[jfremder]

I have a new Rossi M92 Lever Action Carbine in .45 Colt I'm breaking in. I want to develop some accurate loads with the Missouri Bullet Cowboy #1 and Cowboy #4 (Lead 200+250 gr RNFP #12 Brinell)

I Have AA#2, AA#5, IMR4227, Universal Clays, Blue Dot, H110

Has anyone had experience in this area they'd care to share?

[Gryffydd]

Slug your bore. Make sure your bullets are sized appropriately. This will help keep leading down as well. I don't know about the Rossi '92s, but I know the Marlin .45 Colt rifles tend to have pretty loose bores (.453-.454)

[ArchAngelCD]

Of the powders you have I think AA#5 ans Universal are the two you should try. The others are either too fast or too slow IMO.

Universal will closely mimic Unique but will meter better and shoot cleaner. AA#5 also produces very good .45 Colt ammo.

From the Hodgdon site:
200 GR. CAST LRNFP Universal 1.600" 6.4 749 5,700 CUP 8.8 1067 13,600 CUP
250 GR. CAST LRNFP Universal 1.600" 6.5 742 9,200 CUP 7.8 941 13,000 CUP

From the Accurate site:
No.5 210 MCB RN BB 10.9 gr 904 fps 12.1 gr 1,027 fps 12,500 psi 1.620"
No.5 255 LC SWC 9.4 gr 846 fps 10.4 gr 961 fps 13,400 psi 1.600"