Not sure this is the correct place for this, but we'll give it a go ....I have been reading a lot about using 444 Marlin, and blown out 303 cases necked to 375 for use in the Enfield actions ( thats the English SMLE style NOT the P14 ) also using the 6.5/350 rem. mag. case necked to 303 ( .312 ) and .375 in the same actions.
My problem is the thought that the 350 rem. case necked to .375 is a hell of a round and too powerful, pressurewise for the Smellie action.....any thoughts?....anyone built one ?

Roger

Nothing wrong with using a larger case/caliber only NOT LOADING TO TOO HIGH A PRESSURE...bullet size and case size has nothing to do with pressure rating...there are lots of large cal SMELYS out there doing great work...and many threads concerning this very concept.

Good Hunting

Absolutely NOT! the SMLE, meaning the #1s and earlier, are not designed for magnum pressures and bolt thrusts. The internal case diameter has everything to do with back thrust; it's basic physics. I do not use these actions, nor the #4s, for anything over 40K psi. Not things over 50K such as the 350 Rem Mag. We aren't worried about the radial pressure with modern steel, but the rear locking action and thin SMLE receiver is not made for it.

WHOOPS...THAT ORIGINAL POST CAME OUT TOTALLY MUCKED-UP AND I CORRECTED IT.

My meaning was to illustrate that it's NOT THE PUBLISHED pressure OR CASE SIZE/BULLET DIAMETER that is of a concern but the RECEIVER'S ACTUAL PRESSURE LIMIT THAT IS OF THE CONCERN.

You are also on very thin ice when you start comparing a rifles metallurgy say from one built at the beginning of a conflict period with those built toward the end when short cuts and all the other problems come into play.

Not only that but the actual metallurgy is questionable from country to country...and rifle to rifle comparing time frames.

It seems to me that so much of this historical and actual information is lost in translation when we start to argue and have to be right.

Wiki has all the formulas needed to calculate a number BUT the fact that the beginning number...the actual receiver pressure is questionable starts the whole argument off falsely.

I load my 458 American SMELY AND Marlin 336 around 40 Kpsi +/- ~2 K with 300-500 gr bullets... except for my Browning BLR which can go to 60+ KPSI...the recommendation from one of the powder companies for two of their powders. I load my 375 JDJ, basically a "375 American" to the same 40 K in my NEF S.S., but to 60+ K in my Savage Axis receiver.

I can guarantee any animal hit with any of the above calibers/bullets, whether in a SMELY, Marlin or NEF...or Savage...is meat on the table and I don't need to strain the boiler to get it done.

Good Hunting

you should be concerned about bolt thrust, as much or more than absolute pressure -- this are springy stretchy actions

More; as I said; modern chrome moly steel will take any pressure involved with any cartridge; but the back thrust is what is important.

As already mentioned the SMLE is not the best action to build on. But if you must use a #4 action, they will handle a little more pressure than the # 1 will.Case life will be better with a # 4. I would also suggest you stay with the 303 improved case, either the Epps or the Ackley version.

The charts in Wiki are misleading; they first give the correct formulas, using the internal case pressure vessel area, then go on to publish charts using external brass measurements.
I know, err on the safe side; ok.
Why not just give the correct readings?
You can't circumvent the laws of physics.
As for the #1 vs #4 actions; limit #1s to under 40k psi and 30 for a 45-70; #4s might go a bit more but why? Those pressure are plenty for any purpose to which these actions might be put.

As for the #1 vs #4 actions; limit #1s to under 40k psi and 30 for a 45-70; #4s might go a bit more but why? Those pressure are plenty for any purpose to which these actions might be put.[/QUOTE]

dpcd I don't think I made myself as clear as I could have. I was NOT suggesting that a # 4 action be used so you could increase pressure. I was suggesting that a person should use a # 4 action to increase their safety margin and to reduce case stretching. Re-barreling to an odd calibre ina SMLE is likely going to result in 100 % handloads to feed it. Loads over 40K are likely going to result in case head separations after a couple firings.(especially in a # 1) Case life in a # 4 is a little better but only if you keep pressures around 40K. Anyone who is loading a SMLE and finds their cases are separating after a couple reloads should soon catch on to the fact they are on thin ice. I have a friend who has a 35-303 Epps Improved built on a #4 action. That rifle is quite a little thumper on moose bears and deer. SMLE s can make useful rifles but only if you keep the pressures down.

Wiki used the MUCH SIMPLER external measurement because it is very difficult to measure an interior space...WHERE do you decide what POINT TO MEASURE AT due to the tapered and rounded interior shape...and the fact that comparisons of interior and exterior measurement calculations are very close and essentially inconsequential to the results.

