375-388 aka 375 Taylor

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Prairefire

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Recently picked up a gun in this somewhat uncommon calibre and am hoping that someone would be able to help with load data to keep this fine old rifle well fed. Please feel free to private message with load data.

375-338 Taylor seems to have many different names depending on where I search, aka:
- 375 Chatfield-Taylor
- 375 Belted Newton
- 375 Durham Magnum
- 375 Epstein
- 375 Short Magnum

Was working on down-sizing and passing along some guns that were not getting used when the opportunity to acquire this intriguing calibre came along. Suppose that several out and one in still stays with the principle of downsizing somewhat. It is custom built on a P17 receiver and with a well tuned brake has recoil on par with a 30-06.

Although the rifle came with brass, die set and several mixed hand loads, unfortunately I was not able to obtain any load data or notes from the previous owner. Word has it the previous owner had built this gun for a trip to Africa and since all the brass is head stamped 375 HH that is most likely the case. It seems that many hand loaders neck up .338 Win Mag brass to form this cartridge but that could pose issues in some countries as the head stamping would not line up with minimums.

A trip out to the range with the hand loads to satisfy my curiosity proved that this old beast can really reach out with serious authority. Seems to be operating in 375HH or even 375 Ruger territory. Perhaps one day if everything lines up right I will be able to take it back to it’s natural habitat on safari, in the meantime it should serve well on elk, moose and the occasional unlucky deer.
 
I subscribe to Ammo Guide which has lots of load data for wildcat cartridges. I personally own about 15 wildcat cartridges and Ammo Guide has good starting data for all of them.
 
4fifty8 said:
.375 Taylor parent case .458 WM 0.532" base dia. & 2.5" case length similar case volume as .375 Ruger (0.532" base dia. & 2.58" case length) might start there for load data.
Click to expand...

Careful, I have owned and used a couple 375 (Chatfield) Taylor rifles over years, and the case capacity isn’t even close to the 375 Ruger.

Will check in my loading stuff and find some loads I have used.

Ted
 
Why Not has it right. Capacity of the 375 Chatfield Taylor is not similar to the 375 Ruger. It is very close to the std 375 H&H. Ballistics of the Chatfield Taylor and the H&H are very close
 
Case volumes can vary by source & manufacturer -

.375 H&H - 92 gr
.375 Ruger - 98 gr
https://www.africahunting.com/threa...godzilla-vs-mothera-with-handload-data.14933/

.375 Ruger - 85.5 gr
https://www.nosler.com/375-ruger

Someone used QL to calculate .375 Taylor - 87.63 gr
http://www.outdoorsmenforum.ca/archive/index.php/t-283544.html


.375 Taylor & .375 Ruger case volumes looking pretty close.


Pulled these off the web dimensions might be accurate -

6UMITdS.jpg


wP98tHA.jpg
 
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The 375 Taylor should have a case capacity that is 8-10% smaller than the 375 Ruger, and 6-8% smaller than the 375 H&H, hence at the same pressure, MV's for most bullet weights should fall 50-75 fps lower.

If you just want to start loading for it, knowing that in the 375 H&H full cases of H4350 can be used with bullet weights up to 300 grs, if you stick with powders at the Burn Rate of H4350 or slower (e.g. Reloder 17, IMR4350 H414, etc.) for all bullet weights, you won't be able to load enough powder to exceed 60K psi.

This is not a bad thing as when I had a 375 H&H, H4350 was a great powder for my gun.
 
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4fifty8 said:
Case volumes can vary by source & manufacturer -

.375 H&H - 92 gr
.375 Ruger - 98 gr
https://www.africahunting.com/threa...godzilla-vs-mothera-with-handload-data.14933/

.375 Ruger - 85.5 gr
https://www.nosler.com/375-ruger

Someone used QL to calculate .375 Taylor - 87.63 gr
http://www.outdoorsmenforum.ca/archive/index.php/t-283544.html


.375 Taylor & .375 Ruger case volumes looking pretty close.


Pulled these off the web dimensions might be accurate -

6UMITdS.jpg


wP98tHA.jpg
Click to expand...

Nosler measures case capacity with a bullet seated to the shoulder. Most everybody else measures to the case mouth. .375 Ruger case capacity is 98-100gr.
 
So load considerations aside, what is the preferred method of forming cases?

Starting with 338 Win Mag cases (have access to a ready supply of brass/wrong head stamp but unable to chamber in a .338): clean, lube up and run them through the sizing die? Tried this on a couple of beater cases that I had under the bench, initial results were intriguing. Cases held together and more or less took the form but the case length was shorter than the formed brass that came with the rifle. All other dimensions measure out but the neck length is noticeably shorter. Have seen mention of running through an expander to .385 then run into sizing die to bring back down. Is this worth the extra step or should I fireform the cases after running through the sizing die? Would the fire forming process result in neck length growing to take up the difference?

Starting with a 375 HH Mag case (have a limited number of these cases/closer to correct head stamp if rifle ever goes on safari/potentially could be mis-chambered in a 375 HH mag?) : information that I can find talks about “trimming to length then run through sizing die”. When trimming, should I start with taking cases down to a bit longer than 338 Win Mag OAL case length, form and then trim to suit for proper neck length?

Starting with 458 Win Mag cases (not readily available/potential to that someone could mis-chamber these in a 458 Win Mag resulting in a “hotdog down a hallway” situation): a few sources state these can be run through a sizing die and loaded up.

There are a couple of sources of bespoke brass south of the 49th that can supply stamped/formed brass for $$$. But that would severely curtail my limited reloading budget. With a wildcat cartridge there is something appealing about learning the process/skills and the resulting pride that comes with the success of building something.

Fireforming process: many older sources talk about using light charges of pistol powder with cornmeal packing for fire forming. Does anyone have any experience with this process? I have access to a collection of active primers that have been decapped from disassembled handloads that have come into my possession over time and was thinking that with the current state of primers this would be a good use. Maybe I am being too cautious but since I have no way of verifying the condition of components/accuracy of loading process by unknown parties I end up salvaging some components from these handloads but do not use them as built. Something about touching of explosives in close proximity to my head that cause me to have pause. I do not want to be in the thick of it and thinking “wonder if that reused primer will fire” or “ I am pretty sure that guy said he thought he used ### type of powder in these loads”.

Thanks for any information.
 
The simplest and best way to reform 338 brass properly is to first anneal the neck and shoulder area of the case.

Then expand the neck to 40 caliber. Expanding to 358 does nothing, as the neck needs to be expanded to 375 not sized down.

Now resize the expanded brass with your 375 Taylor sizing die a bit at a time until the bolt just barely closes with a crush fit on the resized case.

You now have a reformed case that fits perfectly in that particular chamber, and do not need to fire-form or trim.

Set the locking ring on the die in place, and resize the rest of your brass.

Ted

PS: fire-forming is best accomplished with full power, not reduced, loads.
 
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