Insane M1 Carbine 502 Thunder Sabre conversion


December 14, 2003, 07:06 PM
Check this out - saw this on (

M1 Carbine
502 Thunder Sabre conversion

I just finished up converting a Universal M1 Carbine to fire the new 502 Thunder Sabre cartridge. Designed by Robyn Church at Cloud Mountain Armory, the 502 TS is simply a 50AE case with a 7.62x39 head on it.

The rounds single stack in a standard mag with no mods. I used the same gas system as the Univeral M1 30 had. I will test fire it on Sunday and let you know how it shoots.

Trajectory is about like a 44 Mag, but with a bigger bullet. About 100-125 yards is about it.

Tony Rumore
Tromix Corp

If you enjoyed reading about "Insane M1 Carbine 502 Thunder Sabre conversion" here in archive, you'll LOVE our community. Come join today for the full version!
December 14, 2003, 08:01 PM

December 14, 2003, 08:13 PM
Sounds like the mad scientists at Tromix are up to no good again...

:D :D :D

4v50 Gary
December 14, 2003, 08:40 PM
Is there any metal left on the bolt that encompasses the rim?

December 14, 2003, 09:10 PM
I remember reading of a conversion a few years back in a popular gun rag. If memory serves me, the .50AE model came with a polymer replacement stock as the common birch stock would crack directly behind the action under the dramatically increased recoil. I never heard of such a conversion since, until now.

A very interesting concept.

December 15, 2003, 12:34 AM
is simply a 50AE case with a 7.62x39 head on it. What is the reason for that? Is it due to the small bolt head? How would you get brass for such a round?

December 15, 2003, 12:50 AM
Yeah, I'm guessing thats why. Though, I'm no gunsmith.

Uh...dumb question: How is the rear of the case reinforced?

Also...what is the life expectancy of a carbine with this modification? Seems to my (admittedly inexpert) eyes that it would beat the thing to death in short order.


December 15, 2003, 01:01 AM
Tony is reinvented the wheel again, but i bet its better, This was donea few years ago but it was in 45 win mag

December 15, 2003, 04:00 PM
Waste of a perfectly good carbine. :rolleyes:

December 15, 2003, 04:21 PM
The very first word in the thread title aptly describes this conversion.

Black Snowman
December 15, 2003, 04:59 PM
Looks like for the brass they just turned down the .50 AE on a lathe, there shouldn't be any additional re-enforcement of the case nessisary the webbing on the .50 AE is incredibly thick and it's already designed as a rebated rim. You technically lose some strenth but just knock a grain or to off the max load and you should be OK.

Is there seperate load data for the 502 TS from 50 AE?

If there is what's the max with H110 and the Speer 325gr GDHP? For the .50 AE Speer puts it at 32.5 grains I think (or was it 32.2? Check your manuals and the website, I can't from work :( ) for about 1300 FPS out of my 6" Desert Eagle with about 3 feet of flame. In a carbine like that I bet even a reduced load will push 1500 FPS easy.

December 15, 2003, 05:14 PM
I'd be happy with just a 7.62x25 or 39mm from an M1 Carbine...

December 15, 2003, 05:30 PM
I don't know them, and I don't own any of their products, but I love Tromix. Those guys come up with the craziest yet coolest ideas. Hey you want an AR that shoots like a semi auto 45-70, hey why not! :D

December 15, 2003, 05:47 PM
"Waste of a perfectly good carbine. "

My thoughts exactly.

I don't own anything made by Tromix, but I do own a .458 Socom AR15 that was designed by Tromix.

Andrew Wyatt
December 15, 2003, 06:09 PM
I fail to see why it's a waste of a perfectly good carbine. this converrsion turns a poor stopper at best into the equivalent of a semi-auto 20 gauge shooting slugs.

that's some serious juju.

December 15, 2003, 09:34 PM
Me, personally? I would NEVER convert a carbine that appeared to be mostly in original condition - that would be destroying history. But I see receivers for sale.... hmm....

