Looking for a little help for my 375. It's a REM 721 action, new Douglas 1 : 10.5 twist. I broke the barrel in slowly and with a great job of cleaning in between all the shots/groups of shots. All break in was done with factory ammo. 20 rounds of 300g Nosler Partitions, and 10 300g Swift A-Frames. And now have shot about 50+ rounds through it. Best groups I'm getting are 1.5" - 1.75". I have dies and a box of 300g TSX, and powders available on hand are H4895 and W760. Using once fired Fed nickel cases, CCI 250. I'm hoping to get 3/4" group or better, is this realistic or should I settle with the factory group? I'll be going to Zim and tagging along on a couple leopard with hound hunts and possibly do my own buffalo hunt if time permits. But going to be carrying the rifle in case things get hairy or we happen to surprise something that doesn't like surprises in the bush. I have a Leupold VX-R 2-7 on it. Any suggestions or tips would be appreciated.

Welcome WestCo! I have had several 375 H&H's in the past, now only two. All shot well with factory ammo, if I found one it liked. If I took some time to work up a handload with the bullet I wanted, I could get some very small groups. I have a Dakota model 10 that I think will be a real tackdriver, haven't had time to shoot it much lately, but will this summer.

WestCo:

I would think you can do better. I have settled on using NorthFork soft and solids for my .375 Sako and my .375 Brno. The Sako is extremely accurate 1/2" to 3/4" the norm at 100 yards.

I have found R15 to be the most accurate powder. Tried some IMR4064 but it lacked. I use Federal GM 215 primers and a mix of brass mostly Winchester.

Do a search on this site for data. Lots of TXS users. I think you will find that Reloader 15 is a favorite powder for this cartridge.

Good luck

All of my .375's are tack drivers. You just haven't hit upon a load yet. Keep experimenting.

Check bedding and upward barrel pressure, if any. If it is free floated, add some. It should shoot a bit better.

Barrel was bedded by the Smith that put the new barrel on it. Not sure how to check to see if it is done good or if the barrel has any upward pressure on it. The gunsmith is well known in my town and has been doing it forever. Should the twist rate of 1:10.5 be OK with the 300g bullets? Had one guy say it was way to fast of a twist. I'm just scratching for any direction to go with this thing.

Double check that twist; Douglas does not make any half inch twists and none less than one in 12. in 375.
See if you can slip a dollar bill between the barrel and stock. If so, it is free floated. If not, loosen the front guard screw and see if the receiver springs up; if so, it has upward forearm pressure; hopefully just at the tip. Whichever you find, make it the other one and shoot it. Make sure the stock is not touching the barrel any place but directly upward at the tip.
See how it shoots with 270 grain bullets. Sierras.

I checked the barrel a couple times with the tight patch method, marking the rod with tape and pulling it back until it makes 1 complete rotation, it came out to 10.5" both times. Might have misunderstood or misheard him say what brand the barrel was. Trying to stick to 300g so that I can use some of the Woodleigh solids on buffalo for a follow up shot.

I would find out for sure what the barrel is, then. Might not be a good one.

I've only had two, but RL 15 was the powder, and both opened up on groups when past the mid 2400 fps with a lot of different bullets

There could be a lot of things limiting your accuracy running from your particular loads to the way you are holding and shooting your rifle. Are those three-shot groups, five shot groups, or...?

This is a hunting rifle, not a match rifle, isn't it? Just because many rifles in .375H&H are capable of sub-MOA groups doesn't mean every hunting rifle is. Shooting to 1.75" at 100 yards means 3.5" at 200 yards and less than 5-1/4" at 300 yards. Just how long a shot do you anticipate for a treed leopard and your buffalo?

Loads can be worked up for best possible accuracy but also things like highest velocity, safe pressures in very hot environments, reduced recoil, flattest trajectory, etc. No single load is best for every purpose. What is your priority?

I'm just a perfectionist I suppose. I have a 7mm Mag that is my go to elk rifle and shoots sub 1/2" groups. I feel pretty good about my shooting techniques, and really concentrate on my breathing and squeezing the trigger. I'm not looking for crazy velocities, as the same with my 7mm, I'm more concerned with accuracy than speed any day. I am planning on hunting a kudu, and zebra for sure, and if I can make it work or have time after the other two are finished with their leopards, then possibly a buffalo. I just want to know that my rifle is hitting where I am aiming, especially if I need a follow up shot or worse case in a last ditch effort on a charge. And after seeing the capabilities from others 375's on here, I know the cartridge has the capability to be sub 1" and possibly even down to 1/2".

In my Winchester the 300 grain TSX liked 67 grains of H4895 for sub MOA groups at right at 2500 fps. That's the max load in the Barnes manual so work your way up to that.

With the 300 grain Barnes banded solids I ran 70 grains of H4895 for almost 2600 fps. That's below max in the Barnes manual.

IMR4064 shot at 2490 fps (67 grains) but accuracy was 1/2 MOA for three shot groups with the 300 grain TSX.

Reloader 15 gave me the best groups with the 300 grain Banded solids and they hit within 1/2 an inch of the IMR4064 300 g TSX loads at 100 yards.

Don't fall into the trap that a friend did, way back. He got is rifle to shoot good, sub moa groups from the bench, spent lots of time developing loads and shooting small groups, from the bench. Never practiced any shooting from field positions. Got into the hunting field and found NO bench rests out there, and could not hit a barn at 100 yards.
Lesson; there are no .5 MOA or even 1.5 MOA rifles when you are hunting. The important thing is where does your FIRST shot from a cold barrel hit?
Another thing, now, is we do not know the maker of your barrel. It might be shooting as well as possible.

