Hello, I am new to this forum, and I have a few questions about the Lee moulds in .375 and .47-70 cal.
First, I wonder if the .375 win. mould can be used in .375 h&h mag., since it is listed with a dia. of .379. Will it chamber, and if it does, will there be any accuracy problems using a bullet .004 too big? have anyone tried this?
My second question is about the 340 grains 45-70 bullet from Lee. Its diameter is listed as .457. Isn't this too small in a marlin 45-70? Does anyone have any experience with this?

Great forum by the way, I've found a lot of info here.

Isak,
First, for the questions to be answerable, you have to know the actual bore/groove diameters of your barrels. You cannot assume the size, every barrel is different and you have to actually measure it to eliminate a lot of trial and error in finding an accurate boolit.
Then you have to realize that the diameter of the boolit that comes from the mould also depends on the alloy from which it is cast. Optimum size for a boolit is .002 over groove diameter, but at the lower velocities and pressures used with cast, it probably won't be a big deal if it is a bit oversized.
Will it chamber? Maybe. Probably. Slug the throat or better yet do a chamber cast with cerrosafe and measure the neck. A careful measurement of the outside diameter of the neck of a fired case may give you a useful answer, but not necessarily an exact one. Try it and see. Chambering reamers vary from different manufacturers and their sizes change over their working life with each subsequent sharpening. Every chamber is different.
The main question is one of accuracy, and the only way to find out is to do some testing. A boolit that is slightly oversized is likely to be more accurate than one that is slightly undersized, though you can sometimes get better obturation with an undersized one by using a softer alloy. Most commercial moulds including Lee's are undersized for optimum accuracy, and that is more likely to be the problem you encounter rather than oversized regardless of the published numbers. The good news is that there are easy methods to bump aluminum moulds up a few thousandths in diameter.
Remember to make sure ALL the copper fouling is completely removed from the barrel before you start testing any boolits in it, or you are going to see poor results even with a perfect fit. Also be aware that the working velocity limit of gas checked cast boolits is generally no more than 2200fps, even for your H&H. Cast loads feature slow heavy boolits. I would start with the .45-70 as it will be easier find a workable load for it - the case capacity is better and there is a greater variety of moulds available for it. After you get done reading past posts here, you might also want to check out www.castboolits.gunloads.com

Most 375 H&H rifles will have a generous throat. A 0.379" bullet should work fine and may even be smaller than optimal.

Isak, I have the 340gr. Lee mold (.45-70) you describe and I must size it down to .459" so as to fit my Marlin's bore. Their 405gr. hollow base cast even larger, but this isn't always the case with Lee molds.

I just got a Lee 459-405HB and with 20:1 was disappointed that this one won't make it to .459". I have an old Sharps Borchardt with a .4593" groove diameter barrel that I want to shoot. THinking of calling Lee...but probably need to go try it out first.

Thanks.

I'm prepared to do some experimenting, the thing is that I wanted to ask here and see before I would bother to buy the moulds and give it a try. I've been casting the Lee C309-150-F for my Marlin 30AS in 30-30 with a fair amount of success, and I thougt it could be fun to try it out in som other calibers as well.
Like the idea of shooting low cost, low recoil rounds for practise, and I enjoy making stuff myself.

All, The problem with many commercial molds, e.g., Cramer/Saeco, Lee, Lyman, RCBS, is that they may be undersized (either body or nose if a bore-rider, or both). Compounding this is the lack of agreement on the "standard" (alloy) used for determining final dimensions, worn cherries and variation in actual bore dimensions, both rifle and pistol. To cite an actual example, I purchased a like-new Cramer RG-4 for my .30-06 that cast ~.308" on the body and ~.300" on its nose. A second one, which I am borrowing, casts much larger. My Lyman #311291 also has an undersized nose. Judging from the comments on the Gunloads>Cast Bullet forum, this is hardly unusual. On the other hand, many of the off-the-shelf molds, e.g., Ly. #311644, are excellents.

Isak,
That combination is one of my favorites, too, in lots of different actions. Another really good one is the Lee 113gr "soupcan". I don't know if Alliant Powders are available in Norway, but RE-7 is a favorite of mine with both boolits. For some unknown (to me) reason, the .30-30 is much more forgiving than any other .30 cal case I have tried. (.30carbine, .30Herrett, 7.62x39, .308, .30-06) Where others want .310 or .311, the .30-30 does fine with .309 or even .308 cast.
Pfeifer,
I don't know as you'll have much luck dealing with Lee's CS BS. If it doesn't do what you need it to, you will likely have better luck "beagleing" the mould up a few thou yourself than trying to fight with them about it. It's really easy to do.

Well I had some time today and I call Lee up and they said to send it back with a letter. So off it went today. I'll let you know how it goes. This one wouldn't even come up to .459" with 20:1.
JP

Thanks for all the replies.

I think I must get the soupcan mould too, I've heard a lot of good things about it. In Norway there are mostly Norma and Vithavuori that are easily available, so I've been using n-135 in the 30-30. It's been especially fun to get the cast bullets accurate in my micro groove Marlin because most people said it wasn't worth the effort, but it was definatly worth it.

Anybody that tries to tell you that cast won't shoot well in a microgroove barrel is either just repeating something he read, or he was trying to load the cast up as if they were jacketed bullets: too fast for the strength of the alloy. I have pushed the soupcan up to around 2700fps (1/2 wheel weights & 1/2 linotype) without any barrel leading problems and very good accuracy, but not every barrel will do them that fast. None of the deer in the freezer have had any negative comments, either.

Just a follow up... The good folks at Lee sent me another 459-405HB mold in return a week or two back. Got to casting with it last weekend and it throws .462" bullets with 20:1 alloy - YES! ... now we can go forward with my old Sharps Borchardt loads!
Jeff P

Pfeifer, the Lee bashers feel so robbed now.

Got my .4605" sizing die back from Stillwell today so getting closer to doing some load trials.