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1:9 Twist 223

EricF517

Online Training Member
Full Member
Minuteman
Jan 5, 2009
659
0
Howell, Michigan
Would a 1:9 twist 24" be enough to stabilize the 80g A-Max? The wife wants a 223 bolt gun and was looking at the 5r. Wish it was a tighter twist, myself, but she likes my old one.
 
Re: 1:9 Twist 223

Using the Miller stability equation along with the velocity correction of say 2950fps which would be pusshing it according to QL your getting a Value of 0.93. 1.4 or higher is considered good.

The highest you can probably go is 77's assuming your 1:9 is a true 1:9 and not slower.
 
Re: 1:9 Twist 223

That is a bummer since there is such a bc loss to the 69. Looks like I hope she likes the Savage then since they have the 223 in a 1:7.
 
Re: 1:9 Twist 223

A 20" 1:9 with 69 SMK's will do pretty well out to 800 yards or so. If you need a 1000 yard .223 you'll definiately have to go to a higher twist rate although I've been meaning to try the new Berger 75grains which help stretch things out a bit, check out the below thread.

75gr Berger thread
 
Re: 1:9 Twist 223

Eric, check this out

http://www.snipershide.com/forum/ubbthre...585#Post3060585

Not a 80smk but slightly higher bc .423 vs .420 and can be pushed faster.

LOL jagged77 beat me

Update:

I missed you where wanting to use a 80g A-Max. No, it wont work in a 9 twist and a 8 twist with the standard 223 chamber would be right at the edge. Your going to want a twist in the 7's (7, 7.5 or 7.7) for all conditions IMHO.

When I get around to it I will be putting a 7.5t on my tactical just for that reason. Right now it is shooting so well with the 75vld I am not going to mess with it.

FWIW, I have a 7 twist match 223 chamber with a long throat for the a-maxes, barreled with a rock creek cut to 21.75" and with that bullet I am just into the low 2800's using varget. I havent played with it much beyond load development so there very likely could be a better powder with more velocity.







 
Re: 1:9 Twist 223

That 1:9 would work really good with 69gr SMK's with 26gr Varget!
 
Re: 1:9 Twist 223

I may be wrong here but there is not much a 80 Grainer can do that a 77 can't or at least I have not found it to be true.
 
Re: 1:9 Twist 223

I've been running 75gr A-Max's, in a 1 in 9 Savage, for the last couple of months on the 900,990 and 1000yrd targets that we shoot, with no problem's at all and surprising results.I run the 69gr SMK on everything out thru 720yds.Re-tuning the A-Max load today at a known 320yds on my range,on the 300yd setting I put the TMR center cross hair,of a MK-4 ,6.5x20 Leupy , on the right eyeball of a grey squirril quartering away from me and took off his head,so looks like it shoots OK ?
 
Re: 1:9 Twist 223

DWT I hopt that the LRPV that I bought her will give her the same results.

JStar, reason I am looking at the 80 Amax is that it will almost mimic the BC of the 175smk out of my 308. BC's are real close, and speed it right close to the 175 as well.
 
Re: 1:9 Twist 223

Good luck Eric,from everything I found in my research,you have about a 50/50 chance with the 1 in 9 trist,I have a great one no doubt ! Try VV N540,not much info on it but the Sierra manual has it tops with the 69smk,I just adjusted and carried over to the 75gr A-Max,PRESTO !!!