Building a precision AR-15: Questions about barrel, bolt, twist, etc...

[SWThomas]

So I'm gearing up to build my second AR-15. This one will be specifically for precision target shooting and the occasional varmint hunt. So weight is really not a factor.

I'm going to have a Bartlein barrel made for this build so it will be customized to my specifications. It'll have a quality high powdered scope, PRS stock, etc... I will be handloading its food.

I have a few questions about this build before I put in my order.

1. What would be the perfect length, profile, and twist? I was thinking something heavy, 20", 1/7 twist, rifle length gas system.

2. Is a custom chamber possible? I was going to ask the builder to spec the chamber to where mag length rounds won't have so much jump to reach the lands.

3. Is there such a thing as a match bolt/carrier assembly? The barrel maker was telling me to send him the bolt I want to use and he'll match it to the barrel.

4. What are some tricks I can apply to smooth things out? I plan to use Lapua brass and match bullets. I wanna try to not beat the brass up as much as a combat AR does. I've read about trimming the ejector spring and employing certain types of buffers.

That's pretty much what I'm curious about. If you have any additional information that would help this build, please post it.

 

[gimpy]

I think you will not see the return on investment from the Lapua brass. I tried that route and am back to using weight sorted LC. The longer gas system will reduce a lot of the abuse to the brass.

I use a mk12 mod0 upper as my target upper and can't complain about the results at 18 inches with 77 SMK. 20 inches should also do all that you want, and balance the rifle a little better with the PRS stock.

 

[SWThomas]

I think you will not see the return on investment from the Lapua brass. I tried that route and am back to using weight sorted LC. The longer gas system will reduce a lot of the abuse to the brass.

I use a mk12 mod0 upper as my target upper and can't complain about the results at 18 inches with 77 SMK. 20 inches should also do all that you want, and balance the rifle a little better with the PRS stock.

Are you shooting those 77's loaded to mag length or are you single feeding them?

 

[wareagle700]

18" Noveske SPR would be hard to beat.

77 SMK's can be loaded to mag length with great accuracy.

 

[rjacobs]

1. What would be the perfect length, profile, and twist? I was thinking something heavy, 20", 1/7 twist, rifle length gas system.

2. Is a custom chamber possible? I was going to ask the builder to spec the chamber to where mag length rounds won't have so much jump to reach the lands.

3. Is there such a thing as a match bolt/carrier assembly? The barrel maker was telling me to send him the bolt I want to use and he'll match it to the barrel.

4. What are some tricks I can apply to smooth things out? I plan to use Lapua brass and match bullets. I wanna try to not beat the brass up as much as a combat AR does. I've read about trimming the ejector spring and employing certain types of buffers.

1: lots of guys running 18" SPR profile, rifle length, 7 twist barrels with great success. Not going to gain much out of a 20" IMO, maybe 50 FPS. BUT its up to you to decide.

2: if you have a smith doing 100% of the barrel work, yea its possible. BUT most AR barrels are pre done and are already chambered. I dont personally think you gain a ton in an auto loader from being right up on the lands, but I am sure others will dis-agree. I guess I dont see it to often, most guys just run what the barrel came with(lots running Wylde chambers now). Possibly getting into the land of spending money on diminishing returns. I asked a couple smiths about doing 100% of the workup on a Bartlein blank and the prices I were seeing were double the cost of the barrel(600 in work on a 300 barrel). This was cutting to length, profile, gas port, chamber, barrel extension installation, thread the end, etc... There are a TON of excellent pre-done barrels on the market for 350-500 bucks that you just install and go and they provide excellent, verifiable results. If doing 100% full custom turned barrels on auto loaders gave great gains, I think you would see more people doing them.

3: If the smith is installing the barrel extension they can match the headspace to your bolt you are going to use. Again, not that common IMO and I think it starts to venture into that diminishing returns land again. Its pretty easy to fire a few rounds out of your barrel/bolt combo and setup your sizing die to match that measurement and get pretty close to the results a matched bolt/barrel extension are going to provide you. Other thing I see is if you happened to break the bolt, your headspace could be all jacked up vs. using a slightly looser headspace and being able to run any bolt you want.

4: currently doing a build for a guy using a JP Low Mass carrier, JP silent capture spring and Syrac adjustable gas block. I think this gun will be absolutely slick as shit and soft shooting once we get it built and tuned. I dont really like trying to mess with ejector springs or anything like that. I guess I just dont notice my ejector's on any of my guns tearing the shit out of my brass unless I am way on the hot side of comfortable and I generally only venture there occasionally during load development.

Thats my 4 cents.

 

[gimpy]

RJacobs summed it up nicely. As far as the 77 SMK goes, I mag load them, they don't seem to mind the jump. It's more about a quality load than the jump to the lands in my experience with semi auto rifles. I have found that 8208 works quite well with the heavy projectiles. Others here have been finding the same.

