Mihec's #503 Mold, .44 Keith style

[baladel45]

Hello to everybody. I am new in this forum and I'd like to have some help from you. Several weeks ago I bought a Mihec #503 6-cavity mold to get bullets for my M29-2 with .433" cylinder throats. So I need to buy a die for my Magma Star lubricator. According to Mihec info the mold will drop bullets of .432+". Could you tell me which diameter should the die have? :smile:

[LAH]

You may be able to lube with a .433 die but certainly with a .432.

[cbrick]

Welcome to Castboolits baladel45,

Cast a few with your mold first to make sure it is casting .432"+ ""with your alloy"".

If it is because of your "measured" throat diameters use the .433" die to lube only. It will work great, I do it all the time with my Star.

Check to be sure they chamber easily at this diameter and then head to the range.

Rick

[baladel45]

Thanks for your answers, Rick and LAH. I'll do it and tell you about the results.

[lathesmith]

If your gun's cylinders really are .433", then a .434 die would get you a very snug throat fit for your gun. If your slugs are dropping at least .432 from your mold, then you can lube/size these with a .433 die. Like others have said, though, it would be a good idea to load some "as cast" slugs in your brass,and see if they chamber in your gun. All this ought to give you some good info on helping decide what sizer you want to get.

lathesmith

[LAH]

Mr. lathesmith, question to a machinist: Will an object fit in a hole when both measure the same diameter?

The reason I ask, a SBH which had .431 throats wouldn't pass a .431 bullet unless I drove it through with a dowel & hammer. A .430 could be pushed through by hand. I know my measuring tools aren't those of a machinist but could you enlighten us on these things? Thanks & God Bless....................Creeker



Dry Creek Bullet Works
Dry Creek Firewood

[lead4me]

Mr. lathesmith, question to a machinist: Will an object fit in a hole when both measure the same diameter?

The reason I ask, a SBH which had .431 throats wouldn't pass a .431 bullet unless I drove it through with a dowel & hammer. A .430 could be pushed through by hand. I know my measuring tools aren't those of a machinist but could you enlighten us on these things? Thanks & God Bless....................Creeker



Dry Creek Bullet Works
Dry Creek Firewood

We call that a light tap fit, a press fit would be .0005/.0015 over anything larger would require heating the female to insert the male piece. That said I would think that a lead object would with min force would go into a steel object of same size.
But not having tried it before maybe someone with history in this could better answer your question.

[MtGun44]

How did you determine the diameter of the throats at .431? If you measured with a
caliper you are very unlikely to have an accurate measurement. No offense, but it is
real difficult to do (tending to produce undersized measurements, tho). Also a caliper is
only accurate to +/- .001", so you measure .431 (with zero user error) and that means
it is between .430 and .432 somewhere. Then how did you measure the boolit? If
with a micrometer accurate to .0001, then OK. If with a caliper, back to +/- .001. So
you could easily be pushing a .432 boolit thru a .430 hole.
If you used gage pins, they have a + or - range, I use the - range. So can be off by a large fraction of .001". That much measurement error is *very* easy to have, and a .001 interference fit requires significant force to push a boolit thru.

Measuring things this closely isn't trivial and requires some good tools, good techniques and
thorough thought to the tolerance on each measuring tool.

As to the original point of the thread, you want to have at least the same diam boolit as throat, and
I have had best results with .001 or even .002 larger. I'd start with a minimum of .433. The
Mihec 503 is an excellent mold and excellent boolit, I have it and it works great.

Bill

[LAH]

Measuring things this closely isn't trivial and requires some good tools, good techniques and
thorough thought to the tolerance on each measuring tool.


Bill


I use a bullet driven through the throats & measure with a caliper. Considering the spring back of alloy & error of the caliper, guess I'm not close.

So I size my bullets to be pushed through the throats. If they fall through under their own weight, too small. If said bullet must be driven through, too large. But if I can push them through with a dowel, just right.

So I use a slip fit. Not saying anyone else should, that's just how Creeker does it.

Thanks Bill, excellent post.




Dry Creek Bullet Works
Dry Creek Firewood

[lathesmith]

Mr. lathesmith, question to a machinist: Will an object fit in a hole when both measure the same diameter?

The reason I ask, a SBH which had .431 throats wouldn't pass a .431 bullet unless I drove it through with a dowel & hammer. A .430 could be pushed through by hand. I know my measuring tools aren't those of a machinist but could you enlighten us on these things? Thanks & God Bless....................Creeker


Creeker, to answer your question: In theory, a perfectly round.431 pin will fit into a perfectly round .431 hole. However (always something, eh?) , in the real world, even with the best, most expensive equipment, it is just darned near impossible to make that "perfectly round" pin or perfectly round hole. Now, take making an object, such as a revolver, and expect it to have 6 perfectly round holes, at a price that you and I can afford, and it just ain't gonna happen. So, a better answer would be: the closer the two are to the same size, the tighter the fit, and the cleaner they must be, etc, for them to slide together. Toss in a little out-of-roundness, a little roughness...these are all factors, and as the pin gets closer to the bore size the more important they become. I think you get the idea here....

As a practical matter, Bill has a pretty good post there, and your method of fitting your slugs to your revolver throats sounds like a good one. I always tell people, if what you are doing is working, then by all means keep doing it! No need to re-invent the wheel...

lathesmith

[MtGun44]

LAH,

Thanks for the kind words. Working in industry and having to actually put precision parts
together and have them fit to tight tolerances pounds this into your head. I am not any
kind of an expert on tolerances and fits (I do work with some, tho) and I have picked up
enough to know how tricky it gets when you try to work measuring and fitting stuff down
around 0.001", and especially with holes. Lathesmith's comment that holes are almost
never round is right on the money. From what I know lapping is the surest way to get a
pretty nearly round hole, but that is imperfect, too. Reamers can do pretty well, but often
chattering or bouncing causes a multisided hole, kinda like a circle. Polishing/lapping
can make this better, but. . . .

revolvers are really precision machines and I am impressed with the usual good quality
we get. Sometimes the tolerances are off, and I have reamed and polished throats on
one BH, but most others have been good enough that I just fit the boolits. Gage pins
was a huge breakthru for me, and I think for most folks that are trying to learn to
please their revolvers.

Fun topic, no really guarenteed answers but a lot of stuff that will "usually work".

Back on topic, if you start with a snug push fit you will be providing a good chance that
the boolit will get launched straight in the throat, and if the throat is a tad larger or the
same as the groove diameter of the bbl, then you have a good chance of it getting started
straight in the barrel. If the design of the boolit is good and the load is "acceptable"
(whatever THAT means!) you have really good shot at an accurate load. The fit stuff will
also almost always prevent leading with 'known good' designs - altho some designs -
notably the Lee TL designs - are short on lube and work in a somewhat unpredictable fashion - OK for some, dismal for others.

Bill