Rossi Rifleman

To select a cast bullet diameter, do I add .002" to bore's land or groove diameter?

Groove.

What Sarge said. The idea is to completely fill the bore so the gasses don't get by the slug.

Make smoke,

Ohio3Wheels wrote:What Sarge said. The idea is to completely fill the bore so the gasses don't get by the slug.

Make smoke,

THIS ^

There is some leeway, depending on the bullet alloy and the charge in question.
A slightly small bullet CAN be bumped up a little if the charge is enough and the alloy allows it but if the charge is light and the alloy is hard a bullet that's under diameter allows gasses to blow by the slug.

It's a little more reliable for a slightly large bullet to be swagged down and that typically works with a light or a heavy charge.

In addition if you went just a couple thousandths over the land diameter that means at the worst case, no diameter bump, you'd only be engaging a couple thousandths of bullet metal to get the bullet spinning. The chances of stripping out that couple thou and getting inconsistent spin out of your loads would be high.

That all makes sense. I wanted confirmation .

So, the bullets I cast with my .44 .429" 200 gr. Lee mold would be ideal for a .427" groove diameter?

Blind Hawg wrote:That all makes sense. I wanted confirmation .

So, the bullets I cast with my .44 .429" 200 gr. Lee mold would be ideal for a .427" groove diameter?

If they drop at .429 and the alloy isn't too hard they should be fine. The only way to know for sure is load 'em and shoot 'em.

Make smoke,

about 7-8 years ago I was given a couple hundred cast swc's that were sized .429 (44 mag) and tried them in my (then owned) Ruger Super Red Hawk. It didn't matter whether loaded mild, medium or hot, the leading was pretty bad. A year later I tried them in my 2013 Rossi R92 ... not quite as bad as the experience in the SRH, but still totally unacceptable in my opinion. I think I still have about 150 of them left. I may just throw them into my can that I keep scrap boolits in to give my buddy to re-cast into something more user friendly.

For me, it's either plain based .431's or gas checked .430's or .431's. That's just from my somewhat limited experience.

jd

jd,
I've had some of those donated bullets that I've been convinced just didn't want to shoot.
Almost made me swear off lead bullets entirely.

In particular I still have a couple hundred 30 caliber 165 grain NBCs I think I bought and about 30 left from several hundred donated .452" Speer 200 grain LSWC that probably should be for the melt pot. Those Speer LSWCs have frustrated at least 3 or 4 reloaders I know.