AR15 Upgrade priority for precision

[rabbithuntr]

Great topic I’ve been have some off the same questions as, with the addition of keeping the weight down. I will say that I think the grip can have more effect on ergonomics than the stock, going from an a2 to a b5 definitely was an improvement.


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[def90]

The barrel is everything on an AR. Most everything else can be swapped out with negligible consequences. Handloading goes a long way as well.

 

[MEdude]

The barrel is everything on an AR.

What would you anticipate for accuracy from a mid priced barrel?

 

[gman82001]

What is a mid priced ar specifically? If it’s a 16” blaster palmetto or s&w mp15 type don’t expect any real super duper precision. It’ll be accurate enough to do what that type of gun does.

I built a 6.5 Grendel based around a Saturn barrel and bolt that outshoots all but 2 of my bolt guns and even then if I’m having a good day none are noticeably better than it. That what I’d consider mid priced around $800 before scope. But its goal in life is to be more accurate than a blaster style AR.

Make sure you’re getting something that’s capable of doing what it is you want and not just something you hope will do what you want.

 

[MEdude]

Thanks for your observations. That is exactly the info I’m seeking.

 

[RockAndSage]

I'm going to be slightly contrarian here, and put choosing a quality upper at the top of the list, or at least the first part I'd start considering. Everything said above about importance of barrel, bolt, optic, etc is right on the money, so no disagreement with all that. But the importance of a good upper is often overlooked.

A cheap, loose, wonky upper can cause all those other parts to be out of alignment/concentricity in various ways. There are methods to tune up a loose/junk upper, but the higher quality you start out with, the less you'll have to worry about. A common problem with cheap uppers is the face of the threading, where the flange of the barrel mates against the upper - if that's not machined with precision, it won't be a flat surface, or squared to the bore axis of the upper. That can cause the barrel to sit in the upper wonky, and without fully mating up against that face. That's two different issues, both of which can cause accuracy and precision problems. Again, there are methods to correct this, but fewer of these problems arise with a quality upper.

Another common but little-recognized issue with cheap uppers is at the alignment-pin notch on top front of the threads of the upper, where the barrel's alignment pin goes in. If that's got some slop in it, you can end up with your barrel/extension clocked a little - I've seen that be bad enough to where the bolt lugs peen the lugs of the extension and even simply not lock up or go into battery. You can shim that pin and notch, but it's absolutely unnecessary to worry about if the notch is tight to begin with, and machined top dead center. Pin slop and a clocked barrel can also lead to multiple reliability problems. On a clocked barrel, if the gas block is properly centered on the gas port it means the gas tube will not fit properly into the upper, including being out of alignment enough to have the gas key on the BCG slamming into it, leading to failures to go fully into battery, and harmonics issues with accuracy. If the gas block is aligned TDC on a clocked barrel, then that gas port will be somewhat occluded by the gas block, resulting in insufficient gas to cycle the action properly, or just weakly, with mystery failures to eject and failures to chamber occurring.

All that can and does happen from a sloppy alignment-pin notch. And it gets worse with the tolerance stacking that can occur with alignment pins or barrel extensions being even slightly out of spec, and gas ports being improperly drilled.

This is a big part of what you're paying for with expensive, high quality parts - precision that minimizes all these little problems that bug cheaper builds so often.

 

[Yoder]

Can an AR even possess the potential accuracy of a precision bolt gun?

I have two that shoot 1/2 moa and they are straight from the manufacturers shooting box ammo. I don't see why not.

 

[rabbithuntr]

I'm going to be slightly contrarian here, and put choosing a quality upper at the top of the list, or at least the first part I'd start considering. Everything said above about importance of barrel, bolt, optic, etc is right on the money, so no disagreement with all that. But the importance of a good upper is often overlooked.

A cheap, loose, wonky upper can cause all those other parts to be out of alignment/concentricity in various ways. There are methods to tune up a loose/junk upper, but the higher quality you start out with, the less you'll have to worry about. A common problem with cheap uppers is the face of the threading, where the flange of the barrel mates against the upper - if that's not machined with precision, it won't be a flat surface, or squared to the bore axis of the upper. That can cause the barrel to sit in the upper wonky, and without fully mating up against that face. That's two different issues, both of which can cause accuracy and precision problems. Again, there are methods to correct this, but fewer of these problems arise with a quality upper.

