375 H+H reloading advice

[John Marshall]

So, I purchased another gun. Winchester model 70 in 375. It came with 3 dies and I am wondering if there are any expeirenced reloaders of this round on the forum. I would like some advice as to were to start and I plan on using 300 gr bullets.

 

[rgv]

the old stand by load for 300's is 68 grains of 4064. If a rifle will shoot, it will shoot load well.

If you are after top velocities, H4350 and RL-15 are good with 300's as well

 

[Johnn Peterson]

With the 300gr Sierra SBT or the 300gr Hornady RN IB, 77grs of IMR 4350 has worked fairly well for me, accuracy wise. In the latest Sierra manual I have they list the following;
- Accuracy load 66.7grs of IMR-4064, 2500 f/sec
- Hunting load 68.0grs of IMR-4064, 2550 f/sec.

 

[JasonYuke]

I played with a buddys M 70 classic and found the gun loved 270 gr Hdy sp or Interbonds, Likes both with a charge of IMR 4350. I think 2-3 frain under max , in the middle some place?

My 375 loves 4064!

 

[buckbrush]

I have also found 68 -4064 with 300 br bullets extremely accurate in 2 .375 h+h's. Rel 19 and 4350 are also highly recomended.

 

[machinistbutler]

I like rl-15 in the 260-270 gr weights but found IMR 4350 gave me the best results in the 300 gr loads.4831 was ok as well.Great caliber!I also found the imperial sizing wax caused much less trimming than normal case lubes.

 

[Dogleg]

I've had good luck with 4350, Reloader 15 and W760/H414. My standard load for two different .375s is 77 grains of W760 and any bullet between 270 and 300 grains. That usually seems to be a 300 Hornady roundnose for plinking and a 270 TSX for hunting. Reloader 15 gives the higher speeds with 270 grain bullets, 2800 is within reach. I'll likely switch someday, but since the ball powder is so nice for volume loading and still kills things maybe not.
I've noticed a few quirks with the caliber that may be of use to you. First off, they are throated for a 300 grain roundnose, and that can leave a wild amount of free-bore with many other bullets. One of mine will only shoot bullets that reach reasonably close to the lands, and is truely pathetic with anything else. The 300 grain Hornady Roundnose in Interlock and Interbond, the old (and now new again) pattern Hornady solids and encapsulated solids match the throat and shoot well as long as I can keep seating out to the lands. 1700 rounds in 14 months took 120 thou out of the throat if anyone cares.That gets me to the end of the looooong CZ magazine and puts the barrel on borrowed time.The 270 and 300 grain TSXs and 300 grain banded solids do well for hunting loads. My other .375 will shoot everything I tried except the Nosler partition.
Make sure you at least try some standard rifle primers as well as the magnums. It seems to be a bit of a trait that groups can be improved with the milder primers. I can't really think of any reason this should be, except that perhaps it helps keep the burning powder in the case. That sloped shoulder sure doesn't. It has made the difference between "good enough" and 5 under an inch for me.
Don't size your practice cases any more than necessary, many of these chambers are real generous in dimensions.

 

[Gatehouse]

H4350
IMR4350
RL 15
RL 19



Since the case is long and tapering, make sure you only partially size the case if they chamber is generous.

 

[savagefan]

300gr interlock rn 75 gr IMR 4350
260gr Accubond 77 gr IMR 4350 in a Brno 602.

 

[Bigbear]

375

Rl 15

 

[Why not?]

Another vote for 68 gr of 4064 with the 300 gr.

I have also shot 65 gr of 3031. It is a stout load and very accurate in my rifles.

Ted

 

[crazy_davey]

I have had great results using IMR 4350 and 4895. I use 4895 for my 300g TSX loads and 4350 for my 380g Rhino loads. If you want load data, shoot me a PM and I will look up all the fine details.