69 SMK with a 12 twist

[mr.big]

it is not supposed to work I know but I shot 5 rounds from the CZ 527 Carbine with 12 twist 18 inch barrel,,5 shots were just under one inch and all holes looked round and no signs of key holing,

anybody ever tried this ?? you think it was a fluke or will some 12`s actually shoot the 69SMK,

load was with LC brass CCI 400 primers and 25 grs Varget and the 69 Sierra bullet..

 

[DaveB]

No, shoulda keyholed. Well, hmm. Standard 22-250 is 1:14 and while it stabilizes a 60 gr Partition, a 69 grain absolutely would keyhole. Maybe the slightly faster twist rate is enough to stabilize the 69 grain bullet.

 

[rdl65]

No, but I will have to try it since you posted your results. I have a friends rifle here that i need to work up a load for and the lightest bullet I have is 69gr. It is a 1/12 twist .223.

 

[DaveB]

Take a look at some of the 223 AR-type advertisements. They always mention twist and 1:9 or 1:8 is high as they go. Need the faster twist to stabilize the bullets or as you thought, they would keyhole.

 

[mr.big]

my AR is 9 and my 527V is 9 twist they both shoot the 69 SMK very well with the CZ averaging less than 1/2 MOA at any sane range,,some groups at 100 will be 1/4 for 5 shots,,even shot some 2.25 groups at 500 with it,

I got the Carbine to have as a coyote gun and leave out so I dont have to run to the safe when one wanders through the yard,,I was just messing around and shot the 5 shots just for kicks and I was surprised they even hit the target,

I will try it again in the next few days and see if it is repeatable,,

I know the 80 Berger hits sideways at 25 yards from the 9 twist AR but will shoot pretty dang good from the 9 twist CZ,,
I will try and measure the actual twist with a cleaning rod as my 527V 9 twist actually measures 8.25

 

[rdl65]

Mr. Big,
I went to the range today with a friends Handy Rifle that has a 1/12 twist barrel. It shot the 69gr SMK's just fine. Also I loaded up some 70gr Berger VLD's and it shot them also with no signs of key holing. But the SMK's grouped better out of this rifle.

The 69gr SMK groups were right at 1" average @ 100 yds. I fired 30 rnds and no key holing. I did see some flattening of primers though. Maybe 25gr of Varget is to hot for this rifle.