Another common but little-recognized issue with cheap uppers is at the alignment-pin notch on top front of the threads of the upper, where the barrel's alignment pin goes in. If that's got some slop in it, you can end up with your barrel/extension clocked a little - I've seen that be bad enough to where the bolt lugs peen the lugs of the extension and even simply not lock up or go into battery. You can shim that pin and notch, but it's absolutely unnecessary to worry about if the notch is tight to begin with, and machined top dead center. Pin slop and a clocked barrel can also lead to multiple reliability problems. On a clocked barrel, if the gas block is properly centered on the gas port it means the gas tube will not fit properly into the upper, including being out of alignment enough to have the gas key on the BCG slamming into it, leading to failures to go fully into battery, and harmonics issues with accuracy. If the gas block is aligned TDC on a clocked barrel, then that gas port will be somewhat occluded by the gas block, resulting in insufficient gas to cycle the action properly, or just weakly, with mystery failures to eject and failures to chamber occurring.

All that can and does happen from a sloppy alignment-pin notch. And it gets worse with the tolerance stacking that can occur with alignment pins or barrel extensions being even slightly out of spec, and gas ports being improperly drilled.

This is a big part of what you're paying for with expensive, high quality parts - precision that minimizes all these little problems that bug cheaper builds so often.

Good information, what brands would you recommend looking at when buying an upper?


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[cal30_sniper]

Good information, what brands would you recommend looking at when buying an upper?


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Just grab one of the BCM blemished uppers they sell and be done with it.

I’ve worked with about 3 dozen uppers from every brand imaginable and never found any that has the problems referenced above. I’ve only run into one that had any misalignment of the barrel flange with the receiver (an el cheapo AR Stoner), and a quick hone with the tool Brownells sells fixed that problem.

I personally prefer the BCM uppers for the price because they have dry moly coating and a slightly tighter than spec interface for the barrel extension that removes the slop most have in that interface.

Others that I’ve really enjoyed building with: V Seven, 2A Armament, Zev, Centurion, Rock River, Colt, FN, Aero.

For barrels, Criterion is extremely hard to beat in their price range. If they make something in the cartridge, profile, and length that you like, go for it. You’ll be pleased. Rainier Arms Match and Ultramatch barrels are also extremely good for the price. Proof makes a top notch AR barrel, but the price tag reflects it.

 

[spike camp]

I'm going to be slightly contrarian here, and put choosing a quality upper at the top of the list, or at least the first part I'd start considering. Everything said above about importance of barrel, bolt, optic, etc is right on the money, so no disagreement with all that. But the importance of a good upper is often overlooked.

A cheap, loose, wonky upper can cause all those other parts to be out of alignment/concentricity in various ways. There are methods to tune up a loose/junk upper, but the higher quality you start out with, the less you'll have to worry about. A common problem with cheap uppers is the face of the threading, where the flange of the barrel mates against the upper - if that's not machined with precision, it won't be a flat surface, or squared to the bore axis of the upper. That can cause the barrel to sit in the upper wonky, and without fully mating up against that face. That's two different issues, both of which can cause accuracy and precision problems. Again, there are methods to correct this, but fewer of these problems arise with a quality upper.

Another common but little-recognized issue with cheap uppers is at the alignment-pin notch on top front of the threads of the upper, where the barrel's alignment pin goes in. If that's got some slop in it, you can end up with your barrel/extension clocked a little - I've seen that be bad enough to where the bolt lugs peen the lugs of the extension and even simply not lock up or go into battery. You can shim that pin and notch, but it's absolutely unnecessary to worry about if the notch is tight to begin with, and machined top dead center. Pin slop and a clocked barrel can also lead to multiple reliability problems. On a clocked barrel, if the gas block is properly centered on the gas port it means the gas tube will not fit properly into the upper, including being out of alignment enough to have the gas key on the BCG slamming into it, leading to failures to go fully into battery, and harmonics issues with accuracy. If the gas block is aligned TDC on a clocked barrel, then that gas port will be somewhat occluded by the gas block, resulting in insufficient gas to cycle the action properly, or just weakly, with mystery failures to eject and failures to chamber occurring.

