5.56 1:8 twist question

[SigEquinox]

Considering a PWS MK114. Is a 1:8 twist going to shoot 75gr and 77gr accurately? Or do you have to have a 1:7?

thanks,

SigEquinox

[captbilly]

Yes 1:8 will be fine

The only bullet that needs a 1:7 barrel is the 90 grain SMK or some tracers, everything else, from 77 - 25 grain will shoot fine from a 1:8.

[FeuerFrei]

It is the length of the bullet that matters with regard to twist rate.
Longer bullet needs faster twist. Shorter works with slower rate.
Military needs 1/7 for tracer rounds and M855 62gr "green" tip.


From L... M193 , M855, M856, Sierra MatchKing HPBT

[starsnuffer]

It's not just length, it's length and MASS. Military needs the 1:7 because tracers are very long but very light, IE not dense. You're not going target shooting with aluminum bullets, so no need to fret.

-W

[UserM4]

I have a match barrel 1:7.7 twist and shot 77gr SMK .25 MOA. I think you'll be just fine.

[RugerNo1]

It is also not just the OAL of the bullet that determines the requisite twist rate. The length of the bearing surface of the projectile is the determining factor. There are general rules of thumb that work in most cases, but when you start talking lead content, secant/tangent ogive, or profile (boattail or flatbase) you will start to see that general rules do not apply.

[nicoroshi]

Mine is a 16" SDI S.S. barrel with 1:8 twist
It likes the 77 grain bthp but LOVES the 69gr Nosler bthps

[high_revs]

i have 2 1:8 twist. they shoot fine up to 77gr also (my highest in the ammo inventory).

[SgtJT27]

I have both 1:8 and 1:7 barrels and have shot 52-75 gr bullets, both works great.

[RRichie09]

The RECCE rifle uses 1:8 twist and was designed to be used with 55gr to 77gr so you should be fine.

[ejhc11]

Hornady Reloading Manual tests their 75gr reloads with a 1:9 twist barrel and I own a 1:8 AR upper and it shoots the 75gr HPBT Hornadys perfectly.

[SigEquinox]

Sounds good then -- thanks all for the replies.