I would definitely not want to be on the 'bleeding edge' with this. In other words, I will wait and see who gets serial number 002 and how they like it.

Phil in Seattle
December 15, 2003, 11:58 PM
Waste of a perfectly good carbine.

Naw he used a Universal. Now that Tonys been into it, it should actually work.

Sylvilagus Aquaticus
December 16, 2003, 12:13 AM
The article about cracking wrists on wooden stocked M1 carbines in .50AE and .45WM were in an artice about Tim LeGendre (LeMag Firearms) about 4 or 5 years ago; seems like it was a Guns Magazine Annual, Snowdog.

IIRC the wood stocks were good for about 10 rounds before splitting, but he 'had plenty of old originals to replace them with'. The replacement was a Hogue or Choate, I think. LeGendre had developed both a long and short-stroke gas cycle and the long stroke was somewhat easier on the shoulder than the short stroke, which was reported as just short of brutal.

I bet any M1 carbine firing something approaching a half inch diameter cork would be a mighty nice popgun, no matter who makes it. Tromix seems to have a lot of good rocket science in their products. I'd love to see this one for myself.


December 16, 2003, 01:25 AM
"I fail to see why it's a waste of a perfectly good carbine. "

I just like the carbine as it is. As Sven mentioned, they are a piece of history. I realize this is a civilian commercial version, but if I need a bigger gun, I will use a bigger gun - designed from the start to be a bigger gun. I also realize that many people don't share this point of view, but it is mine.

December 16, 2003, 08:14 AM
I fired the carbine for the first time on Sunday. Ran about 65 rounds through it in the shop while I dialed in the gas system. Then I took it to the range and ran a few more through it. I am running the same basic original design but gave the gas piston a bit more travel than the original. It ran fairly well, with only a couple of feeding stoppages whereas the return spring did not have enough umph to strip a round from the magazine. I will probably beef up the springs a bit. I didn't shoot it for accuracy, but the 50AE is only good for about 100 yards anyway, so I don't think accuracy is really an issue here.

Recoil was very robust, leaving a pretty decent bruise on my shoulder after 100 or so rounds. I am still concerned about bolt strength/life so you won't be seeing S/N 002 until I have several thousand rounds through this particular sample.

Granting, these wild-??? conversions aren't for everyone, but I just build this stuff for my personal enjoyment. I find the thing quite entertaining myself.

Tony Rumore
Tromix Corp

December 17, 2003, 10:18 PM
Tony: you are not the only person amused. Thanks for sharing your findings - please keep us updated.

December 18, 2003, 01:23 AM

Welcome to THR!

Still would love to see a 7.62x39mm, or even a 10mm...Hm...I'll be back...okay, x39 is waaaay too long (surprise, surprise). Didn't have the 7.62x25mm handy. 10mm fits in the mag, with about the right tension, but it has that extra .3" or so of extra empty space in the mag, because of the shorter length.

December 18, 2003, 02:02 AM
JShirley, are you talking about a 7.62x52 or 10mm conversion for a M1 carbine? Your post wasn't very clear to me.

I'd like to see one too.

December 18, 2003, 02:31 AM
10mm fits in Carbine mag, but not as long as the mag.

7.62x25mm not on hand. I think OAL similar to 10mm, though.

7.62x39mm too long for Carbine mag.

7.62x51mm...get an FAL. :)

December 18, 2003, 08:05 AM
If you're going to go with a 10mm, it might was well be the longer 10mm Magnum. My dad has been talking about doing 10Mag for several years now.

