I'm having my 375 rebored into the Ackley Improved version. Anyone have any load data they'd like to share?

Pete

Your case will have the same capacity (or very nearly so) as the 375 Weatherby. The load data section of the main AR website has a section devoted to the 375 Weatherby. It was written by RIP.

lawndart

talen,

If it's not cut yet I would reconsider. I have been stuck with a 375 AI. How are you going to make cases? Mine weaken at the expansion web when the shoulder blows forward.

I may buy some 375 Weatherby brass and see if that chambers or make cases from 416 Rems.

I wish I had bought a standard 375 H&H chambered barrel.

I was planning on just fireforming them from standard 375 brass. Is the weakening you're experiencing happening immediately after the cases are formed, or after they've been shot a few times?

Pete

It's a continual thing as I don't load all that hot. No data you know!

I would go over to the African forum as there is talk that a rifle and ammo must be marked for a particular cartridge for African use? The 375 Weatherby is a standard cartridge.

I ordered some 375 Weatherby brass just now. They are about $2 ea but I am going to load them up and see how they last. I will get my barrel stamped 375 Weatherby if they fit.

On the other hand the .375 AI is a nice looking round. My throat seems to have freebore and a lot of it too. It was chambered by Douglas about 1970.

Here it is.


I have not shot it much over the decades. I was made by the late Floyd Butler. It will shoot very small groups most of the time with 300 gr Sierras at 100 yds. I demonstrated it to an AR member in fact. It would be neat for this old Butler rifle to be introduced to one of those premium custom rifles I read about so much here.

But I digress........

Savage99: Have you had any case head separations, or case ruptures? Have you done any failure tests or are you just worried about case weakening? If you haven't pushed the cases to failure, you might want to try it.I am not saying to load above hot 375 Weatherby loads,just load hot,put the gun in a vice and try it. Another idea is to fireform HH cases and only use them once more for hunting .Last suggestion ,just rebarrel to HH.

Longshots,

I have had no separations etc. I use a feeler gage and I throw them out when I feel a significant weak area. Sectioning the case helps one establish a bench mark.

Sav 99 There is no reason for weakening your cases when you fireform your brass.Sounds like you have a little headspace when you fireform the cases and you may also be moving the shoulder back a few thou each time you re-size your cases. Both of these things will weaken cases just in front of the belt.When fireforming cases you can seat your bullets out far enough to engage the rifling so you feel some firm resistance when you close your bolt. If you have too much freebore to do this take your NEW cases and neck them up to .416 and then resize only a portion of the neck so you feel firm resistance when you close the bolt.There will be no stretching cases during fireforming if you do this. Also you may want to adjust your sizing die so the shell holder does not come up tight against the bottom of your die. That will prevent you from moving the shoulder back each time you re-size.. I have a 375 Wby and I form all my cases from 375H&H brass and they last longer than my regular 375 cases last.

snowman,

There is a significant reason for the case stretching and that is because the interior shoulder of the .375 H&H case is hit with the energy from the burning powder. This pulls the brass forward and weakens the web.

I do not have a .375 AI FL die! Never did. I neck size only and seat using a 378 Weatherby die.

Yes I could neck them up or size down 416 RM's.

I cannot seat any bullet out long enough to reach the lands. The 285 gr Speer RN will do it if seated backwards as it has a very flat base but those are almost gone.

The bottom line to this is that the belted improved wildcats are the worse of the worse design wise.

Savage,

I have owned 3 different 358 STAs and no problems at all.

When you think about, necking 375s up to 416 and then running through the 375 Improved die is the same as running 375 H&Hs through the 358 STA die.

Mike

Savage 99: I bet you could work out a nice barrel trade with one of the members here. Would be an inexpensive way to solve the problem. Should be be nothing to it. Looks like a Mauser action?

Savage99-

To me, it seems as though the actual case expansion with caliber is fairly small. I would think that it wouldn't weaken the brass more than any other AI conversion. Is there anything specific to the 375 AI that is different than the others?

Since the barrel is already stamped 375H&H, I figured that I'd get by having the properly headstamped rounds issue taken care of by just using standard 375 brass.

Pete

quote:

Originally posted by talentrec:
Savage99-

To me, it seems as though the actual case expansion with caliber is fairly small. I would think that it wouldn't weaken the brass more than any other AI conversion. Is there anything specific to the 375 AI that is different than the others?

Pete

"There is a significant reason for the case stretching and that is because the interior shoulder of the .375 H&H case is hit with the energy from the burning powder. This pulls the brass forward and weakens the web."

A .375 H&H case as fired in my M70 is .445" at the shoulder and a fired case of the .375 AI is .495". That's .050" more. The fireformed case looses .022" in length in the process.

In comparison the 30-06 AI grows .010" at the shoulder. So the 375 grows 500% more.

[/QUOTE]

"There is a significant reason for the case stretching and that is because the interior shoulder of the .375 H&H case is hit with the energy from the burning powder. This pulls the brass forward and weakens the web."

A .375 H&H case as fired in my M70 is .445" at the shoulder and a fired case of the .375 AI is .495". That's .050" more. The fireformed case looses .022" in length in the process.

In comparison the 30-06 AI grows .010" at the shoulder. So the 375 grows 500% more.[/QUOTE]

Alright, you've convinced me. I'll leave it the way it is. Thanks for the insight!

Pete

The new .375 Weatherby brass came. These were made by Quality Cartridge and cost almost $2 each. They seem to be about the same weight as WW .375 H&H brass.

I loaded them up with a light work up load. I don't have any data anyway for the 225 gr Hornady so I used an internal program and 375 H&H data as a guide. Even with the heaviest load the pressure was too light but I got good gas sealing and some decent groups.

The bolt is a little hard to close with these Weatherby cases in a 375 AI whatever chamber. This is really a good thing in a way. I checked the fired cases and there is no way there is going to be expansion web thinning with this brass.

I don't know if I have the nerve to shoot factory 375 Weatherbys out of this chamber? I am sort of stuck on this.

For now I am going to reload the Weatherby brass as it's cheered me up. The fired cases go back into the chamber with ease.

After shooting the 225 gr work up loads I fired a few of the "regular" loads with 300 gr bullets and well over 80 grs of powder. Ouch!