300gr .338 Lapua Mag COAL question

[tomhol]

Current AI mags allow 3.6" COAL and the new AI CIP mags will supposedly allow 3.75" while the seekins BM system will allow 3.9" COAL. How much difference would seating the bullets 0.15" or .3" longer make shooting at 1K and beyond. I'm debating using an A3-5 w/ seeking BM or AICS stock in a 338 build and want input.

Thanks

 

[ChrisGarrett]

Re: 300gr .338 Lapua Mag COAL question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: tomhol86</div><div class="ubbcode-body">Current AI mags allow 3.6" COAL and the new AI CIP mags will supposedly allow 3.75" while the seekins BM system will allow 3.9" COAL. How much difference would seating the bullets 0.15" or .3" longer make shooting at 1K and beyond. I'm debating using an A3-5 w/ seeking BM or AICS stock in a 338 build and want input.

Thanks </div></div>

That's the crux with shooting the two 300s at mag length, you do, in theory, handicap yourself. This being said, unless you're pushing 2000 yds, you should still be able to group well at X, Y or Z mag length.

Chris

 

[Lt. Arclight]

Re: 300gr .338 Lapua Mag COAL question

The biggest factor is regardless of COAL-you have to develop a load that is going to be consistent.

A consistent load running at 2775 is better than extreme velocity swings around 2900. I've shoot out to a mile and had good results from my existing 300SMK loads. My AI is the CIP variety and I have no interest in changing platforms for case capacity that I'll never need.

I had a McMillan Tac338 that had been rebarreled once and was chambered to around 3.75 coal. I had the 2nd barrel set back after around 1000 rounds and the chamber cut to the CIP dimension. My accuracy increased.

Fact is the longer COAL is allowing you to really push the 300SMK-how much depends on how far you really want to reach out.Not to mention if you really want to shoot past 1700-2000 yards-I'd consider a 375/408 anyway.

 

[tomhol]

Re: 300gr .338 Lapua Mag COAL question

Thanks for the input guys. I think I'll stick with my original build plans using an AICS/CIP mag system then. Thanks