Others may disagree with this, but I believe another issue Ganderite is having with his groups is the Campro bullets.
What kind of accuracy would you get out of a 357 mag handgun with those bullets at 50+ yards? Don't expect better out of your lever action rifle.
I ran into the same issue and a local Cowboy Shooter tuned me in on his findings. He shoots his lever action rifles a lot with moderate pressure loads, behind mostly cast lead bullets.
I had picked up a couple of thousand CamPro 158 grain FCP at the Chilliwack gunshow last spring and even though I was satisfied with them in my revolvers, I could not get them to shoot well at 50+yds.
I tried different powders, primers and cases. Played with seating depths, etc. They shot into 2-4 inches consistently.
I didn't get "stringing" issues, just clusters. I shot off my normal bench rests.
At 25 yds the loads shot 1-1.5 inches very consistently.
It was perplexing as the bullet weights were very consistent and the finish was excellent.
I gave up on them in my rifle, a Chiappa, model 92, with a 20 inch bbl and factory sights, which thankfully didn't need to be adjusted, right out of the box.
The Cowboy Shooter told me he had the same issue with all three of his rifles, which were made by three different manufacturers. Two Italian and one Winchester.
That's fairly conclusive, IMHO.
He showed me his targets, and loads, which were similar to mine.
He had purchased a thousand CamPro FCP bullets to see if he could cut down on his casting/prep time. I don't know if they are allowed for Cowboy Action Shooting, but his idea was to use them for practice and his cast bullets for competition.
Anyway, he decided to try "other" manufacturer's jacketed bullets and found they shot tighter groups out past 50 yards.
He knows his stuff, when it comes to lever action rifles in 38spl/357 and several other calibers, so I decided to try some different brands of bullets of similar design.
I used some 125grn Lawman(Speer) bullets I have on hand and the groups tightened up substantially. So then I went to some 158 grain, half jacket hollow points from Speer and they shot into an inch at 50 yds and also worked well in the "insert" barrel of my 12ga. SXS.
One other thing he suggested was to use "rifle" loads from the manuals, rather than pistol or Cowboy Action Loadings.
He knew what he was talking about.
I was to the point of selling the Chiappa if I couldn't get it to shoot acceptably. I'll be keeping it now.
I also tried some 180 grain Hornady XTP bullets over 12.5 grains of 2400/CCI 450 primers. These gave 1500+fps in my rifle and shot the best of all the jacketed bullets, sub 1 inch.
I have a mold which throws .361 diameter bullets, weighing 175 grains. I powdercoat them and they measure .363 in. My rifle shoots these very well, with 2400. Need more work though. I only had 20 left when I loaded them up.
I would like to say the longer, heavier bullets shoot best, but the 125 Speer Lawman bullets are almost as good.
