The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

I finally got around to doing a Lead Impact Cast of the chamber of my 44 magnum Marlin 1894. Surprised how easy it actually was. After much measuring and calculating I set to looking for a Mold.

Found this on the Accurate Molds site, seems someone has already done the groundwork and I'll bet they designed it for a Marlin. It was spot on to my calculations in terms of parallel length forward of the crimp groove:
Question is, do I order the diameter as bang on and specify 20/1 Lead/Tin alloy mixture or bigger to alloy for different alloys such as Range Lead/Pure Lead and then a resize? At first I intend to Tumble Lube with 45/45/10. Don't want to order a Mold and with a change of Alloy find I'm casting undersize. How much lattitude is there really for sizing to throat diameter?

Bullets should always be sized to fit the freebore so long as that will chamber, so go with the biggest your rifle will take you can always size them down.

0.430" Looks good to me, what does your freebore measurement show.

I wouldn't worry about the alloy as you will not be shooting hard cast bullets, generally harder the alloy the bigger the bullet, going from "pure" lead to 50/50 lead range scrap isn't going to make that much of a difference, again soft alloys will obdurate withh all but the lightest loads.

If you specify your desired as cast diameter and your alloy then Tom will enusure that the mould will drop a bullet at your chosen diameter with your chosen alloy. That is why he asks.

Thanks Adam. Freebore at the point level with the start of the Ogive is 0.434. So it would just touch at that point (assuming I ordered 0.434 diameter), but there would be no parallel Boolit to Freebore contact. Any larger diameter is going to cause loading problems OAL is fine.

You do need to check that a 0.434" round will chamber, that is quiet big and the case will need to be expanded to seat the bullet, once expanded will the cartridge fit?

0.434 chambers fine. I have been using some as cast 0.4335/0.434 Shellhouse Hard Cast crimped in the Lube groove to give the extra length. I'm using NOE 0.434/0.432 Expander Plugs and belling the cases very slightly to start seating the Boolit. Round does look a bit pregnant though. Might have to make a reamer and ream out my Lee Sizing Die's Carbide Ring with diamond paste to rectify this.