Barrel Selection

[AzMandella]

So I am going to be building a new AR15 in 5.56 for distance shooting . I am a right hander but shoot left . So will be building a left hand AR15. My question is what barrel length and twist do recommend for up to 600yrds ?

 

[fkimble@charter.net]

Across the course, we use 1-8 twist or a little faster, and 26 inch seems to be the normal length. 80 Sierra's are the easy button over Varget or Reloader 15. Lots of other combinations but these seem to show up the most. And a "good" barrel cut by an AR gumsmith.

Frank

 

[jelenko]

I would add that many cross the course shooters are successful with 20" barrels. With the lower muzzle velocities with a 20", most use either 1:7.5 or 1:7.
For 24 and 26" barrels, 1:8 is usually better [so the bullet's rpms are within mfgs recommended rates].
In addition to the SMK 80, Nosler makes a similar 80 grain bullet as does Berger [the fullbore one, not the VLD]
In general, VLD version bullets take more trial/error to get the right seating depth than non VLD ones.

 

[RegionRat]

The rules of the game you like determine if there is a limit to bbl length or even overall weight of the rifle, so set your goals according to your rule book.

Service Rifle is a 20" bbl.
A typical match rifle, (meant for position shooting that is more than just prone), is often 26". A dedicated prone match rifle is often longer. The longer ones are meant to help with distances beyond 600 yards.

You can see some examples on the White Oak web site under Service Rifle Uppers, and then you will also see the other bbl lengths under the open match rifle class. The twist rates are as jelenko and fkimble described.

Most of us single feed a round for the 600 yard line which is longer than magazine length. Those stages are not rapid fire and not fed from the magazine. The 80 grain rounds are popular at the 600 yard line and will do much better on windy days than ones that fit the magazine.

Here are some good examples of the typical bbl profiles.

Match Rifle
https://www.whiteoakarmament.com/match-rifle-uppers.html

Service Rifle
https://www.whiteoakarmament.com/a4-service-rifle-optic-upper-post-ban-1-7.html

 

[bullseyeshtr]

I re-barrled my 20" service rifle with a white oak shilen 7.5 rachet 223 wydle service rifle barrel. Thing hammers with berger 70vlds at mag length and berger 80vld. The 80vld is very easy to get a load for. Set it 0.020" off the lands and find the powder charge it likes. I am using 24.5 N140 with both above bullets just different seating depths. Attached is a 300yd rapid fire I shot with the 70vlds during our state championship.

 

[Pawnee Bill]

When you decide what you want, call the folks at Compass Lake Engineering. They do good work and are nice people.

 

[mdram]

look at compass lake, white oak, fulton armory
they will usually have bartlein, kreiger barrels