Home AR-15 Smyth Busters: Should You Bed an AR-15 Barrel?

Smyth Busters: Should You Bed an AR-15 Barrel?

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Brownells Gun Techs™ Caleb Savant and Steve Ostrem are back to put another firearm myth to bed, one way or another. Today’s myth is that you can improve your AR-15’s accuracy by bedding the barrel into the upper receiver. “You mean gluing it in place?” queries Steve. Actually, yes. The barrel extension usually fits into the receiver with a slightly snug slip fit. Proponents of “bedding” an AR-15 barrel use green Loctite® 294 to anchor the barrel extension in the receiver. These folks think bedding the barrel prevents it from wobbling, thus making their AR-15s more accurate.

This might help secure a particularly loose-fitting barrel extension. But under normal circumstances, a properly tightened barrel nut locks the barrel firmly in place. When the barrel nut is torqued down, the shoulder of the barrel extension is pressed tightly to the front of the receiver. Also, tightening the nut actually compresses the receiver around the barrel extension, almost like a collet. Some AR-15 manufacturers even make their upper receivers slightly undersized to obtain this extra-tight compression fit. BOTTOM LINE: Wobble or flexing of the barrel in the upper is normally not an issue.

If the barrel extension fits so poorly that after you tighten the barrel nut, it’s still shimmying around like a dancer in a 1980s MTV music video, your upper is probably seriously out of spec. Rather than reaching for the green Loctite®, the better solution is to get a new, in-spec upper receiver.

If you do decide to bed your AR-15’s the barrel, you might as well lap the receiver to get the straightest, cleanest possible metal-to metal fit. Brownells offers an Upper Receiver Lapping Tool for this purpose. But with most high-quality uppers, lapping is not necessary. (Ssshhhh! Don’t tell the Marketing Dept. Caleb said that.)

So the myth that you should bed your AR-15 barrel is BUSTED. Bedding may have been necessary years ago when manufacturing tolerances on receivers and barrel extensions were looser. If you think you need to bed a barrel, you probably have other problems and should look into just getting a different upper receiver and/or barrel extension.

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37 COMMENTS

  1. I'm surprised these guys even explained this. If your common sense isn't good enough to immediately realize how stupid of a question this is then you shouldn't be playing with, building, or firing guns in the first place.
    Whoever truly needed this video needs a sticker on the back of their car just like "Student Driver" so I know to watch out at the range, on the road, and everywhere else in life that involves anything harmful.
    Your intellectual ability is far too low for the safety of society. You're at a Private Pyle level of capability and safety.

  2. That's got to be just about the DUMBEST thing I've ever heard any fool say……. EVER!
    The barrel is SUPPOSED to be a very snug fit in the upper receiver. If there's slop and a loose fit between the upper receiver and barrel extension, then that means something is wrong and you need to replace the barrel OR the upper receiver. Bedding an AR barrel to the upper receiver is SOOOOOOOoooo completely laughable.

  3. Also, remember this, in addition to my response below – when most people bed a barrel in, then take it back for CONSISTENCY trials, most people don't have genuine match triggers, or a stable enough platform to wring the extra consistency out of their rig enough to physically see the difference. I see a TON of guys doing consistency testing on wobbly benches, not using a stiff rear bag (this isnt prs), total crap bipods, or having their barrels clean enough to show this consistency difference. Hell, most people actually have NO IDEA how clean or dirty their barrels really ARE! That in itself makes a huge difference. If you don't already have your consistency game REALLY tight, shedding a quarter minute will be absorbed by the bad and inconsistent shooting position.

  4. Do you guys have a video out there on where to use grease on an AR-15? I see Caleb mentioned he uses it in this video. I watched should I use loctite, but think it would be good to know where to use grease or anti-seize for that matter. Thanks!

  5. If you don't lap the barrel into the upper then its not even worth the time to bed it.
    If your trying to cut a ¼" group by a fraction of a fraction then its worth it but fk that noise.
    Im not that competitive…

  6. I lapped the upper receiver and bedded the barrel extension last time I built an upper. Can I tell if it's more accurate if I didn't do that? No. It's a Hodge barrel so it was already a good barrel but I just wanted some peace of mind, plus I was bored 🙂

  7. My AR is not an uber expensive one. Good quality mid grade gun. It is mechanically more accurate than I will ever be. If I put up a 6" target at 50 yards…and I can hit it anywhere on the target…I consider that to be plenty accurate for my needs.

  8. I wouldn't bed, but I do "Lap" the receiver. I use a Brownell's Lapping tool for both the AR15 and AR10 <– I know, not an AR10! For simplification. I think for a more precision build like an SPR type build, not a basic set up, it can't hurt.

  9. You don't need any of that with modern ar builds. Just put em together, and torque em down. There are tons of these guys who always think that more is better. When in fact it does nothing and inherently can cause issues down the road. Just torque it down and run it.

  10. I've gotten into the habit of using stainless shims and a lapping tool, I used green LT once and it seems to really not do much but squirt out and make a mess. unless it's a BCM upper which I've gravitated to using more often. I've seen a tiny improvement on a couple of rifles, like 1/4" group reduction at 100 yards. I did however see a really great improvement on a PSA upper, but that could have been a torque thing. In any case, it doesn't really hurt anything so why not?

  11. AMU used to bed the barrels, don't know if they still do. Also, some companies made uppers that with overly tight bore that need to be heated to install barrels. Other companies have made oversize barrel extensions to take up the slack. Your myth buster is busted.

  12. I have personally experimented with it. I found that even with parts from highly reputable manufacturers, I could tighten up my groups by up to 1/4 MOA by bedding the barrel. Many people may not care about this amount of improvement on an AR15 style rifle. If tightening your group is important to you, it can make a difference. I tried it on a few rifles, where they were shooting slightly over 1 MOA, and after bedding they were a little under 1 MOA. Although we may want absolute answers that are always right, the true answer is usually "It Depends".

  13. All I can say is .. I put a ballistic advantage barrel (20 inch fluted 223 Wylde) and used a Lantac receiver for a build. I shot it to see what kind of accuracy I would get. I was getting sub MOA at 100 yards…. Then I took it apart , lapped, and bedded the barrel. Then went back to the range… It cut my grouping almost in half!!!! I was getting holes in holes…. So for me…. That is proof enough that lapping and bedding works… Of course, I don't know exactly which one actually worked (bedding or lapping). But I have the tools, so for me, if I'm building, I'm going to be doing both….

  14. yes don't lap and true the face, and don't get the nice super tight barrel fit…preferably with a nice oversized barrel extension, those who shoot competition will love you if you arrive with one that is fitted to shoot at old refrigerators out in the desert. Joe Carlos is knowledgeable and the first to test this and write about it and explain why these few steps are needed to improve the precision of a competition rifle, hard data on the group size has proved it over and over again. But please don't do this and show up for a match.

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