Can anybody tell me about this caliber? I saw a Griffin and Howe listed in this caliber and know nothing about it?

JAB: I'll take a stab at your question but I know nothing personally about this cartridge. Accoding to P.O. ackley's "Handbook for Shooters & Reloaders", vol.1, pg. 433, the .300 Apex is the same case as a 6.5 Apex but necked up for .30 cal. bullets. He lists 3480 fps for a 150 gr. bullet & 65 grs. of 4895 powder. Also, 3213 fps with a 180 gr. bullet and 69 grs. of 4350. Keep in mind, his info is seriously dated. The powders listed should be Hodgdon's, IMR didn't offer these when Ackley wrote the books.
The 6.5 Apex (pg. 373 in the same book) were made by shortening & necking down .300 H&H cases. There's more info in the book but this is the gist of it. Hope this helps some. Bear in Fairbanks

JAB: Ooops, sorry. I read your heading as ".300 Apex" rather than ".338 Apex". There is no listing in Ackley's books for a .338 Apex. bear in Fairbanks

Bear,
That's pretty much what my Ackley says about my .300 Apex. I do get 3400 out of my rifle with a 150 grain Nosler. My rifle is my favorite bolt rifle, a "go to gun"! It's a bit rough on the brass with the steeper shoulder.

I've been through my material and I haven't come accross a mention of an 338 Apex. Wish Sam May and the Apex Rifle barrels were still alive and in business. Sam would know!

Rusty
We band of brothers!