Loading .375 H&H Ackley Improved

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Well, I’ve finally put all the pieces together (at least temporarily) for my custom M98 .375 Ackley Improved project. Hoping to get out and shoot it over the next few weeks and see how it performs.

I’m uncertain as to the history of the barrel itself (but the price was very right on it), other than it was originally a stock H&H factory barrel of some sort, so a good portion of my testing will simply be to see how well it shoots compared to my Brno ZKK.

Regardless, anyone here got load recommendations for the .375 H&H AI?

I’m thinking I’ll form using the cream-of-wheat method to start, so as to not burn up too many pricy .375 bullets. Any suggestions on powder for forming as well? I have a fair amount of pistol and shotgun powders on hand.
 
Well, I’ve finally put all the pieces together (at least temporarily) for my custom M98 .375 Ackley Improved project. Hoping to get out and shoot it over the next few weeks and see how it performs.

I’m uncertain as to the history of the barrel itself (but the price was very right on it), other than it was originally a stock H&H factory barrel of some sort, so a good portion of my testing will simply be to see how well it shoots compared to my Brno ZKK.

Regardless, anyone here got load recommendations for the .375 H&H AI?

I’m thinking I’ll form using the cream-of-wheat method to start, so as to not burn up too many pricy .375 bullets. Any suggestions on powder for forming as well? I have a fair amount of pistol and shotgun powders on hand.
You can use 375 Wby data, except for coal. Just start low and work up. Note that is the 375 Wby, not the 378. - dan
 
The 375 H & H Ackley Improved is an excellent cartridge. Same capacity and data as the .375 WBY.

You can fire .375 H & H as well as the .375 WBY in a .375 H & H Ackey chamber.
 
Why not just load and shoot? The brass will form as you go, thats always been the advantage of Ackley cartridges

16 grains of Unique and the COW method will form your cases. Or you could just shoot H&H ammo and get some off-hand practice in. That will negate any waste of components.

A few years back I shot lots of full house .243 Win through my old .243 AI to form brass, but sadly the sheer price of .375 bullets these days is holding me back right now. I have a good stock of primers, but only a couple hundred bullets…

If I can coerce a friend to loan me his mold, I might try forming brass while slinging some 270gr hardcast boolits at gophers though.
 
I have used Unique & C O W to for lots of 38-56 cartridges from purposely undersized former 45-70 cases. I discovered they formed better at the thicker case base if I just filled the case body with the C O W and then filled the neck with carpenters glue and let it set overnight...seemed to build pressure a bit before releasing the glue plug ( I only used 8-9 gr of powder with standard primers).
The reason I "purposely undersize the brass blanks first is that I discovered when I tried sizing in sizing dies to fit the chamber, the "brass spring back" was enough that they wouldnt chamber so now I size small on purpose & fire for to fit chamber...all the brass chambered easily after doing this....good luck with your project.
 
I have used Unique & C O W to for lots of 38-56 cartridges from purposely undersized former 45-70 cases. I discovered they formed better at the thicker case base if I just filled the case body with the C O W and then filled the neck with carpenters glue and let it set overnight...seemed to build pressure a bit before releasing the glue plug ( I only used 8-9 gr of powder with standard primers).
The reason I "purposely undersize the brass blanks first is that I discovered when I tried sizing in sizing dies to fit the chamber, the "brass spring back" was enough that they wouldnt chamber so now I size small on purpose & fire for to fit chamber...all the brass chambered easily after doing this....good luck with your project.
Interesting, that makes a lot of sense though. What did you use to under-size your cases?
 
A few years back I shot lots of full house .243 Win through my old .243 AI to form brass, but sadly the sheer price of .375 bullets these days is holding me back right now. I have a good stock of primers, but only a couple hundred bullets…

If I can coerce a friend to loan me his mold, I might try forming brass while slinging some 270gr hardcast boolits at gophers though.
The Speer 235 grain is relatively cost effective, it’s close to the only one these days. 35 bucks for 50 and they are a lot better than people who haven’t used them would think. I should put in the disclaimer that I haven’t used them in the ‘bee, just the H&H.


Cast bullets are a different thing; there’s not much thats more fun than a bigger rifle and an ice cream pail of cheap ammo :)
 
The Speer 235 grain is relatively cost effective, it’s close to the only one these days. 35 bucks for 50 and they are a lot better than people who haven’t used them would think. I should put in the disclaimer that I haven’t used them in the ‘bee, just the H&H.


Cast bullets are a different thing; there’s not much thats more fun than a bigger rifle and an ice cream pail of cheap ammo :)
I’ll have to see if the local shops have any 235’s, that sounds like a fine idea. For medium game around here, they oughta be fine anyway.

I have some 250gr Sierra SPBT GameKings, but found that even at 2850fps+ MV they don’t expand on deer size game.
 
Interesting, that makes a lot of sense though. What did you use to under-size your cases?
Being a sort of reloading geek I used to reload for 32 different calibers) I have a large assortment of dies for other calibers that were "close" to the dimensions I needed, sometimes i have to use an assortment to achieve what I want....and I have a lathe to make case mouth expanders to my spec or modify an old die to what I need.
You might throw your hands up and say "I dont have all that sh!t but have faith...gunshows have a lot of tables that offer old dies and part set very inexpensively
 
I’ll have to see if the local shops have any 235’s, that sounds like a fine idea. For medium game around here, they oughta be fine anyway.

I have some 250gr Sierra SPBT GameKings, but found that even at 2850fps+ MV they don’t expand on deer size game.
The 375s are very versatile and can do a lot with one bullet weight. They are even better when used as conceived with bullets in 235, 270 and 300 grains. The 235s do a fair job of making an H&H into makeshift 300 Mag out to longish real world hunting ranges. The 300 Mags are seldom noted for slow killing on deer sized game. :) Somewhere around 90 % of the worlds game isn't any bigger than a big western whitetail or mule deer buck and practically nothing is thick skinned and buffalo, hippo, and elephant sized.

As an aside, makers of factory ammo do a pretty good job with their cheaper ordinary
baseline loads, knowing full well that most animals shot aren't very big, tough or far away.

Bit surprised with Sierra results, I've never used those ones.
 
The 375s are very versatile and can do a lot with one bullet weight. They are even better when used as conceived with bullets in 235, 270 and 300 grains. The 235s do a fair job of making an H&H into makeshift 300 Mag out to longish real world hunting ranges. The 300 Mags are seldom noted for slow killing on deer sized game. :) Somewhere around 90 % of the worlds game isn't any bigger than a big western whitetail or mule deer buck and practically nothing is thick skinned and buffalo, hippo, and elephant sized.

As an aside, makers of factory ammo do a pretty good job with their cheaper ordinary
baseline loads, knowing full well that most animals shot aren't very big, tough or far away.

Bit surprised with Sierra results, I've never used those ones.
You’re definitely correct on the versatility! To be fair, I spoke with the Sierra techs about my experience afterward and they admitted the 250gr is really built for elk and grizzly, the jackets are much thicker than needed for whitetail- even more so than most 270gr offerings.
 
Well fellas, I loaded up the first few rounds for fireforming today, and was wonderfully impressed.

I didn’t get myself any cast bullets yet, but I found a box of 270gr Hornady SP-RP that cost me nothing, so I loaded them in Winchester brass over 65gr of Reloder 15. This produced very comfortable recoil and grouped under 1.5” at 100m, even with a stout wind blowing.

I’ll post again as I develop some full-house loads.
 
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