Mold mods ???

[XWrench3]

i have a lee 457 340g flat nose, flat base mold that i am using for my 45/70. i get mediochre accuracy with this, and mostly with quite reduced pistol powder loads. full power rifle powder loads just lead the bore. it throws boolits at .457", which really should be .002" smaller than what they should be for industry standards. for the life of me, i have no idea why lee makes, and markets molds and sizers to the .457" spec. but anyway, i also have a ranch dog mold that throws boolits @ .460". those get wonderful accuracy. i have been thinking about this for a while. i have beagled the mold, but the boolits come out so egg shaped by the time i get them to .460" that it isn't funny. i am seriously thinking about modifying ONLY the back band to .461 or.462", and then size them down to .460" i have already modified the sizer to .460 so i could seat gas checks on the ranch dog bullets. my thought is that with only modifying the back band, i will be less likely to mess up the rest of the mold, and hopefully it will cast boolits that will seal up (the bore size is .4585") and hopefully be usefull and accurate. at this point, the mold, and boolits it casts are about worthless. so if i mess up the mold, oh well. it is not like it cost a ton of money. my question is, does this sound like a reasonable thing to do? do you think it may work? thanks.

[Doby45]

I would just lap the full cavity. Pour you some boolits and make sure you keep them separate, so back cavity one pile and front cavity another pile. Dip them in a thin oil and then in Comet and spin them in a drill. Worst case scenario you ruin a $20 mold. Best case scenario you have a mold that throws the size you want.

[Trapaddict]

There is a lot of truth to the old addage "You get what you pay for" No truer words were ever spoken especially with regard to Lee molds.

JK

[Doby45]

Then how do we explain Lyman molds as of recent?

[Catshooter]

Xwrench,

Yes, I would venture that that would work. I don't know your skills or what equipment you have but you could make a cutter that would enlarge the base band to the diameter you need. You wouldn't need to harden it, not with the mould being aluminum.


Cat

[Skipper488]

I'd be real tempted to try the following procedure to open the mold up 0.003" http://www.castpics.net/subsite2/MoldMods/MoldLapping1.pdf

[geargnasher]

I have that mould too, and it also casts exactly .457" with WW metal, I use it for thumper loads in my .45 Colts, sized and lubed .454" and then run through a .452" push through to yield .4525" boolits that perfectly fit my revolvers. Lubing them on the first sizing preserves the wimpy lube grooves via the law of hydraulics.

I've never had any kind of luck with light (less than 400 grain) boolits in the 45/70 or 45/90.

Gas checks and 500+ grains or PB and 500+ grains cast of 30:1 with a compressed load of ffg has worked for me.

I have purchased hundreds of dollars worth of Lyman moulds in the last couple of years, they have almost all been junk, and I will never buy another after trying multiple times to get Lyman to fix it.

Lee says that 340 grain boolits is a .457. It is exactly what it's supposed to be. I guess you do get what you pay for from them: A $20, cheaply made mould that has a $100 cavity.

Gear

[XWrench3]

i have tried lapping another lee mold (six cavity 45acp). it took FOREVER to open it up 0.001"! way to much messing around to do that again. i think the main problem with lapping, with a cast boolit is that the boolit is so much softer than the mold material, that the boolit wears at 10 times the speed of the mold. maybe i should have used pure linotype for the boolits. but i did not, i used ww's. in any case, i am not going through all of that again. if this works, great, if it does not, i will chuck it in the garbage can.

[DragoonDrake]

Yes linotype works a lot better for lapping. I did not know the difference my first lap attempt and I used 20-1. Got some lino and no more problems. I cast about 6 good bullets from each cavity and let my mold cool completely off. then put comet on my lapping bullets and closed the mold on .005 brass shims bought from hobby town. I used a drill at a low speed. I would run a bullet for about 1 min for about 5 bullets per cavity. Once I was done with that I used my last bullet from each cavity and put flitz on and polished the mold ( I did not use a shim at this step). I was able to open some of my 30 cal molds and 45 cal rifle molds this way. I also want it noted that I have only modified Al molds this way. I tried a steel mold once but I got no where fast.

Sorry for the bad sentence structure and punctuation. I am in a hurry, but wanted my method stated to see if anybody can use it.

Adam

[XWrench3]

thanks! i also do not worry about proper english or punctuation. i passed all the way through school with a D average in english. i only had one class (a creative writing class) that i did fairly well in. that class i averaged a B+. go figure!

[onondaga]

The Lee 457-340 RN-F Is perfect for my Colt Sauer .458 Win Mag that slugs at .4570". The Lee mold drops at .459" for me. That is unusually large for that mold but I have Leemented with toothpaste, Q-tips and an electric drill a few times and it is old. New It dropped at .458. I use H4895 powder and BPI Original Filler for a 104% compressed load yielding 1610 fps and .700" groups at 50 yd,


You need a bigger diameter bullet for your 45-70. I have enlarged several Lee 30 cal. molds using a bullet cast to a hex nut as discussed for Leementing in the stickies.

I make 4 of them to do a 2 cavity mold. With the sprue plate removed I paint the mold cavities with Ivory liquid straight and lightly. I have premixed a thick paste of extra fine 500 grit Dental Pumice. I brush the pumice paste accurately onto the bands only of a hex nutted bullet . Place the bullet in the mold and gently close ---do not squeeze shut. Take 4 turns, open the mold, Remove the bullet and vigorously water flush mold, not the bullet. Now with the abrasive still on the bullet put it back in the mold and this time you can increase your grip to a light squeeze that doesn't stall and cut some metal. Take 20 turns.

Do that procedure 3 times with a total 60 turns with a light squeeze. I stop about half way and change to fresh hex nutted bullets. A little squeeze and twirling a ratchet and I have opened 30 cal molds .002 on their bands. A 45 cal mold will likely take more turns

Others have posted a similar method using valve grinding compound. I wanted about 500 grit and the pumice I had was just right for the job using soap instead of petroleum and valve grinding compound in my molds. Cleanup with water was the easiest.


Cast and check before going too far!!!!

Gary

[BOOM BOOM]

HI,
If you just do the back band, you are ignoring throat fit. Lap or use a cutter & do the whole mold.:Fire::Fire: