Cast bullet weights for 375 Winchester

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Bearskinner
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Cast bullet weights for 375 Winchester

Post by Bearskinner »

I’ve loaded 375 win Ammo for my brother for years, using factory available 220 and 200 jacketed bullets. As they are no longer available, I’m looking at bullet molds, and really like the 250 grain gas check design. I’m not that familiar with the 375 Winchester round ( in a 20” barreled Marlin) how many of you like a little heavier bullet, and does it really hurt or help cartridge performance?
Hate to purchase molds, if they don’t perform well. I’m sure someone shoots these regularly. He is dropping the rifle off to me as he hasn’t shot it in over 5 years now. Open to thoughts
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Re: Cast bullet weights for 375 Winchester

Post by AJMD429 »

Can’t help much all I’ve shot is 220 grain, but someone here likely has shot other weights.
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earlmck
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Re: Cast bullet weights for 375 Winchester

Post by earlmck »

I've been happily shooting a 250 grain cast/gc in my Marlin 38/55 with 18" twist -- I think 250 grain is the most common size used in 38/55 and a lot of folks prefer the 275 grain. That 375 Win has (according to my twist-rate info) a 12" twist. Sheesh -- you could shoot 350 grainers out of that baby! But before you go ordering moulds you need to be sure what your bore size is: I'm guessing your 375 there is a .375 to .376 barrel but us 38/55 shooters have got gun shy since some makers use .375 or so and then others seem to use .379 to .380 as their standard.

I have a nice lyman mould that throws a 275 grain bullet that I'd really like to shoot in mine but the mould throws about a .376 bullet and this Marlin mics a full .380 so that bullet is a little skinny for my needs and I've not even bothered to try it.
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Bearskinner
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Re: Cast bullet weights for 375 Winchester

Post by Bearskinner »

So probably a .377 sizer. With a gas check Bullet, that should seal perfectly.
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Re: Cast bullet weights for 375 Winchester

Post by JFE »

A lot of moulds available are designed for the 38/55, which uses a slightly longer case. As you are likely aware the 375 cases are slightly shorter. You can always crimp into a lube groove but a Lee FCD allows you to crimp anywhere along the bullet to achieve the correct OAL.

Ranchdog did a lot of work with the 375 and designed some moulds to fit its unusual throat. I think you can find his designs these days at NOE. The 375’s throat is long and wide and was designed to blow off pressure quickly. It will pay you look up the SAAMI specs for the 375 and 38/55 to see what you are dealing with.

The moulds generally available from the big makers are in the 250-280 gr range. If you want heavier, CBE in Australia makes some heavyweights that work well. I have a CBE 376300 FNGC which has the correct crimp groove location. It’s a very accurate bullet.

I have another mould made by Mihec - he does a lot of group buy moulds on the Castboolits site. This one is a 250gr HP design which admittedly I haven’t tried yet. Like all his moulds it is well engineered. This one is designed for several 375 applications however using a Lee FCD will allow you to crimp it to the correct OAL.
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Re: Cast bullet weights for 375 Winchester

Post by JFE »

Bearskinner wrote:
Sun Mar 14, 2021 1:22 pm
So probably a .377 sizer. With a gas check Bullet, that should seal perfectly.
With the wide throat a 378 or 379 sizer will work better as some moulds will drop bullets that are 378/379 in diameter.

With any straight wall case I like to use the largest diameter bullet that still chambers and cycles in the rifle. It helps to centralise the case in the chamber and helps with the wide, long throat that the 375 Win has.
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Re: Cast bullet weights for 375 Winchester

Post by fordwannabe »

If you look on GB for cast bullets there is a guy from Dell Mt can’t think of his business name off the top of my head but he sold me 20 bullets of several different molds for the 375 as a trial pack. He goes by Dan the bullet man really good guy to talk to.
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6pt-sika
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Re: Cast bullet weights for 375 Winchester

Post by 6pt-sika »

It’s been awhile but seems to me I used the RCBS 37-250GC and Lyman 264 gr GC and the pair of RD molds the first was 210 grs and the second was 235 grs both GC . I always used a .379” lubrisizer die . Killed deer with each of those bullets as well .
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TedH
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Re: Cast bullet weights for 375 Winchester

Post by TedH »

