SAECO bullet mold

[Frank46]

When one laps a bullet mold, can only the nose portion be lapped to bring up bore riding diameter. I have two lyman molds 311291, 311041 and nose or bore riding sections only come out at .299 this is with wheel weights and 2% tin. As I understand the procedure one cast a bullet with part of a threaded screw inbedded
in the casting. Then coat nose section with lapping compound. Close mold and rotate
the casting with screw with a variable drill set on the lowest setting. Of course the mold halves will be closed. Any suggestions, comments will be appreciated. Thanks, Frank

[cajun shooter]

You may want to shoot a PM to Buckshot as he makes and fixes moulds and dies. He makes lubing dies for the Lyman and RCBS sizers. He has done work for me that is 100% top notch.

[Bent Ramrod]

The operation you describe is definitely doable, but it helps to have a lathe with collets. I took an Ideal 311291 with a badly undersized nose and a greatly oversized driving portion, chucked a casting in the lathe collet by the nose, and turned off most of the driving portion of the boolit, leaving only a small rim at the base. The casting was then drilled and a tap put into the base for a driving shank. The nose was loaded with Clover 320 and the lap was used on the mould cavity, driven by a variable speed electric drill. I stopped the operation every twenty seconds or so to wipe off any migrating Clover compound. When the lap spun easily at slow speed with the mould closed as tightly as possible (and no Clover or crud between the blocks), the mould was cleaned, another boolit cast and the nose measured again. If it wasn't big enough, the same operation in the lathe was done and the boolit used as a lap again. As I recall, it took 3 or 4 iterations of this procedure until the nose was large enough to ride the bore of the 7.7 Japanese rifle I was customizing it for.

Without the collets, the nose could be carefully chucked in a lathe chuck, or, lacking a lathe, the driving bands could be filed off once the tap is put into the base for driving the lap. Leave a little bit of the base full size to keep the lap properly oriented in the cavity,

[singleshot]

Don't use a drill, use a screwdriver or nutdriver and count the turns...

[Frank46]

I've had the 311291 and 311041 for many years and both are single cavity molds. Even with lyman #2 I still get .299 at best. Decided to lap them out. Thanks for the tips. Frank

[nanuk]

good info here

I have a 462560 that I thought I'd lap the nose out for my MG handi rifle 45/70

I want a heavy boolit that won't sit too deep in the case and I have a couple options first.

if they don't go, then I may have to take the drastic measures with the 560.

Can you let us know how it worked for you, and how you decided to do it?

thanks

[bhn22]

The slickest way I've tried for lapping is to heat the mould up to normal casting temperature, then cast a bullet in each cavity with the sprue plate open, pouring the lead through an ordinary hardware nut, centered over the cavity. After everything cools, open the mould & put the lapping compound on the bullet, and close the mould. Turn the nut with a ratchet & socket, I use my 1/4 in drive set, until you reach your stopping point. Clean the mould, cast a few more to check your progress, and repeat if needed. I suppose a guy could put a little grease on the areas you don't want to enlarge to make the lapping go a little smoother. It might even keep the lapping compound from migrating to areas it's not wanted.

[Frank46]

Probably won't happen anytime soon. The garage hit 110 the other day. Frank