Thread: Choosing cast bullets in case I get a 45-70

I'm thinking that the next logical step in my development is to play around with a 45-70. Consequently I want to figure out what projectiles I should be using so that everything can fall into place quickly when I get the urge and the opportunity to splash out on a new rifle.

I know that the 405 grain projectiles are the standard for this calibre. However it is the diameter of the bullet that I find attractive, and I figure why waste lead (and powder) unnecessarily? A 340 grain bullet has a sectional density of over 0.2, which seems plenty for me considering that my 125 grain .357 bullets work well with an SD of around 0.139

While the theoretical best procedure for selecting a projectile involves slugging the bore and making careful measurements, I like to trust that a new rifle will have a bore with standard dimensions and I like to be able to just buy a standard mould and use the bullets as cast. This has worked well for me with .308 and .357 rifles.

I like the look of the Lee 457-340-F mould, but I'm perplexed with its nominal diameter being smaller than the nominal bore size of a 45-70 (considering that the other Lee moulds I've got are labelled as 0.001" bigger than the standard bore diameter). I assume that Lee know what they are doing, and I'm willing to buy a mould and try it.... but I am a little nervous about the sizing, especially when I consider that a couple of their moulds are sized at 0.459" which I think is the 'correct' diameter. Initially I would be casting these bullets from soft lead and shooting them around 1000fps, and I'm thinking that a quick shunt up the rear end with Trail Boss or another pistol powder might increase their diameter a little. Dunno. I've also read that using Alox lube can add a bit to the diameter. I could go to the trouble of paper patching or powder coating, but I don't want to.

Or I could simply get a .459 diameter mould and send extra lead downrange with a bigger bang. But I'd rather use the lighter projectile.

It would be great to read comments from folks who've had experience with this type of thing. Thanks in advance. Best wishes.....