I've shot a lot of cast in the 375 from the RCBS molds, both of the Lyman molds, and the 235 gr Ranch Dog mold. After a lot of range time, and killing deer with the heavier Lyman bullet, and the Ranch Dog bullet, I sold the Lyman and RCBS molds and use the Ranch Dog exclusively. I cast them from a Lyman #2 alloy duplicate, size to 0.379" and oven heat treat, then lube with Lee alox. I can drive them very accurately in excess of 2200 fps in my Marlin 375, and they kill a whitetail in impressive fashion. If you are wanting to cast for a Marlin, that's the one you want. The deer in my avatar picture was the first to fall to my Ranch Dog bullet.
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Bearskinner
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Re: Cast bullet weights for 375 Winchester

Post by Bearskinner »

well I looked at a lot of bullet designs and weights, and Looking at the 375 cartridge, I ended up with a 250 grain bullet design.
I don’t hunt with a rifle, unless I’m going to Canada,( only done that 4 times so far) but I do want a very accurate load. The Accurate mold throws a .380 Bullet, with gas check and a nice flat meplat for lever gun usage and impact.
I’ll check the dimensions, to see what it should be sized to. These marlins in 375,I’ve read, we’re only produced for 3-4 years in the 80’s. The chambers are supposed to be much tighter on the marlins, so the .382 etc chambers from older 38-55’s shouldn’t apply. I already have a .378 lube sizer die, so I’ll start by casting a few sized there, and try a few speeds, to check for accuracy.
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Re: Cast bullet weights for 375 Winchester

Post by Bearskinner »

The accurate mold I picked is a 38-250BG.
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earlmck
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Re: Cast bullet weights for 375 Winchester

Post by earlmck »

That should work nicely Bearskinner. I'm using the 38-250G which appears to be identical except for the wider meplat on the BG.

My concern would be that the 375 is too tight in the chamber to allow a bullet much larger than .376. But I'd bet that by switching to 38/55 brass you would get a thinner case neck that would allow larger diameter cast bullets. Do you 375 shooters know if that supposition is correct?

I actually owned a Marlin 375 for a few months before I traded it on for something more my style. I just blew out some 30/30 cases to try it out but was not fond of the carbine style gun and sent it on down the road: gotta' have at least 24 inches of barrel to fit properly in my gun safe. Since I never acquired genuine 375 cases to play with I have no real-life experience with the cartridge.
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TedH
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Re: Cast bullet weights for 375 Winchester

Post by TedH »

earlmck wrote:
Mon Mar 15, 2021 11:24 am


My concern would be that the 375 is too tight in the chamber to allow a bullet much larger than .376. But I'd bet that by switching to 38/55 brass you would get a thinner case neck that would allow larger diameter cast bullets. Do you 375 shooters know if that supposition is correct?
My Marlin will freely chamber .379" cast bullets in 375 Winchester brass.
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earlmck
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Re: Cast bullet weights for 375 Winchester

Post by earlmck »

Interesting how these things work in different guns. My Marlin "Cowboy" 38/55 with a full .380 bore won't let me get away with .382" bullets although .381" seems OK (this is in Starline brass). Thus I was afraid Marlin might be kinda' stingy in the chamber dimension area, which may be an unfounded fear for the .375 cartridge.
TedH wrote:
Mon Mar 15, 2021 11:33 am
earlmck wrote:
Mon Mar 15, 2021 11:24 am


My concern would be that the 375 is too tight in the chamber to allow a bullet much larger than .376. But I'd bet that by switching to 38/55 brass you would get a thinner case neck that would allow larger diameter cast bullets. Do you 375 shooters know if that supposition is correct?
My Marlin will freely chamber .379" cast bullets in 375 Winchester brass.
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Re: Cast bullet weights for 375 Winchester

Post by 4t5 »

I ordered some for my Winchester Big Bore, from Beartooth Bullets, and they sent me .377 dia.
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Re: Cast bullet weights for 375 Winchester

Post by EdinCT »

I have loaded the NOE 235 which is similar to a Ranch Dog with standard lube groves with a gas check over 30 gas of Reloader 7 in Starline 38-55 short brass and it groups very impressively. Not a barn burner but it would kill any deer, black bear or elk I am sure.
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Re: Cast bullet weights for 375 Winchester

Post by Bearskinner »

I know jacketed bullets with a flat nose in 375 are hard to come by. There was a gentleman on here with a bunch of extra bullets, both cast and factory jacketed. I picked up quite a few. I also have 3 handguns that shoot .375’s, so a great assortment of bullets to try. The single shot pistols
(375JDJ, and 378GNR) will take anything, just one at a time. The revolver and lever gun need the flat points ( pointed is too long for even the stretch frame cylinder)
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