Quote:
Originally Posted by shocker
My experience with cast bullets (no GCs) in bottleneck cartridges originally meant for smokeless powder is keep velocities around Mach 1. Push too hard on them and accuracy goes to pot. I guess I found out why old blackpowder cartridges used heavy bullets and slow velocities.
This link is to 30-30 but it will give you an idea of what I'm talking about.
30-30 Ackley Improved Powder Weight /Velocity Data for the 170gr RNFPbb
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I agree. I follow the same approach with my Model 94s in .38-55. A 280 grain bullet at around 1100-1200 fps is the sweet spot.
One of the challenges in the .30-30 and .25-35 and a few other rounds from dawn of the smokeless powder era is that they were not designed for either black powder or cast bullets.
At 2000+ fps velocities leading is an issue and a gas check is only a partial solution. A lead bullet needs to be closely fitted to the throat of the rifle (no more than .001" under throat diameter). Way to many hand loaders make the mistake of thinking the bullet should be .001" over the bore diameter. That almost always leave the bullet way undersized relative to the throat.
For example, in a .38-55 the bore diameter may be .378"-.379" but you may need a bullet in the .382" range to fit the throat. In the .30-30, the bore may be .308-.309" but a .311 or .312 bullet may be needed to fit the throat.
In addition, the alloy needs to be soft enough to quickly obturate in the bore and prevent gas cutting. At the same time the alloy needs to be hard enough so that it won't skid or strip in the rifling. 2000 fps is where the lines on the graph intersect and large problems occur meeting those two now conflicting criteria particularly with moderate pressure rounds like the .30-30 where you don't have an excess fo pressure to obturate a very hard cast and heat treated bullet.
For that reason, black powder rounds tended to use large, heavy, but still comparatively short bullets that could stabilize in slow twist rifling when fired at comparatively low velocity well under 2000 fps.
That wasn't the case at all with the .30-30 and was even less so with the .25-35. The use of jacketed bullets went hand in hand with the new smokeless powders used in those two cartridges. They don't make great candidates for cast bullet use if you want accuracy and no leading, unless you are willing to load them down to the 1100-1200 fps range.
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I get pretty good results in .30-30 Model 94s using 150 gr plated bullets, provided I keep the velocity under about 1800 fps. Above that I've noted the Xtreme plated .30-30 bullets start giving flyers as the plated jackets occasionally start coming apart.
I get excellent accuracy in my 1885 High Wall at around 1780 fps in its 30 " barrel. It'll shoot 1 MOA 5 shot and 1.5 MOA 10 shot groups at 100 yards using a tang sight and globe front sight.