Jump to content
SASS Wire Forum

ar platform barrell length


Trigger Mike

Recommended Posts

Posted

If both lengths are same O.D. and quality barrels, the biggest plus would be around 100 fps velocity gain with the longer barrel, That may, or may not, translate to more accuracy.

Posted

Accuracy depends more on the chamber and barrel quality than barrel length. Also twist rate vs. bullet. A 16" will shoot accurately as far as most want to. I use my custom 16" out to 600 with 69gr match loads. After that I use my 20" with 77gr. IF I had a 7 twist instead of an 8 I would use 80gr in the 20" gun. As it is on a reasonable day it reaches out to 900. I have high end glass on both guns and they aren't "rack grade".

Posted

I am no expert with the AR platform. I have a Colt AR-15 A3 6721 on order. I like the 1:9 twist as I will be shooting mostly 55gr and 62 gr projectiles that are shorter and should be perfect. I also like the HBAR type barrel. I have done much book time/ research and both talking to folks and such before I made this purchase. Can't wait to share a 'novice' review soon :) as far as barrel length? As far as as everything is equal....the 'a little' post above covers it.

 

Why I even posted this I don't know I guess I'm just excited to get the AR platform in my hands.

 

GG

Posted

Accuracy depends more on the chamber and barrel quality than barrel length. Also twist rate vs. bullet. A 16" will shoot accurately as far as most want to. I use my custom 16" out to 600 with 69gr match loads. After that I use my 20" with 77gr. IF I had a 7 twist instead of an 8 I would use 80gr in the 20" gun. As it is on a reasonable day it reaches out to 900. I have high end glass on both guns and they aren't "rack grade".

this brings up something else, twist. if I get 1/8 twist, then Hornady 77 or Federal 62 will be good? If I use 1/9 then I need lighter grains?

Posted

I am no expert with the AR platform. I have a Colt AR-15 A3 6721 on order. I like the 1:9 twist as I will be shooting mostly 55gr and 62 gr projectiles that are shorter and should be perfect. I also like the HBAR type barrel. I have done much book time/ research and both talking to folks and such before I made this purchase. Can't wait to share a 'novice' review soon :) as far as barrel length? As far as as everything is equal....the 'a little' post above covers it.

Why I even posted this I don't know I guess I'm just excited to get the AR platform in my hands.

GG

:D :D
Posted

I am no expert with the AR platform. I have a Colt AR-15 A3 6721 on order. I like the 1:9 twist as I will be shooting mostly 55gr and 62 gr projectiles that are shorter and should be perfect. I also like the HBAR type barrel. I have done much book time/ research and both talking to folks and such before I made this purchase. Can't wait to share a 'novice' review soon :) as far as barrel length? As far as as everything is equal....the 'a little' post above covers it.

 

Why I even posted this I don't know I guess I'm just excited to get the AR platform in my hands.

 

GG

Welcome to the 'Barbie-Doll' world of AR-rifles ^_^ ..........Just dress'em like you want :lol:

LG

Posted

Trigger Mike: I think you may have your brands mixed up:

Bullet maker: Style: Weight: Twist needed:

Hornady: BTHP 75 8

Hornady: A Max 75 7

Sierra: Match King 77 8

Berger: VLD 75 7

Berger: BTHP 77 8

 

Both the Berger VLD and the Amax are LONG and need the faster twist to stabilize.

All bullets I know of that weight LESS than 75 grains will stabilize in a 8 twist 223 barrel.

 

With a 9 twist you need to start over.

It will stabilize the Hornady 75gr BTHP. It will NOT stabilize the Sierra 77gr. Match King. It will NOT stabilize the 77gr Berger BTHP.

With a 9 twist you need to stay with 68 grains or less. It will stablize the 68 grain Sierra Match King but NOT the 69 grain Lapua scenar.

It is VERY rare to have a problem with "over spinning" a bullet. So even a 52 grain in a 7 twist barrel works fine.

I hope this helps.

Posted

yep my Hornady is 75gr BTHP "Match" but the federal is 62 gr. and I have a few surplus 55 gr. Based on what you sent me, 8 twist should be fine, right?

strange how I never cared about twist when I was serving.

Posted

I have a heavy barrel 1-8 twist 16 in. barrel and it shoots out to 900 yd. with what ever I feed it....also I use a top end scope made for the AR. However I mostly shoot 55 and 62 gr. military issue ammo.

Posted

I can't even see my house at 900 yards, much less hit it. :D

Posted

I can't even see my house at 900 yards, much less hit it. :D

 

 

If they are 900 yards, I'm going to call in artillery.

 

Yes, on both counts!

Posted

900 yds is not that far when you shoot it a lot, the local range has out to a 1000, and the range at Blue Steel Ranch in San Jon NM. has marked targets from 100yds to one mile. Your right about seeing targets or even shooting out to 900 yds + is a difficult thing to do but it can be done even with a 5.56 round from a shorter barrel than usual.

Posted

Trigger Mike, I have been away from the computer until now. 8 twist will be just fine. I gave you data to allow for low elevation and low temperature. You can't always be shooting at 8000ft. and 90 degrees. Correct Density Altitude and high muzzle velocity can allow for marginally stabilized bullets to perform OK under the right conditions, but why take the chance??

Posted

One difference I noticed just recently between my boy's 16" carbine and my 20" HBAR is muzzle flash. I thought mine had a bunch until he touched off a 30 round mag. This was in twilight. Man, what a fireball!

Posted

One difference I noticed just recently between my boy's 16" carbine and my 20" HBAR is muzzle flash. I thought mine had a bunch until he touched off a 30 round mag. This was in twilight. Man, what a fireball!

There is fun in flame :D

 

GG

Posted

Yes Sir!!! But I couldn't see the tracer show!

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.