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

[Lazer]

Swthomas , I have the perfect gun for you. It's a tight chamber 223 , 20 in kreiger in a rock river platform has a threaded barrel 1/2 -28. It's a drill and fits your description it's new and I have a target that has 40 plus rounds on it all 3 shot groups the average is .410 and get this every group is a different load! Send me a pm if your interested

 

[SWThomas]

Thanks for the offer. I'm not interested in a rifle that's already assembled. Part of the satisfaction for me is ending up with an accurate rifle that I built.

I ended up ordering a barrel from Compass Lake Engineering. I went with a 20" Douglas Air Gauged SS bbl with a rifle length gas system, heavy contour, 1/7 twist, threaded, CLE match chamber, matched bolt, SS gas block, and gas tube. Should have it in a few weeks.

 

[stool]

frank white( compass lake) did my 223 br bbl as a custom( my bbl my reamers, his work) ...he no longer does custom work. if you check his site, he has a very nice way of chambering bbls. i would expect you will like the bbl...but sticking with a 20 vs a 24/26 is gonna hurt your options on long distance.

 

[SWThomas]

frank white( compass lake) did my 223 br bbl as a custom( my bbl my reamers, his work) ...he no longer does custom work. if you check his site, he has a very nice way of chambering bbls. i would expect you will like the bbl...but sticking with a 20 vs a 24/26 is gonna hurt your options on long distance.

We will see. I can always build another rifle later. ;D

 

[stool]

yep ..that is the fun of ar's.
its easy to do the next one..
have fun..lets us know how it works out....

 

[SWThomas]

yep ..that is the fun of ar's.
its easy to do the next one..
have fun..lets us know how it works out....

Will do. Thanks again for the advice.

 

[rcw3]

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.

If you want accuracy, here's my reply:


1. If you're running 20" - 26" in barrel length, stick with a rifle length gas system. 7" twist is faster than what you typically might need (unless you're trying to run the 90's) although you won't be prejudiced by it with a 223. Disregard people advising a 2" extended port and the suggestion the port needs to be drilled in the groove as neither one of these situations leads to better accuracy or function. If you're looking for accuracy (both inherent and in an ergonomic sense) stick with a barrel that has some weight and balance for the rifle, something like a 24"- 26" barrel, 1" dia. behind the gas block and .850" or greater diameter forward of the gas block (and don't dare put a puny 1/2" x 28 pencil threading on the muzzle - - leave the meat on at the muzzle). A 20" barrel is o.k. but it doesn't necessarily balance well, and isn't ergonomically the easiest to shoot, especially off a rest or in the bags.

2. Use the Compass Lake Match Reamer design (it has a shorter throat). Stay away from a Wylde - - long throat, sloppy chamber (it's like a big "one size fits all" shoe).

3. A "match bolt carrier" assembly is an illusion and won't generate tighter groups. Good quality parts is where you want to go but pretty much all manufacturers who make carriers and bolts don't mess around so that's not a real problem you will necessarily need to address.

4. Don't screw around with special buffers and buffer assemblies - if you don't know exactly the finer points of how an AR gas system works, you're just asking for trouble. Make your AR to function well with the normal buffer tube and assembly and you'll be good. I have never seen an after market buffer assembly that makes an AR more accurate or function better. In a .223, I am not sold on Lapua brass, mainly because the neck metal is real thick relative to domestic 223 brass and it makes it harder to keep a consistent neck tension and release for your loaded ammo.

Robert Whitley
www.6mmAR.com

 

[SWThomas]

4. Don't screw around with special buffers and buffer assemblies - if you don't know exactly the finer points of how an AR gas system works, you're just asking for trouble. Make your AR to function well with the normal buffer tube and assembly and you'll be good. I have never seen an after market buffer assembly that makes an AR more accurate or function better. In a .223, I am not sold on Lapua brass, mainly because the neck metal is real thick relative to domestic 223 brass and it makes it harder to keep a consistent neck tension and release for your loaded ammo.

