Chamber-Neck Dia.

[BrushBuster]

I wonder if I could have advice on the following?

I have recently completed chamber casting my .348 Winchester, with the intention of shooting both Cast and Jacketed bullets in this lever-gun.

My bore size is .3475, and from what I have learned, this should have me looking for a sized cast bullet dimension of .350 and more.

What has me a little concerned, is that the chamber Neck dia. is only .002 over the factory loaded .348 jacketed cartridge (.001 all around)! Now this is a great fit for a jacketed bullet, and I won't be resizing the neck because I want the capability of shooting both types of bullet, but does this mean that when I begin seating .350 dia.(min.) cast bullets, I could be entering into a high pressure situation and possible chambering difficulty? I'm intending to use CB's with a BHN-18 minimum.

I haven't purchased a mold or made cast bullets of that size to try out, so this is hypothetical, but I would like your opinions as to this close tolerance leading to problems of inflexibility with different bullet diameters. Am I concerned unneccesarily?

Thanks
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[gunnut69]

I am not an avid cast bullet shooter but From my limited experience your dimensions, I'd use a bullet casting .348 to ,3485 or so..  A cast bullet wil bump up and seal from the pressure pushing on the base..  Slightly over bore size is all that's needed(not groove diameter bore diameter).  Let me know how it works for you, I've set of blocks and a 71 that I also intend to use with cast slugs..  You may ask the guys over in the cast bullet forum,, they really seem to know their stuf...