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.

[Obscenejesster]

I'd personally just do a SPR build and call it a day. I don't think the velocity gain from 18" to 20" is enough.

You could go either 1/8 or 1/7 but you will find more precision oriented barrels in 1/8 which is what I'd personally go with.

I never really cared enough about matched bolts. To tell you the truth, I can't shoot good enough to benefit from them and personally, I don't even know if they do improve accuracy.

Sent with a Gen 2 Nexus 7

[MistWolf]

The difference between in velocity between 18 & 20 isn't much different than the difference between 16 & 18. But the difference between 16 & 20 when shooting long ranges is enough to make it worth going with the 20. The 18 doesn't give enough of an advantage in velocity to make it worth choosing over a 16 inch barrel and not handy enough to choose it over a 20.

Properly matching bolt to barrel does improve shot to shot consistency and is worth it for a varminter.

A heavy profile is no guarantee of accuracy. A quality lightweight barrel will be more accurate than a so-so heavy barrel. It may be after a certain point, a heavy barrel could be a detriment to accuracy. Check out the two threads about upper flex in the sticky section of the Technical Discussion forum.

The 223 Wylde chamber is known for accuracy yet has a longer leade to accomodate 5.56 loads. You'll have to experiment for yourself to see if using a shorter leade will help your accuracy.

Tighter twists are needed to stabilize longer bullets. Longer bullets are usually, but not always, heavier. Best thing to do is figure out what style & weight range you want to shoot with. If you're going to be shooting boatailed bullets up to roughly 55 grains, you might be best served with a 1:9. Barrels with 1:8 or 1:7 twist tend to work well with boatailed bullets running about 70 - 80 grains. A longer barrel will be more forgiving stabilizing longer bullets because muzzle velocity is increased.

I built a varminter with a 20 inch Lothar-Walther barrel with a 223 Wylde chamber and 1:8 twist. It prefers boatailed bullets between 70 & 80 grains. It has a HBar profile and unloaded the rifle weighs 10.75 lbs. A bull barrel would have added more weight than I want to carry.

Varminter is the top rifle in the photo below

[SWThomas]

I'm reconsidering my idea to go with a custom barrel. WOA and Raniers seem to make some fine barrels that are exactly what I'm looking for.

I don't need the ability to shoot 5.56 in this particular rifle. Would I be better served to just go with a 223 REM barrel or does the 223 Wylde have other benefits other than being able to fire both cartridges?

[Obscenejesster]

I'm reconsidering my idea to go with a custom barrel. WOA and Raniers seem to make some fine barrels that are exactly what I'm looking for.

I don't need the ability to shoot 5.56 in this particular rifle. Would I be better served to just go with a 223 REM barrel or does the 223 Wylde have other benefits other than being able to fire both cartridges?

Yea, Rainier and WOA make some good barrels. If you aren't going to shoot 556 then you can just go with a 223 chamber.

Sent from my SGH-T999 using Tapatalk

[JBecker 72]

I too am looking at building a precision rifle right now. In my searches I came across http://highcalibersales.com/ for SPR builds. They sell the same barrels used on the SOCOM SPR rifles, and from what I've read they work very well. The chamber and twist were chosen to work with the MK262 77gr OTM ammo. I'm gonna be buying one of these barrels for my build.

Just throwing an idea out there for you.

[opsoff1]

Yea, Rainier and WOA make some good barrels. If you aren't going to shoot 556 then you can just go with a 223 chamber.

