AR-15 with 16in barrels. 1/7 or 1/9 twists. Which do you prefer?

[thousm]

Hi

I am rebuilding a Pre-Ban Bushmaster, M4 style. I called Bushmaster to order a new barrel but they said 16in only come with 1/9 twist. I could go with another manufacturer. Considering a Daniel Defense upper receiver assembly.

But the vast majority of the ammo I will be shooting is M193 55gr or M855 62gr which a 1/9 is good for. But I may like the option of using some Mk 262 77gr. Although sparingly.

If you were building an AR-15 which twist would you go with?

 

[vellnueve]

1/7, because it handles everything 55gr and up well enough.

 

[thousm]

That was what I was thinking. What manufacturer would you go with?

 

[Skald]

DD makes a good barrel, or if you want a lightweight build, the BCM LW 16" are pretty nice.

if you got the money, nothing beats a Noveske barrel.

 

[Admin]

1/7

http://www.rainierarms.com/?page=shop/browse&category=ar15completeuppers_noveske

 

[wolf223]

for plinking and SHTF, 1/9, 16" zombie killer

for "serious" bench shooting, i have two with 1/7, them son' B's are expensive to feed and not accurate at all with 55gr ammo. both are 20" barrels, one is white oak, one is YHM. i'm talking 1" groups at 100 yards with good ammo vs. 4" groups with 55gr .223

if I could turn back time, i'd have gone with a 1/8 twist... just my .02

 

[thousm]

I have the lower the way I want it. 1,400 for an Noveske upper? I was going for the 1,000 DD upper...This is going to be a 2,500 AR!?!?!?!

 

[Admin]

Look at BCM then.

 

[ShadeWPI]

1 in 9 twist will stabilize the vast majority of commercial ammunition.

It will properly spin 55gn bullets out as far as you're likely to be shooting.

The 1 in 7 twist was adopted to properly stabilize the longer, steel core SS109 bullet (M855) at extended range (te test range for M855 ammunition is 400m and it must penetrate 4mm thick steel plate. The AP effect of the steel penetrator requires a well stabilized bullet out to this range to ensure 90 degree strikes.

1 in 7 will provide better stabilization for heavier bullets (especially if you're going to shoot 75grain match ammo) but isn't necessary unless you're shooting heavier bullets at extended ranges.

All that said, I've opted for 1in7 barrels for my own AR-15 builds.

 

[thousm]

I don’t mind the investment. If it’s worth it. This one I plan on keeping.

 

[jasons]

I have the lower the way I want it. 1,400 for an Noveske upper? I was going for the 1,000 DD upper...This is going to be a 2,500 AR!?!?!?!

What's your budget?

I prefer 1/9 for rifles that eat lots of cheap 55gr Walmart ammo, and 1/7 for "accurate" rifles that get the expensive stuff.

 

[Skald]

You get what you pay for.

You can also get a BCM upper for a tad less than a DD. I personally prefer the BCM builds.

 

[thousm]

No budget to speak of. Was thinking 3,500 with ACOG sight.

Lower receiver was striped and was sent to be blasted and recoated.
Everything was replaced on the lower. Restoring to new condition.

Geissele SSA triger.
Magpul trigger guard.
Ambidextrous safety and mag release.
LMT Sopmod Buttstock Assembly.
All pins a springs replaced and more.

Has on it as of tonight a new Bushmanster flat top upper with a Knight's Armament RAS and flip up rear sight. But am considering selling the upper unfired and upgrading. That 1/9 twist just bugs me. In no rush.

Will post pics tomorrow.

 

[jasons]

If I were you I'd stop over-thinking things and go shooting. 1/9 is fine (arguably preferred even) for 99% of the ammo you're likely to shoot.

 

[thousm]

Maybe you’re right. My other thought was keep what I have and if a year from now I still wanted a 1/7 twist I could always just change the barrel. My Bushmaster is very nice as is.

 

[jasons]

Maybe you’re right. My other thought was keep what I have and if a year from now I still wanted a 1/7 twist I could always just change the barrel. My Bushmaster is very nice as is.

Robert is your mother's brother.

