Improving the 375 H&H

AZDAVE · Mar 27, 2018

I looked at my quick load program (A little older version) it didn't have Rhino bullets listed (The manufacture is Rhino correct?)

So I looked up the two closest in weight that I could find. Kept the loads below MAX pressures.
Using woodleigh 350gr welded core RN 46D 81gr S365 in a 24in barrel . 2495FPS at 60254psi chamber pressures (these are estimates)
woodleigh 350gr welded core 46C, 82gr S365, 24in barrel 2500FPS at 61169 psi

Barnes 350gr banded solid 81gr S365 24 in barrel 2494FPS at 59713psi

The other two powders were way to fast and pressures were through the roof.

You should be able to get 2300FPS or real close and keep the pressures below max, however every gun has its own personality. The standard safety tip to start 10 % below and workup carefully.

I happen to be one of the guys that like AI chambers and don't worry about resale.. As others have pointed out if it doesn't work you can always rebarrel to a 404.

Good luck on your project

MAdcox · Mar 27, 2018

375 Ruger Fan said:
Improving the 375 H&H?????????

I believe Ruger did that already...........

Ding, ding, ding... starting the next round :V Chair:

IvW · Mar 27, 2018

gizmo said:
I have to agree with Velo here but..... If your going to keep the rifle for ever and ever I get the idea. I know when I buy a rifle I stay away from any or the AI's even though I a reloader. I don't want to get in a situation where I'm hunting somewhere and my ammo got lost, damaged, stolen, forgotten, etc and cant go to the store and by more in a pinch.

You can shoot standard 375 H&H ammo in the AI version.

IvW · Mar 27, 2018

AZDAVE said:
I looked at my quick load program (A little older version) it didn't have Rhino bullets listed (The manufacture is Rhino correct?)

So I looked up the two closest in weight that I could find. Kept the loads below MAX pressures.
Using woodleigh 350gr welded core RN 46D 81gr S365 in a 24in barrel . 2495FPS at 60254psi chamber pressures (these are estimates)
woodleigh 350gr welded core 46C, 82gr S365, 24in barrel 2500FPS at 61169 psi

Barnes 350gr banded solid 81gr S365 24 in barrel 2494FPS at 59713psi

The other two powders were way to fast and pressures were through the roof.

You should be able to get 2300FPS or real close and keep the pressures below max, however every gun has its own personality. The standard safety tip to start 10 % below and workup carefully.

I happen to be one of the guys that like AI chambers and don't worry about resale.. As others have pointed out if it doesn't work you can always rebarrel to a 404.

Good luck on your project

Thank you so much for that information and that you took the time to do that. I like this forum more and more everyday.

If I do it I will also double check the jump to the lands with the 380 gr bullet to further ensure as low as possible chamber pressure.

I have always been using S355 but the last batches are not as good as the earlier ones.

Goose Cracker · Mar 28, 2018

IvW said:
You can shoot standard 375 H&H ammo in the AI version.

Which is how I planned to fireform my 338-06 AI cases. I've heard that in some instances, firing standard ammo in AI chambers can even be pretty accurate. Ammo availability in this instance isn't really a big deal, at least in my view.

And as long as the reamer specs match the specs of the AI die set you have, the AI alternative is an interesting one. And even in the event that the specs don't match, you could have a custom die set made. Not cheap, but it would be perfectly fitted to your specific chamber. That was just a step too far for me, but YMMV.

Shootist43 · Mar 28, 2018

Goose Cracker said:
I may be missing something but I think a 95 fps increase over 2645 is a 3.59% increase?

You are 100% correct. That misplaced decimal will get you every time.

Shootist43 · Mar 28, 2018

IvW said:
Hi that might be interesting, kind offer.
We have Somchem, S335, S355 and S365. May also be able to get hold of Vihtavuori powder.

PM Alchemist, he lives in Pretoria and very familiar with Somchem Powders. He is a great guy (not that AZ Dave isn't) but being a South African is much closer to the reloading issues you face. If I could, I'd like to buy one of your old BRNOs and you could buy a 404 Jeffery from Gert Odendaal's gunsmith buddy.

