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Just snagged a marlin 375 Winchester so I’m starting from scratch, thanks for sharing the info!

AA 1680 seems to be the velocity boss in this round. I was getting 2375 fps under 220 vollmers from a 20" marlin. No pressure signs. It is boomy, though.

another good thread!
Bugger

I acquired a 94AE from a member here a couple months ago, and it ended up being real fond of N130.It's not a barnburner powder for speed, but the accuracy was better than any other powders I tried. IMR3031 wasn't bad, either, but it's on the slower side for velocity, too. I'm not going to be using it for long shots, anyway.

1500-1600fps was the sweet spot with .376 260gr cast for both powders. They were old commercial cast, and I did end up having to heavily sort the bullets, because they were very inconsistent. About 60% of them were .376/262gr, and the other 40% were all over the place between .375-.377 and 258-265gr.

Haven't worked up a good jacketed load yet. I think I'm going to give the 200gr Shock Hammers a whirl, since they are readily available, and I've had good luck with Hammers in a couple other cartridges.

My 375 has a steel Lyman aperture rear sight and a brass post up front. I’m not at my computer so going from memory the Barnes 255 bullet got about 2 MOA. I think 200 yards to be about maximum for me with this light rifle, iron sights, & blunt bullets. I’d be happy to get that with the Sierra’s since this rifle will mainly be used on White Tails. I’m going back out next week end and would be carrying this rifle if I could find the right load.
So far cast loads are shooting straighter than Sierras or Hornadys. They are a little less than 3 MOA too. Maybe I should try those.

2-2.5MOA (50 yard groups) is what I am getting with cast too, using a Skinner peep on the rear and a white bead front sight.

I have been looking at different manuals and write ups. It seemed like everyone likes Reloader 7. However, a Lyman manual shows better accuracy with H322 with the Barnes 255 grain bullets. Ken Waters said nice things about 4198 and 3031, but like others, praised the RE 7 as best all-around load and most accurate Jacketed load.
I will be trying H322 since I have a partial pound of it, albeit a little old.
Not today though gusts up to 50 MPH and blowing snow. My how I wish I had an underground 100-yard range sometimes.

RL-7 is my fav in the .358 Win.

DF

I see 375 brass is available several places now. I just ordered from Brownells.

Buffalo Arms usually has it in stock. I bought a couple hundred Starline from them when I bought the rifle. It's a bit heavier walled than the older Winchester brass I had from 15-20 years back.

Don't remember the charge off the top of my head but I use H4198 and a hard cast 200 gr bullet I cast myself. and powder coat.

We don’t have the range of powders you have in the US but from what’s available here the best is Reloader 7, followed closely by H4198. I prefer to use Reloader 7 for all full power loads from 200 - 300gr.

A fun load I use for plinking and small game hunting is 255gr FN PB cast (Lyman 375248) backed by 6.5 gr of Red Dot. It’s very accurate and economical.

I use Ramshot Terminator for my Winchester .375. Works well. I chanced upon it when it was all I could get about 18 months ago, see no reason to change even though other powders are now readily available.

A cast bullet natural. I have some jacketed and wonder why.

I have a Winchester big bore .375 with a Williams peep sight. Loading the sieera 200 gr bullets but also got some 200 gr and 235grain bullets from Hawk Bullets and they are accurate.

what load are you using for the hawk 200s just got some

I just finally shot a bunch of the 200gr Shock Hammer test groups yesterday. It liked them pretty slow. 1500-1550fps was the sweet spot. Everything beyond 1600 was pretty terrible regardless of powder/primer combination.

N130 was the hands down winner for accuracy. IMR 3031 was not quite as good, and R7 shot flat out lousy.

Best group was 27gr N130. Shooting was at 55yds with a Skinner sight. Recoil was mild with this load... mean velocity of 1502fps.

i have a new to me marlin .375 just made up 2 loads both starline brass first in 35gn R7 with hawk 200 the other is 37.8gr R7 with sierra 200 will check back after i shoot them.

Shot a new to me 99A in 375 loaded with 38 grains of H4198. They did really well