Most accurate loads for a 9 tw 308win.

[troupe]

Looking for some suggestions for the most accurate loads in my new 308 9tw 308 rifle, Schneider barrelled. I do have some 168 and 175 MK's as well as Lapua brass. This all will be shot at 100yds. Anything in the light bullets would be better, 112 to118 would be nice, but I know the twist may be to much. Speed is a none issue.

Thanks in advance,

Tom

 

[afret]

I recently put together a 10 twist 308 bolt gun and I think it has the standard .09 freebore. I was able to find some Berger 150s and 115s. The 115s are too short to reach the lands since there was only about 2mm of the bullet in the case neck. The 150's were fine. I loaded up some Lapua LRP brass with 43 grains of AR Comp and the 150s seated touching the lands.

Took the rifle to the range last month to zero the scope and shot a couple of 5 shot groups at 100 yards. It did kinda OK but definitely needs more work. The problem is that the Berger 150s seem to be hard to find right now. I think I will order a slower 13 or 14 twist barrel with a Fullbore chamber that should have a shorter freebore next time for the lighter bullets.

 

[troupe]

That is what I have considered, selling this new barrel and getting a slower twist.

 

[Orr89rocz]

Seems like a good barrel for 168-200’s

 

[D-4297]

If you are loading single-feed , then you may want to try the Berger 185gr Juggernaut Target . Sounds as though there is enough chamber space for them , and they are accurate . Try a starting load of VV-N-150 at around 42.6gr , and go up till you get to around 2650fps . Looks like you have a shorter barrel , so I won't give up a F-TR load for a 30" - 10 Twist .

 

[benchracer]

The 9 twist won't hurt anything. I have a 9 twist with the 2013 FTR chamber, which is cut for Berger 200.20X. With a fast twist and a long chamber, here is how it shot Sierra 175 TMK's during a seating depth test:

 

[troupe]

I have a 15 twist Hart barrel that was chambered for another, smaller 30 cal cartridge. Hopefully the barrel will be nice. Supposedly un-fired. Looking forward to it.

 

[clowdis]

I've got a 9 twist .308 Brux on a Panda action that will shoot the 200 grain Sierra Matchkings great but smaller, lighter bullets like the 155's not so much.

 

[FrankG]

I had a 8 twist 308win. Shot box Hornady ammo 168AMAX's with no issues. Handloads typically where 175SMK in front of 42gr of Varget.

 

[troupe]

May give the factory ammo a try.

 

[CJ6]

Why use such a fast twist for medium to light weight bullets?

 

[FrankG]

Why use such a fast twist for medium to light weight bullets?

I wanted to play with it because for the ASR solicitation all 30cal barrels had to be 8 twist. Didn't matter if it was going to be chambered in 308w or 300 Norma. That's what they standardized on for the twist rate.

Is it better than a 1-10? I'll say no.

As long as you are shooting good quality bullets / ammo the 8 twist isn't going to hurt you with the lighter bullets.

Spin drift of the bullet will go up some though.

Later, Frank
Bartlein Barrels

 

[Konocti's Wigwam]

As long as you are shooting good quality bullets / ammo the 8 twist isn't going to hurt you with the lighter bullets.

That's true, but it would certainly help for heavier bullets. My question is, do we have the bullets to take advantage of that? Seems we're more in the 180-190 grain for some of the heavier bullets, although I do have some 210 grain SMKs I shoot 300 bo subsonic. A completely different beast. Maybe a 1:8 would stabilize a 210 SMK in the 308, but I would be skeptical. What say ye, Frank?

 

[FrankG]

That's true, but it would certainly help for heavier bullets. My question is, do we have the bullets to take advantage of that? Seems we're more in the 180-190 grain for some of the heavier bullets, although I do have some 210 grain SMKs I shoot 300 bo subsonic. A completely different beast. Maybe a 1:8 would stabilize a 210 SMK in the 308, but I would be skeptical. What say ye, Frank?

Bullet length not bullet weight and velocity dictate twist needed.

I don't have any 210smk laying around to measure. I did measure a 230ATIP which is 1.76" long and a 230SMk which is about 1.74". At 1100fps they need a 1-7 twist min according to my numbers.

So a 1-7 should work for ya.

I built my kid a AR15 in 300BO. It's a 7.5 twist barrel and with box Hornady Amax 208 ammo... which is basically subsonic as it comes out of the gun right around 1090/1100fps if I remember correctly and that thing will give you .5moa at a 100 yards day in and day out with no complaints.

Later, Frank

 

[shoot4fun]

Bullet length not bullet weight and velocity dictate twist needed.



Later, Frank

I'm confused but this statement (nothing new).
I always thought it was more about a bullet's bearing surface length than the overall length.
Is it not the bullet's OAL that effects BC? (why we sort, trim and point bullets)
With all the polymer and/or aluminum tipped bullets out there today the OAL is all over the scale.

 

[FrankG]

I'm confused but this statement (nothing new).
I always thought it was more about a bullet's bearing surface length than the overall length.
Is it not the bullet's OAL that effects BC? (why we sort, trim and point bullets)
With all the polymer and/or aluminum tipped bullets out there today the OAL is all over the scale.

It's bullet length. I don't measure bearing surface when doing a twist rate calc.

Another issue I feel that comes into play is the balance of the bullet/design and it's not talked about a lot.

Some bullet makers try to compensate by running a faster twist to offset the balance of the bullet to make them fly better but your only masking the problem when this is happening.

 

[D-4297]

Both the Finns and the Russians made Mosin-Nagants with 9-1/2 twist barrels and the bullets were primarily 148 - 152gr bullets . Velocity was average 2780 , and some were extremely accurate . Barrel length was 29-1/2" to 30" .
FWIW ; The Soviet Sniper round , 7N1 was a 152gr HP , and "Deadly" accurate out to 750 meters .