Improving the 375 H&H

[Rule 303]

IvW I have not read the whole thread so this may have been mentioned. It sounds to me all you are doing is reinventing the 375 Weatherby.

 

[CoElkHunter]

View attachment 330394


You have to do that , very important , the master looks down on you !

The cartridge 9,3x64 Brenneke is the King of the cartridges caliber 366 / 9,3mm !

Just googled the 9.3x64. Excellent looking cartridge! Case is very similar size wise to the .338WM and similar family of cartridges. Neck it up to 9.5 and you have a belt less .375 that fits in a long instead of magnum action? Neck it down to 8.5mm (.338- I’m learning!) and you have a beltless .338 Magnum? Both would have mildly rebated rims though if that matters?

 

[grand veneur]

The master thanks !

 

[Standard Velocity]

IvW I have not read the whole thread so this may have been mentioned. It sounds to me all you are doing is reinventing the 375 Weatherby.

If I’m not mistaken the OP just wanted to achieve a reasonable velocity with a markedly heavier bullet than standard. The Weatherby is an improved case with loaded ammunition available and does make the most sense to me.

The only reason to go AI rather than Weatherby is to get less case stretching. With a belted cartridge this is not a terrible idea.

I don’t think the intention was ever to achieve RUM velocities with 300 grain bullets, though that option would exist if he wanted to.

 

[IvW]

Ivan,

I now its an old post but have you done the conversion yet?

If you can give me the Details on the 380gr Rhino I can play with QL but seems S365 or equivalent in Vitha will be better suited powders for the 380gr.
I have a friend who got his 375 turned into AI and very happy with it although he didnt do it for the 380gr he did it to get more speed from the long 300gr TSX bullets.
350gr Woodleigh would also be a good choive and running them 2350fps would not be an issue out of a 25" barrel you have never mentioned the barrel length from the rifle you want to convert. So the AI might just hit 2300fps or just fall short without too much pressure.

As for SAPS pain in the butt always and long waits.

Hi I have two 375 H&H rifles both on ZKK 602 actions, one original the other with a custom(heavy profile) 24 " barrel. This is the one I want to convert to AI. I already have the reloading die set. 375 H&H IMP 40 degree.

I have always felt 2300 Fps is the best killing speed for DG rifle cartridges. If I could get the 340 gr Rhinos solids and softs or the 350 gr or 380 gr Rhino soft close to this with low pressure I would be very happy.

If it does not work I will then have the rifle re barreled to 404 Jeff but as mentioned the process is becoming a pain in the arse.

 

[Wyatt Smith]

What’s the normal speed for a 350 grain bullet in the standard H&H. I thought 2300 was achievable.

 

[IvW]

What’s the normal speed for a 350 grain bullet in the standard H&H. I thought 2300 was achievable.

Probably is but if the same velocity is achieved in the AI 40 degree chamber it surely will be at lower pressure? I do not need high pressure in a DG rifle.

380 gr Rhino expanding bullet will not achieve 2300 in standard H&H.

 

[Wyatt Smith]

Probably is but if the same velocity is achieved in the AI 40 degree chamber it surely will be at lower pressure? I do not need high pressure in a DG rifle.

380 gr Rhino expanding bullet will not achieve 2300 in standard H&H.

I like low pressure too. Some day in the distant future I hope to hunt a buffalo with my H&H, I plan on using north fork 350s at 2300 or a little under. I wish swift would make a 340 or 350 A frame for the 375.

 

[Tanks]

and you might find the rem brass lasts longer than norma
bruce.

Well, my experience is otherwise, but that is because they get cut most likely.

 

[IvW]

340 gr Rhino SD .345
350 gr Rhino SD .356
380 gr Rhino SD .386

 

[WAB]

Hi I have two 375 H&H rifles both on ZKK 602 actions, one original the other with a custom(heavy profile) 24 " barrel. This is the one I want to convert to AI. I already have the reloading die set. 375 H&H IMP 40 degree.

I have always felt 2300 Fps is the best killing speed for DG rifle cartridges. If I could get the 340 gr Rhinos solids and softs or the 350 gr or 380 gr Rhino soft close to this with low pressure I would be very happy.

If it does not work I will then have the rifle re barreled to 404 Jeff but as mentioned the process is becoming a pain in the arse.

I am getting 2300 fps with 350 gr Woodleigh Weldcore out of my .375 H&H with no pressure issues. If that is what you are trying to achieve I think you may be wasting your money on the mod.

 

[IvW]

I see below posted on a different thread.

According to Ackley himself, the 270 gr bullet is maxed at 81 grs of 4064 for 2830 fps. The 300 gr is maxed at 78 grs of the same powder for 2630 fps or 88 grs of 4350 for 2740 fps. List also the 350 gr bullet at 88 grs of 4831 for 2650 fps.

 

[Wyatt Smith]

What powder are using? There not much data out there for the 350s.

 

[IvW]

https://www.africahunting.com/threads/load-data-for-375-h-h-p-o-ackley-improved.5607/

 

[WAB]

I am getting 2300 fps with 350 gr Woodleigh Weldcore out of my .375 H&H with no pressure issues. If that is what you are trying to achieve I think you may be wasting your money on the mod.

I’m not sure what your concern is with the std H&H at this loading. I’ve run a lot of these loads through my .375 with no issue. I am not pushing the envelope at all to get 2300.

 

[bruce moulds]

be careful of ackley's loads.
while they were probably sound when written, some powders have proven to have altered burning rates since then.
bruce.

 

[fourfive8]

be careful of ackley's loads.
while they were probably sound when written, some powders have proven to have altered burning rates since then.
bruce.

Agreed! Ackley didn't have or use pressure equipment. Some of his "published" load data when compared to current pressure tested data is very suspect. He blew up more than one action while developing cartridges and loads. He used the "load to failure" method. Which is not all bad but the "load to something short of failure" method is not very comforting.

 

[Major Khan]

I would recommend getting it re barrelled to .404 Jeffery , especially since you already own a .375 Holland & Holland magnum calibre rifle and a .500 Jeffery calibre rifle . It seems that now , only a .400 series calibre is missing from your battery . You get to use a 400 grain bullet in yours with reasonable velocities . I know that you predominantly hand load , IvW. But getting the rifle re barrelled to a .404 Jeffery , instead of a wild cat calibre also does allow you the option to use factory loaded ammunition if you ever need to .

 

[IvW]

You can shoot factory ammo from an AI chamber

 

[CoElkHunter]

I’m just curious as to the benefits of using a bullet heavier than 300gr in the .375 h and h? Of course the heavier and thus longer bullet pumps up the bullets ballistic coefficient and sectional density I believe? I’m about to reload my .375 for the first time using 300gr Nosler Accubonds (bullet seconds from Midway) and THEY seem long? Just new to reloading the .375? Thanks!