All that can and does happen from a sloppy alignment-pin notch. And it gets worse with the tolerance stacking that can occur with alignment pins or barrel extensions being even slightly out of spec, and gas ports being improperly drilled.

This is a big part of what you're paying for with expensive, high quality parts - precision that minimizes all these little problems that bug cheaper builds so often.

This aligns with my post about starting from scratch…

When you purchase an upper receiver, you can lap and true the barrel extension yourself.

The barrel pin is another factor, and you can also imbed the barrel to the receiver.

All kinds of ways to true an AR if you’re seeking maximum accuracy.

 

[BigNate]

If you're building one from scratch it'll be cheaper than buying twice most likely. You can choose parts based on your desired end result.

I'll second the BCM upper recommendation, barrels are all over the place, and can be quality at a reasonable price if you are patient about shopping.
The last two I did I used BCM uppers. One with a Ballistic Advantage Hanson series 1:7, the other I used a Faxon also in 1:7, bolts were both Toolcraft if I'm not mistaken. Both shoot well.

Spending more isn't always needed nor a guarantee of performance. My son had an $1800 upper from a major brand that he just couldn't make function suppressed in spite of the mfg insisting it was designed for it.

 

[wind gypsy]

Don’t buy a mediocre AR to improve, buy a decent one or at least decent upper out of the gate.

RRA uppers are economical and seem to shoot accurately if you don’t want to spend a pile.

 

[RockAndSage]

Good information, what brands would you recommend looking at when buying an upper?


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There are a number of good ones and a few great ones. @cal30_sniper mentioned some above, all of which are at a quality level you shouldn't have to worry about - almost all the ones he mentions are premium, including Zev, V-Seven, and 2A Armament. 2A Armament was my preferred to build on, but they were purchased by Nemo Arms and the line is now gone. Nemo, however, does have receiver sets that should be great quality. Aero Precision has been hit or miss with me, and I've had to send a barrel back recently from them where the gas port was significantly misaligned from the alignment pin in the barrel extension. Customer service was great though, and they replaced the barrel, sending the new one out within a day of receiving the original.

Additional uppers I'd definitely consider are Blackout Defense, and Vltor.

When looking, you can often get just the upper, or receiver sets of matching upper and lower. One advantage to going with a matched set, beyond them just having matching aesthetics and quality, is that they tend to lock up more precisely and mate up better.

All this being said, when you really get into the details of properly building ARs, there are still no guarantees that even the best companies won't have a bad batch, or a one-off mistake, or something the new guy did that wasn't quite at the level it should be. Even the best of the best occasionally fail when gauged out with proper gauges. For example, I've never once had premium upper where the face of the front was perfectly square, when I check it with a little light lapping with a lapping tool. There's always at least one little high spot or low spot. The higher the quality the less out of square they tend to be, but even the best have slight imperfections in the finishing or coatings that they come with. With those top quality receivers those imperfections may simply not be enough of an issue for most people to notice in terms of rifle performance and accuracy, but they're still there. But again, the higher the quality, the more precision has gone into the machining.

The question is how much it matters to you. You did mention precision as your priority here, so I'm offering up what I can on precision. But that's not so much an end state as it is an end of the spectrum. Others have mentioned some cheaper uppers they've had good experiences with, and their advice is sound too.

 

[def90]

What would you anticipate for accuracy from a mid priced barrel?

I think if you can reliably get 1 moa out of any AR barrel you are doing extremely well and should buy a lottery ticket. There are people that claim they have sub moa ARs but I think that is an anomally, I've never seen one in person. The military spec is 3-4 moa. You can even buy a dozen of the same barrel and have significant variance in moa between them. I have an AR with a 16 inch BCM pencil barrel on it and I get minute of pie plate with it, was supposed to be one of the most accurate barrels out there for that profile. I believe the SOCOM profile barrels are supposed to be pretty good accuracy wise if you don't want to go with a full on bull barrel.

