Looking for feedback on first casting results

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horseman308
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Looking for feedback on first casting results

Post by horseman308 » Mon Jan 22, 2018 6:23 pm

I just finished my first batch of cast bullets, and I'd love some thoughts on what I could do to improve. I'm loading for a Pedersoli Sharps in .45/70. The alloy I mixed was 20/1 lead to lead-free solder (95/5 tin and antimony) - I basically mixed 20lb of scuba weights and roofing flashing with 1 lb of the solder in 5 lbs increments. I used a Lyman Big Dipper casting furnace with the 10 pound pot.

The mold is a Lee 459-500-3R. I know it's probably not ideal but I picked it up a year ago when I had an Amazon gift card. I figure I can at least try it out before moving up to a Lyman Postell or something. I kept the alloy temp about 675 to 700 degrees.

Such much for background. I cast about 100 bullets that were good enough to keep and probably did another 100 or so that were rejects while I tried to get the hang of the technique and find a temp that wouldn't leave wrinkles.

Here's my biggest question: 2/3 of the bullets dropped st an average of 475gn, another almost 1/3 were about 478 average, and a small handful were over 480gn. I sorted them by 3-grain spreads. One single bullet came put at 500gn, and the next heaviest were 5 bullets that were 484 to 486.

Most of the bullets dropped frosty, rather than shiny, no matter the temp, but I don't know how much that affects things. I did degrease and smoke the mold prior to use.

So, why might i have light bullets, and what should I do different next time if these don't shoot well?
The only bullet you fire is the one in the chamber. Make it count.

Brent
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Re: Looking for feedback on first casting results

Post by Brent » Mon Jan 22, 2018 8:36 pm

Maybe you have heavy bullets. Perhaps you got lead specks between the two halves of the mould preventing them from fully closing.

Close the mould in a dark room and hold the mould up to the light or a bright window while looking into it from from the top. Do you see any faint glimmer of light between the two halves? If so, you have lead on the mating surfaces somewhere that needs to be carefully removed. A burr in the mould or a problem with the pins could do the same. But check for this.

Also, find a piece of hardwood about the size of a hammer handle. Close your mould as normal but then give it a light rap with the stick -don't hit the mould directly but hit the jaws of the handles while you are squeezing them firmly. This will uniformly "set" the two halves against each other and much more uniform weights will be attained. Make sure you have your mould closed before you tap it with the handle.
I'm not from here, I just live here.

Brent
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JoinedCOLON Sun Nov 20, 2005 9:12 pm
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Re: Looking for feedback on first casting results

Post by Brent » Mon Jan 22, 2018 8:38 pm

Oh yes, next time, keep track of the order in which you cast the bullets. Then see if the heavies and the lights come early or late in the casting process. That might indicate a mould heating problem, the aforementioned lead interference problem, or something else.
I'm not from here, I just live here.

horseman308
PostsCOLON 55
JoinedCOLON Wed Aug 09, 2006 1:29 pm
LocationCOLON Maryland

Re: Looking for feedback on first casting results

Post by horseman308 » Wed Jan 24, 2018 4:52 am

Thanks Brent. I checked Las night and do indeed have lead splatter on the mating surfaces. I mic'ed my bullets and they're out of round by about .003", so I'll melt them down and start over.

The splatter didn't come off when I heated the mold, but I want to be careful. How would you suggest I clean it? Also, your trick with tapping the handle - is that between each pour?

Thanks again.
The only bullet you fire is the one in the chamber. Make it count.

Brent
PostsCOLON 1644
JoinedCOLON Sun Nov 20, 2005 9:12 pm
LocationCOLON the most boring real estate west of Illinois

Re: Looking for feedback on first casting results

Post by Brent » Wed Jan 24, 2018 7:48 am

I usually remove such spatter with a very sharp knife or razor blade VERY carefully. With an aluminum mould, even MORE carefully.

Yes, tap the mould between every bullet.
I'm not from here, I just live here.

horseman308
PostsCOLON 55
JoinedCOLON Wed Aug 09, 2006 1:29 pm
LocationCOLON Maryland

Re: Looking for feedback on first casting results

Post by horseman308 » Wed Jan 24, 2018 8:29 am

Thanks again. I've had a few free minutes this morning and did essentially what you just mentioned after reading several other folks say the same. I cast a few dozen tapping the mold joint between each. While the out-of-roundness improved, it didn't go away.

I got down to about .0015" out (.4585 one way and .4600 the other measured with digital calipers, turning the base 1/4 turn at a time) on average across about 12 sample bullets. Some were nearly perfect round but most were about. 0015 to .002 out. Also, no matter how clean I got the faces and pins of the mold, no matter how hot, there was still a visible gap at the nose. It got much smaller as the mold heated of course, but never fully closed. Obviously this is not preferable.

However, is there an "acceptable" range for out of round bullets? I wasn't sure if the obduratuon when firing would make a certain amount of variance immaterial, since - in theory - the bullet would then completely fill the bore and become fully round (except the nose of course, which would be a problem, no?). Hope that makes sense....
The only bullet you fire is the one in the chamber. Make it count.

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