Best practices for accurizing an AR

[Jimbee]

What's an expected precision level with a "reasonably accurate AR"? I have a LMT but really haven't played with it much.

 

[rbutcher1234]

What's an expected precision level with a "reasonably accurate AR"? I have a LMT but really haven't played with it much.

I'm perfectly happy as long as it bangs 30 shots 2" or under

 

[AZ_Hunter]

Do you plan to shoot suppressed?

 

[AZ_Hunter]

What's an expected precision level with a "reasonably accurate AR"? I have a LMT but really haven't played with it much.

“Reasonably” is subjective. I would hold it to your whatever standards you have for your hunting bolt gun. An AR can be a 1 moa gun pretty easily. Just don’t feed it junk and expect miracles, like any rifle.

 

[justinspicher]

I would say it’s just as important to learn how to shoot an AR effectively as it is to have a good rifle. An AR is its own style of shooting, even thought the fundamentals are the same-they are just applied slightly different due to the ergonomics and the fact that its a semi-automatic rifle.

 

[jjohnsonElknewbie]

Do you plan to shoot suppressed?

Possibly, and I've seen where gas management is important when doing so. Living in Iowa, these are pretty limited to varmint hunting unless a guy gets a 350 Legend or 450 BM upper.

 

[wind gypsy]

I would say it’s just as important to learn how to shoot an AR effectively as it is to have a good rifle. An AR is its own style of shooting, even thought the fundamentals are the same-they are just applied slightly different due to the ergonomics and the fact that its a semi-automatic rifle.

How? Is "shooting style" different than shooting a bolt gun in a AR style chassis?

 

[dster3]

This is also true. The brownels lapping tool is good to use. Takes one minute of time usually to clean up the receiver face.

You can technically bed the barrel extension with red locktite or the like, or use stainless shim stock, but unless you are hand loading to the extreme, you won’t notice a difference if you are using a good barrel.

Also some receivers are a “thermal fit” (like BCM) meaning that receiver is slightly undersized relative to the barrel extension, so use of a heat gun on the receiver to slightly expand it is required to allow the barrel to be installed.

I’m sure there are YouTube videos of all this these days. It’s all super easy to. That’s makes the AR system fun, it’s like legos for adults.

Great info here - these are the three things I do when assembling my AR precision builds.

Locktite retaining compound is what you'd be looking for - I believe the one I have is Locktite 620.
Lapping is a quick process but well worth it. BCM is the way to go for a thermal fit. Pick up a JP enterprises bolt.

A good barrel is going to be key - Ive had great results with proof research. Expect to spend $500 on up for a good SS match barrel. Carbon fiber is going to be $1000+.

I've done all of this work on previous builds and have seen improvements, with the lapping and bedding being the only work done between testing. Saw a rifle go from 1.7 MOA to 1.2 or so using match ammo.

The biggest improvement will be a good quality barrel. However, the three steps AZ Hunter mentioned are worth doing. If at the very least, peace of mind, at the very best, it ensures that your barrel isnt going to shift on you and has a good surface to be compressed against. I now do this on all of my ARs - my competition AR shoots sub minute with factory ammo

 

[slowelk]

What's an expected precision level with a "reasonably accurate AR"? I have a LMT but really haven't played with it much.

My LMT is a 1.5-2" gun for 10-20 shot groups. I've been feeding it AAC 77gr OTM and AAC 77gr SMK. The DD I had before it was 1.3-1.7", so it was a little annoying that the more expensive rifle was less accurate, but again, 1.5-2 is OK for me.

I often use it as a stand-in for my bolt guns. Most of the drills correlate IMO.

These sub 1" ARs like Ridgeline is building seem fairly unnecessary, but that doesn't mean I don't want one.

 

[justinspicher]

How? Is "shooting style" different than shooting a bolt gun in a AR style chassis?

Maybe it’s just me, but I shoot my AR differently than I shoot a bolt gun. The ergonomics are different as is the way recoil is managed, therefore my shooting style is different. Fundamentals are the same, but applied differently. Again, this is just my opinion so take that for whatever it’s worth.

 

[Harvey_NW]

I don't geek out on AR's or reload for them, but I've seen some wild results with different ammo. I have a $300 Daytona Tactical 80% kit rifle I built that initially put PMC FMJ range ammo into a shotgun pattern 10" group, and then proceed to put bulk reloaded stuff with 55gr V-Max from ammoseek 10 shots into about 1.5".

 

[rbutcher1234]

Maybe it’s just me, but I shoot my AR differently than I shoot a bolt gun. The ergonomics are different as is the way recoil is managed, therefore my shooting style is different. Fundamentals are the same, but applied differently. Again, this is just my opinion so take that for whatever it’s worth.

ARs have a longer lock time than bolt guns. Fundamentals of shooting are fundamentals of shooting, but your follow through is more important on a gas gun.

 

[Sccritterkiller]

For me it's loading my own rounds...556 or 6.8 spc. Just seems like I get better accuracy than off the shelf ammo. Two stage SSA triggers help as well.

Perfect example is 6.8spc...the Hornady 120gr SST factory won't hold a group. I load my own 120 SSTs over the right amount of aa2200 and it's a 1 MOA gun.

All my ARs have older PSA barrels when they were getting then from FN plant down the st. No idea where they are made currently.

 

[Jimbee]

My LMT is a 1.5-2" gun for 10-20 shot groups. I've been feeding it AAC 77gr OTM and AAC 77gr SMK. The DD I had before it was 1.3-1.7", so it was a little annoying that the more expensive rifle was less accurate, but again, 1.5-2 is OK for me.

I often use it as a stand-in for my bolt guns. Most of the drills correlate IMO.

