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

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.
 
Re: Building a precision AR-10: Questions about barrel, bolt, twist, etc...

ar10 or ar15...you list both...

what distance and what accuracy will you desire ?
cannot just pull kcrap out of the air....
short range.. 1/14 twist...chamber based on 2.240 coal with br bullets( 50-55gr)...not production bullets
24"/26" will allow you to cut and rechamber as it wears.
 
Re: Building a precision AR-10: Questions about barrel, bolt, twist, etc...

stool said:
ar10 or ar15...you list both...

what distance and what accuracy will you desire ?
cannot just pull kcrap out of the air....
short range.. 1/14 twist...chamber based on 2.240 coal with br bullets( 50-55gr)...not production bullets
24"/26" will allow you to cut and rechamber as it wears.

Sorry about that. AR-15.

I thought it was pretty well implied that a precision rifle would be used for greater distances. I guess not. Yes, I plan to shoot for maximum accuracy out to about 600 yards. Maybe a little further.
 
Re: Building a precision AR-10: Questions about barrel, bolt, twist, etc...

stool said:
24"/26" will allow you to cut and rechamber as it wears.
[br]
Would you also shorten the gas tube and retune cycling when you do that?
 
Re: Building a precision AR-10: Questions about barrel, bolt, twist, etc...

Steve Blair said:
stool said:
24"/26" will allow you to cut and rechamber as it wears.
[br]
Would you also shorten the gas tube and retune cycling when you do that?

Crap, you beat me to it. Also, precision AR barrels usually have their gas holed drilled in a groove. Lining up for a shorter barrel could be very tricky.
 
SWThomas said:
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.

My F-TR AR-15 rifle sports a 26 inch Krieger in a 1:7.7 twist. This twist handles everything up but not 90gr bullets. It's awesome with 80JLKs.

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.
I got Krieger to chamber min in their 5.56 Match chamber; it's very tight and accepts the 80 grainers without issues.

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.
Sure there is, anybody will sell you one at a premium. They may even have a story or reason behind it, but it's lost on me. Yes, the person who will chamber your barrel will want your bolt even though it's not technically needed to headspace and AR due to its barrel extension design. But it's best to be sure.

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.

I think Lapua brass is a bit of a waste in a gas gun, but it won't hurt accuracy. I switched to Winchester because the brass does get beat up some, regardless of what you do to it. I use a chrome-silicon buffer spring and a Tubb CWS and the ejection is well controlled, but it's still semi-auto.

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

Yeah, I got lots of other observations, but I have posted in depth about this issue here not too long ago. If you have specific questions, I'll be glad to answer. Stuff like loads, grips, trigger, etc.
 
Varmint and don't care about the weight? Definitely a 24-26" barrel is recommended!

The twist rate will depend on your use. Precision at 300y, 600y, or 1000y comes down to the bullet you shoot.

A 1:12 for 50gr or lighter varmint bullets
a 1:9 for up to 77gr bullets (but could be marginal at 77gr each barrel is slightly different)
a 1:8 to ensure 77gr bullets aren't a problem, and even 80gr bullets (COAL is beyond mag length for 80gr, so you're single feeding past 77gr, and most VLDs above 70gr)
a 1:7 for a long-range heavy bullet rifle which will shoot up to 90gr
a 1:6.5 for 90gr long-range only.

Bolt matched to barrel is for proper head-spacing. I'd recommend keeping the bolt a quality mil-spec unit (true for all parts in the AR). thanks to the AR design, the bolt has tolerance to "float" for proper alignment so past the bolt the carrier, buffer, and other items are more for the gas cycling of the rifle. I'll leave that for a separate discussion.

A tuned gas system can reduce the brass wear, so can an AR catch bag, or I found that a piece of felt glued to the brass deflector can eliminate case denting. Better still, look for an upper with no brass deflector (watch your face if you have a right eject upper and shoot lefty)

my F-AR AR-15 (yes you read that right, its a local sub-set of F-TR http://www.ziarifleandpistolclub.com/Documents/F-ARFlyer.pdf) has a 20" WOA bull barrel 1:7 twist. It loves everything except velocity, I should have gone with 26" of barrel. WOA Wylde chamber has given me trouble with some 5.56 match ammo and pierced primers.

-Mac
 
You might want to talk to Robert Whitley (RCW3 here on the site). He has built some AR tack drivers. He has a web site with some pretty interesting stuff on it.

