jtallen83 Posted October 13, 2016 Report Share Posted October 13, 2016 (edited) Getting my rifles set up in anticipation of receiving my tax stamps for cans I have waiting. I'm finding the threads on the muzzle of my AR-10B are extra long compared to my other rifles. I've stacked 8 shims to get it to clock where I want it, 2x 2mm, 4x .41mm,1x.25mm, 1x.075mm, .235 inch total when I measure the stack. Until this rifle I only used 3 max and none of them 2mm's. Will this be an issue? Should I try to find a larger shimm than the 2mm to cut down on the number? It is just a flash hider so should I just forget about clocking it and bottom it out on the muzzle with some rocksett on the threads and call it good? I haven't found any kits with larger shims available........... Measurements are .743 inch from the muzzle to the shoulder on the barrel, The 3 prong AAC 51T measures .563 inch from shoulder to where it bottoms on the muzzle. Edited October 13, 2016 by jtallen83 Quote Link to comment Share on other sites More sharing options...
Rsquared Posted October 13, 2016 Report Share Posted October 13, 2016 I only used the AAC flashider on one rifle, and that was a PTR G3 clone (so that doesn't count for this). Other than that, I've used the AAC brakes and comps on all of my 10 B's. Never had to stack that many shims in order to time them. I would guess that you could just bottom out the flash hider, and not worry about it. Maybe, just use a couple shims just to fill the gap so you don't have any threads exposed (just for GP's). Any reason why you wouldn't want to use a comp instead? They're pretty nice, in my opinion. How long till the cans arrive? Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted October 13, 2016 Author Report Share Posted October 13, 2016 46 minutes ago, Rsquared said: I only used the AAC flashider on one rifle, and that was a PTR G3 clone (so that doesn't count for this). Other than that, I've used the AAC brakes and comps on all of my 10 B's. Never had to stack that many shims in order to time them. I would guess that you could just bottom out the flash hider, and not worry about it. Maybe, just use a couple shims just to fill the gap so you don't have any threads exposed (just for GP's). Any reason why you wouldn't want to use a comp instead? They're pretty nice, in my opinion. How long till the cans arrive? Cans are sitting at the LGS, they let me rob the flash hiders so I could start prepping the rifles, hard to walk away from them. They will let me bring a rifle in and shoot with them but I'm not big on shooting at a 20 yard indoor range, hitting the steel makes enough noise to require ear pro anyway so I'll wait till I get the stamps and head outdoors. Word is there are two people in Iowa that have gotten their stamps and they sent the paperwork in the day the law was signed, I'm three weeks behind them. I've got a 51T comp I scored on ebay for $50 but it has an even shallower threaded section than the standard 51T flash hider. I'd also prefer to stick with FH's since the rifles will be shot with the can 95%+ of the time, comps are said to cause the can to erode just a bit faster and have no benefit with the can on. I may just try it with the muzzle bottomed out since the actual crown would not be touching, not sure if it will carbon up faster and possibly interfere with the crown? It does cover all the threads when bottomed out so no issue there. Bottomed out will clock the FH a bit off but then symmetry doesn't really matter except in my anal retentive mind. LGS could not find any shims thicker than what I have. I'm going to get the Geissele gauge to check for anything off center before I shoot one so maybe I'll wait till I get one and check it both ways, shimmed and bottomed out. Just thought it was odd to have such a long threaded portion compared to other barrels I've messed with. Quote Link to comment Share on other sites More sharing options...
unforgiven Posted October 13, 2016 Report Share Posted October 13, 2016 Even if you don't put a can on AAC Breakout is a great device. See if you can find a competent "smith" that can set it up without all those shims. Just a thought brother Jim. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted October 13, 2016 Author Report Share Posted October 13, 2016 1 minute ago, unforgiven said: Even if you don't put a can on AAC Breakout is a great device. See if you can find a competent "smith" that can set it up without all those shims. Just a thought brother Jim. I only see two fixes, bigger shim or trim down the barrel, maybe a JP jam nut instead of a shim???? https://www.jprifles.com/buy.php?item=JPJN.58B.750 Quote Link to comment Share on other sites More sharing options...
unforgiven Posted October 13, 2016 Report Share Posted October 13, 2016 Black jam nut....you might be on to something there bro. Quote Link to comment Share on other sites More sharing options...
98Z5V Posted October 13, 2016 Report Share Posted October 13, 2016 I'd run the jam nut and be done. Quote Link to comment Share on other sites More sharing options...
Magwa Posted October 16, 2016 Report Share Posted October 16, 2016 yep Jamnut that sum Bitch! Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted October 30, 2016 Author Report Share Posted October 30, 2016 So I order the JP jam nut, caveat is they don't recommend them for use with suppressors. I'm going to give it a go regardless, I have an alignment rod coming from Geissele so I can check before I light it up. Quote Link to comment Share on other sites More sharing options...
KS63 Posted January 16, 2017 Report Share Posted January 16, 2017 I know this is an old thread, but instead of shimming or having your muzzle shortened and re-crowned, just have a machine shop make a stainless steel spacer with a .625 I.D and an O.D. to correspond to the barrel O.D? It made one for a 5.56 that wouldn't index with the required shims. Quote Link to comment Share on other sites More sharing options...
jtallen83 Posted January 16, 2017 Author Report Share Posted January 16, 2017 The JP jam nut is going to work like a spacer. The collar on the FH will go over top the jam nut, just hiding it and letting me index it. I won't know for certain this works till the can gets out of jail and I can check the alignment but it looks like it should be fine. Quote Link to comment Share on other sites More sharing options...
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