Sent from my SGH-T999 using Tapatalk

Gotta chime in here - going with a 223 Remington chamber in an AR is ridiculous. Practically speaking, a 223 Remington chamber and more precisely, the throat is for all intents and puposes useless in an AR - much less a precision AR. The throat on a 223 Rem was designed to digest light bullets - 40-50 gr type. It uses an extremely short freebore and has a leade angle of nearly three times a 556 anything. If you want to build an AR with a 1/12 or 1/14 twist and shoot 50gr FBHP - then by all means go with a .223 Rem. If you want precision, with better bullets at distances that are actually meaningful- then use any one of a myriad of custom 556 chambers.
If you want specifics - let my know and I'll pull my chamber prints on a 1/2 dozen different 556 & 223 Rem reamers that I own.
The 223 Wylde isn't in nearly any way a 223 Rem. Bill Wylde started the development of that chamber by using the 223 Rem as the base - it is completely different than a 223 Rem. The Wylde actually has a longer throat than a 556 NATO and is known for it's ability to digest a wide range of bullets - accurately and reliably. There are many others too....
From another post in a different thread – I had submitted the following and it is appropriate here:
“there is a plethora of 223 / 556 reamers that have been "re-engineered". 556 Trophy - specifically dimensioned for shooting mag length 69/77gr match ammo for across the course (200-600yds) matches.
Another is the 556 Target - specific to optimal length match ammo utilizing 80gr Sierra's.
Still another is the 556 LR - set up for the 90gr VLD's for 1000yd use.

All share the tightest free bore that can safely / reliably run ~ .2240-.2242". The first two use 1 deg 30 min leads while the LR uses a 1 deg 10 min lead (matched to the VLD design secant type ogive.)

The Wylde chamber is a great chamber - it is a do it all type and one can expect very good accuracy with a huge range of bullets. Bill Wylde was a pioneer in the development of the 223 as a viable competition / long range cartridge. His chamber generally runs a little loose in the neck - even more so than a 556 NATO. Numbers wise the neck dia at the mouth are .254 for a 223 Rem & the 556 NATO. The Wylde runs .2558". The neck dia at the shoulder is .255 for both the Rem & NATO, while Wylde's runs .2568"
The Wylde has a tight free bore just like the Remy.
One very big difference is the free bore lengths - the Remy run .025", the NATO is .0566 and Wyldes is .0619 - longer that the 556 NATO - and one of the reasons it handles pressure as well as 80gr projectiles.

There are many other minor differences as well - specifically in case body diameters. Unfortunately, some companies still chamber in 223 Rem. I have Rem 700 SPS in 223 and it has a SAAMI spec 223 Rem chamber - it is SHORT!! I only shoot 50-52gr pills out of it and it is very sensitive to seating depth."

I'll also add, that if a prospective builer of a precision AR plans on using a custom / match grade bbl, then by all means get a match chamber to compliment the barrels inherent accuracy.

[SWThomas]

opsoff1,

Thank you for the very detailed response. You explained the differences between the 3 chambers very well and I appreciate you typing all that out.

I've pretty much sworn off going the custom route. With that said, do you have any recommendations? Specifically brand, length, gas system, twist...

I'm not going to shoot 90g bullets, so those can be discounted for this rifle. The plan right now is to stick with 69-80g match bullets (primarily 75's and 77's), handloaded to magazine length, and shooting them out to around 500 yards. Maybe a little further. I don't have the ability to shoot 1K where I'm currently stationed.

[opsoff1]

opsoff1,

Thank you for the very detailed response. You explained the differences between the 3 chambers very well and I appreciate you typing all that out.

I've pretty much sworn off going the custom route. With that said, do you have any recommendations? Specifically brand, length, gas system, twist...

I'm not going to shoot 90g bullets, so those can be discounted for this rifle. The plan right now is to stick with 69-80g match bullets (primarily 75's and 77's), handloaded to magazine length, and shooting them out to around 500 yards. Maybe a little further. I don't have the ability to shoot 1K where I'm currently stationed.

