Reloading for 303/375 - p14 Enfield

A

Archibald

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Regina, Saskatchewan
I have inherited a p14 Enfield, which has been sporterised and re-bored to 375". The resulting caliber is a 303 British case with a 375 bullet.

So far, I have fire-formed 20 cases from 303 British. I annealed the cases for a count of two seconds in molten lead, then quenched in water. Then de-primed in a universal die, set a new primer, loaded with 10 grains of titegroup, filled the rest of case with oatmeal and then topped off with lard to keep it all in. The cases formed quite nice, as you will see in the photos. I still think they will still stretch a little, but I believe it's good enough to start developing a load.

For a reference, I am going to use load data from 375 Winchester and work my way up. I picked up some 225gr hornady interlock for the task, and will experiment with surplus WC735 which lists as 5% faster than H335 or close to H322. I hope to get well over 2000 fps, but will take my time getting there as this is my first wildcat. This cartridge has much more volume than the 375 Winchester, so I am hoping for good things.

I have a question for you guys out there, how would you go about neck sizing this case? The body of the 375 Winchester is more narrow than my 303/375, and is not going to work without resizing my new nicely fire-formed case. I also have 375 h&h dies but they are likely too long (didn't even bother trying). I am sure I can seat any number of bullet seating dies and am not worried about that.







A comparison of 303 british to the 303/375


A comparison of 375 Winchester (actually it's black powder parent, the 38-55 Winchester) to the 303/375
 
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Yeah if it comes to that I will order custom. I don't know how much I want to spend on dies or how long I want to wait to have them made, especially if I had a simple way of getting some neck tension.

Last night I tried screwing the 375 h&h die into the press upside down (from the ram side), and removed the expander ball rod. I was able to resize 1 case, but crumpled about 3 because the taper on the upper side of the die is not very forgiving so it's not a good practice, plus it's not optimal as it doesn't resize the inside of case without the expander portion installed in the same step.

I got looking at that full length die for the h&h and if it was shorter it would probably size the neck, but I can't get my case high enough in there. From looking at my manual, I bet I would be alright if I could get my hands on dies for 375 Styre, but I think that's an oddball cartridge so it more frustrating than it is productive looking for that.
 
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Good luck with a hacksaw cutting a size die OP, those puppies are hard ... they need to be ground shorter.
Last I checked, LEE has suspended custom orders due to overwhelming demand for their regular catalogue product.
So maybe a Lee FL .375 hh die and a trip to the local machine shop?.
 
vviking said:
Good luck with a hacksaw cutting a size die OP, those puppies are hard ... they need to be ground shorter.
Last I checked, LEE has suspended custom orders due to overwhelming demand for their regular catalogue product.
So maybe a Lee FL .375 hh die and a trip to the local machine shop?.
Click to expand...

That's what I suspected. More like dremel tool and or grinder than hacksaw right... Lol

Damn I just want to shoot this thing, not fool around with dies
 
Archibald said:
If I can't figure it out with what I have, I may order a lee collet die for 375 h&h and hack it up, I bet that rifle die is not going to want to chop easily though.
Click to expand...

If I remember right you send them the order and a couple fired case's and they'll make it up for $55.00
 
vviking said:
Good luck with a hacksaw cutting a size die OP, those puppies are hard ... they need to be ground shorter.
Last I checked, LEE has suspended custom orders due to overwhelming demand for their regular catalogue product.
So maybe a Lee FL .375 hh die and a trip to the local machine shop?.
Click to expand...

Answer's are a phone call away
 
bcsteve said:
$83.20 for a two die set from CH4D.
Click to expand...

Yes, and they are great guys to deal with, as well. When I needed a 9.5X56 MS die set they had it on the way in a few days.

A few times when in a hurry, we annealed a 7/8"X14 bolt, chucked it in a lathe and bored a neck-only resizer die. Polished to correct diameter for the brass I was using. Didn't bother hardening the die at all. Just used it as it was, and it was still working fine when I sold it with the rifle.

Ted
 
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To what outside diameter must the neck be sized? I have used handgun sizing dies, and Lee lube-sizers as neck-sizers in the past. 9mm Luger sizing die? 0.401" Lube-sizer?

http://stevespages.com/page8d.htm
 
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Hey Andy, that link lead me to notice the 375 JDJ cartridge. I will have to double check my measurements but it looks similar to my case. Although I know that cartridge is slightly longer than mine.

cd375jdj.jpg


From what I read that's a superior cartridge to the 375 Winchester.
 
The .375 JDJ is closer to the case capacity of the 375-303 than is the 375 Win, but that doesn't help you as load data is practically non-existent, and dies are special order and expensive. For a cheap neck sizer, just run your micrometer over the neck of your loaded brass, subtract about 0.002" for neck tension and you'll know the sized outside diameter you'll need. It will take some luck to find an existing die that's the correct diameter. The idea of cutting down a die that's larger in the body, but has the same neck size is a good (I've done it), but don't assume that the 375 H&H or 375 Ruger will work - measure first. You can fiddle with neck turning if it's close, but too tight. The idea of cutting off a 7/8"-14 bolt and drilling a hole through it is a good one - once you know the required outside diameter, a drill in the 25/64", 10mm, "X" range would be about right.

As for loads, the 375-303 has a case capacity almost 20% greater than the 375 Win. The 358 Win is a better bet to look at - its case capacity and bore is just a bit smaller than the 375-303, so any loads for it (which are plentiful) can be used, and the resulting pressure will be lower in the 375-303. The P14 is a very strong action - you'll have no difficulty achieving 2400 fps with a 225 gr bullet at 50K CUP, but it's the 250's and 275's that are better suited for that bore size. With the 225 gr bullet, I'd work in the 40.0-45.0 gr range with WC-735, and stop at 2300 fps.

Very cool rifle and chambering - thanks for sharing.
 
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What about data for the .375 Express made from .444 marlin brass? Ken waters Pet loads book.....then there was a .375 Axite based on the .303 case..3 fired cases and a letter to C+H will get you dies at least......Harold
 
Last time (last year) I sent spent cases to the USA, they were seized by US customs... and the explanation letter too... well...

CH4D is your way to go. Very good choice indeed.
 
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