Cast bullet size

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Originally Posted by Black Jaque Janaviac

Outpost,
I'm not sure I'm understanding everything properly, but not all chambers are the same. I have Rossi '92 lever actions chambered for the straight-case .357. Their "throat" is not like the diagrams posted in this thread. They have something more like a cone. So to size for throat diameter you'd need a .375 boolit or something like that which would not do. Basically it would be a like a big .22 longrifle with boolit and case the same diameter.

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In "black powder type" rifle chambers, typically in revolver "Cowboy" calibers such as the .38 Special, .44 Magnum, .45 Colt and .45-70, in which there is no "throat" or "ball seat," before the origin of rifling, load a lead bullet of the largest diameter which provides safe case release clearance, producing a loaded cartridge diameter which measures 0.0015"-0.0020" less than a chamber cast at the case mouth. This permits a loaded cartridge to be chambered easily and extracted without firing, doing so without difficulty. Light marking of an exposed front driving band or exposed bullet ogive which does not impede easy chambering or extraction of unfired rounds does no harm.

In my Marlin Microgroove rifles I load .360" in .38/357, .433" in .44 Magnum, .455" in .45 Colt and .460" in .45-70. Your mileage may vary.

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Originally Posted by Outpost75

In "black powder type" rifle chambers, typically in revolver "Cowboy" calibers such as the .38 Special, .44 Magnum, .45 Colt and .45-70, in which there is no "throat" or "ball seat," before the origin of rifling, load a lead bullet of the largest diameter which provides safe case release clearance, producing a loaded cartridge diameter which measures 0.0015"-0.0020" less than a chamber cast at the case mouth. This permits a loaded cartridge to be chambered easily and extracted without firing, doing so without difficulty. Light marking of an exposed front driving band or exposed bullet ogive which does not impede easy chambering or extraction of unfired rounds does no harm.

In my Marlin Microgroove rifles I load .360" in .38/357, .433" in .44 Magnum, .455" in .45 Colt and .460" in .45-70. Your mileage may vary.

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Thanks for this. I was worried my Ruger 77/357 chamber was wrong. It measures 0.3615" just ahead of the case mouth. I'm planning to get a NOE mold since they claim a diameter of 0.360" for their 38/357 bullet molds using wheel weights. The 360-154-WFN-AN1 seems like it would work well.

Here is useful example, Accurate #31-215B as-cast at .316" diameter in Yugo nny 7.62x54R brass, chambered than extracted from a Tikka M39 rifle. Rounds with the unsized .316" bullet chambered without resistance, and upon extraction shot light, but distinct marking at the throat and also on the forepart where it contacts the origin of rifling.

This demonstrates perfect bullet "fit" and yes, these bullets shoot very well indeed.

Attachment 225946

because if the cast bullet is too small you will get gas cutting and that will completely ruin accuracy . lead is a totally different situation to deal with, hardness,lube, shape, etc all according to velocity. and of course leading of the bbl which no one ever wants.

Obturation of a bullet will have something to do with accuracy and leading.

I have shot a bunch of bullets unsized with no ill effects and very good accuracy.

I shoot a .45 Schofield made in 1876. I have been using cast .454 230-grain bullets from Montana Bullet Works in it and getting excellent results (much better than I get in my Uberti Schofield clone, which has never been satisfactory). I was rather dismayed to find that Montana Bullet Works no longer stocks a 230-grain bullet in the .454 diameter. I understand that using a .452 diameter will cause tumbling and consequent inaccuracy.

I looked online and there are plenty of 230-grain .454 bullets available, mostly from Speer, but these would be commercially "speed"-cast, subject to variations in weight and balance, and I'd rather not use them

I have written to Bruce at MBW to ask for help, but was wondering if anyone here has suggestions. I don't have the facilities to cast my own bullets, so am looking for something to buy.

I bought an NOE 359-121-RN-R-3 mold to cast 9mm. 9MM translates to a little over .354. Do you folks think that I have the right mold?

First thing is slug your barrel, always get ihe exact groove diameter, size to the groove diameter or no more than .001 over. Cast bullets without a hollow base, do not obturate....expand with pressure.

If you have a messed up barrel, big, little, big, well not very much is going to help that, but a rebore or new barrel. Cast shooting for accuracy at any longer distance requires good, clean and smooth, grooves and lands.
You can throw rock and hit a can at 10 feet.

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Originally Posted by Outpost75

If you forget EVERYTHING you ever read about slugging barrels and simply cast chambers from now on, and get bullets to FIT THE THROAT you will be far happier in the long run.

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I greatly appreciated your post. There is a lot of good info in there! I made a chamber cast of my old 30/40 Krag. See attached image. Based on everything you've said, I would be well suited to size my cast bullets to .311. Correct?

It seems a lot of people recommend that the front end of the cast bullet "kiss" the lands. I take that to mean it should almost touch. Maybe .001-.002 away from touching? The front part of the boolits I've been making will never touch the lands because the only part that measures .311 is the part inside the case. The entire front half of my boolits measure around .300". Only the portion inside the case measures (or will measure after I size them to .311) large enough to fit snug in the throat.

Is that a problem?

Attachment 310235

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Originally Posted by Dusty Bannister

Don't you guys mean to size larger than groove diameter?

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I was just wondering about that!