The Search Begins

I measured chamber throats on both guns and found them to be a uniform .451, so I figured just trying different loads would solve the problem. Several loads were assembled using bullets from .451 up to .454.

Using the RCBS #45-255 KT sized to .454 over 6.0 grains of Red Dot (and also 6.0 grains of Clays) saw the Cocobolo .45 averaged well under 1-1/2" while the walnut gun came in over 3".

An assortment of bullets sized to .451, including the RCBS #45-270 and the Lyman #454424 over 6.0 grains of Red Dot and 6.0 grains of Clays shot even better in the Cocobolo .45 — groups averaging just under 1". The walnut-stocked .45 remained a lost cause. The Cocobolo Colt Mountain Gun shot everything well and the walnut-gripped .45 continued to shoot poorly. Handloading didn’t solve the problem — so now what?