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Posted: 1/22/2018 12:39:21 AM EDT
[#1]
I’ve always heard 30-80 ft lbs. I personally do 50 ft lbs and call it good. I would shim
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Posted: 1/22/2018 12:45:27 AM EDT
[#2]
I'd shim
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Posted: 1/22/2018 12:57:10 AM EDT
[#3]
Just go high. How far off are you at 90 lbs?
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Posted: 1/22/2018 1:03:55 AM EDT
[#4]
I didn't go much over 85 and that was about 2/3 of the way to the next slot.
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Posted: 1/22/2018 1:07:13 AM EDT
[#5]
Quote HistoryQuoted:
I didn't go much over 85 and that was about 2/3 of the way to the next slot. I don't sweat that at all. If you do, you will need to swap parts or shim. |
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Posted: 1/22/2018 7:45:59 AM EDT
[#6]
One could always remove the one offending tooth and then you could easily torque it to however many pounds you'd like.
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Posted: 1/22/2018 8:21:12 AM EDT
[#7]
Quote HistoryQuoted:
One could always remove the one offending tooth and then you could easily torque it to however many pounds you'd like. |
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Posted: 1/22/2018 8:41:45 AM EDT
[#8]
27 is low. Shim it.
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Posted: 1/22/2018 8:52:11 AM EDT
[#9]
Quote HistoryQuoted:
One could always remove the one offending tooth and then you could easily torque it to however many pounds you'd like. Definitely appreciate it, fellas. |
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Posted: 1/22/2018 12:37:54 PM EDT
[#10]
Quote HistoryQuoted:
Well, this may be the best solution for me without having to find shims. Definitely appreciate it, fellas. Quote HistoryQuoted:
Quoted:
One could always remove the one offending tooth and then you could easily torque it to however many pounds you'd like. Definitely appreciate it, fellas. |
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Posted: 1/22/2018 2:25:38 PM EDT
[#11]
I agree with not modifying the barrel nut, but for different reasons. I would shim it or torque it a bit heavy if I had to.
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Posted: 1/22/2018 5:01:44 PM EDT
[#12]
If were to go the shim route, where can I find them the cheapest without having to buy an assorted pack?
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Posted: 1/22/2018 7:51:39 PM EDT
[#13]
https://www.midwestindustriesinc.com/MI-GEN2SS-GEN2T-Series-Barrel-Nut-p/mi-bng2.htm
That is the barrel nut in question. To me, it seems like I could shave off the problem tooth and torque appropriately like suggested above... It feels sturdy enough and the anti rotation tabs are on the sides. Would there be any possible issues with doing that? |
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Posted: 1/22/2018 8:03:15 PM EDT
[#14]
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Posted: 1/22/2018 8:05:55 PM EDT
[#15]
If you're going to FO with buying anything forget about the shims and just buy another barrel nut or two.
A mil-spec barrel nut is like $5. Save the one you have now for a future build. EDIT: just noticed it has a proprietary nut. Gotta use the shims I guess... unless the MI nuts are easy to purchase alone and cheap. Maybe MI will allow you to exchange? |
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Posted: 1/22/2018 8:10:35 PM EDT
[#16]
Quote HistoryQuoted:
https://www.midwestindustriesinc.com/MI-GEN2SS-GEN2T-Series-Barrel-Nut-p/mi-bng2.htm That is the barrel nut in question. To me, it seems like I could shave off the problem tooth and torque appropriately like suggested above... It feels sturdy enough and the anti rotation tabs are on the sides. Would there be any possible issues with doing that? Your handguard rail has indexing stops that slide into the gas tube grooves on the barrel nut to index the handguard perfectly. You MUST have the gas tube cut-out in the barrel nut perfectly centered with the gas tube hole in the receiver, with this design of handguard. |
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Posted: 1/22/2018 8:11:22 PM EDT
[#17]
Just remember you're more likely to break something if you try and chase those high numbers.
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Posted: 1/22/2018 8:13:59 PM EDT
[#18]
Quote HistoryQuoted:
Just remember you're more likely to break something if you try and chase those high numbers. Not saying damage cannot happen, but I have done plenty without issue. Statistically anytime it lines up perfectly and is just shy of the minimum torque, this happens. I'd say 1 in 5 using standard barrel nuts do this. Unless you have a box full of barrel nuts, you have to keep going. Modern handguard designs without gas tube holes in the barrel nut (noveske, geissele, BCM) negate this issue. Novesk still has it to some extent, as you must index the handguard attachment holes, however their nuts are reversible so it is like getting two nuts in one. I have to flip it around about 25% of the time to get the torque spec I want. |
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Posted: 1/22/2018 8:42:06 PM EDT
[#19]
Quote HistoryQuoted: Yes there would be issues. Your handguard rail has indexing stops that slide into the gas tube grooves on the barrel nut to index the handguard perfectly. You MUST have the gas tube cut-out in the barrel nut perfectly centered with the gas tube hole in the receiver, with this design of handguard.  
You are absolutely right. I'll try to torque down a bit more to see where that gets me. |
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Posted: 1/22/2018 10:03:41 PM EDT
[#20]
You could also loosen and tighten it several more times. You will find it requires less torque as you do this. As long as you make it to the final recommended torque spec you will be fine. I have done this a few times and have yet to have a problem.