These sub 1" ARs like Ridgeline is building seem fairly unnecessary, but that doesn't mean I don't want one.

I'll be happy with 2" groups.

 

[77TMK]

Things I do:
High quality barrel. WOA, Douglas, Krieger, Bartlein. AR Performance (Blackstone), etc
Lap the receiver
Use a thermal-fit upper receiver or use stainless steel shim stock to thermally fit the barrel
Free-float handguard with a reputable barrel nut design that doesn't need a ton of torque like past ones did
5/8x24 muzzle threads are ideal but 1/2x28 will work, albeit you can get more heat effect from the reduced barrel thickness at a 1/2" muzzle opening up for gas leakage.
Lap feedramps with some polishing material and conical polishing bit. Doesn't take much.
Use PMAGs or others that angle the round up a bit, to prevent first and last shots from being weird sometimes.
High quality ammo. 52, 69, 77 SMKs, TMKs, some BTHP from others, etc. Hornady 55 gr FMJBT are reliable 1-1.5" performers in nice barrels.


Rest is shooter, which can be aided by good glass, stable position, good trigger, etc. Sometimes overgassed rifles group bad because of the effect of the overgassing on follow-through.

 

[SloppyJ]

I always true the face of the barrel collar and use retaining compound to make up any gaps between the upper and barrel. Being careful to wipe out any that gets inside.

Not sure how much it helps but I've yet to build one that doesn't shoot. I think if you stick with most big name barrel makers you'll be fine.

 

[gwak06]

Great info here - these are the three things I do when assembling my AR precision builds.

Locktite retaining compound is what you'd be looking for - I believe the one I have is Locktite 620.
Lapping is a quick process but well worth it. BCM is the way to go for a thermal fit. Pick up a JP enterprises bolt.

A good barrel is going to be key - Ive had great results with proof research. Expect to spend $500 on up for a good SS match barrel. Carbon fiber is going to be $1000+.

I've done all of this work on previous builds and have seen improvements, with the lapping and bedding being the only work done between testing. Saw a rifle go from 1.7 MOA to 1.2 or so using match ammo.

The biggest improvement will be a good quality barrel. However, the three steps AZ Hunter mentioned are worth doing. If at the very least, peace of mind, at the very best, it ensures that your barrel isnt going to shift on you and has a good surface to be compressed against. I now do this on all of my ARs - my competition AR shoots sub minute with factory ammo

What kind of groups were you getting with the Proof barrel? I have thinking of going this route for a while.

 

[dster3]

What kind of groups were you getting with the Proof barrel? I have thinking of going this route for a while.

I'm just under 1 MOA with a 20" 6mm arc SS proof barrel.

 

[RockAndSage]

OP, as has been mentioned, the lockup between barrel and bolt is a critical factor in accuracy. There's 3 parts to it:

TL;DR: Buy a matched/mated barrel and bolt set, carefully lap your receiver face, use the proper tools to prevent clocking your barrel extension.

1) Headspace - to translate in this context, it's the front-back spacing between the bolt and the barrel extension, when the bolt is locked up on a chambered round. The more space, play, and slop between the lugs of the bolt and the lugs of the extension, the harder it will be to get top accuracy, and it can also loosen up the tolerances even further, quicker. Precision builders often have multiple bolts on hand, and individually fit up a new barrel with a bolt by going through them to find one that fits up nice and tight. You can also find some companies who match up headspaced bolts and barrels and sell them as a set. As another person mentioned, JP bolts are a great choice, and as I understand it are slightly larger than milspec to help with tight headspacing. I personally use LMT's Enhanced Bolts, and have found them to be slightly oversized as well, allowing for great lockup.

2) Cant/axial alignment of bolt and barrel - this is how evenly the backs of the bolt's locking lugs mate up with the locking lugs of the barrel extension when the round goes off. You don't want any high spots. Ideally, you want each lug mating up exactly the same as each of the others, identical. This is one the primary benefits of a well-done lapping job on the face of the upper, where the barrel mates up - it helps ensure the barrel is evenly pressed against the face, and keeps that alignment during shooting. It's also where you can create imprecision if you lap too much and put an angle to it unintentionally. If that barrel and extension are in there crookedly, you'll get one side of your lugs hitting each other before the other side, and that will reduce accuracy. One of the harder to find services is that of a gunsmith who knows how to actually fit a bolt to an extension - they use dykem on the backs of the bolts to check for high spots, and take those high spots down until you get even wear and an even, fully mated set of lugs.

3) Clocked barrel/extension - If you assemble improperly, it's easy to twist the barrel slightly and clock it out of timing with the bolt lugs, causing the corners of the bolt lugs to peen against the edges of the barrel extension's lugs. Minor clocking might just raise burrs that can scratch your bullets and casings, but those burrs can also result in uneven lockup in some situations. The best way to prevent this is to assemble your gun with a reaction rod that has a sail on it, that slides into the space above the bolt where the gas key and charging handle go, so that you cannot easily over-rotate your barrel while you torque your barrel nut or muzzle device down.


If you buy a top quality barrel and match it with a tight fitting bolt, and make sure you assemble carefully with the right tools, that will result in the majority of your accuracy, provided you're using good ammo.

If you're genuinely trying to build a reliable, precision AR, understand that it's more than legos - legos don't come with torque specs and specialized tools for truing up parts and assembling with precision, and they don't bend or break in the absence of those. Take your time, however, do your research on best practices, tools, and torque specs, and you can do some really cool stuff.

 

[awildswanger]

I’m not much of one to tinker, if you had to associate an out of the box AR with Tikka-like qualities, which one would it be?