Home Forums Hunting & Shooting Ask The Gunwriters .375 Ackley improved?

I got a buddy that lives in Alaska. He emailed me about wanting reloading info. Quite frankly, I know nothing about the cartridge. Do any of the reloading manuals have a section on it, that I could pass the info on to my friend?

Mad Dog

The only manual that I found loads for the .375 Magnum Improved (Ackley) is in the Ackley manual. In that book Ackley states "There are several versions of this cartridge like the .375 Weatherby which are equally as good as the Ackley version."

In that book the loads for both the .375 Magnum Improved (Ackely) and the .375 Weatherby are ostensibly the same.

I have had a custom .375 Ackley Improved for many years made up for me by the late Floyd Butler and I have worked up loads on my own using both the data and my observations.

There must be data online.

The Barnes #1 manual has data for the 375 Weatherby which is close to the 375 H&H AI.

There is some data for the 375 Weatherby on Accurate Reloading.

John Ricks rebarreled a 700 for me with a 20", #5 SS Pac-Nor and I stocked it in a piece of Turkish walnut. It is likely the most accurate rifle I own. With 5/16" of cast at the heel and 1/4" at the toe and about 8 1/2# it is a kitten to shoot.

I have used it for a Kodiak bear (with Rick Bin and Muley Stalker) a number of deer and at least one black bear I can remember. I have been shooting 270gr XFBs in it and will change to the same weight TSX when the box runs dry. I have never recovered an X from it.

I get just a hair over 2700 with 74gr of IMR4064 in cold weather. There was no such thing as load development as the rifle is extremely forgiving. Though, it does not like the Failsafes I tried, at all!
art

Not knocking the AI, (I have two AI chambered rifles...a 257 AI and 7X57 AI), but why would someone decide on the AI, instead of the 375 Wby? This isn't meant to slight the AI and is asked as a serious question for my edification.

375 Wby ammo is still around a bit, and brass, too, FOR A PRICE. I'm glad I have all I'll ever need.

Brass is cheaper and the sharp shoulder makes the brass last forever... No stretching at all it seems.

PO said he thought the 7x57 was the best AI example, so you should see all the good if anyone can!

I have had two Ackley's and one Wby. There is one significant difference. The Wby chamber is cut about .02" shorter than the H&H and the Ackley, which are both the same. Occasionally you cannot chamber uncrimped 375 H&H in the Wby chamber whereas you can in the Ackley. This is only an issue if you are in some remote location and are stuck with the H&H handloads (most factory H&H ammo has enough crimp to enter the Wby chamber). If an H&H is rechambered then there is no issue either. The throating of the Wby is a little longer too. Both are pretty much wildcats so I would get the Ackley cause it looks wilder.

I shoot a 375 Weatherby , but if I had a 375AI I would use starting loads for the Weatherby(Hodgdon has data) and work up . Top loads should be lighter because of maybe no freebore in the AI chamber . I would expect 2900+fps for 270 grainers and 2700+ for 300 s , with powders in the 4350 range .

I do love the 7X57 AI I have in a re-chambered HVA. I also had a 7X57 I.C.L. Tortilla a while back; same thing but with a 45 degree shoulder.

I've not had much problem with the 375 Wby brass stretching, but my 300 Wbys stretch the pizz out of brass. The 375 is a re-chambered FN action Sako; it has just a bit less freebore than a Weatherby, and I get good velocities using mid Wby loads.

I use the 375 wby load data for my AI, It will shoot a 270gr Tsx to the same point as a 270gr h&h in my rifle.
Charlie

Any idea what the difference is between the 375 AI and the 375 Ackley Magnum is? PacNor lists them both?

375 Ackley Magnum

375 Ack Mag Imp

There several iterations of the "improved" 375 H&H, among them the Wby, the Ackley Imp., and the less often mentioned, the 375 Mashburn. I had the latter in a Ruger Tropical for awhile. And there are probably some I don't know of but all give roughly the same increase over the H&H.

In the past I just compared three or four reloading manuals to get a handle on what a top or near-top load for the H&H was (and compared it to the top in this rifle also as I shot it as an H&H for awhile before rechambering) and started there for the Mashburn and worked up a bit. As I recall, i experienced an increase in velocity of 100-175 fps over the old warrior depending on powder and bullet weight. Sorry, I don't have those notes any more so can't be more specific.

I have a M-70 in 375 AI, I used RL-17 to power 270 gr TSX's to 3100 fps looking for excessive pressure, never found it and suspended experiment at that level, backed them down to an even 3000 fps, accuracy is a bit over an inch for 3 at 100 yards.

Your friend can start at 83 grs of RL-17 and work up if you wish, that will start you in the neighborhood of 375 H&H performance.

Gunner

That's some awesome performance right there. Seems like a neat one and pretty relevant if you didn't want a WBY.

How do your rifles shoot standard 375 loads? Just wondering how they would shoot if you needed to run some in a pinch.

I have never fired factory H&H ammo in my rifle although I've heard it works well.

I seat 235 gr Speers very long and fireform with RL-15, the fireform loads are plenty accurate enough to hunt deer out to 250 yards or so if you wanted to.

Gunner

Thanks for the word Gunner. Thinking I wouldn't mind one built on a M70 either!

It's a dandy, mine is a put together model, I blew the throat on my M-70 7mm STW Laredo, saved the action and had a Smith screw a stainless factory barrel in 375 H&H that he had reamed to 375 AI, had a beautiful walnut stock built for it and even bought some very nice stainless bottom metal from Dirtfarmer here on the fire.

It's a one piece at a time kinda rifle, but that ornery bitch delivers a very serious reply.

Gunner

That's pretty similar to what I wanna do as well

10-4, Good luck, it's was a fun build.

Gunner