Dr Ray · Mar 30, 2018

IvW said:
I own two 375 H&H rifles one is an original ZKK 602 with pop up sight and the other also on a ZKK 602 action has a custom 24 inch barrel.

I am contemplating having the one rechambered to 375 H&H Ackley Improved. (I have a 40 degree die set for the AI)

The reason I want to do this is that here in South Africa we have one of the best bullets available manufactured by Rhino. I love the heavy weights.

I want to use the extra case capacity to shoot these 380 grain Rhinos at about 2350 Fps without excess chamber pressure. I cannot imagine a better combination for all PG through to Buffalo.

The other option is just to rebarrel to 404 Jeff but this is costly and then I need to re licence the firearm.

Thoughts and comments appreciated.

Sounds very good.

Alexandro Faria · Mar 30, 2018

IvW said:
May also be able to get hold of Vihtavuori powder.

If I may ask, where are you getting Vihtavuori Powder in RSA?? Feel like sharing with a Pretorian

Hearties · Mar 30, 2018

Alexandro Faria said:
If I may ask, where are you getting Vihtavuori Powder in RSA?? Feel like sharing with a Pretorian

Plenty at S&O down here in the Cape

meigsbucks · Mar 30, 2018

Improving on the .375 H&H is tough but considering you want to use some real heavyweights, I can see why you want additional case capacity. Have you considered the old .375 Weatherby? A factory "improved" .375. Brass is available from Weatherby and should you be caught without ammunition, you can fire H&H ammo in it (although at reduced performance).

IvW · Apr 2, 2018

Alexandro Faria said:
If I may ask, where are you getting Vihtavuori Powder in RSA?? Feel like sharing with a Pretorian

Safari and Outdoor.

Alexandro Faria · Apr 2, 2018

Dankie

HWL · Apr 8, 2018

375 Ruger Fan said:
Improving the 375 H&H?????????

I believe Ruger did that already...........

You are wrong,... improving the .375 H & H means, to throw that barrel away and install a .404 Jeffrey!

:Finger:

HWL

Bill Bunn III · Apr 8, 2018

HWL said:
You are wrong,... improving the .375 H & H means, to throw that barrel away and install a .404 Jeffrey!

HWL

That would be the only way I could see to improve the 375 H&H. I will know for sure when my Dad's 404 gets to him.

Alexandro Faria · Apr 9, 2018

Guys, question, there's a lot of complaints about feeding issues with AI cartridges... Has anyone else heard this? Has anyone EXPERIENCED this? If so, isn't this a really undesirable thing especially seeing as the rifle may be used for DG?

IvW · Apr 9, 2018

Alexandro Faria said:
Guys, question, there's a lot of complaints about feeding issues with AI cartridges... Has anyone else heard this? Has anyone EXPERIENCED this? If so, isn't this a really undesirable thing especially seeing as the rifle may be used for DG?

Not on the 375 H&H, mate of mine has one and he has never had any feeding issues. I plan on a 40 degree shoulder as I have a reloading die for it.

Alexandro Faria · Apr 9, 2018

Might I ask who you will be sending your rifle to for this??

IvW · Apr 9, 2018

Alexandro Faria said:
Might I ask who you will be sending your rifle to for this??

Guy in Potch can send you the details if interested, he does quite a few AI conversions and has done so for a long time.

Spooksar · Apr 9, 2018

Go with the AI, I have a few Improved rifles so I bought cheap but I dont sell firearms so doesnt matter to me, As far as feeding a good gunsmith will solve those problems for you.

Improving the 375 H&H

AZDAVE

MAdcox

IvW

IvW

Goose Cracker

Shootist43

Shootist43

Dr Ray

Alexandro Faria

Hearties

meigsbucks

IvW

Alexandro Faria

HWL

Bill Bunn III

Alexandro Faria

IvW

Alexandro Faria

IvW

Spooksar

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