Cort
 
Re: Building a precision AR-10: Questions about barrel, bolt, twist, etc...

not so..i have three ar's built specifically for short range br.

most has been covered. you can move the gas block out 2 inches and rechamber to a std length..so do 26 then 24.
a gas valve/adjustable block/ weighted carrier/trimmed ejector spring will help save the brass.
if just shooting one weight bullet, get the chamber set up for it. you can do a min spec chamber/small neck( not turned) and set for your bullet.

put a flat on the bottom of a free float tube if shooting off a rest. if a rear bag is used build up the stock on the bottom to get it nearly flat on the bag.
SWThomas said:
stool said:
ar10 or ar15...you list both...

what distance and what accuracy will you desire ?
cannot just pull kcrap out of the air....
short range.. 1/14 twist...chamber based on 2.240 coal with br bullets( 50-55gr)...not production bullets
24"/26" will allow you to cut and rechamber as it wears.

Sorry about that. AR-15.

I thought it was pretty well implied that a precision rifle would be used for greater distances. I guess not. Yes, I plan to shoot for maximum accuracy out to about 600 yards. Maybe a little further.
 
mac86951 said:
my F-AR AR-15 (yes you read that right, its a local sub-set of F-TR

-Mac

Awwh, not that crap again! Well, I'm started my own little interpretation of the game and I call it F-AR for Air Rifle. It's currently limited to 600 yards only, no more, no less. You have to use .177 pellets, factory loaded of course, none of this .22 crap for us hardy competitors. We don't want any advantages here. We use the F-class centers, of course. The rules are simple; you only have one pellet (single load) and you start shooting it downrange from the firing line. After you fire it, you have to walk down to find it, load it again and fire it from where it landed or behind. You can't for example, pick up the pellet and take a step forward and shoot it again. You keep shooting it and then walk forward to retrieve it and shoot it from there, until you hit the target. Then you go back and start over again. If you can't find the pellet within 30 minutes of firing it, it's recorded as a miss. You can shoot it as many times as you want to score but once the pellet has passed the target line, it's dead, finished and the score recorded. The trick is to get all 20 rounds on paper in 20 minutes. You do have unlimited sighters in the first match of the day and 2 non-convertible sighters from that point on.

Now, strategy comes into play here and some people walk all the way to the target and shoot point blank on the X, but others will actually shoot the paper as soon as they feel they are in range and then run back for the next shot. You have to carry your shooting mat, and rear rest throughout the firing of the pellet, but some people have been known to use carts to drag their equipment. We do allow the use of CO2-powered air rifles, but the real competitors use a pump action of varying types.

Some people paint their pellets to make them easy to find, and one enterprising competitor is now using an RF tracker to find his pellets. It's time-consuming fitting the RF transmitter to each pellet and it can get expensive when the battery dies and he can't find it; the battery lasts 12 seconds, but he's working on a Lithium polymer, boosted with hydrogen that will increase that time to 14 seconds, which could be a game changer. Some of his fellow competitors have been objecting to his use of a generator which he keeps in his cart to recharge the battery; the noise and the pollution. So we had to alter the rules to make sure he only starts it, by hand of course, for the time that he needs to charge the battery (40 seconds usually.)

We make up the rules as we go along, so for example we no longer allow steel pellets, so the smart *** with the huge electro magnet in his cart is out of luck. Since not everybody could afford to buy such a device, there was no way we were going to allow it for those who could. Also, don't tell Joe, the guy with the RF locating device I mentioned earlier, but as soon as his battery lasts more that 14 seconds, we are going to change the rules to disallow that technology. It goes against the spirit of the game which is all about marksmanship, and reading the wind. Oh,and keeping track of your pellet and being good at spotting it on the ground.

Pit duty is a total bore and since it takes so long for the pellet to travel to the target, many fall asleep, or go to the restaurant or worse, we frequently have to call for a mark. We had the case at the last match, where one of the guys doing pit duty simply went home without telling anyone. The shooter was pissed because when the pellet finally go to the target, the target would not go down and his scorer had to walk all the way back to the firing line to call for a mark, which never came. This case was extreme, of course. Usually the pit guy is somewhere in the vicinity and will manage to get to the target to pull it down, mark it and raise it back up.

Of course, you want a competent target puller, because there's nothing worse than having to walk all the way back to the firing line to ask for a re-disc after you waited so long for the mark in the first place. The good thing is that it has cut down dramatically on the number of challenges. And also everybody has been getting in better shape for the grueling competition that is F-AR.

If anyone is interested in a set of rules for F-AR, we can put it up on a website or Facebook or something. As I said before, the rules are "evolving," so you will need to update frequently, say before during and after every match.

We are on hiatus for winter because nobody wanted to shoot in the snow, well all except Joe with his RF stuff, but he seems to forget that batteries don't last as long when it's cold. Some of us are considering having a match in February just to see Joe scramble after his $3000 miniaturized RF transmitter before the battery dies in 5 seconds, dragging all his equipment. Did I mention the range of the signal is about 27 inches? We do allow carts, but not sleds.

Mack in Wyoming
 
Thanks for the info fellas! I'm rethinking the custom barrel part of this build. WOA and Raniers look like what I'm after. Now I just need to find one.

