I'm loading for the 375 H&H for the first time and have a few questions to ask. I've loaded 10 rounds each with Rl-15, and IMR 4064, 4350 under a 270gr Hornady @ 2,600 fps. I used some old Win 120 primers that I wanted to use up. I was told this was a fairly hot primer and others on this site have used reg primers in the H&H with good results? Are the win 120 primers ok to use? These will be my practice rounds. I will use Barnes X's or SAF for buff
I used a stony point tool to set the bullet jump to the rifleing. I had to set the 270gr Hornadys .050 off the rifleing to get it to fit in the mag box of the Ruger SM. Is this amount of bullet jump common with 375 guns?
Thanks Donato

If you are using those rounds in order to get the "feel" or recoil of your new 375 H&H I say go for it. However, if you are practicing for hunting/accuracy/zeroing in the rifle I'd recommend using the load you are planning to use. I personally like Winchester Fail Safe in 270 grain with IMR 4831 launched at 2700 FPS. If you want to stick with the same powder, 300 grain Nosler Partitions at about the same speed give very good accuracy in all 375 H&H rifles I've shot. There is or was a 200 grain flat nose made by, I believe, Sierra that worked well on elk or deer. Never got the chance to try it on rabbit though. Good shooting! Mike

I just finished reloading a bunch of 375 this evening working up loads for Tanzania in July. Regarding primers, your 120's should be OK. I would not worry about seating depth because it probably will not coincide with your cannelure, and you should crimp your 375 loads. I have had loads that were 'just right,' but would not fit into the magazine. Remember relilability is everything with dangerous game.

I reviewed my loads in weights from 250 to 300 grain, and found that again and again WW760 gave me the best velocity and accuracy. It works well. I have also found 4320, 4831, and 4350 useful and accurate.

Assuming that you are shooting dangerous game, I would recommend that you try Federal Premium solids and soft points in 300 grain loadings. Practice with the Hornady 300 soft point and shoot the factory loads on your trip.

Your need for mid-weight loads is marginal because your ph will get you right on top of most of the large animals that you will hunt, and you can use a lighter 30 or 7mm magnum for smaller species. These will shoot much flatter than the 375 even with 250 grain bullets. Zero for 100 yds with the 375 and you will be within an inch to 125yds, and your ph isn't going to let you shoot at any dangerous game further away than that. Zero your light magnum with 175-180 grain soft points for about 225 to 250 yards (plus or minus 3"), and let the good times roll. Good hunting. Kudude.

FWIW - I chronographed some 300gr Hornadys in my 375 this afternoon.

76.0gr H4350 netted me 2530 (avg.)
77.0gr ran 2580

That's with WW brass and Fed 215 primers.

Reduce yours and work up.

In my experience, you don't need magnum primers for 375 H&H loads. The old Winchester 120 primers, or today's WLR (Winchester Large Rifle) primers work well.

As for powder, I know that numerous ones work well, but I've gotten the best velocity and accuracy, using 270 or 300 grain bullets, from heavily compressed loads of H 4350 -- it works better than IMR 4350 in this cartridge. Look at Hodgdon's loading manual for the amount.

You can safely use ANY kind of Large Rifle primer or Large Rifle Magnum primer, provided you start with loads at the loading manual starting load level, and quit increasing the powder charges at or before you reach the maximum level for your particular gun!!

quote:

Originally posted by El Deguello:
You can safely use ANY kind of Large Rifle primer or Large Rifle Magnum primer

I keep reading that in posts. Why wouldn't one use Magnum primers?

It certainly can't be the expense.

quote:

Originally posted by new_guy:

quote:

Originally posted by El Deguello:
You can safely use ANY kind of Large Rifle primer or Large Rifle Magnum primer

I keep reading that in posts. Why wouldn't one use Magnum primers?

It certainly can't be the expense.

I was developing a load w/270 gr. accubonds and RL 15 and was disappointed with the 1 1/2" groups using Fed. 215 (mag) primers. Swithched to Fed. 210's (standard large rifle) and had a 3 shot .470" 100 yd. group working when something came loose in scope and it would no longer focus.

Looking forward to getting scope back from factory to continue the 5 shot string.

I have had same experience in the past on other magnum calibers, so always give the std. primers a try and use what works best.

Regards,
hm

Thanks guys for the help in answering my questions. I shot the loads I made in above post and they shot very well. Looks like reg primers work well in the 375.
Below are the groups I shot using a 4x scope and being a first time shooter of the 375, the biggest rifle I ever fired. All were 3 shot groups
Rl-15 = 15/16 and 5/8 inch
IMR 4064 = 1 and 1 1/8 inch
IMR 4350 = 1 1/16

Does any one have a load they shot using a 270 gr Barnes TS at 2,700 fps of a little better using Rl-15 or IMR-4064. I like to keep this bullet at just over 2,700 fps not 2,800 fps
Thanks again for all your help on reloading the 375 H&H

Whether to use a standard primer v magnum primer? I let the load tell me the answer to that.

If you have a chrono use it throughout your load development - consistent velocities and minimal spread between high and low figures is preferred and tells you you're getting good ignition. Of course your shot groups will let you know if the accuracy is better or worse with the Std v Mag primer too. Obviously watching for pressure signs along the way is paramount, but I've noticed no obvious jumps when switching primers.

Rifle loading is a precision game and it gets incredibly interesting the deeper you delve into it. But for the average hunter wanting around 1" groups for his big game rifle it doesn't have to get that complicated usually.

Let your groups and velocities tell you which primer to use.