Robert Whitley
www.6mmAR.com

I have been rethinking the Lapua brass lately. At least for now. The way I'm planning to size this brass will be with a FL resizing die with the ball removed, and then use a mandrel to open the mouths up after sizing. The necks will effectively be sized from the inside and should provide very uniformed neck tension without turning necks, or the possible shoulder distoriton from an expander ball.

 

[SWThomas]

1. If you're running 20" - 26" in barrel length, stick with a rifle length gas system. 7" twist is faster than what you typically might need (unless you're trying to run the 90's) although you won't be prejudiced by it with a 223. Disregard people advising a 2" extended port and the suggestion the port needs to be drilled in the groove as neither one of these situations leads to better accuracy or function. If you're looking for accuracy (both inherent and in an ergonomic sense) stick with a barrel that has some weight and balance for the rifle, something like a 24"- 26" barrel, 1" dia. behind the gas block and .850" or greater diameter forward of the gas block (and don't dare put a puny 1/2" x 28 pencil threading on the muzzle - - leave the meat on at the muzzle). A 20" barrel is o.k. but it doesn't necessarily balance well, and isn't ergonomically the easiest to shoot, especially off a rest or in the bags.

I took your (and a few others) advice and switched it to a 24". That's really as long as I wanna go with this barrel and I'm sure it's more than enough. It'll be 1" behind the gas block, but I'm going to stick with the 0.750 forward of that. 0.750 is pretty much the industry standard for gas blocks and it'll leave me some options for a possible switch to an adjustable later on down the line. I'm also going to keep the threading on the muzzle. I'll be adding some sort of muzzle device when I get it. I haven't decided on what yet. One, I'll gain great satisfaction out of having something the gun-bragging liberals don't want me do have. ;D And two, it'll add a little to asthetics of the rifle and protect the crown.

 

[stool]

EASY TO GET a gas block that is larger on interior dia...like .9xx..i have one that way.
rcw3 knows what he is talking about...he has built, shot and reported on a bunch of ar's he has built.

i would buy 1000 win brass and sort them....my last batch got me a lot of about 500 and one of 400.

glad to see you went with a 24"

 

[SWThomas]

EASY TO GET a gas block that is larger on interior dia...like .9xx..i have one that way.
rcw3 knows what he is talking about...he has built, shot and reported on a bunch of ar's he has built.

i would buy 1000 win brass and sort them....my last batch got me a lot of about 500 and one of 400.

glad to see you went with a 24"

I'm definitely not questioning his knowledge of the subject. I appreciate all the advice very much.

Is there any downside to keeping the forward portion of the barrel 0.750 and having the muzzle threaded? If so, please enlighten me because I can't see any.

 

[stool]

read what he said about the muzzle dia......
the last thing the bullet sees is the muzzzle/crown.......reducing dia( from manufactured od) can change the internal dia.

 

[SWThomas]

read what he said about the muzzle dia......
the last thing the bullet sees is the muzzzle/crown.......reducing dia( from manufactured od) can change the internal dia.

I saw that part. But what would be a negative effect it would cause? There are a lot of precision rigs out there with MDs that seem to do just fine.

 

[SWThomas]

Alright.... I hate you guys.....

I'll call her back and forego the threaded muzzle and have them turn it to 0.850 forward of the gas block. You guys have more experience in this area than I do and I'm inclined to take your advice.

I'll be putting a PRS stock on this rifle so it should balance well with all that weight in the front.

 

[Turbulent Turtle]

Just to help you out, this is what my F-TR .223 Match rifle looks like:

 

[stool]

you just do not need a muzzle brake on a 223 that will be that heavy....way too little recoil in my opinion......

 

[SWThomas]

you just do not need a muzzle brake on a 223 that will be that heavy....way too little recoil in my opinion......

I had no illusions that it would actually serve it's purpose as a brake. Heck, my 14.5" barreled AR has next to no recoil. I was mainly going to attach one to protect the crown. But I'll be overly careful with this rig I'm sure.

I'm very impressed with how patient and professional CLE has been with my changes after the order. Not an impatient tone of voice at any time and very polite. We need more people like that.