Here is the chrono data for the cowboy load I described above, as well as recipe & velocities for the hunting load. All data was collected 15' from muzzle over a Oehler 3 screen chronograph, it has not been corrected to give muzzle velocity. Conditions were 65 F, 30% relative humidity, wind calm.
Sight setting was using rear sight with the staff laid down, top of front sight even with top of the square notch of rear sight, not the top of the "V".
Cowboy load that prints dead on @ 25 yards, center hold. 1st shot from clean barrel, 596 fps, remaining shots averaged 572 fps.
Hunting load, with center hold, prints 4" high @ 25 yards, 5" hi @ 50 yards. For first shots from clean bores 4.5" @ 25, 5.5" @50.
1st shot velocity 990 fps., remaining shots averaged 976 fps. I'll use a bottom hold on the deer.
Interesting note: cowboy load windage is dead on, the hunting load is 2.5" right of center @ 25, 4.5" right @ 50. So, you might want to readjust the rear sight if you want to use this load for hunting.
Here's the recipe for the hunting load: 28gr by volume (14.8 on Std Belding & Mull charge tube if you have one), Swiss 3F, Federal magnum large pistol primer, once-fired Starline annealed brass, neck sized, moderate roll crimp, 365 gr. Rapine bullet 20:1, sized to .512", SPG lube, 0.030 Walter's wad, 0.035" compression, no drop tube, from a Lyman 99 measure, 1.503" loa. Group size @ 50 yards, 3" wide by 2.5 high.
I think I'm done messing around with this rifle now so don't look for any more from me until after hunting season. I plan to try for a whitetail with this beastie.
Thanks to all the Spencer Shooting Society members for their helpful posts & emails along the way. This has been a great project.
Email me if you have any questions.