375-338 Lapua Improved

D

dyoung

Sergeant
Full Member
Minuteman
Sep 26, 2009
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CA
#1
Is there any one out there that can help me with a re-barrel project that I was considering. I have a Sako M995 in the Lazzeroni warbird and I am tired of burning up barrels. Want to rebarrel in to 375 in a 338 Lapua Improved...but can not find print or any ballistic data, barrel twist etc.

Has anyone done this?
 
#4
Re: 375-338 Lapua Improved

That's asking a lot, to push a bullet that is 50 grains heavier at the same velocity. I would say 2800 or something in that neighborhood, maybe a little better is more realistic. You are going to push the .338 bullets faster in that configuration, and if you are going to run the same weight bullets as the .338, you are going to sacrifice Ballistic Coefficent. I think the only way you are going to beat the .338 Lapua (improved or not) with a .375 bullet is to go with the .375-408 or another higher velocity .375 cartridge. If you want to stay with the Lapua bolt face and action, stay with the .338 caliber, that is my opinion. No reason to pay more for bullets and get less performance
 
#6
Re: 375-338 Lapua Improved

Thanks Guys
I hear you Dave about less performance than a 338L but I have a GAP 338LM already so I wanted to make 375 to hunt with (maybe a few trips to Africa too) not necessarily to "beat" the 338L at long range. I figure it will out perform the 375 H&H by a lot. Rocky Mountain makes a high BC 370 gr hunting bullet...but at the sacrifice of speed of course. That's why I was hoping to find someone that has done it. Dave Viers from Black Diamond Rifles got a print made for me and said he can chamber and make my dies too. I was thinking of a 10.5 twist.

Anybody want to chime in?

Doug
 
#9
Re: 375-338 Lapua Improved

Dave- One thing he'll have going for him with the heavier bullet is that the bore is bigger. A 338-06 will throw 250gr SMK's as fast as 210 VLD's come out of a 30-06 because you have a large increase in pressure area on the bullet base. I have similar effect with my 6mm-223. It will shoot 100gr 6mm BTSP's at the same speed my 223 will throw 75 BTHP's, the bearing surface is within 10% and so is the bore diameter, but the pressure surface is about 22% greater.

You may not get 3k with it, but 2950 might happen with the right powder.

I think this would be an interesting round to make and it should only improve on the barrel life of the 338 LM.
 
#10
Re: 375-338 Lapua Improved

don´t work with the 350 SMK´s. Way to mutch bullet. Use 330 LEHIGH .375-100.

Have don it in a "non AI" .338Lapua case.
Just neck it up....
Getting 2850fps using the Lehigh hBN-coated from a 28" BBL

You may get some +fps from the AI, but don´t think it´s worth the affort...

Best
2RECON
 
#11
Re: 375-338 Lapua Improved

Thanks Recon
What do you mean when you said "way too much bullet"? I was trying not to shoot solids...as I want to be able to hunt with it. Anyone use the Rocky Mountains?
 
#13
Re: 375-338 Lapua Improved

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dyoung</div><div class="ubbcode-body">Thanks Recon
What do you mean when you said "way too much bullet"? I was trying not to shoot solids...as I want to be able to hunt with it. Anyone use the Rocky Mountains? </div></div>

Just so you know.RG Henson (HAT)=Henson aluminum tipped, makes High BC .338 hunting bullets.

Steve
 
#14
Re: 375-338 Lapua Improved

Thanks guys...I think I am going to go for it and do the 375 Lapua improved.

It of course will take a while to get my barrel. Thinking 26"Brux standard 6 groove 10.5 twist.

Steve can you send me a link for the HAT bullets for my other rifle (338LM)? Can't seem to find it.

Doug
 
#17
Re: 375-338 Lapua Improved

I know some one who is building a 375-338lapua improved and with the cutting edge new hunting 330gr BC.850 and 350gr BC.900 should equal the ballistics of the 338 lapua imp with a SMK 300gr. Kirby has already done one and has info on his web site ie: 28 inch barrel 2900fps 350gr, the guy that is building the 375-338Lapua imp is going to use a bartlein 32 inches barrel and is hoping for at least high 2900s if not 3000fps with the 350gr. The extra barrel life the 375 should give over the 338 version should mean alot more fun at the range.
 
#18
Re: 375-338 Lapua Improved

Not to throw a wrench in your spokes, but have you considered a 375-416 Rigby? Same bolt face as the LM with more case capacity...
 
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