I ran the ROUGH numbers from reputable sources including WIKI for 303 Brit(0.455" d), 308 Win (0.470" d) and 458 WIN (0.513" d) cases...bolt thrust was ~8600 flb for SAMMI PRESSURE/VELO, 303...~9100 flb SAMMI PRESSURE/VELO, 308 and ~9300 for my MAX 45 Kpsi 458 Amer...300 flb over The 308 cal 2A/2A1 Smelly...AGAIN THESE ARE ROUGH NUMBERS AND I DON'T RECOMMEND ANYONE DOING ANYTHING LIKE THIS...INFORMATION ONLY.

To understand the limitations of the SMLE all you have to do is check out WIKI and see the number of variations of SMLE rifles produced in several countries over MANY years and in several calibers with MANY pressure levels for the various cartridges.


Saying one particular SMLE number is "better" or can handle a higher/lower pressure it totally ludicrous to me considering the number of these rifles(SOMETHING LIKE 17 MILLION and still in production) that have been produced...especially considering the fact that "proofing" can be a nebulous and highly speculative process in some of the countries...and I'll bet NO ONE HAS DONE ANY STRUCTURAL TESTING, DESTRUCTIVE OR NON-DESTRUCTIVE on any particularity Smelly. Just saying that a ounce of prevention is worth a ton of some unknown quantity/quality of B.S.

As far as case head separation goes, that's more down to reloading and total misunderstanding of pretty much all the tenants governing the safe handling and reloading of wildcat cartridges, I think. I have/had NO PROBLEMS with case head separation with my 458 Amer Smelly. During my testing phase I was getting over 10 reloads per case before I sectioned a few to check on case stretching and tossed the remainder. Cases stretched the most during the first two or three firing then settled to ~0.001-2 per firing. The whole time I stayed below ~45 Kpsi partly because of case capacity vs powder density, COAL, bullet length vs mag length etc...INCLUDING BOLT THRUST CALCULATIONS between the ~52 Kpsi 308 SAAMI and Magnum case 375/458/etc ~45 Kpsi limit. I might add that my velos were the same as several reloading manuals low end 458 WM reloads so you could stretch the veracity and say I was shooting a 458 WM as the chamber WAS cut with a 458 WM reamer and I COULD single load a hand-loaded, SAFE FOR THIS RECEIVER, 458 WM... NOT A COMMERCIALLY LOADED 458 WM CARTRIDGE!!!! and fire it getting very similar chrono velos and getting similar pressures according to QL...of course with an appropriate powder that filled the larger case.

One problem that is rampant of this AR forum is people jumping to conclusions and reading into statements something that ISN'T THERE...but it's the same on every forum I've gone to.

I think we all can agree that the Smelly's pressure limit should be kept on the lower end...at least from the standpoint of the original design back in the early 1900's...but I'm not so sure whether that is because of the early cartridge pressure/powder limitations, receiver/metallurgy limitations or what. I haven't seen or heard of any actual, late, SCIENTIFICALLY BASED, actual pressure check to destruction testing...just a lot of human based conjecture based on unknown speculation.

I would welcome any observations that IS NOT "I did this and it went BOOM"...I've done enough of that myself when I had my head up my nether regions...accidentally and MINDLESSLY

NO FLAME OR DISS INTENDED TO ANYONE, JUST MY OWN OBSERVATIONS AND ATTEMPTS TO DO THE "DIFFERENT" THING...we ALL interpret this thing from varying experiences...AND we are ALL right or wrong from various positions...HOPEFULLY we will survive our hiccups with little or no lasting scars.

Good Hunting

If you must use an SMLE you could start with one of the more recent 308 models. My info is that these are not just converted 303's but have been designed for 308 pressures, so they should be safe for your wildcat.

It appears that once again I have created a contentious subject which has led to some serious " conversation "......I believe this is a good thing.

These opinions aside, I must state that my intention for the original post was purely for information, opinion and possibly as a warning to unknowing wildcatters.

If someone has learned something cautionary from this, good!....if it has created some dissention amongst posters, I apologise.

At this point I have no intention of building a 'cat on these cases as I already have a 7x57R, 257 Rob. rimmed, 303B and a 375x2 1/2 FL NE on these actions.

Roger

Doesn't take much to get a "contentious" thread going on AR, Yuma, lots of very knowledgeable gents here with hardened viewpoints...no apology needed.

Wiki has all the information required to determine WHICH MODEL SMLE is good for what pressure and only the 2A/2A1 was designed for 308/52 Kpsi pressure and that the only model I would use for conversion to other calibers near that pressure limit.

