Joined
·
416 Posts
The earlier thread about the 6.5 Carcano set me to thinking about its rep as being terribly inaccurate. I can’t believe that any military (except our own, and I’m not going into that here) would design, manufacture and equip its troops with something that bad, although neither of my Carcanos shoots worth anything. They are both solid guns, chambers aren’t sloppy, and although I could measure freebore I haven’t – I don’t think that’s the problem anyhow. I came up with a couple of ideas, maybe wrong, maybe not, and I’d sure be open to anybody else’s theories.
First off, the Carcano was made for a .265” diameter bullet, not our standard .264”. I don’t know how much difference this makes. The cast bullets I’m shooting are sized to .264” from an as-cast size of about .266”. Maybe try them as-cast?
Second, and I’m thinking this might be more on the right track, the Carcano utilizes gain-twist rifling, from about 1 in 19 to about 1 in 8. I don’t know the theory behind that, but does that maybe make the gun more sensitive to the load? The original military spec was a 162 grain jacketed bullet at 2296 FPS. I don’t know of any .265” jacketed bullets on the market, but Hornady makes a 160 grain round nose (#2640) that might be close enough. I calculate 34.1 grains of IMR4350 (35.0 grains max load) will drive that bullet out at just about the mil spec velocity. Would that make a difference?
Open to any suggestions.
DC
First off, the Carcano was made for a .265” diameter bullet, not our standard .264”. I don’t know how much difference this makes. The cast bullets I’m shooting are sized to .264” from an as-cast size of about .266”. Maybe try them as-cast?
Second, and I’m thinking this might be more on the right track, the Carcano utilizes gain-twist rifling, from about 1 in 19 to about 1 in 8. I don’t know the theory behind that, but does that maybe make the gun more sensitive to the load? The original military spec was a 162 grain jacketed bullet at 2296 FPS. I don’t know of any .265” jacketed bullets on the market, but Hornady makes a 160 grain round nose (#2640) that might be close enough. I calculate 34.1 grains of IMR4350 (35.0 grains max load) will drive that bullet out at just about the mil spec velocity. Would that make a difference?
Open to any suggestions.
DC