Cast Bullet weight variation.

[grendel]

Just got back from testing my new digital scale (Dillion).  I weighed 31 bullets that I had cast earlier this year.  These bullets had already had the obvious culls removed and then had been lubed, sized and gas checked.

The mold was a LBT 44cal 280g.

The average weight was 288.59g
The weight ranged from 285.7 to 290.6 or 3.6g (1%+?)
Average deviation was .74 (What ever the hell that is, it has been 20 years since I did this in college)
Standard Deviation was .98 (Ditto)

If I throw out the lightest and heaviest, the numbers change to

Average weight = 288.62g
Range = 287.0g to 290.3g or 3.3g
Average deviation = .62
Standard deviation = .76

So my question is, How am I doing?  Is my sample to small?  Should I give up casting and stick to buying bullets (note that I also weighed some store bought cast lead bullets, only a few but the spread seemed about the same)?  A three and a half g spread seems high but these are 290g bullets (close enough).  I honestly don’t know if this is good or not.

Comments?

Grendel

[Lloyd Smale]

shoot them youll never notice a diffence in a handgun.

[Black Jaque Janaviac]

I would keep casting and shooting.

I used to worry about this.  Strangely enough, I found a big factor to tightening the weight spread was to over-pour the mold.  By this I don't just mean "make a big puddle on the sprue-plate".

I mean dump an entire ladle full of lead over each mold cavity, letting the excess spill off back into the pot.

Don't ask me why this makes a difference.  But it does.

[grendel]

Might be true, but the only 44mag handgun I have is a S&W Mountain Gun, in it I use 255g or lighter bullets (the factroy recomends 250 or lighter for accurace (per personal phone call with the custom shop when I had them do a trigger job)).

These bullets are for my Win94 in 44mag.  It wears a scope, at least it does now, after I work a good load for it I'll take the scope off and use the Marbles tang sight.

Thanks

Grendel.

[The Shrink]

Grendel

I also think that I've found that ment temp affects weight.  My guess is that cooler temps = heavier bullets.  Can anyone confoim this?  

Anyway, it seems that keeping the melt at a reasonably constant temp across the casting is important.  

Wayne

[Don in PA]

My experence is different the hotter the melt the heavier the bullet. I try to keep the pot temp + or - 10 deg, between 750 to 760 degs. If I'm carefull and hold the temp. I can cast bullets + or - .5 gr. I normaly cast 250 bullets at a time with 80 to 90 % within 421.0 to 421.9.  My Lyman pot is getting old so I have to montor the temp continully through out the casting session. If the temp gets away from me and goes up 10 to 15 degrees the bullets get heaver by .5 to 1.5 grs.
Don

[BobS]

My experience has also been that higher temps (within reason) give heavier bullets and more consistent weight.  Each of my moulds has a "preferred melt temp" for each alloy.  I leave the thermometer in the melt; most of my casting is at 720-770 with WW; 650 - 700 with lino; I cast with a dipper.   Since I have been watching the temperatures, weight dispersion in a hundred .30 cal rifle bullets is +/- 0.2 grains; and most will be within +/- 0.1 grain.   I may get 2 or 3 "rejects" for weight in that group of 100, a "reject" being outside that band of median +/- 0.2 grains.

Resp'y,
Bob S.