LOTS of case/calibers available to wildcat. I did one, might do a switch barrel in another caliber but won't do a complete rifle...there are a TON of other, much better modern receivers available to wildcat...besides the caveat that there are already too many calibers available on racks, why bother with wildcatting except for the bragging factor...that's always a nice campfire chat.

Good Hunting

There is a cartridge that just might interest you. It's called the 375 American. Basically all it is, is a 303 British cartridge case necked up to .375 and that's it. Just for fun I made up a tapered expander and installed it on one of my "M" dies.Lightly lubed the expander and down about halfway rotate the case 180 degrees and back up again for a full stroke. Had an old 300 grain .375 bullet and seated it with a seater die from my RCBS 375 Win die set. I have a .375 barrel blank but the groove diameter is .377 so maybe intended for 38-55. If I ever got serious would order a true .375 groove diameter barrel blank. Frank

I don't want to appear rude as I don't know who came up with the idea first, but I can't see it being called the 375 American.I think it originally would have come from New Zealand where its called either the 38/303 or the 375/303.One thing I do know is that they've been using it for years.
Please don't take this as a personal attack.
Yes, it is actually a very useful and popular round, and easy to form. Its a shorter version, by a quarter inch, of the 375x2 1/2 Flanged Nitro Express.

Roger

I'm guessing this cartridge's originator has been lost to history and/or there probably been several originators being the 303 Brit has been around for a couple years by now and it's a fairly easy conversion.

As to the name and the country of origin, call it what you wish from whatever country you wish...this wildcat probably happened in several places and has many names, at the same time.

There are several BP versions or very similar "old timey" cases, new "modern" rimmed and rimless versions and they ALL do their jobs.

I have several 375 cal rifles and have several "wildcats" in mind for future projects and just about any straight walled, rimmed, rimless or belted case is up for grabs.

Good Hunting

There is another 375 version on the 303 British case. It's called the 37 American, basically it is the 303 British case necked up to 375 caliber with no other changes.Currently looking for a #4MKII with bad barrel so I can get a 375 I.D. barrel threaded and chambered. The members on the NitroExpress forum were kind enough hunt down a print of the cartridge. In necking up to .375 there is a very small shoulder left on the case and is also shown in the print.Will have to get the reamer spec'd out but since I will be shooting mostly cast bullets I figure a 14 or 16 twist. I have a 1x12 twist 375 barrel but cannot figure out who made it. Or cut to the chase and have the P13 actions ears removed and d&t for scope bases. Only reason for the P13 is that it is easier for suitable rings and bases to be found.Frank

375 JDJ would be the best choice; and no need to reinvent something and have special reamers made for whatever you want to call a 375/303. Just use the 444 case to start with.
I seem to recall that the original 375 based on a 303 case was from Westley Richards in 1905 or so.
Now, if you use a P14 then you can load to any pressure you want.

Roger

As said, P14 was a platform for Early Weatherby as I have read and great plenty for anything reasonalbe. Last of the SMLE 4's were chambered, very limited, in .308, excuse me 7.62 x 51 NATO, so they should be o.k. within reason. Not fond of overworking ancient metal. I was very surprised to find in an old manual given me by a close friend/gunsmith that the .405 Winchester was just a .303 case (or .30/40 Krag case) blown out straight. There was a .35 Winchester that went no where fast. Should work o.k and limited factory ammo. Luck. Happy Holidays. Happy trails.

....not quite....while a lot of cases share that same basic body diameter, ones like the 405 are longer and not actually 303 based.
Some rimmed cases with similar base diameters...

303B......460"
444........464"
9.3x74R......469"
30-40..........457"
405W........462"
x57R.........472"

Roger

quote:

Originally posted by iiranger:

Last of the SMLE 4's were chambered, very limited, in .308, excuse me 7.62 x 51 NATO, so they should be o.k. within reason.

I am think the were used in 7.62 for "full bore" range shooting.

At higher pressure accuracy and extraction goes out the window.

Actually, if you keep increasing the load/pressure I doubt you ever hurt one because extraction problems would stop you. I know, because I tried The action stretches and of course the cases moves back a bit and when pressure drops the bolt forces the case back into the chamber and you won't extract the fucker

There are still quite a few in Australia using the improved 303 case from 303/22 through to 303/375.

For chasing roos and pigs from a WWII Jeep or those early 1970s Suzuki soft tops they are unbeatable. If I had a dollar for every roo, pig and emu I have shot with the SMLE in 303/25 and 303 from the Jeep or Suzuki I could buy out Bill Gates