If I'm going to be shooting 223 handloads and have no intention of shooting 5.56 from this gun, would a plain 223 chamber be the way to go? Or does the Wylde offer some benefit other than being able to fire both loads?
 
silly to use a 223 reamer on a semi custom target rifle.
why give up accuracy potential with a sloppy (by target rifle std's) chamber?
why not go with a bbl blank from krieger or broughton or such and a custom chamber ?? there are ar'smiths out there that do this work.




SWThomas said:
Thanks for the info fellas! I'm rethinking the custom barrel part of this build. WOA and Raniers look like what I'm after. Now I just need to find one.

If I'm going to be shooting 223 handloads and have no intention of shooting 5.56 from this gun, would a plain 223 chamber be the way to go? Or does the Wylde offer some benefit other than being able to fire both loads?
 
stool said:
silly to use a 223 reamer on a semi custom target rifle.
why give up accuracy potential with a sloppy (by target rifle std's) chamber?
why not go with a bbl blank from krieger or broughton or such and a custom chamber ?? there are ar'smiths out there that do this work.




SWThomas said:
Thanks for the info fellas! I'm rethinking the custom barrel part of this build. WOA and Raniers look like what I'm after. Now I just need to find one.

If I'm going to be shooting 223 handloads and have no intention of shooting 5.56 from this gun, would a plain 223 chamber be the way to go? Or does the Wylde offer some benefit other than being able to fire both loads?

But what's the cost? And is the bang going to be worth the buck compared to barrels half the price?
 
Shilen has one of the best deals going,you get the barrel of your choice with a fitted new mil spec bolt.It is a drop in.
 
jonbearman said:
Shilen has one of the best deals going,you get the barrel of your choice with a fitted new mil spec bolt.It is a drop in.

I found this set in stock at Midway. Seems to be what I'm looking for. They also have the same set but with the ratchet rifling. Not sure about that.

http://www.midwayusa.com/product/156629/shilen-drop-in-match-barrel-with-bolt-ar-15-223-remington-wylde-service-rifle-hbar-contour-1-in-8-twist-20-stainless-steel

If I went with this set-up, is there a specific carrier I should get for the bolt? Or will any old carrier be fine?

Would the 1/8 rifling be good for 69-80g match bullets?
 
nothing wrong with that setup..except for the chamber..
it allows 80gr bullets to be single loaded at 2.45x or so coal.
which means it is unlikely that you will get near the lands with mag length ammo.

do not get me wrong that chamber shoots, but it is a compromise chamber for 200/300/600 yd shooting...with the 600yd being single loaded.
i talked to bill wylde when i designed my chamber reamers....mine are short range .
you really need to explain exactly what you want to do...what distance, what precision, what bullet weight.....
make up a dummy round, shorten it by .030 or so for throat wear and send it off and get a reamer made.

ps...
1/8 is excellent. but 24/26" is better
80's are designed for single loading, not semi auto.
 
stool said:
nothing wrong with that setup..except for the chamber..
it allows 80gr bullets to be single loaded at 2.45x or so coal.
which means it is unlikely that you will get near the lands with mag length ammo.

do not get me wrong that chamber shoots, but it is a compromise chamber for 200/300/600 yd shooting...with the 600yd being single loaded.
i talked to bill wylde when i designed my chamber reamers....mine are short range .
you really need to explain exactly what you want to do...what distance, what precision, what bullet weight.....
make up a dummy round, shorten it by .030 or so for throat wear and send it off and get a reamer made.

ps...
1/8 is excellent. but 24/26" is better
80's are designed for single loading, not semi auto.

From my second post in this thread, which was a reply to you....

"Yes, I plan to shoot for maximum accuracy out to about 600 yards. Maybe a little further."

From the post just above you last reply....

"Would the 1/8 rifling be good for 69-80g match bullets?"


What's the heaviest match bullet I would be able to load to mag length?

I'll be conducting an OCW test at 100 yards when I work up the loads. I will probably do most of my paper punching from 100-300 yards and occasionally stretching it out to 500 or so. I'm not going to be competing in any matches, but I want the rig to be as accurate as my loads and me can be, but also be reliable and feed from the magazine. I'm building this rifle for fun. I like to play around with different powders, bullets, seating depths, and techniques to see what's the most accurate.
 
i believe the 77's are the heaviest for mag length.

so get a dummy 77 loaded up to 2.260 and then push it back .030 and get a reamer to match.

honestly for a fun gun just for with the bbl you listed.
for all out accuracy get a reamer and a krieger or similar bbl blank.
or go to kreiger and have them make what you want.

go look at kreiger ar bbls..about 470-520 or so for an ar bbl
 
Thanks for all the info fellas! It's greatly appreciated. Now I gotta do some shopping and part with some of my greenbacks. I'll report back once it's all build and I dial in an OCW.
 

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