SW,
There are a number of bbl makers that offer basically drop in match grade bbls. Unfortunately it usually comes down to what are you willing to pay and how much accuracy you want - the old adage relating to cars is appropriate here - "speed cost money - how fast fast do you want to go?" Same same - accuracy cost money - how accurate do you want to be?
With that being said - Holliger at White Oak Precision (part of WOA) uses Shilen, Kreiger & Pac Nor bbls. Frank White at Compass Lake uses Douglas & Krieger that I know of. There are plenty of others - each one can be had with a match grade chamber precut. There are mfr's that offer fully finished match grade bbls w/ HS'd bolt - I would strongly urge you to consider this route - different bbls will require you to part with different height stacks of dead presidents ($$$) but - you get what you pay for.
I have a rack of AR's where each one is purpose built - they all wear various bbls - I have primary & backup NM rifles that have Kreigers (cut rifled), Douglas (button rifled) and Pac Nor (button rifled). A DMR with a Badger (broach cut), and a long range rifle with a Noveske / PacNor. I've used others and wouldn't go back to them. Perfect example is Wilson - shot great but was effectively shot out in 1800 rds. I get 5-6-7000rds out of a Krieger - so in the end - the Kreigers are actually cheaper. Another aspect is consistency - I can work up a load for a Krieger bbl and use that same load on the next bbl and the next and the next. Other lesser bbls have to have the load tweaked at every replacement. I shot a Rocky mountion bbl on a NM course gun back in 05 - best shooting bbl I have every had - literally a laser. Next one shot minute of barn door. Stopped using them. I thing some of the best bargains out there are the Douglas bbls. I've used them on bolt guns and gas guns, AR's, M14's, M1's and customs autoloaders as well - they all shot great. Never had a bad one.
If you are looking for precision at ranges out to and in excess of 500yds - then I would absolutely go with a 20" bbl. It's free velocity. It also allows easier handloading by using heavier bullets and slower powders.
Twist? 1 in 7.5 or 7.7 to be safe - or a straight 1 in 7. A 1 in 8 is USUALLY fine - however in button barrels - the buttons tend to slip a bit and you end up with a twist that is a bit slower than advertised. A 1 in 8 is on the hairy edge of stabilizing an 80 gr bullet.
An 8 twist will shoot 77's all day long and they are great at 500 and shoot pretty dam good at 600 as well.
But again caveat emptor - a drop in Kreiger with matching bolt (read head spaced to the bbl) fully chambered / finished is north of $500. They shoot and they last -
Also - going with a 20" bbl will equate to using a rifle length system.
Using heavier bullets and slower powders will change the gas system - the AR does operate fairly well with a relative wide variety of bullet weights and powder burn rates, but when you egt on the outer fringe - goofy things start to happen.

Some of the bigger / better bbls guys out there:

Obermeyers are cut (Krieger started mfr bbls working for Boots)
Hart - button (push) (VERY VERY good button bbls - big in BR)
Schneider - button (pull) Tubb uses them
PacNor - button (very good and consistent - offer odd land arrangements)
Shilen - button (push) (huge in short range BR)
Lilja - button (big in 6mmBR & considered among the best in 22RF)
Broughton - button (pulled)
Brux - cut (big in F Class 6.5mm & 7mm)
Bartlein - cut
Border - Cut (Obermeyer style - mfr in Scotland)
Kostyshyn - button (big in 30BR)
Lawton - cut & pull button (big in LR BR)
Spencer - button (very big in 1000yd big bore BR)

There are more - but IMHO, I'd stay away from any chrome plated bbl. Go with a stainless bbl. Use a 1/7 - 1/7.7 twist, 20" and get a match grade chamber cut by the mfr or smith.
PM me if you need more info.

Edited to add: As far as 1K shooting with an AR - WHOLE different ball game - purpose built and highly specialized - so don't even equate that to anything else even remotely connected to any other AR type precision shooting.

[SWThomas]

Again, huge thank you for taking the time to be so exponentially helpful!!! You're a gentleman and a scholar.

Being a military man, my cammies weren't tailored with deep pockets. So going super-huge on a barrel is pretty much off the table. I've been scouring the interwebs looking for AR barrels from WOA, Shilen, Ranier, Bartlein, Kreiger, and a few others. I'm not coming up with a whole lot. WOA and Raniers seems to have some options but they're all backordered.

I did find a Shilen barrel/bolt set that looks promising, but it has a 1/8 twist. If it had a 1/7 twist I would be posting this reply to tell you I had bought it.

http://www.midwayusa.com/product/156...tainless-steel