barrel twist

[sean223]

buying a heavy varmint barrel for my 223, will be mostly shooting 53grn hornady rounds. After reading up on it am still not sure of which of these is the best. 1:12 or 1;9. for shooting that round. its for shooting rabbits and targets inside 500 yards. you guys will no. Thanks.

[gbal]

Sean,'in sort of theory' 1 in 12 might just have a slight accuracy advantage for light bullets at shortish range (52/300).Bench rest rifles (not of course in 223) tend to take advantage of the slower twist options,but there .1 moa is a huge amount,and ranges are 1/200y.

As you know,the faster twists have overwhelming advantages for stabilising longer,heavier higher BC bullets,needed for longer range (up to 80+/500y+).So such barrels keep that option open.They may or not be slightly less precise with lighter bullets-it just seems to vary with rifles-and whether very small differences are noticeable,or matter,especially in field conditions.In general,we can accept that the 1 in 12 will not be less accurate at short distances.

Likely,members will give actual shooting results in their rifles.I have two sakos-the slow twist 222 with 36-50g is no more/less accurate (.2) than the 1 in 8 223 with 55g.So a relatively fast twist can be the equal of the slower twist,especially for all 'practical' purposes.(the 6ppc sako won't do any better).

The difference between rifles is likely to be not negligible,let alone the general precision of different makes.

gbal

[247sniper]

If you have a choice go 1/9 over 1/12 for the 53 grain VMax as stability may be marginal with a 1/12 twist. A 1/9 will allow you to shoot the likes of 40-69 grin bullets no problem.

[22cf]

In your boots I would go 1 in 9 or maybe even 1 in 8 which could give you the 75amax as an alternative for the long range shots if you were to compromise on the throat.

[Big Al]

I have a 1:9 twist and it shoots 40gr to 69g very well indeed, 0.5 MOA or less in decent conditions.

[247sniper]

I have a 1:9 twist and it shoots 40gr to 69g very well indeed, 0.5 MOA or less in decent conditions.

Exactly M 8

[Si-Snipe]

buying a heavy varmint barrel for my 223, will be mostly shooting 53grn hornady rounds. After reading up on it am still not sure of which of these is the best. 1:12 or 1;9. for shooting that round. its for shooting rabbits and targets inside 500 yards. you guys will no. Thanks.

Sean I went 1:12 in my 223AI but have not had consistent year round results with 53g vmax or 55SBK both of which are a similar length and require similar twist to fully stabilise. If you look at the work of ballistician Brian Litz he would suggest a 1:9 is much more suitable for 50-55g bullets.

I am convinced my accuracy didn't remain consistent due to instability in certain conditions. According to his work a 1:12 is almost a risk with 50's!! A 1:9 seems just about right for 50's.

[Si-Snipe]

A 50g V max which is much shorter than the 53's. 0.772 vs 0.827 (IIRC) produces the following stability results:

 

1:9 twist

Best case 2.13

Nominal 1.86

Worst case 1.61

 

It is recommended that you use 1.4 or above. So given that info I'd be running 50's with a 1:9 which is nicely stablised but not excessive.

 

A Nosler 55 ballistic tip which is shorter than the 53 at 0.806" gives the following with a 1:9

 

Best case 2.07

Nominal 1.81

Worst case 1.57

 

Go 1:9 mate. It's a safer bet. Also consider if you would want to shoot heavier bullets too as you may want to consider 1:8.

[sean223]

A 50g V max which is much shorter than the 53's. 0.772 vs 0.827 (IIRC) produces the following stability results:

 

1:9 twist

Best case 2.13

Nominal 1.86

Worst case 1.61

 

It is recommended that you use 1.4 or above. So given that info I'd be running 50's with a 1:9 which is nicely stablised but not excessive.

 

A Nosler 55 ballistic tip which is shorter than the 53 at 0.806" gives the following with a 1:9

 

Best case 2.07

Nominal 1.81

Worst case 1.57

 

Go 1:9 ,. It's a safer bet. Also consider if you would want to shoot heavier bullets too as you may want to consider 1:8.

Thanks si-snipe. thats what am thinking to, so have gone with a 1:8 twist tikka t3. just hope that it doesnt do away with the lighter rounds like the 50gr to 55gr. time will tell.

[Si-Snipe]

Thanks si-snipe. thats what am thinking to, so have gone with a 1:8 twist tikka t3. just hope that it doesnt do away with the lighter rounds like the 50gr to 55gr. time will tell.

I'm sure you will be fine. The 1:8 gives the following data for a 55 vmax (which is a flat base essentially) and 0.811" long requiring less stabilisation than a 55 SBK or 53 vmax.

Best case 2.58

Nominal 2.25

Worst case 1.95

 

All those stats are very much within comfortable stabilisation yet not excessively spun either.

 

Good luck.