Of course you want a free floating set up.

In the end the bolt locks directly in to the barrel extension and machining on these things is so good these days that making the claim that other unrelated parts will make a difference I think is wishful thinking. I don't think the average human can even come close to being able to shoot consistently enough to even be able to measure that.

 

[RockAndSage]

In the end the bolt locks directly in to the barrel extension and machining on these things is so good these days that making the claim that other unrelated parts will make a difference I think is wishful thinking.

I'm not trying to be abrasive here, but this is simply not true. At all.

I could tell you all the ways it's not true, whether through imperfectly machined parts to tolerance stacking to improperly fitted parts.

But the easiest way for you to discover this yourself is to simply put dykem on the back of your bolt lugs, and cycle it with a dummy round a couple of times. If that dykem's not consistently removed uniformly across the back of those bolt lugs, it's not match-grade mating surfaces. IE, the barrel extension and machining are not good enough to achieve that. And you just don't find that without hand-fitting from a competent gunsmith. Just getting a bolt that headspaces close, rather than sloppy, is a crapshoot. Some companies even offer matched pairings of AR barrel and bolt to help with this.

The result of improperly mated bolt lugs and barrel extension lugs though, is the bolt and its lugs will not be square to the bore axis during firing - and that's one of many places minute of pie-plate accuracy comes from.

That one spot alone requires precision parts properly fitted - generally hand-fitted by someone who knows what they're doing.

 

[cal30_sniper]

I think if you can reliably get 1 moa out of any AR barrel you are doing extremely well and should buy a lottery ticket. There are people that claim they have sub moa ARs but I think that is an anomally, I've never seen one in person. The military spec is 3-4 moa. You can even buy a dozen of the same barrel and have significant variance in moa between them. I have an AR with a 16 inch BCM pencil barrel on it and I get minute of pie plate with it, was supposed to be one of the most accurate barrels out there for that profile. I believe the SOCOM profile barrels are supposed to be pretty good accuracy wise if you don't want to go with a full on bull barrel.

Barrel profile has far less to do with accuracy than barrel quality. My Proof, Noveske, Criterion, Hodge, RRA NM, and Rainier barrels all shoot under MOA. My BCMs, Spikes, Aeros, DPMS, CMMGs, and Colt/FNs do not. JP, Odinworks, and a few others are close to MOA, but picky for one reason or another. The only one I have that fall into the “minute of pie plate” category is a 11.5” pencil barrel from Charlie’s and a worn out FN M16A4 upper. Everything else that didn’t shoot well found itself wearing a new barrel.

Barrels are everything on an AR as far as accuracy is concerned. Everything else is a distant second.

 

[JRS3]

Save up and get a Proof CF barrel. There are deals from time to time. The barrels I have shoot very nicely. One in .223 is consistent around 1/2 MOA with BH 60gr SPs. My other is around 3/4 MOA with the same load. I wouldn’t be surprised if it shoots better with another load but haven’t really tried looking and am pleased with the accuracy.

After the barrel, get a good trigger. I have Trigger Tech, Timney, and a few others and they help round out the accuracy potential.

 

[BigNate]

I've heard so many hit or miss stories about Proof I personally wouldn't risk them.
White Oak armory is another one that is stellar but I don't think has been mentioned.

 

[JRS3]

I've heard so many hit or miss stories about Proof I personally wouldn't risk them.
White Oak armory is another one that is stellar but I don't think has been mentioned.

I have 5 Proof CF barrels and like them a lot. I will buy more.

 

[Thinkingman]

Can an AR even possess the potential accuracy of a precision bolt gun?

Absolutely.
My Rock River has a Wilson 1/8 Wylde barrel, free floated handguard and a RRA two-stage trigger.
With a Nikon Monarch 6.5-20 it will shoot 1/2MOA at 200yds reliably with 77gr HSM Matchkings.
I would(did) just buy a Rock River Varmint or Predator Pursuit and go shooting