.303 Brit reformed to ??? (what have I got?)

[obssd1958]

So, I was going through some of my boxes of brass and misc. collected stuff, and I stumbled on a couple of cartridge boxes that are marked in black marker - ".303 Brit.". When I open them, it's obvious that the empty cases inside may have started life as .303 British (as they are headstamped), but they are now a tapered case, with no shoulder.
I've gone through my "Cartridges of the World" but can't seem to come up with anything that really matches.

The dimensions are:
Rim dia. .525
Neck dia. .410
Case length 2.145
and about .388 inside the case mouth

They actually appear to have been fireformed, as there is a .165" tall band around the base, that measures @ .003 smaller than the brass above. It looks like something (tape or something similar) was wrapped around the base, just above the rim, and kept it from expanding as much as the case just above. Maybe to center it in the chamber?

Just curious, and thought that I would throw it out here for thoughts and opinions!



Don

[mrrch]

Shotshells? Some Indian 303's were converted to shotguns

[longbow]

Might be .416 Strauss:

http://www.thefirearmblog.com/blog/2009/05/30/416-strauss-a-303-wildcat/

There's been a few discussions on .303 wildcats over the years and the Aussies seem to have the market on most.

I thought about blowing them out to .44 for a .444 like round. .44 Rhino was a shortened and blown out .303 or .30-40 Krag (can't recall for sure but either would work).

Longbow

[Outpost75]

Yup! .410 2-1/8"

[leebuilder]

With neck sizing and trimming it could be .375 nitro flanged. It was based on the 303. Similar to 405 win.
be well

[ascast]

With neck sizing and trimming it could be .375 nitro flanged. It was based on the 303. Similar to 405 win.
be well

this would be my guess

[15meter]

this would be my guess

Problem is the 375 Flanged is 2.5", I've made them from 405's, wish I could use 303. They just aren't long enough.

[ascast]

I have owned 2 guns in my life sold as "38-55", both drillings or capegun, : combo rifle/ shotgun. Neither were 38-55, nor could I find anything in "Cartridges of the World" or else where. Both chambers were sloppy with a factory 38-55 in them; and sloppy beyond what be called a typical black powder era chamber.
Could be a 9.5 mm or 9.3mm of some kind, homemade. A straight taper reamer is easy to come by.

[ascast]

what was your base dia.? after the tape you mentioned

[leebuilder]

Problem is the 375 Flanged is 2.5", I've made them from 405's, wish I could use 303. They just aren't long enough.

You are right, gonna hit the books later and find a reference. I considered rebarrel a 303 to a 375 cal. 303 max trim lenght is 2.222"
There are a few old versions of 375.
Thanks for the input!!
Be well

[obssd1958]

There are a lot of cartridges that are just enough longer than what I've got, that I don't think they were reformed for that purpose. Besides being short for the parent case, these show signs that they have been trimmed.
The base is .452 just above the rim, where it appears to have been wrapped or taped, and .454 just above that. Then it tapers to .410 at the outside of the case mouth.


Don

[GOPHER SLAYER]

I anneal 303s and use them in my 40 Krag. You could also use them in the 30-40 Krag but they would be a trifle short.

[longbow]

Okay then... I didn't read carefully enough! "and about .388 inside the case mouth" so not .416 Strauss but likely .375/.303 which I have to think is somewhat different than .375 flanged express.

Seems to me JeffinNZ has written about .375/.303.

[texasnative46]

ascast,

Your drilling/cape-gun just may be a .378 Express, which was fairly popular in the UK & Africa at the beginning of the 20th Century for reboring pitted tubes/chambers. - The .378 was .303 British-based, if I remember correctly.

A chamber cast & careful measurement will probably "tell the tale".

yours, tex

[samari46]

There is a cartridge called the 375 Special or similar name. Basically just a 303 case necked up to 375 caliber with no other changes. Does have a tiny shoulder more like a ring than anything else. Could this be the mystery case/cartridge you refer to?. Frank

[hornady308]

I remember that some Canadian Ross rifles had greatly enlarged chambers to help prevent jamming when used in the trenches of WWI. Unfortunately, I no longer have a fired case from the Ross I used to own, so I cannot provide the dimensions.

[Mgvande]

I remember that some Canadian Ross rifles had greatly enlarged chambers to help prevent jamming when used in the trenches of WWI. Unfortunately, I no longer have a fired case from the Ross I used to own, so I cannot provide the dimensions.

It was all 303's that were enlarged. I have both Ross and Enfield's of WW1 and I can say both chambers produce larger brass and are dimensionally different. I'm assuming the reamer wasn't standard as I have some pretty weird chambers. I might add this was due to mud in the trenches and the problems that go along with chambering dirty ammo.
Side note. I purchased a new Criterion 303 barrel for a 303 Brit P14. I followed the same load that I do with the weaker no1 mk3 rifle as they were going 2350fps. Figured it would be a good starting point. Upon firing these rounds in the. New barrel I noticed some recoil, so I chronied these rounds. I was getting 2650ish fps. Basically the old enfields chambers were significantly larger. The proper velocity for 303 is about 2450fps

To the OP. Check to see if they chamber in a 410 shotgun. People have been know to wreck good 303 brass by making 410 u out of it.

[obssd1958]

...To the OP. Check to see if they chamber in a 410 shotgun. People have been know to wreck good 303 brass by making 410 u out of it.

They do chamber in a bolt action .410 that I have - but so do standard once-fired .303 Brit cases. The extractor seems to be working harder when any of the .303's are chambered, but I'm attributing that to the thicker rim.
One of our members asked for some of these to try in his .410, and I sent a few to him. Hopefully he'll update us with how they work out, once he has a chance to try them. (my .410 is a work in progress/parts gun, and won't currently safely fire anything!!)

[leebuilder]

I am at a lose. I purged alot of old notes I had. I am sure it was based on 303 and calibre 375, maybe the 303, 410 convertions. Must off been something unobtainable for me not to follow through on it.
Be well.

[Dan Cash]

Problem is the 375 Flanged is 2.5", I've made them from 405's, wish I could use 303. They just aren't long enough.

I have used both .303 and .30-40 brass for my .375 2 1/2 inch Flanged rifle and while the cas is short, it works very well. Just seat the bullet to cartridge overall length. Lots of bullet forward of the case but it shoots well.

[Blanket]

375 Epps

[gunseller]

If the inside case mouth was a little bigger I would say someone fired 303 rounds in a 410 smile rifle. Had a guy hand me some straight walled 308 cases once and ask what they were. I believe someone fired 308 in a 30-06. Blanket could be on to something. A 375 or a 9.3 something.
Steve

[longbow]

Straight walled .308 cases might be from a .444 rimless chamber.