 

[Dressed to Kill]

Hi

I am rebuilding a Pre-Ban Bushmaster, M4 style. I called Bushmaster to order a new barrel but they said 16in only come with 1/9 twist. I could go with another manufacturer. Considering a Daniel Defense upper receiver assembly.

But the vast majority of the ammo I will be shooting is M193 55gr or M855 62gr which a 1/9 is good for. But I may like the option of using some Mk 262 77gr. Although sparingly.

If you were building an AR-15 which twist would you go with?

Ironically my second AR I built much like yourself , pre-ban Bushmaster lower I ended up going with a 1/7 twist Noveske. I just finished my third AR ( a Stag lower ) a K.I.S.S. rifle and when it came barrel time it wasn't important to me the twist because I wanted to keep this gun around $1K so I thinking a 1/9 barrel but I ended up buying a brand new Daniel Defense 1/7 M4 barrel for $175 shipped ! I doubt I'll ever shoot anything heavy out of the Stag but it's always nice to have the option.

 

[Jose]

Why is the twist even a question?

There is no downside to a 1/7 or a 1/8. None at all.

 

[thousm]

Woke up this morning and the 1/9 twist still bugs me…

My AR started with this rifle.

Had lower receiver completely refinished.

Now it is this rifle.

I do own a Colt pre ban with a 1/7 twist and I like the way it shoots.

If I have gone threw all this trouble I think I should just get the barrel I want. Only question is, just the barrel or another complete upper. I can easily sale the upper I have for what is cost me.

 

[Supermoto]

For me gas length and barrel weight are more important than twist. For a short fast gun, I'll go with a lighter, shorter barrel, but the carbine gas system will be more violent. For a longer range gun, a rifle length gas system on a heavier barrel will make a smoother gun, but slower to move. Then I'll pick twist rate for the type of bullet.

What are you planning to use the gun for? Having a bipod on a short harsh gun with a VFG doesn't make much sense.

 

[thousm]

"What are you planning to use the gun for? Having a bipod on a short harsh gun with a VFG doesn't make much sense."

bipod off diferent gun. Just put it on to take easy photo. Use, for anything. Not just target shooting.

 

[MassMark]

Get a mid-length gas, 1:7 BCM and be done with it....

 

[ShadeWPI]

Why is the twist even a question?

There is no downside to a 1/7 or a 1/8. None at all.

Faster twists apply more stress to the bullet, you lose a little velocity and increase barrel pressures a little - This is why S&W went with a much more expensive "progressive twist" for the .460 S&W Magnum.

In .223 / 5.56mm, the higher stresses on the bullet can cause problems with high velocity, ligh weight, thin jacketed bullets such as the typical "varmint" bullets. So there is some downside, depending on the application for the rifle.

 

[thousm]

Changed my mind. Sold Bushmaster upper for just about what I payed for it. Bought BCM mid length 16 in upper with Daniel Defense rail. Light weigh barrel. 1/7 twist. Very happy…

Interesting comparison between a mid length and a standard civilian carbine. Both 16 in barrels. But the BCM has a mid length gas system. Frunt sight/gas block is moved forward. Improving reliability. More rail and the sights are further apart. More accurate. The Colt is in the classic configuration. The Bushmaster lower and BCM upper is the modern version. Both very light and nice.

 

[Jose]

Faster twists apply more stress to the bullet,

I agree

you lose a little velocity and increase barrel pressures a little

I doubt it.

This is why S&W went with a much more expensive "progressive twist" for the .460 S&W Magnum.

Do you have a technical source at S&W that I could ask that question to?

In .223 / 5.56mm, the higher stresses on the bullet can cause problems with high velocity, ligh weight, thin jacketed bullets such as the typical "varmint" bullets. So there is some downside, depending on the application for the rifle.

That is true in any caliber, but the problem is FAR less widespread than what it is made out to be.

When I shot across the course highpower, I bought 500 Winchester White Box 45 grain varmint rounds just to try at 200 yards. I lost not a single one when shot through a 1/7 Wylde chambered (not that the chamber matters) 20" AR.

The only varmint bullet I've lost were .264" 95 grain Hornady V-Max loaded in a 260 Remington and shot through a 28" 1/8 barrel. I don't know the MV but it was north of 3000 fps.