.338 jtm ???

[Jim338]

I have an old custom rifle I’m working over for a friend of mine. The ol gent that built the rifle is long sense passed away and we have no loaded ammo or load data to go off of. First off has anyone heard of or have any info on this .338 JTM. Apparently it was inspired by a magazine article from the early 70's. I haven't been able to find anything on it. It’s a 375 H&H necked down to .338. If not how does one calculate the burn rates and such to come up with the correct powder and starting load? Any help will be much appreciated.

Remington 700
Krieger barrel (We think)
1:12 twist 26”

 

[18panther]

John L. Turner, Austin Texas.

Great man,Great cartridge!!!

I'm actually fireforming brass for a 7x308imp. he built.

 

[Jim338]

Very good, that's a start. Thanks for the reply!

 

[wadebrown]

If it is a .375 H&H necked down to .338 its case capacity will be close to the 338-375 Ruger so you may be able to use load data that is available for that round as a starting point.

Just a thought.