338 Lapua question

[DaDavis]

30" custom Hart barrel w/9 twist
300 grain berger hybrid bullet @2715 fps

Rifle was built in Montana (4000' elevation) and shot 10" @ a mile. Brought rifle to Texas (25' elevation) and accuracy is not quite the same.
Question is, is that 300 grain bullet too heavy to stabilize, or even on the edge of stabilizing, at this altitude in Texas?.......... I'm dealing with my hard headed cousin from Montana....... lol

 

[davidjoe]

I stabilize 300 grain bullets at similar elevations. I don’t believe I have any LM barrels as fast as a 9 twist, either. 10 twist is considered adequate for heavies in factory guns, I believe.

I don’t think stability is the issue. It would stand to reason that denser air, whether still or moving, exacerbates the bullet deviating from its original path more than less dense air would.

I would add though, that 300 grain Bergers seem to have a following in higher elevation ELR settings, while I personally have had better luck with Lapua Scenars at the lower elevations I shoot at. Elevation may or may not factor into this, but it’s the way the bullets have sorted out for me, and low elevation is where I’ve shot most of my .338 rounds.

 

[snowpro440]

9 twist is plenty fast, might check your tune at that temp and altitude . Then again your cases might have grown a lil if they sat for awhile.

 

[Diverjeff]

According to Berger's Twist Rate Stability Calculator you should be fine.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

 

[Ledd Slinger]

If you have stability issues, you should be able to see it on the target with how the bullet passes thru the paper, but I highly doubt stability is the cause with a 9” twist.

Changing elevation that drastically is the same as changing your powder charge weight in a load. Probably just need to re-tune the load or go back to the drawing board all together and test different powders/seating depths

 

[DaDavis]

If you have stability issues, you should be able to see it on the target with how the bullet passes thru the paper, but I highly doubt stability is the cause with a 9” twist.

Changing elevation that drastically is the same as changing your powder charge weight in a load. Probably just need to re-tune the load or go back to the drawing board all together and test different powders/seating depths

It's my cousin's gun and

 

[DaDavis]

It's my cousin's gun and

He's hard headed and thinks because it shot there, it should shoot here. He's very discouraged and I'm just trying to help him out . Thanks for the input!

 

[miningshawn]

Altitude Density is a factor here. I live in Montana and tune my loads at 6000 ft of elevation. When I go to the lowlands (pretty much not here) I often need to change my seating depth, and not much else.

I wish I could tell you "X" one thousandths for "X" change in DA - but it doesn't work that way. When I have an event, I seat long and set depth during the tuning session. Having a tuner or tuner brake also helps a lot.

FWIW I also use an OCW method for powder/primer selection.

Good Luck!

 

[DaveTooley]

1-9 is plenty. 9.3 has been the standard for all the barrels I've done for various military organizations. Just needs tuning. Maybe
Got a question though. How do you get a 10" one mile group in your wallet?
I could say everything is bigger in Texas but I won't.

 

[Sandstorm]

Just need to re tune the load.
Completely different atmosphere in Texas..
And I don’t mean that in a bad way either.

 

[ronemus]

A 1:9 twist will stabilize Badlands Precision 285 gr, Warner 285 gr Flatline, and Lehigh Defense 254 gr copper monolithic bullets at 960' elevation in my .338 LM (all of which are much longer than 300 gr lead-core bullets), so I doubt that stability is the reason for the difference.

 

[Ledd Slinger]

He's hard headed and thinks because it shot there, it should shoot here. He's very discouraged and I'm just trying to help him out . Thanks for the input!

If he’s ignorant about climate change effects on accuracy, then I would assume he’s not very adept at reloading and the rifle was never in tune in the first place. Most likely just went with the first load that shot good and thought he was done. Probably never ran any ladder tests with small changes in charge weights or seating depths. So any climate or elevation changes like that on a load that’s not tuned in the middle of a good node will throw the accuracy completely out of whack.

I hunt and shoot at a lot of different elevations from 3000 feet to 7000+ feet in Montana. When my rifles are tuned to good nodes, my drop charts can vary with big changes in elevation, but the accuracy remains relatively the same.

 

[C.O. Shooter]

I have shot the 300 Berger EOLs and currently shooting the 275 SBD2 Badland Precision, with great success!

30” Bartlein, 1-9” twist, 5R, heavy palma contour.

 

[Mike TackleBerry]

30" custom Hart barrel w/9 twist
300 grain berger hybrid bullet @2715 fps

Rifle was built in Montana (4000' elevation) and shot 10" @ a mile. Brought rifle to Texas (25' elevation) and accuracy is not quite the same.
Question is, is that 300 grain bullet too heavy to stabilize, or even on the edge of stabilizing, at this altitude in Texas?.......... I'm dealing with my hard headed cousin from Montana....... lol

You have a SG of 2.36 which is more than enough.

 

[majohnson]

First you need to check your twist rate, and see what it really is. I shoot 300gr OTM Bergers here in Colorado, and environmental conditions are light & day difference. You need to rework your load if you can expect any kind of accuracy. Check your weather using the same settings just change your altitude see what you come up with.