Cast Bullet dia vs bore dia


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jerrard
December 7, 2009, 02:42 PM
Is there a rule of thumb such as : cast bullet dia same as bore dia/ .001
over bore dia? Thanks for any help.

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James2
December 7, 2009, 02:49 PM
It is usually recommended that the cast bullet be 0.001 to 0.002 larger than the bore. Since bores vary a bit, it is common practice to drive a pure lead bullet/slug into the bore then remove it and measure it. Now you know how big your bore is.

jerrard
December 7, 2009, 03:02 PM
Thanks James. Using Uberti 73 winchester, slugged out at .427. Have seen
cast bullets and dies / molds available in .428 thru .430. Kind of confusing.

Walkalong
December 7, 2009, 03:07 PM
They should be slightly over bore (Groove really, or am I confused again. :D) diameter. Cast bullets should fit your throats, which are hopefully .001 to .0015 over groove diameter.

.357 Mag cast bullets should be .358.

Some .44 carbine barrels are oversized, as my M-94 was, so they may need oversized cast bullets instead of the standard .430.

We call it bore diameter all the time when we really mean groove diameter. Like calling a mag a clip, except with no "bore nazis". ;)

James2
December 7, 2009, 03:23 PM
Bullet diameter out of the mold will vary some depending on the alloy. They may also be slightly out of round. I have always sized my cast bullets using Lyman tools. (4500) You can also get sizers in a number of sizes.

The 44-40 uses bullets at .427, and 44 Spl at .429 in jacketed bullets. So cast would be slightly larger, and given the variation in barrels, you need some choices there in that range.

rcmodel
December 7, 2009, 03:38 PM
Have seen cast bullets and dies / molds available in .428 thru .430. Kind of confusing. You want to make darn sure you pick a bullet designed for the 44-40 WCF, and not for the .44 Spl/.44 Mag.

Many of those will be too long when loaded to the crimp groove to work through the action of a 73 Winchester.
And you have to crimp them for the tube magazine.

rc

armoredman
December 7, 2009, 05:18 PM
I size 38 at .358, and 9mm at .356, with good results.

Vern Humphrey
December 7, 2009, 05:33 PM
Lee offers the 429-200-RF. This is offered as a ".44 Special, 44 Remington Magnum" bullet, but is short enough to feed when loaded into a .44-40. Lee also makes a very low-cost sizer which works on your reloading press -- and applies pressure from the base, so no nose plug is needed.

jerrard
December 7, 2009, 06:33 PM
Thanks guys, appreciate all the info.

The main reason for asking is because I have a large supply of 215 gr H&G #44 .429 RNFP with crimp groove.

I bought these years ago for .44 special and never used them. I was leery of using .429 in .427 grove dia.

I guess I could just get a .428 seizer and run them through if you think it's worth it. I think H&G #44 was actually designed for tube feed 44-40.



Thanks again. To tell the truth I haven't shot in about 20 yrs. Just retired and am just getting back in to it. So guess I will

probably be bugging you guys with a lot questions for a while. I'm glad I found this forum today, very active.

Galil5.56
December 7, 2009, 08:24 PM
.002" over groove diameter for cast bullets has never been a problem for me ever in any caliber I use cast for (rifle and pistol/revolver). Might try to load a few on the mild side/make some dummies, see how they chamber, and potentially save yourself some $$$ and time. If they camber easily minding proper OAL, IMO and experience you are in business.

For those who may not know, bore diameter is from lands-to-lands, groove diameter is groove-to-groove, as this nice diagram from my Lyman #45 demonstrates:

http://img101.photolava.com/2009/12/08/img_8861-hxxsrp9b.jpg

You want to consider groove diameter for proper sizing.

Walkalong
December 7, 2009, 08:41 PM
That pic sure beats my explanation. Excellent. I'll have to save that.

fecmech
December 7, 2009, 08:49 PM
Jerrard--Load them and shoot them,.002 over groove is no problem.

Brimic
December 8, 2009, 11:44 AM
Too big is not a problem so long as they chamber. Too small- almost always a problem.

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