What size mold for a .375 H&H?

[stubert]

Just picked up a Win. 70 Alaskan in .375 H&H, and am looking to get a mold for it. I see molds that are .375 diam. and I see .379 diam. Are the bullets that fit a .375 WCF. the same? Gas check or not? Any help or recommendations please.

[dondiego]

They can be the same. They may need to be sized to different sizes but they should be close. I have both. You will want a gas check design if you want to push them very fast.

[Outpost75]

Cast the chamber and get a mould which will let you size to chamber throat size. Ignore the groove diameter of the barrel. Most .375 H&H rifles I have shot cast in needed a .377-.379" cast bullet. #375449 is a proven performer with 13 grains of Bullseye for 1300 fps without the GC as a smokeless equivalent to the .38-55 black powder round, or with gascheck and 60 grains of 4895, 4064, RL15 or Varget with a 2.0 grain Dacron fiber filler to occupy the free air space, for about 2000 fps as a hunting load. OK to increase the charge to get best accuracy, for most rifles the "sweet" spot is in the 60-65 grain range.

[JonB_in_Glencoe]

Disclaimer: I have never shot cast in my 375.

My story: I 'had' a Interarms Mark X in 375h&h, I set forth to load for cast. A member swapped with me and sent some sample boolits (225gr and/or 250gr) that were sized to .379 as that member told me, that is what he found to work best in his gun, I don't recall what make/model his gun was? I didn't slug my bore or do a chamber cast before I got the boolits. I made some dummy rounds, and it wouldn't chamber no matter what OAL I tried. I did a 'quick' slug of the Muzzle, as I wasn't up to slugging the full length that day, and I measured a Groove Dia of .375
>>>and that's where the story ends, I put the project on the back burner...and then a year or so later, I sold the gun.

I still have those samples (25 or so), I just went and looked at them. I have no notes about what they are or what they are sized to (to confirm my memory of them being .379). Some have GC's, and some don't, I suspect those without GC are unsized, but there are some loose GCs in the bag as well. If you are interested in them, they are yours for the $7 ship fees. I also have two Lyman size dies .375 and .376 (the .375 is the older style w/o Oring, the other is the newer style and is stamped .375 but I used it twice and the boolits came out .376). PM me, if you are interested in either of those.

[wmitty]

I have the RCBS 37-250-FN and the Lyman 378674 and my Model 70's groove dia. is .377" while the M 700 is yet to be slugged. I sized the RCBS boolit to .375" for years before I learned better and the M 70 shot the undersized boolit so well I'd be accused of stretching the truth if I posted range and group size.

[runfiverun]

I use the 375449 sized to 379 in both of my 375 Winchesters.
I would do the same in the H&H as that is what one-two others I know do in them.
they do pretty well with the Unique load posted above and with 2400.

[dh2]

I have a Rem 798 in .375 H&H Mag. it takes very well to cast boolits I use Lyman Mold #375449 38-55 WCF 264 Grain Flat Nose Gas Check the mold drops .379 But I size .377 The mold is made to drop .379 because of the old 38-55 but sizing the small amount off of the boolit is no problem at all,

[skeettx]

Lyman 375449 with Hornady Crimp on gas check sized to .377
60 grains of Old 4831
Clover leafs at 100 yards
Mike