This is an update on getting my Ruger #1 45/70 to shoot cast boolits accurately. I bought this little rifle as a light weight hunting rifle for sambar deer (an elk like animal) and though it shot J words well, it nearly broke my heart with cast. Adding a Limbsaver recoil pad made it fit like my shotgun and I was determined to use it for hunting.
Initial groups with a variety of .458" cast bullets saw it shooting like a shotgun too! Patterns instead of groups. The bullets all over the place and key-holing starting at 1400 fps.
I wanted maximum velocity and even my old Marlin would shoot 400 gn cast boolits to nearly1800 fps accurately though not comfortably. Whilst these are listed as safe loads in lever guns I found it quite alarming shooting them in that action.
Knowledgable people from this board advised larger diameter bullets which worked to a certain degree but accuracy was not good enough at more than 1700 fps to hit a deer at 150 yards. I suspected it was the rough constrictions in the bore under the barrel band and fore sight band that I discovered when slugging the bore. I read that sometimes excess heat used when soldering these fixtures to the barrel at the factory can cause this.
Last chance before a new barrel was fire lapping. Even though being warned it might ruin the barrel I figured it was no good anyway so had nothing to loose.
The upside of 30 rounds of fire-lapping using a fine abrasive was the removal of the roughness and constrictions in the barrel but the downside was the removal of the start of the lands (there was never much of a throat). It sure made the bore shiney and smooth though. The question was though, would it shoot?
Well, I loaded up some stiff loads of Beagled RCBS 405 GC boolits that run .461" and weigh 420 gns with WW plus 2% Sn and headed out to try them with no great optimism. What a surprise. As the target shows accuracy peeked at around 1940 fps which is as fast as I can load them with the powders available to me. I used AR2206 (like IMR 3031) and AR2206H (H4895) with compressed loads and although my goal of 2000 fps looks out of the question I am content with what I have.
The three groups pictured were shot at only 55 yds and are only 3 shot groups, but I feel the 1/2" to 3/4" spreads show great promise. The recoil generated by these loads combined with the low weight of the rifle meant the damn thing was leaping like a trout off the bench anyway. After 40 odd shots the muscles in my arm were jumping too and I was lucky to hit the target.
At this stage it looks like fire lapping has worked for me though I suspect it was a fluke and probably not repeatabe. I can not recommend anyone knowingly accelerate the wear of their barrel like this. It was a last chance option for me and was worth the gamble. I can't help thinking though what a new cast boolit dedicated barrel would be like.
Now to try it at longer range; then to make some of Bruce's soft points, wait for the weather to cool and the hunting season to begin.