Lap 311 out to 314

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Jessegreenwood

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Hey, looking for molds for my 303, and wondering, is it posible to lap a mold for 308, out to the diameter of a 303? Increase about 3 thou, evenly and keep it round? And consistent between multiple cells?

Also, what is the heaviest that should stabiles in a 1:10 twist, at around 1800, as well as half that?
A 247grain flat nose in EE got me wondering on both of these.

Thank you
 
Except the "new" Lyman .314 molds rarely measure .314 buy a .316 from NOE you can always size down.
 
From what I've seen lately if you are buying new there's not a lot of difference in cost between a Lyman or RCBS mold and some of the custom ones.

Unless you have a free or almost free Lee and want to mess around it's easier and more likely to be successful to trade for or buy the right mold.
 
You can always try powder coating to get a few extra thou.
One chap on here p/c'd his .452 bullets for .45 Auto up to .457 for his .45/70 with good results.
 
cooter303 said:
Just buy a brand new lyman .314 mold for the 303. It will be easier and work allot better.
Click to expand...

After fighting with Lyman about this mould being undersized for over a year, I had one cavity opened up to .314” from .312”.
This was done by using a cast bullet and valve grinding paste in a drill press.
My two cavity mould now has a .312” cavity and another in .314”.
The only problem was that I have to now use custom gas checks for a good fit. Later, I bought a gas check maker to resolve that problem.
 
slug said:
You can always try powder coating to get a few extra thou.
One chap on here p/c'd his .452 bullets for .45 Auto up to .457 for his .45/70 with good results.
Click to expand...

That would be me and "good results" is an understatement to be sure.

I have "beagled" an old Lyman steel mold fro .308 to .310 long before Powder coating was even thought of...it worked but on an "easy to do scale: of 1-10 with 10 being the hardest, I would rate beagling at a solid15-18 ( using the same method as Boolitcater) and Powder coating up to a wanted dia a solid 2 on the same scale ( I would rate it as a "1" but you will have to give them a couple or three coatings).
The benefit of beagling is that every bullet you cast after the turn-out will mirror what you achieved whereas powder coating after multiple coats will require "informing" with an appropriate sizing die.
 
fingers284 said:
That would be me and "good results" is an understatement to be sure.

I have "beagled" an old Lyman steel mold fro .308 to .310 long before Powder coating was even thought of...it worked but on an "easy to do scale: of 1-10 with 10 being the hardest, I would rate beagling at a solid15-18 ( using the same method as Boolitcater) and Powder coating up to a wanted dia a solid 2 on the same scale ( I would rate it as a "1" but you will have to give them a couple or three coatings).
The benefit of beagling is that every bullet you cast after the turn-out will mirror what you achieved whereas powder coating after multiple coats will require "informing" with an appropriate sizing die.
Click to expand...
Do you mean "uniforming"?
 
I've done that plenty of time's. I've polished out LEE sizing dies from 286 to 300,302,304,306,310,314,316 and 318.
I used a US issue GI 30cal patch holder from an M1 Garand cleaning kit. Started with 400 grit and went from there. No lube, dry. Chucked it in my small drill press that was clamped to the bench
 
Beagling out sizing dies is a very much easier task than beagling a bullet mold unless it is a smooth sided PP bullet mold.

Sizing dies are smooth sided & as you say just a simple rotary tool with a grinding compound will do the job but with bullet molds the grease grooves prevent "the simple way" from working.
 
When I want to increase the size of a mold I get out the roll of aluminium muffler tape from Cambodian Tire.
I cut itty bitty strips of foil tape and carefully place them around the cavity in the mold.
They stay in place and the heat from the casting process doesn't affect the sticky on the tape.
I haven't noticed any concentricity issues with the boolits being out of round. I have tested this with a .0001 micrometer.
This works best if you only put tape on one side of the mold. Tape on both halves gives you little fins, and probably out of round issues...
 
Jessegreenwood said:
Hey, looking for molds for my 303, and wondering, is it posible to lap a mold for 308, out to the diameter of a 303? Increase about 3 thou, evenly and keep it round? And consistent between multiple cells?

Also, what is the heaviest that should stabiles in a 1:10 twist, at around 1800, as well as half that?
A 247grain flat nose in EE got me wondering on both of these.

Thank you
Click to expand...


If you're talking about a single cavity mold, get a bud to chuck it up in a 4 jaw chuck in a lathe and with an inside cutting tool, open up the grooves. It can be done successfully on multi cavity molds as well, if the chuck is large enough and the machinist is experienced enough.

I actually tried opening the indent ridges the same way, to see what would happen with a 308 mold I wanted to open to .316 diameter.

Opening the inner surfaces up by .009 OD actually worked quite well. I left the gas check diameter alone and there weren't any leading issues.

Accuracy improved a lot.

Lapping is OK, but it can make concentricity issues.
 
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