8.15x46R

[Berlin1960]

Goodmorning.

I am shooting the 8.15x46R in two Gew 98's which were built for the cartridge. Both rifles have .316 dia bores...

My question is...when it comes to cast bullets (boolits) should I shoot .316, .318 or can I shoot the .320? I ask about the .320 because I have some H&N made cast bullets from Germany which were supposedly made for this cartridge and they measure.320 dia. I was told these are the most accurate bullets in these rifles...

Basically, I am not clear on the cast bullet sizing...do I go with the bore dia or do I go with a larger dia?

thanks for your time.

Ben

[Bret4207]

Bore diameter is the measurement across the lands, groove diameter is the measurement across the grooves. You want to be at least groove diameter. The first question is are your grove measurements actually .316 or have you been told they are .316? If you have personally measured slugs indicating they are at least .316 then I would next measure the inside diameter of a fired case from the particular gun in question fired with a full power load. That will let you know the max diameter you can go without neck reaming, etc. You'll likely be working between those minimums and maximums.

When we speak of "fit" or "fitting the boolit to the gun" what we basically mean is to fill the throat of the gun. That's about as simple as it can be made. That doens't mean that a boolit of throat diameter will be perfect for that gun and load, but 9 times out of 10 it will be a very good place to start. If the throat will allow you to use a boolit that is +.004 over groove diameter you can certainly try that as long as you understand you need to start with low powdered loads and work up. Usually +.002 over groove would be my starting point. IIRC the 8.15x46R is a fairly low powered Shuetzen type cartridge with a slight bottle neck case. The faster powders can be used in that type of case very successfully and reduced loads carry little risk of SEE issues. So you can start with "cats sneeze" loads with your .320s if the gun will accept them. It won't take more than 3-5 shots to see if they show any promise.

If you find the .320 is too large a Lee .312 sizer can easily be opened to .317, .318, etc. with abrasive paper on a rod or by having Buckshot or one of the other members here open it. That would allow you play with sizing the .320 boolits down. Different rifling styles and throat styles can alter what we would normally think of as a common sense area to size to. If you have an odd European style of rifling or throating you may be able to do somewhat unusual things as far as size or it may limit you. You'll have to play with it and see. You can take some comfort in the knowledge that cast is far more forgiving in the way it handles being swaged into an "undersized" barrel than jacketed.

Hmmm, a long winded answer that probably will add to your confusion. Ah well, if that's not clear I can try and condense it for you.