[Swiftriverrob]

Three different primers, 3 different brass, three different powders, three different bullet diameters. We now have a load that will shoot just under 1 inch, center to center, at 100 yards.
Primers were the biggest variable. CCI gave us huge groups, Remington 9 1/2 produced tight groups, but frequently produced a flier, Federal were consistent in performance. Brass, no difference in performance but wall thickness forced changing the crimp. Small problem. Powders. We started with Blue dot, an unusual choice but produced good, not great groups. We appeared to have a problem with it as temperatures were often below freezing. The warmer the day, the better the group. We switched to 4227, an had consistency. We loaded about 8 different powder charges, working down by 0.1 grains each time. Three bullet diameters, .378,.379, .380.
The .380, a coated cast bullet from Chey Tech, out of Cheyenne Wyoming were the best.
So the optimum load, so far is starline short brass, Federal 210 primer, IMR 4227 powder, 21.3 grains, and the .380 coated bullet.

 

[Strugl4xsc]

good job, I love it when your efforts are rewarded, that is amazing accuracy any way you look at it.

Sent from my SM-G930R4 using Tapatalk

 

[JohnM1]

Love my 38-55 Cowboy. Only problem is the my eyesight doesn't allow for long range open sights any more.

 

[GITU1]

Any idea of the velocity fps?

 

[67404]

Three different primers, 3 different brass, three different powders, three different bullet diameters. We now have a load that will shoot just under 1 inch, center to center, at 100 yards.
Primers were the biggest variable. CCI gave us huge groups, Remington 9 1/2 produced tight groups, but frequently produced a flier, Federal were consistent in performance. Brass, no difference in performance but wall thickness forced changing the crimp. Small problem. Powders. We started with Blue dot, an unusual choice but produced good, not great groups. We appeared to have a problem with it as temperatures were often below freezing. The warmer the day, the better the group. We switched to 4227, an had consistency. We loaded about 8 different powder charges, working down by 0.1 grains each time. Three bullet diameters, .378,.379, .380.
The .380, a coated cast bullet from Chey Tech, out of Cheyenne Wyoming were the best.
So the optimum load, so far is starline short brass, Federal 210 primer, IMR 4227 powder, 21.3 grains, and the .380 coated bullet.

I found similar results. Mine settled in with 21.0 gr of H-4198 and a .380" normal lube-in-the-groove bullet. Like you the primer was the difference maker. With 4198 the Winchester Large Pistol primer produced the best results. Faster rifle powders producing medium velocity loads, what the cartridge was intended to produce, have proven best in all my straight wall cartridges 28-30, 32-40, 38-55, 40-65, and 45-70 with cast bullets. 4227 is one magnum pistol powder that can cross over and work well in rifle cartridges. The other two powders worth checking out is good old 5744 and Herco. 5744 was designed to be a smokless replacement for BP and It works great as well. Herco works very good with heavier bullets for caliber running in the BP velocity range. I like it better than Unique. It has a little more volume per weight and a good place to start is with low end Unique load data and work up.

Great results. Now the problem is resisting the temptation for futz with it now that you have it dialed in!