Did some bullet testing today, one mfg vs. another, all else in loads equal, both 405gr, .458" diam in a 45-70, approx 62 gr Goex 2F, two .30 paper wads, and the bullet, about .2" worth of compression, not much crimp. I am shooting them in a Pedersoli RB, heavy bbl. one of the bullets displayed terrible accuracy and a significant keyhole, the other showed much better accuracy, but on close examination of the targets when I got home, there is evidence of lead wiping on one side of the hole on some of the hits, worse with one of the bullets than the other, but evidence of wobble on both. Is the Pedersoli twist rate too fast for 405 gr??? Do I need more lube?? I have never had such a problem before, can anyone give me some insight???? thanks

Don't know much about the load of powder. I can say if you're gonna shoot cast, whether your own or purchased, slug your bore and buy or size to .001-.002" over groove size. Hardness is not near the factor some think it is, but fit is absolutely the most important factor in shooting cast bullets. GW

edit: Personally I would paper patch for that cartridge with cast, but that's a whole new ball game. GW

I would slug the barrel. Chances are the bullets are undersized, too hard, or both.

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MikeG

Pedersoli barrels run .450/458 and need at least a .459 or .460 cast bullet to perform adequately. The 45/70 has a twist of 1:18" which will stabilise bullets up to a Paul Jones 545gn that I use in mine for long range work.

Standard factory moulds like Lyman Postell don't readily cast oversized projectiles that you require! I have a Henley & Gibbs 420gn that casts .460 dia and these shoot well in a number of my 45/70's.

Don't ask how I know. These Peds are very addictive!

Further study reveals a couple more details, the "poor" bullet has four grease grooves, the first within 1/16" of the base, the "good" bullet has one, about 1/2" from the base, then, both are bevel based(I'm thinking this is a no-no in BPCR?) and I'm only using two paper wads under the bullet, so I'm thinking the keyholing is a result of the base and wad,(ergo, gas cutting) BECAUSE, I drove a .490" RB down the bbl, miked at .458", drove a 255 gr soft pistol bullet down the bore after "bumping it up" with a hammer, it miked .458" and I took one of the "bad" bullets and drove it nose first down the bbl and it miked the same and was FULLY engraved, and before driving it down it miked about .460" , same as the good bullet.
So I have ordered some .060" veggie wads and will try those and will look for a flat based bullet to use. Any other suggestions of stuff to look at??

You need very soft alloy to shoot with black powder .30-1 to 20-1 works good .All the comercial cast bullets are for smokeless unless they state there alloy .Bevel bases for sure wont help your accuracy.Do some google searches for any one making bullets for Black powder use or cast your own . Buffalo Arms in Idaho is a good source . Arnie