Rebarrelling a 5.56 Bolt Gun

[Scrumbag]

Hi folks,

Looking for some advice.

I have a CZ527 American which I think is coming to the end of it's barrel life (having put as much Swiss 63gr 5.56 through it as I have, I'm not surprised after 10 years of ownership).

I do like the rifle and it has served me well with it's 1:9 twist barrel.

What I am wondering is, when I rebarrel, do I go for a 1:8 to make the rifle more flexible for range work? Will I give up much with lighter projectiles and the ability to shoot 70gr plus bulllets reliably make up for it?

I would appreciate your thoughts.

Scrummy

 

[whatsupdoc]

I have a 223 that is a 1:7 twist that is a laser with 69SMK's and 70VLD's so if it was me I would
go with a 1:8 twist.

 

[DGP4]

I get good accuracy up to 77 grain SMKs in my 1:9 bolt gun. If you want to step up to 80 grain and above, you'll probably want a 1:8 or 1:7 barrel.

 

[Tommie]

I have a 223 that is a 1:7 twist that is a laser with 69SMK's and 70VLD's so if it was me I would
go with a 1:8 twist.

?

 

[whatsupdoc]

?

OP is thinking 1:8 may be too fast for 69-70 gr, they run great in my 1:7 so a 1:8 would not be too fast.

 

[NZ_Fclass]

1-8. No contest. Don't go mad on freebore/throat if you still intend shooting lighter bullets too. I have a .222 with an 8. Works fine.

 

[searcher]

I'd say that depends on how far your range work is. If 300 yards or less - I'd stick with the 1-9". If the vast majority of your shooting will entail continued shooting of 62 grain projectiles (or less), I'd probably stick with the 1-9". As the ability to stabilize heavier (longer) bullets comes with increased barrel wear and lower velocities, shorter barrel life, etc., I'd not make the switch unless you really want to shoot heavier than 62's - then a 1-8" would do you well. In my experience, the slower twist barrels tend to be a tad more accurate with the lighter bullets - so what you gain with a faster twist in ability to shoot heavier bullets may result in a sacrifice of light bullets continuing to shoot as well. Always tradeoffs.

 

[jelenko]

1:8 for 55 through 80 grain bullets.
With 55 grain ones, you'll want to watch the rpms - e.g., at 3200 fps the rpm is 288,000 in a 1:8.
It will be an issue only when/if the throat gets rough and starts to damage the jacket.

 

[SSL]

My 1-8" .223 shoots 50-grain VMax (3,300 fps), 55-grain VMax (3,200 fps) and 68-grain HPBT (2,900 fps) in 1/2" or smaller groups consistently...with the 50-grainers, just over 1/4". These are at 100 yards. No real chance to try extended ranges yet, but no sign of bullet failures.

 

[ChesterS]

My 1:7.7 hammers 52g SMKs out to 200 yds! The only bullet I had trouble with was the SXP bullets that are meant for the 222. They turned into smoke!

 

[Mark W]

My question to the OP would be, what is this rifles intended purpose and is feeding from the magazine important. I doubt most of the bullets that will benefit from a 1:8 twist will fit in a CZ 527 magazine without being seated well below the neck shoulder junction. If he intends to single feed, it doesn’t really matter.