69gr BULLETS

[N1YDP22]

would a 69gr boattail bullet be ok to shoot in a 1.14 twist barrel? how accurate will it be?

 

[mac86951]

Its a bit heavy, but won't hurt to try it. No say on accuracy, that will depend on the rifle.

http://www.accurateshooter.com/cartridge-guides/223rem/

-Mac

 

[premo 2]

did I spell TUMBLE right

 

[N1YDP22]

it'a a cz 550

 

[Laurie]

Not a chance !!!!

Here's what the Miller twist rule says for the 69gn Sierra MK in 1-14:

Don Miller's Twist Rule


Caliber 0.224 Inches
Bullet Weight 69 Grains
Bullet Length 0.9 Inches
Barrel Twist 14 Inches/turn
muzzle velocity 2950 fps
Temperature 59 degrees Fahrenheit (59 is standard)
Pressure 29.92 inches of mercury (29.92 is standard)

Sg = 0.70

Sg shouldn't be less than 1.4. If Sg is greater than about 2.0, you may
gain some accuracy by going to a slower twist barrel.

Sg = the stability coefficient. 1.0 is theoretically just stable, but values of at least 1.25-1.3 are desired and the recommended minimum value is 1.4. 1-10" twist is optimal for most 68-73gn 224s, and hence the common 1-9" works very well as it errs on 'the right side'.

I know from experience with the first batch of .223 Rem Cz527 Varmint rifles that arrived in the UK many years back allegedly with a 1-9" twist barrel but actually supplied with 1-12" rates that test loads with the 68gn Hornady HPBT Match and the 69gn SMK didn't work on a warm summers day. One of them (SMK, I think) would hit the target 'black' at 200 yards, but grouped poorly; the other struggled to hit the frame at all at this distance.


Since it's a Cz550 and 1-14", I assume we're talking .22-250 Rem here? Taking MVs up to 3,500 fps, more than the cartridge could safely provide, still doesn't stabilise these bullets. Sg improves from 0.70 to 0.74 at this velocity and raising the air temperature to 100F still doesn't get you there as the result is now 0.8. If you shot on a mountainside around 6,000 ft ASL in a heatwave, you'd just achieve 1.0 due to the thin, warm air.

 

[N1YDP22]

yes 22/250,so i should go with a lighter bullet? like a 45gr to 60gr? sugestions

 

[SS427]

Try a 52 or 53 grain Sierra Match bullet. For hunting try a 50 grain Nosler BT, Sierra BlitzKing or a Hornady v-max. My .22-250 always shot 50 grain bullets better than 55 grain bullets...the 55s might have been right on the edge of stability out of that barrel.

 

[Cold Bore]

I agree with the above.

Don't waste your time or components trying to make a 69 gr SMK fly out of a 14-twist tube.

As somebody mentioned, try the 53 gr SMK flat base. They shoot wonderfully out of everything I've ever loaded them in.

 

[Beau]

A 69 won't even shoot out of a 12 twist.

 

[JASmith]

Are we sure the OP didn't reference the .243 or .257 or .264 as the diameter of his bullet? I know those calibers aren't in this thread, but a bullet of that weight might stabilize with a 1-14 twist.

 

[Cold Bore]

Are we sure the OP didn't reference the .243 or .257 or .264 as the diameter of his bullet? I know those calibers aren't in this thread, but a bullet of that weight might stabilize with a 1-14 twist.

I'm pretty sure that when somebody says 69 gr BT, and references that against a 1-14 twist, they mean 22 cal....

 

[N1YDP22]

cz 550 in 22/250

 

[jefats]

would a 69gr boattail bullet be ok to shoot in a 1.14 twist barrel? how accurate will it be?

My range buddie tried the 69 Sierra HP's in his 14 twist 223 Cooper and did not hit the target board (24"x24") one time in five shots at 100 yards. This gun can shoot in the .2's for 5 shots with 52 grain Bergers.

 

[bheadboy]

i have a mixed response,

in a rifle it has never worked to shoot higher than 63gr with 14x

in an xp 100 for imhsa i built a 222 with a 14 twith hart bbl, it would shoot .870 groups at 200 meters, with 69gr sierra mk


i have no idea how or why but i changed from the lighter bullets to the 69mk and had many a 40x40

Bob

 

[stinnett1981]

69g Sierra match kings. It say "for 1/9 twist" on the box.