I've shot several 375's over the years and have been impressed with how well they shoot. The one practical piece of info that I can pass along comes from my own experience, IMR 4064 powder seems to be a winner overall. The manuals will show other powders performing better but a medium load with 4064 can generally be depending upon to be quite accurate. I would suggest you try such with 300 grain bullets. I'm guessing you'll be pleased with the results. Good luck...

Play with some loads and I would bet that you will find something better. The TSX has proven to be a very accurate bullet in several calibers that I load for including the 375H&H.
If you don't see anything better than 1 1/2" after tweaking the loads and rifle, don't sweat it. I know you expect better and so do I but a 1 1/2" 375 H&H is going to do everything you want unless you are shooting squirrels.
I've also had the best luck with RL15.

Thanks for all the ideas and options to try. I'll be giving them a whirl here in the next day or so if the weather clears up a bit.

As far a crimping the case, is that a good idea to do once I figure out the best load? I haven't done any crimping in the past, due to reloading only for .223, 6.5-284, .270, and 7mm. I do have a Lee crimper on the way.

WestCo:

I always Lee Factory Crimp Die my .375 rounds. I LFCD from .300 H&H up.

I also make sure the primer pocket is clear and uniform. I then seal the primers on my loaded rounds as well.

Good luck with your load development.

Your rifle is accurate enough. Only on the internet is every rifle a sub 1/2" gun..Usually that comes from shooting 3 shot groups and that's fine for a hunting rifle..The .375 is not a varmint rifle, not a target rifle and a deers kill zone is about 12 to 15 inches at 100 yards or 1000 yards..In many cases a barrel will not shoot its best until 250 to 300 rounds have been shot thru it..regardless of how you break it in...Also your Douglas barrel is more likely to have a 1x10 or a 1x12 not a 10.5..I don't know of any barrel maker that makes a .375 1x10.5 right off hand and I doubt if anyone does. Another factor in target shooting is big bores tend to shoot bigger groups than lighter rifles because of shooter error, even with experts that are not recoil conscious their seems to be a slight difference as caliber gets larger..now as to will they admit it or not is a nuther ball game!

I can't imagine you not knocking over whatever you shoot at with a 1.5 or 1.75 grouping rifle..Get over it!

I would be more concerned with a buffalo rifle that didn't have QD mounts and the iron sight option, and my off hand skills would be of much more concern than the size of my groups at 100 yards off a bench... It sounds like a plenty capable rifle to me, and your groups are supposed to get smaller as the buffalo or Leopard gets closer anyway sooo????, however sometimes thats' not the case!

3/4 groups may be successful in time with the correct loads and some more barrel wear, who knows, who cares that extra 1/4 inch is only icing on the cake...Ive had best luck with RL-15 and IMR-4064 and IMR-4320 has been the powdera for the 375 for as long as I can remember..but I went to RL-15 with a load that produces a mild 2500 FPS and that is a better killer of big stuff than a 375 at the fabled 2600 plus FPS as bullet performance excels at that speed...Try the Woodleigh 350 gr PP or RN, they sure shoot good in most .375s..

I will disagree with Atkinson. That is not acceptable accuracy from a new Douglas premium barrel. Every 375 H&H I ever owned or fired shot extremely well; better than most 30-06 etc.

I think it may be your twist. 1:12 is typical. Also IMR 4064 and Fed 215 Primers are the go to components for 260 grain bullets with a moderate crimp @ about 2700 fps;300 grain @ 2450. Every pre 64 Win 70 in 375 H&H that I owned shot under an inch.

As has been said, 3 shot groups. That is all you need for a hunting rifle.

ETA: I want to clarify. The gun is accurate enough to hunt with, but that is not acceptable accuracy from a DouglasPremium barrel.

Well, he said the twist was one in 10.5; that can't be a Douglas, they do not make any half inch twists and none less than one in 12 for a .375. and the OP is now, not sure of the maker. It could be a no name, bad barrel.
Yes, a Douglas will shoot better than that, given that his bedding is right.

Besides what other have said about checking the bedding, and ensuring your barrel is free floated, I would stick with the W-760.

I use 77 gr of W760 behind both the Speer 285 gr softpoint and the Nosler 300 gr partition. the noslers will shoot into an inch consistently and the Speers have given me some groups I can cover with a dime.. but about 3" to the right of the impact point of the Noslers.

You might have to adjust your bullet seating depth to get the results your looking for, but W760 is The powder for the 375 just like 4895 is The powder for the 30-06.

Good luck!

Only on the internet and in the mind of some beholders who are delusional is that not acceptable accuracy with a Rem. 721 hunting rifle. Im sure some will shoot that a little better but damn few..

Well, my best luck has come with H414 and 260-270 grain projectiles.

i'd give 4350 a try - that has always been the go to powder in 375

I played around with a bunch of loads for my .375.

I found my best compromise of velocity and accuracy was with 72.3 gr of VV N 540 (which is lot dependent, so start lower and work up) with a 300 grain TSX. Moderate crimp into the first groove of the bullet, basically at Barnes'recommended OAL and it gave me sub MOA.

H4350 and RL 17 also did well for me with the TSX.

I also worked up a banded solid load that impacted with the TSX, but that required dropping the powder by half a grain.

My experience is that the .375 generally isn't picky, and is very capable of good accuracy. Factory loads all shot sub 1" in my rifles, so while yours is certainly good enough for buffalo or cat follow up at close range, it sounds like something isn't quite right there.

It could be picky on the bullets/ I had a Ruger RSM in 375 H&H that could shoot anything accurately. My Mauser M03 is a different story. In 300 gr bullets, only likes TSX and Woodleighs (I settled on the TSX). Working on a 250 gr TTSX load right now. I'm getting close.

I found that max loads produce the best results for me. I use Norma 203B and CCI-250s.