doublegunshop.com - home Forums General Discussion Double Rifles, Paradox Guns & Gauge Rifles @ doublegunshop.com Bullet diameter for a 450/400 Lancaster

I would like to get your opinion as to the diameter of a bullet that I need for my Lancaster 450/400 double rifle.  The rifle has a typical Lancaster oval bore with the minimum bore diameter = 0.405" and the maximum = 0.418".  

 I believe the appropriate cartridge combination is a soft lead 270 gr PP bullet, sized to .405" and 110 gr BP.

I shot the rifle a long tome ago with PP bullets (bullets = 0.395") with 2F and wasn't satisfied with the results.  Also  I don't like paper patching and want to try a cast bullets.  

I know that a 20-1 cast bullet will not upset like a pure lead PP bullet.   My concern with a 0.405" cast bullet is that it would not grip the "rifling" (spiral oval) and that there would be gas blow by. 
 
I can make a 0.418" bullet by swaging 44 mag bullets down.  I don't know whether a 0.418" bullet would be that accurate; it seems like a lot to squish down.

What are your thoughts?

I would start with a .410" pp or grease groove bullet myself.

Yes, unless they were going to reinvent the wheel, most 450-400 ammo would probably have a .408 jacketed bullet so a .410 lead should be perfect.

You can use .41 mag pistol bullets in a pinch.