My Martini has a .295 bore and .307 groove.The throat is very large compared to the standard GP 90 chamber in 1889 Rifles.The throat starts at .328 and sort of tapers to groove diameter.My 1889 was .320 at chamber end.
I modified the rear band of a .322 dia mold to. 328.With this it easily breech seats and the initial (over the hood) shooting session at 50 yards shows promise.
Shooting a .020 oversize bullet goes with my theory that throat fit is more critical than bore dimensions.
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