223 bullet weight for 9:1

[Redgum]

As far as I can find out the Steyr scout in 223 is 9 to 1 twist, going to try out before buying tomorrow evening, it I get it then I want to pick up some bullets for it too. Now the rifle will slot in nicely as a fox and Munty rnd and would like to use the heaviest bullet I can. Have a feeling that this twist will suit the 55 to 70gr bullets, is this correct. I use Varget for the 308 so will be using that powder.

[saddler]

I have some 73-gr ? Berger bullets that will also work on the 1:9 rifling

 

The issue is not purely the weight, but the bearing area of the bullet in contact with the rifling.

Mine love the the 52gr A-Max & the 69gr SMK.

The 52gr A-Max are amazing bullets...got some heavier ones to try too.

[Redgum]

Thanks Saddler, have just found a previous post and 1:9 is better for the longer bullets and that's what the scout definitely is. My manual recommends varget right from 50 to 70gr bullets so ideal which is brilliant as have loads of it. My Tikka 308 is so darn accurate and consistant its almost boring and only ever need to load what I use on deer, when ever I go to check zero if I have bashed it or something its one shot and then home again

[Albert 888]

I have a 1:9 cz 223.

55g vmax factory rounds very accurate and good on fox.

55g sp ppu factory 1" group at 100m used on muntjac did the job fine.

60g hornady tap factory 0.5" at 100m

69g ppu factory match ammo shocking.

68g hornady BT and blc2 not very good.

52g amax and 24.5g of blc2 are my target rounds.

Loaded some 40g nozler balistic tips with blc2 and shot very well.

Got some 60g vmax bullets to try next.

Good luck and enjoy.

[wymberley]

This can be a handy guide:

 

Twist Rate = 3.5 x the square root of the bullet MV x its diameter squared all divided by the bullet length in inches.

 

Can be even more useful if you have this handy;

 

http://www.jbmballistics.com/ballistics/lengths/lengths.shtml

[Savhmr]

Another guide is to divide bullet length (in inches) by calibre then divide the product into 150 then multiply by calibre in inches:

 

eg: Hornady V-Max 60g in 223:

 

Bullet length = .870"

.870" / .224" = 3.884

150/3.884 = 39.06

39.06 x 0.224 = 8.75, therefore 1 in 9 twist or tighter will be a good match.

 

Bullet length I'm finding is more important than bullet weight when it comes to what a certain twist rate will stabilise. For lighter bullets, sometimes loading down a bit on velocity if shooting out of tighter twists can help stability too.

 

My 527 now sports a 1 in 8 twist barrel and that shoots everything from 50g to almost 90g fine depending on bullet length.

[Redgum]

Another guide is to divide bullet length (in inches) by calibre then divide the product into 150 then multiply by calibre in inches:

 

eg: Hornady V-Max 60g in 223:

 

Bullet length = .870"

.870" / .224" = 3.884

150/3.884 = 39.06

39.06 x 0.224 = 8.75, therefore 1 in 9 twist or tighter will be a good match.

 

Bullet length I'm finding is more important than bullet weight when it comes to what a certain twist rate will stabilise. For lighter bullets, sometimes loading down a bit on velocity if shooting out of tighter twists can help stability too.

 

My 527 now sports a 1 in 8 twist barrel and that shoots everything from 50g to almost 90g fine depending on bullet length.

 

Well that usually comes together, a bullet can only get heavier in a certain calibre if it gets longer, but thanks for the replies, I'm not much into lengthy calculations to decide what bullet I use but it seems the twist suits a heavier bullet so I will make up a few loads in what is the easiest to source bullet between 55 and 70grns in soft point. Just off ta try the gun out, think it comes with some dies so may also have some good recipes.

[Savhmr]

Yes, of course, but it's also true for example that some match bullets can have quite a long hollow to set the COG rearwards and be longer than say a varmint bullet of equivalent mass, especially when tipped (like the TMKs). It's a suck it and see dependant upon each bullet type, but you should be good from 50 to 70g I would have thought.