1/9 vs. 1/7

[Gringo Loco]

I have a choice between a Rock River Operator 1/9 twist heavy barrel or a Spikes 1/7 twist M4 (regular) barrel.

Which one do I choose? Why?

 

[bsoileau24]

I like a 1/ 7 because I like to shoot 75/77 grain bullets. My 1/9 did not stabalize the heavier bullets

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[CavalryJim]

To me, lighter is better. 1/7 twist is best for 62gr and heavier ammunition. 1/9 is best for 62gr and lighter ammunition.

What is the purpose of th build?

 

[DAVE_M]

Curious why you are limiting yourself to RRA and Spikes?

BTW, my barrels are 1/8

 

[Gringo Loco]

To me, lighter is better. 1/7 twist is best for 62gr and heavier ammunition. 1/9 is best for 62gr and lighter ammunition.

What is the purpose of th build?

My future brother-in-law wants me to build him one. It will be his first.

Curious why you are limiting yourself to RRA and Spikes?

BTW, my barrels are 1/8

I was considering an all Spikes build due to the lower and internals (except for the trigger) being Spikes. But, there's a RRA Operator complete upper just sitting in my house right now.

 

[DAVE_M]

I was considering an all Spikes build due to the lower and internals (except for the trigger) being Spikes. But, there's a RRA Operator complete upper just sitting in my house right now.

Well then your choices are either to spend money or don't.

If you are going to spend the money on a barrel, there are a ton of companies out there. For the price of those Spikes barrels, I'd look at BCM.

 

[Gringo Loco]

Well then your choices are either to spend money or don't.

If you are going to spend the money on a barrel, there are a ton of companies out there. For the price of those Spikes barrels, I'd look at BCM.

I do like BCM.

I guess my biggest question for everyone is 1/7" vs. 1/9" for barrel. Whether it makes much difference if he stays in the 55 grain area.

 

[kz45]

1/9 for light 1/7 for heavy
1/8 best all around

 

[shrxfn]

Curious why you are limiting yourself to RRA and Spikes?

BTW, my barrels are 1/8

Dammit hate to do it but I agree with Dave. 1/8 all the way. I even went mid-length gas as well.

Figure out what loads you are going to use and get appropriate barrel twist. I wouldn't hang up on manufacturer name.

 

[DAVE_M]

Dammit hate to do it but I agree with Dave. 1/8 all the way. I even went mid-length gas as well.

Figure out what loads you are going to use and get appropriate barrel twist. I wouldn't hang up on manufacturer name.

They say 1/9 is good for 62gr and lighter, 1/7 for 62gr and heavier, so why not 1/8 and shoot 62gr very well? lol

 

[shrxfn]

Yeah I did a lot of research when I was looking for a 5.56 barrel and a lot of people that know way more than me were saying how well a 1/8 twist worked. they also mentioned using Mid-length gas to extend the length of service on associated parts. Something about it the impulse of mid-length gas being easier on the parts than carbine gas. So I wound up with a stainless steel BHW barrel that fit the criteria. Love that gun it shoots great even with a wing nut like me behind the trigger.

 

[topgunz1]

I have 1/7 barrels that shoot 55gr great, and 1/9 barrels that do as well. If he is sticking to 55's and 62's, either would be fine. I prefer lighter weight barrel profiles on 16" guns so the spikes would be my choice

 

[Magdump]

Then there are the .223 Wylde barrels...

 

[Spleen]

Then there are the .223 Wylde barrels...

Ahh, you just had to be that guy...

 

[bigtattoo79]

I'm up to 4 Spikes 1/7 twist 16" mid length guns and I'm very pleased with them!

 

[Magdump]

Ahh, you just had to be that guy...

Lol, every chance I get

 

[JWG223]

I have a choice between a Rock River Operator 1/9 twist heavy barrel or a Spikes 1/7 twist M4 (regular) barrel.

Which one do I choose? Why?

1/7 offers more ammunition choice flexibility and will allow/facilitate better expansion than slower twist rates sometimes.

 

[Ellis1958]

Then there are the .223 Wylde barrels...

Got two with a Wylde chamber. One with 1/7 and the other in 1/8.

The 1/7 is in my service rifle for High Power competition. It has only seen 77 and 80 grain projectiles and shoots those well to 600yd.

The 1/8 is in an older technology 3-gun rifle. That one will drill a 52gr A-Max at 100yd sub-MOA. Past 100yd the wind blows them around a bit. Not a barrel problem, just an inherent issue with the projectile. The other end of the scale is that it will send 69gr to 400yd and keep them just over MOA.

Personally a 1/8 is a good all around twist. For a general use AR you can't go wrong there.

 

[xobelkcat]

In my experience, which is limited, the twist rate doesn't seem to be the deciding factor on projectile weight, for me it's been what that particular rifle likes. For example, I had a 1/9 stag 16" that at 100yds there was very little difference in group size when firing 40, 50, 55, 62, 69, and 75gr projectiles. All grouped 1.5"-1.75"

I had a American Tactical AR with a 1/7 16" barrel shot sub moa at 100yds with 75gr projectiles. Couldn't get under 2" with 60, 62, 69gr projectiles. But it would stack 55gr projectiles almost as tight as the 75's, about 1" at 100yds.