Posted: 9/15/2018 10:39:45 PM EDT
[#44]
Quote HistoryOriginally Posted By Marksman14:
Just tried sliding my Bobro T-1 mount on my SR15. I'll be damned, I could see the fucker moving ever so slightly. This is actually the exact reason I sold off my Larue mounts, because if I tightened them to the point they *didn't* do that, they were no longer QD. Makes me wonder how much this impacts precision shooting. I have these mounts on a few rifles, all of which shoot *very* well. Makes me wonder what other mounts I could move if I really tried.... |
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Posted: 9/15/2018 11:03:59 PM EDT
[Last Edit: 1911xdm]
[#45]
This is why we buy larue. You can tension them into any rail. In spec or out.
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Posted: 9/15/2018 11:12:48 PM EDT
[#46]
What is the toqure spec on the Larue rail?
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Posted: 9/15/2018 11:17:26 PM EDT
[#47]
Quote HistoryOriginally Posted By tucansam: I've run a LaRue on my work M4 for over a decade, and literally just tested this, and it moves. However, I would measure the amount of movement as "a c*nt hair" worth. Depending on your upper rail and the movement that happens, it can cause near zero to several MOA of shift. I think it's interesting that the latest Trijicon QD mounts (manufactured with Bobro's QD lever design) have dropped the spring lug and replaced it with a machined in lug. The machined in lug shouldn't experience any shrinkage, so while it may move a thousandth or two, it won't ever be six thousandths. |
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Posted: 9/15/2018 11:19:50 PM EDT
[#48]
Quote HistoryOriginally Posted By ScottyPotty:
What is the toqure spec on the Larue rail? |
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Posted: 6/24/2020 11:09:01 AM EDT
[Last Edit: bluemax_1]
[#49]
Ugh. Pity I didn't see this thread sooner.
Bobro dual lever mount. I mounted the Razor HD AMG 6-24x50 with a NIST calibrated driver to just 18 in-lbs per scope manual (was on a pre-order, so this was when the Razor HD AMG first debuted). Just went to remove the scope and found one of the studs for the forward scope cap is broken. Went to Bobro's website and they don't even have a Warranty section, so I used their contact form to inquire about sending it in for a warranty repair. This was the response I received: Please send it back in to us with a prepaid return shipping label (UPS preferred) and we will take a look at it. Bobro Engineering Attn. Oliver 109 S La Patera Ln Goleta, CA 93117 We will most likely be able to pull the stud and repair the mount, but if there isn't enough for us to grab we will have to sell you a new mount at a discounted price because the new ring styles don't align with the old dual lever mounting holes. Nice. So unlike numerous other manufacturers, I have to pay the shipping both ways, and if they can't fix it, I have to buy a replacement "at a discounted price"? Great way to stand behind your stuff. 
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Posted: 6/24/2020 6:34:32 PM EDT
[#50]
Pretty screwed up response for a manufacturers defect.
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