 

[rjacobs]

One other thing to add. Putting an SSA or SSA-E trigger in also helps in the accuracy department by helping eliminate shooter induced shitty shooting. While it wont add any "mechanical" accuracy to the gun like a high end barrel will, we arent using a robot with a perfect trigger pull every time to shoot a gun, SO putting in an EXCELLENT trigger to HELP us out in the trigger pull department is mandatory in a precision gun IMO.

I have lots of buddies who cant shoot for shit(because they dont understand good trigger control mostly), but I take their gun and give it a nice smooth trigger pull to the break and viola their gun shoots great. So like I said, putting a good trigger in to help eliminate any kind of stacking or grittyness or anything of that nature that can lead to US as the trigger puller to do something shitty with that trigger only helps us wring every little bit of mechanical accuracy out of the gun.

 

[WhiteHorze]

Different companies all tweak the specs on their chamber reamers. Google " 5.56 chamber reamers" and you'll run across a chart that shows who makes what.

With a gas gun things have to be looser so parts can move around, handloading is really the key to getting under 1 moa.

Also, look into the Leupold FX-3 line. They make a good $500 - $700 scope in a 1" tube. The LCS is 30mm and starts at $999 new.

 

[SWThomas]

One other thing to add. Putting an SSA or SSA-E trigger in also helps in the accuracy department by helping eliminate shooter induced shitty shooting. While it wont add any "mechanical" accuracy to the gun like a high end barrel will, we arent using a robot with a perfect trigger pull every time to shoot a gun, SO putting in an EXCELLENT trigger to HELP us out in the trigger pull department is mandatory in a precision gun IMO.

I have lots of buddies who cant shoot for shit(because they dont understand good trigger control mostly), but I take their gun and give it a nice smooth trigger pull to the break and viola their gun shoots great. So like I said, putting a good trigger in to help eliminate any kind of stacking or grittyness or anything of that nature that can lead to US as the trigger puller to do something shitty with that trigger only helps us wring every little bit of mechanical accuracy out of the gun.

Oh believe me, whatever I build will have a Geissele trigger in it.

 

[SWThomas]

Thanks for all the info fellas. I'm reconsidering the custom barrel route. WOA, Raniers, Wilson, and Noveske all have what I'm looking for anyway. I'm going to go with an 18" barrel as my research has confirmed what you gentlemen have posted here.

Being that I'm going to shoot 223 handloads only, should I go with a plain 223 barrel? Or does the Wylde chamber have some other benefit over just being able to fire both cartridges?

 

[coryhenry]

Lilja also does a great ready to go barrel

 

[mjh30]

For a barrel, Frank White, heck hes even Bartlein barrels in stock at the moment, you can spec your chamber and get a matching headspaced bolt with it. I believe Frank even started putting together some tactical type uppers, his finished barrels have been the standard to match for twenty years or more.

 

[johngfoster]

+1 for Frank White. I got a Douglas SPR profile 18" barrel from him that I'm very happy with. I spec'd a Wylde chamber with matching bolt. Sub-MOA if I do my part.

 

[peaceatwar]

I went with a 20" White Oak Armament SDM 1:7 barrel that came with a bolt/BCG gas tube and gas block all of which was matte black from the factory. Combine that with a gieselle DMR and I'm one happy camper. Wanted something lighty enough to do some run-n-gun with but also beefier enough for sustained fire from a bench. 77s at mag length.

A nice krieger barrel would do you some good as well. Or a shillen AR barrel that is supplied with a properly headspaced bolt.

 

[Guest]

I just purchased a Tier 1 Recce upper which included a 16" match WOA 1:7 5.56 barrel, Young Nickel BCG, Troy 13.8" Alpha rail, low pro gas block, mid length gas system, and a BCM charging handle. I'm picking up my lower tomorrow from my FFL then will get a chance to test it out hopefully later this week.

I've seen great accuracy from the WOA barrels, hopefully mine is no different.

 

[jdknotts1]

Don't forget the JP line of barrels/kits. I have yet to have one that won't out-shoot my abilities. Combined with the JP LMOS and Silent Capture Spring, grrrreat combo. Slick as eel shit. And with an adjustable gas block, it will shoot soft and be so much better on your brass.

Oh and their triggers are great as well

 

[MSTN]

My idea of the optimum 18" barrel:

Noveske Custom SS SPR Barrel - MSTN Exclusive! : AR15 Parts at GunBroker.com

We can headspace our bolts (LMT proof round tested, MP-inspected, Ionbond Diamondblack coated down to the gas rings) to 0.001" to best fit your accuracy/reliability needs, polish & contour the feed ramps, or even hammer the whole thing together for you.

Good shooting,

Wes

 

[SWThomas]

Thanks for the input fellas! Upon further review I think I'm gonna give Frank White a call @ Compass Lake.

 

[JCPD556]

Just read the thread and wanted to chime in and say thanks for the good info.
I am in a build myself and this has been helpful.
Thanks

 

[SWThomas]

Just got off the phone with CLE. I ordered a 20" Douglas SS bbl, threaded, 1/7 twist, heavy contour, CLE match chamber, matched bolt, SS low-pro gas block, and a rifle length gas tube. Will be delivered in a couple weeks and then I can get this thing together and do some shooting!