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Posted: 1/22/2018 10:50:12 PM EDT
[#21]
Lap the receiver face. Tool is from brownels
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Posted: 1/24/2018 12:52:59 PM EDT
[#22]
If you have to order something like shims anyway...order a couple barrel nuts.
Use the one that works the best, and save the others for another build. |
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Posted: 1/24/2018 1:42:27 PM EDT
[#23]
IMHO, shims are the better choice. Brownell's has them, buy a couple of packs. Over torqueing is probably not the best way to go since you'll end up putting more stress laterally on the receiver. Depending on your gas block and buffer configuration you could end up cracking the upper. 6000 series Aluminum buffers tend to be more prone to this then 7000. I typically error on the side of caution and start shimming when I hit 60 lbs without correct alignment but 80 is still safe. I like to look at it like this; it's the hand guard manufacturer that's saying 80 is safe and not the receiver manufacturer. To be honest, I'm really not 100% sure if it matters that much but I can tell you that I've never cracked one and I have seen some pictures of ones that did crack.
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Posted: 1/24/2018 3:58:32 PM EDT
[#24]
Quote HistoryQuoted:
IMHO, shims are the better choice. Brownell's has them, buy a couple of packs. Over torqueing is probably not the best way to go since you'll end up putting more stress laterally on the receiver. Depending on your gas block and buffer configuration you could end up cracking the upper. 6000 series Aluminum buffers tend to be more prone to this then 7000. I typically error on the side of caution and start shimming when I hit 60 lbs without correct alignment but 80 is still safe. I like to look at it like this; it's the hand guard manufacturer that's saying 80 is safe and not the receiver manufacturer. To be honest, I'm really not 100% sure if it matters that much but I can tell you that I've never cracked one and I have seen some pictures of ones that did crack. 80lbs is the designed max torque specification from the military TM, using a steel barrel nut with an aluminum receiver. There is zero question that 80 is safe. When receivers are overtorqued well beyond specification, they generally do not crack, the threads on the upper receiver fail. |
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Posted: 1/24/2018 9:34:15 PM EDT
[#25]
Well my buddy needed his torque wrench so I had to go back to my beam type craftsman with a 75ft/lb max. And I maxed it out.
I tightened/loosened 5 or 6 more times and got it to where it needed to be. I actually had to back off just a hair. No idea how tight it is but I honestly don't see myself taking it off. Thanks guys |
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Posted: 1/24/2018 10:20:07 PM EDT
[#26]
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Posted: 1/25/2018 12:03:55 AM EDT
[#27]
Quote HistoryQuoted:
Lap the receiver face. Tool is from brownells 
lapping tool also available from PTG, although that one has been pretty tight on some uppers. I get my shims from Bison Armory, the ones I bought were 3-thousandths-inch thick, looks like they now sell a set with .001" and .002" thick. Bison Armory AR-15 shims |
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Posted: 1/27/2018 3:48:08 PM EDT
[#28]
Send MI an email, they will likely exchange the offending nut for you, they offered a swap to me about a year ago. They have very good CS.
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Posted: 1/27/2018 11:38:05 PM EDT
[#29]
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Posted: 1/29/2018 6:04:07 PM EDT
[#30]
Quote HistoryQuoted:
IMHO, shims are the better choice. Brownell's has them, buy a couple of packs. Over torqueing is probably not the best way to go since you'll end up putting more stress laterally on the receiver. Depending on your gas block and buffer configuration you could end up cracking the upper. 6000 series Aluminum buffers tend to be more prone to this then 7000. I typically error on the side of caution and start shimming when I hit 60 lbs without correct alignment but 80 is still safe. I like to look at it like this; it's the hand guard manufacturer that's saying 80 is safe and not the receiver manufacturer. To be honest, I'm really not 100% sure if it matters that much but I can tell you that I've never cracked one and I have seen some pictures of ones that did crack. |
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Posted: 1/29/2018 8:11:16 PM EDT
[#31]
if you're going with shims, make sure you get the ones that are .001", or .002", or .003". do not get the ones that are .010", .020", .030". and if the shim vendor isn't showing you the sizes, they are probably the tens-of-thousandths shims. good luck sneaking up on the tooth gap with those thick ones!
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Posted: 1/31/2018 4:41:50 AM EDT
[#32]
Over 80 is fine as long as it's not some crazy high torque. I made the same mistake with the low torque value (mine was like 24 pounds) and it seems fine until I grabbed the front sight and it moved a noticeable amount. Torque a little over 80. You'll be alright. Or try loosing and tightening the barrel nut a few more times.
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Posted: 1/31/2018 8:25:58 AM EDT
[#33]
I think we can quit offering him advice. He got it fixed a week ago.
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Posted: 2/6/2018 12:15:14 PM EDT
[#34]
All this reminds me why I dislike freefloat handguards which use a barrel nut that indexes with the gas tube. This feature is necessary for clamp-on plastic handguards that fit into a GI-type delta ring, but definitely not for freefloat designs.
Many of the makers of modern FF handguards have switched to barrel nuts that don't hold the gas tube at all, e.g., BCM and SLR brands. My SLR Solo model's nut tightens with a large crescent wrench to my preferred torque of about 35-40 lb-ft without any indexing to the gas tube. - CW |
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Posted: 2/7/2018 6:21:58 PM EDT
[#35]
Same problem with my same handguard. I went somewhere between 90-100 on mine I think.
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Posted: 2/8/2018 10:43:21 PM EDT
[#36]
Thanks for the suggestions guys but yes, I did get it done already.
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