lapping a mould to increase bullet diameter?

Rex

Active Member
Is this possible? Anyone do this with any success? I have a Lyman 358429 that I wish was .001 or so larger.
 

S Mac

SW Mo Hillbilly
Oh it's possible, been done many times. Need to take it easy, as @Ben says, you can't put it back. Lap a bit, cast long enough to get the mould up to temp, check progress, maybe lap more.
 

RicinYakima

High Steppes of Eastern Washington
Rex, it isn't too hard to do, but you have to take your time. With an iron mould, it is slow but more forgiving as it cuts slower. Should be a thread in the history of several ways to do this. Ric
 

fiver

Well-Known Member
take the bluing out of the cavities and measure a sample, I bet that gives you your .001.
simple easy peasy, a little lapping compound from the NAPA store and a screw in the base of a bullet.
15-20 seconds,, done.
 

Missionary

Active Member
Be very carful with aluminum molds. I turned a wadcutter .358 old into a .365 10x faster than a iron mold.
So I bought a 9MM Mac PA-63 to sort of cover over the big "Opps".
 

JWFilips

Well-Known Member
I have done some radical Lapping of a cheap Lee Mould to see what was possible! I took a .277" up to a .292"
Now that It is done it was a real PITA and "took many lapping Then Casting then lapping" ....you get it Not worth the aggravation and each cavity is a different size & weight......but it can be done
 
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Ben

Moderator
Staff member
take the bluing out of the cavities and measure a sample, I bet that gives you your .001.
simple easy peasy, a little lapping compound from the NAPA store and a screw in the base of a bullet.
15-20 seconds,, done.
Make certain the end of that screw is dulled.
 

Tomme boy

Active Member
Yep, did a 4 cav H&G #503 44 mold. It cast at 0.429" with Lino. It took a while to get all 4 cavities to cast the same at 0.431" where I wanted it. Took almost a week going very slow.