Cast bullet weight variation...

[Smokey Joe]

Cast up my first set of bullets recently. Everything went according to the printed descriptions; had no particular problems. The RCBS bottom-pour furnace did a fine job, as did the RCBS mould for 148 grain target bullets for .38/.357.

The alloy I used was "found bullets on the range." (Mostly cast bullets, some lead cores of jacketeds. A few shotgun slugs.) I can just barely scratch the cast bullets with my thumbnail; I have soft thumbnails.

Haven't run 'em through the lube/sizer yet.

Now, the question: I've weighed a sampling of the 455 bullets cast. Most of them seem to run ~ 151 grains; a few are lighter. How much variation in cast bullet weight is allowable before one starts getting POI variations?

Or do I have to load up the whole batch, shoot 'em, and find out the hard way?

 

[rcmodel]

As long as there are no wrinkles on the sides, or visible voids in the base of the bullet around the sprue cut-off, don't worry about it.

If the bullets filled the mold completely, you will not be able to stand on your hind legs and shoot them well enough to tell the differance in a +/- 1 or 2 grain variation.

If you are very OCD, weigh them all and sort them into light, normal, and heavy and shoot them in lots.

rc

 

[Smokey Joe]

Thankyou!!

R C Model--Just what I needed!

The wrinkled bullets (very few) and the ones that didn't fill the mould, went right back into the furnace, along with the sprues.

Frankly, after reading a bit about having to "warm up the mould," and other such complications, this casting business went amazingly well. I think the bullets began filling up the mould, and coming out nice & shiny, on the 2nd or 3rd cast. I kept waiting for "the other shoe to drop" but the full, shiny bullets kept coming and coming.

Inspected each bullet as it dumped out of the mould onto a towel, and if it didn't have a nice square base, back into the pot it went.

BTW, the RCBS furnace had a temp setting knob on the side, and that agreed with my Lyman casting thermometer within 20° F. Ran the furnace at a 700° setting--Is that about right?

As to the bullets--I'll lube 'em up, load 'em up, and shoot 'em!

 

[rcmodel]

Furnace temp depends entirely on the alloy you are using.

I like to run as low as I can and still get 100% mold fill to keep from burning up the alloy.

It also speeds casting as the mold doesn't overheat as fast and require you to wait longer for the bullet to harden.

rc

 

[snuffy]

RC nailed it as usual. Smokey, congrats on first time success. You're way ahead of the curve, 75% of first time casters have boatloads of trouble.

Yes, 700 deg. is plenty of heat for the type of alloy you're running. The higher the temp, the quicker the tin will oxidize on the surface of the melt. Since tin reacts with the oxygen in the atmosphere more easily than antimony or lead, running too high temps causes loss of tin in the alloy. You can flux it back in, but that takes time and loss of flow to the casting session.

Some use kitty litter to float on the surface of the melt, to shield the tin from the air. Others use sawdust as flux, then leave it float on the lead after it chars.

I used to be real anal about bullet weights. One time I culled a bunch of under weight bullets from a batch, was about to toss them back into the pot. I thought, how about a test? I loaded the culled, but otherwise filled-out bullets, and the ones that were all the same weight into two groups. I shot both at targets trying to be as consistent as possible. No difference that I could see! This was a 45 SA 1911 @ 25 yards, so maybe a better quality pistol or SS would tell a different story. Load was 5.5-231, 200 RNFP from a lee mold.