whats it called?
8mm rm or the 7mmstw to .308

I believe it would be real close to the 300 Jarret. He changed the dimensions a little.

There is also the 300/8 Mag. I had one and liked it. Shilen has the reamer. I eventually put the barrel on a different action and took the opportunity to change it to 300 Wby just because if i decided to sell it I could get a better deal.

There is no functional difference between it and the 300 Wby. I used 300 data to reload with no problems. Even though I started low, I was always able to reach max in the books without undue pressure. And that from an 8" twist!

quote:

There is no functional difference between it and the 300 Wby

Yep they would be real close. My data shows the 300Wby has 3-5grs more capacity. Depending on the source.

Clymer calls it the 30-8mm mag. They have the dimensions on their site. The Jarret has a 35deg shoulder vs the 25 of the 8mm.

30 ackley

jeffe

I admit I'm speculating here but I bet the actual capacity of a 30/8Mag is the same or greater than a 300 Wby, reason being the brass is thinner. If you go by the exterior dimensions you will get that 3-5 grains though. Going by reloading results, I bet in the case of my brass it had more rather than less capacity.

Tiggertate,
You might be right. I was just looking as to what Loadtech called the capacity.

Like I said, I'm just guessing based on anecdotal observance of primers and case stretch. It is a fine round in any form one wants to use it.

300 Jarrett

The case capacity of the 300 Wby with Wby cases is greater than the capacity of the 8mm Rem with Rem cases. It looks like they should be very close but the Wby has the advantage. I took two new cases and plugged the primer holes with tissue. I filled each case full to the top of the neck with W760 powder and weighed the powder. The Wby case held approx 3 grs more. Several other cases were tried and all results were very close to the original 2 cases.