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Posted: 2/15/2011 11:26:17 AM EDT
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Hey all,
Took out the SBR 9MM this past weekend to shoot for the first time and for the most part, it fired like a dream. My configuration is as follows: 7" RRA upper Daniel Defense 7" M4 Rail CMMG Lower Magpul Grip and Stock Eotech Hahn Conversion Block Gemtech Multi-Mount (Soon to be) I tried good ammo, cheap ammo, 115g - 147g and didn't have one jam so I'm pretty confident on the performance. The only thing is how my SBR cycles. It is hard for me to describe, but I think I need a stronger spring. The bolt is too slow for my trigger finger so I have to wait for the bolt to recoil forward before I can take another shot. I did purchase a spacer, but originally when I put it in, the bolt couldn't go back far enough to cycle. Don't know if I can keep the original spring and cut the spacer down to tighten up the spring? I know they make tighter springs, 20lbs, 18lbs, etc. and not sure if that would be an easy fix as well. Your help would be greatly apprecaited. Thanks. Best Regards, Zach |
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Quoted:
The only thing is how my SBR cycles. It is hard for me to describe, but I think I need a stronger spring. The bolt is too slow for my trigger finger so I have to wait for the bolt to recoil forward before I can take another shot. What buffer weight are you running? I was typing real slow and see you posted it above. If you are running a std. CAR buffer and spring, you may have too much resistance elsewhere in the action or the ammo you are using was "low powered" enough. I suppose if the gun were tight or "greased", it could slow the action down as well - just light oil on the bolt. Ramped or non-ramped bolt? A ramped bolt will have less resistance than a non-ramped bolt and will cycle "faster". What hammer spring? You can go with a reduced power hammer spring to reduce the resistance in the action and help speed it up. With blowback guns, it's all about the setup... |
hmmm... It sounds like a upper receiver problem and I would suggest sending it back to RRA, but my current RRA return is and has been a huge headache, RRA's customer service is not what it should be  ...Are you running the upper wet? What ammo are you using? Will the lower function properly with a 5.56 upper on it? (I once had 2 consecutive lower receivers from a very well known "cool aid" company who did a group buy on here, that were machined incorrectly. The buffertube threading was not on the same axis as what the upper receiver should be, when I shot the guns, the BCG would get "stuck" in the buffertube.) Can you cycle the Bolt by hand to see if there is resistance on the magazines, magblock, CH, or upper receiver? |
| Let to be a little more specific here. The buffer I'm using is from Brownells and it was made for a 9MM conversion. The spring might or might not be any different from the .223 spring, but if I recall correctly, I got it from Brownells and it was for a 9mm converstion as well.. The trigger is a 9mm hammer and I have taken several pounds off the pull already by doing a do-it-yourself trigger job. The block is a dedicated Hahn 9mm converstion block. I do have a collapsable magpul stock, mil-spec. Does that give you any idea? For some reason I really think a tighter spring will do the trick, but I don't know what specifications to look for. |
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Quoted: Let to be a little more specific here. The buffer I'm using is from Brownells and it was made for a 9MM conversion. The spring might or might not be any different from the .223 spring, but if I recall correctly, I got it from Brownells and it was for a 9mm converstion as well.. The trigger is a 9mm hammer and I have taken several pounds off the pull already by doing a do-it-yourself trigger job. The block is a dedicated Hahn 9mm converstion block. I do have a collapsable magpul stock, mil-spec. Does that give you any idea? For some reason I really think a tighter spring will do the trick, but I don't know what specifications to look for. Do you have a 5.56 AR? If so, swap springs and see if the 5.56 spring will work. Do you have access to a DPMS hammer/trigger/disconnector or other NON-TRIGGER JOB'D trigger group you can swap out? The one thing I see that sticks out is your "do-it-yourself trigger job". I would suspect that to be the culprit now. Swap out your trigger/disconnector/hammer with something that hasn't been messed with. That could be your solution to your problem. As a last resort, you can buy a WOLF extra power buffer spring. But considering what you've written thus far, I don't think that would fix anything. My money is on your "trigger job". |
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Quoted: This. I seriously doubt the bolt is cycling slow enough for your trigger finger to beat it. If it was, I doubt there'd be enough spring power to actually push a cartridge out of the magazine and fully chamber it. The one thing I see that sticks out is your "do-it-yourself trigger job". I would suspect that to be the culprit now. Swap out your trigger/disconnector/hammer with something that hasn't been messed with. That could be your solution to your problem. My money is on your "trigger job". My guess, your trigger job took too much off of the trigger spring, so it's failing to reset forcefully enough for you. I occasionally have the same issue with my Browning High Power. The problem is that I'm not letting the trigger reset all the way before trying to pull it again. It does seem that I'm beating the slide, but in reality, I just need to let the trigger forward far enough to reset. ETA: This only happens when I'm trying to shoot fast, slow deliberate fire I'm paying enough attention to notice when the trigger resets. IOW, it's a software issue, not a hardware issue. |
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Quoted:
Quoted:
This. I seriously doubt the bolt is cycling slow enough for your trigger finger to beat it. If it was, I doubt there'd be enough spring power to actually push a cartridge out of the magazine and fully chamber it.
The one thing I see that sticks out is your "do-it-yourself trigger job". I would suspect that to be the culprit now. Swap out your trigger/disconnector/hammer with something that hasn't been messed with. That could be your solution to your problem. My money is on your "trigger job".
My guess, your trigger job took too much off of the trigger spring, so it's failing to reset forcefully enough for you. I occasionally have the same issue with my Browning High Power. The problem is that I'm not letting the trigger reset all the way before trying to pull it again. It does seem that I'm beating the slide, but in reality, I just need to let the trigger forward far enough to reset. ETA: This only happens when I'm trying to shoot fast, slow deliberate fire I'm paying enough attention to notice when the trigger resets. IOW, it's a software issue, not a hardware issue. With the right components and ammo, I can get mine to cycle pretty down slowly... You may be on to something with the trigger group though. OP - is the disconnector hanging up or is anything else in the FCG not resetting quickly and cleanly? Might want to look into it... |
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I noticed when you ride the bolt forward, there is some friction between the bolt and the ejector. It is pretty noticeable when you ride the bolt forward. Could that be the issue here? I did try to bend it so it was as close to the bolt as possible but might have bent it too far. I was reading on issues with the RRA uppers and extracting issues was one of them.
Also, regarding the trigger job, I did one of those do-it-yourself deals where you take off one of the prongs off of the hammer spring and trigger spring to lighten up the pull. Polished the trigger up a little too in certain areas. The mod seems to work grea for the .223 but maybe it aint so fresh with the 9mm? With regards to ammo, I am almost positive that isn't the issue. When I was shooting it, I used remington 124g 9mm nato, 147g magtech, and 115g monarch, and it all fired well. If anything, I would imagine the 9mm nato would be some of the better ammo to run through the SBR since it's packs more of a charge, but even the cheap monarch 9mm still cycled well. Thanks again for all yall's help! |
| The bolt should run with no drag at all; make sure bolt and upper are very clean and that the sliding surfaces on the bolt are well lubed, then see if there still seems to be any drag. There should be a VERY CLOSE clearance between ejector and bolt. If the bolt is rubbing on the ejector it will eventually rub its own clearance fit, but that's a Bad Thing for reliability right now. Make sure the ejector stays parallel with the slot in the bolt and apply the tiniest of pressure OUTWARD until you have clearance. |
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