December 18, 2003, 09:10 AM
I'd love to see a conversion that was not as insane. Something that I could take into the woods for deer hunting and not worry about the borderline effectiveness of the .30 carbine. Say a .44 mag.? I saw in SGN where someone is now making new production Stainless M1 Carbine receivers and parts. This would be the ideal situation for a good hunting carbine. All stainless, .44 mag. Great for short fields and brush areas and small enough to swing around in a small stand. But then again, doesn't Ruger make a .44 for this purpose? I know, it doens't look as cool as the M1 Carbine. ;)

December 18, 2003, 12:04 PM
I'd love to see a conversion that was not as insane.
Me too. I'm not a reloader, so I'd love to see something unique like this that I could walk into the gun shop and buy ammo for. 10mm would be perfect in that regard...

Although that .50 Beuwolf (sp?) AR upper they have at the shop here in town sure looks interesting. They're even carrying ammo for it. $25 a box, but at least it's there.

December 18, 2003, 01:54 PM
10mm Magnum? Sounds interesting.

Something like this would seem to qualify under Cooper's "Thumper" idea.

Joe Demko
December 18, 2003, 02:08 PM
I'd be happy with one in .35 Remington.

December 18, 2003, 02:30 PM
Nifty, but about .3" too long.

.218 Bee appears to be exactly the right length, though case head is larger. Close to .223 power...

Joe Demko
December 18, 2003, 02:59 PM
A relative of mine used to hunt the mighty groundhog with a .218 Bee. He seemed to have good success with it. Never had a wounded one charge him, anyway. Now that you mention it, a cute little autoloader like the M-1 carbine in a cute little cartridge like the .218 Bee does sound amusing.

brass shower
December 18, 2003, 06:19 PM
The 5.7 MMJ AKA Johnson Spitfire is a 30 carbine necked down to a .224 bullet and exceeds the 218 bee ballistics. All that's required to convert is a new barrel. Numrich Gun parts sells a conversion barrel, some manufacturers have made it in the past and I believe IAI produces a current factory made model. Ammo is not widely manufactured but I believe NGP also has a supply. Like the bee it would be a reloading proposition.

December 19, 2003, 01:52 AM
> I saw in SGN where someone is now making new production
> Stainless M1 Carbine receivers and parts.

Does anyone have more info on this?

December 19, 2003, 08:27 AM
A 10mm M1 Carbine would be a great idea. I would think that the ballistics would be superb, and a full power 10mm JHP out of an 18 inch tube would be a serious general purpose round.

Now if someone could just persuade Fulton Armory to take the project on.

December 20, 2003, 02:40 AM
I can see 10mm conversions or Tony's .50AE/.502 to have the carbine make a larger hole in the target. What I cannot fathom is why anyone would want to chamber it in 7.62x25?? Other than cheaper ammo cost than .30 Carbine and a theoretical advantage in feed reliability of the bottleneck case over the straighter cartridge body, there is no advantage in power or performance to be had. The 7.62x25 has less case capacity than the .30 Carbine round, and given equal operating pressures it will deliver less velocity for each bullet weight. Case diameters are similar enough that there is no magazine capacity advantage and the aforementioned feeding advantage is lost upon the typically smooth feeding tapered carbine round.

I suppose one could tout commonality of ammunition with the CZ-52 or Tokarev pistol, but the fact that someone can use the same ammo for in their rifle in their obsolescent, ergonomically challenged pistol doesn't appear to be a big selling point. A .30 BlackHawk or AMT AutoMag will take the same ammo as the M1, if that is the case. I love the 7.62x25 round as much as the next guy, and I would gladly a buy well crafted modern pistol made to chamber the round, but here it just doesn't seem worth it to spend the extra money to get a rifle that fires a weaker, yet marginally less expensive round.

If one wants to rechamber the rifle just for esoteric reasons, why not pick a weirder, more fringe calibers. 9mm Mauser Export anyone? 10mm Mag? .224 Boz? 5.7x28? 9x25Dillon? .357 or .44 Automag?

I'm glad some other than the annoyingly self-hyping Tim LeGendre decided to play with opening up the bore on the carbines. It seems like I've seen the articles about LeGendre developing these rifles appear several times in the gun rags, interspersed just enough to keep our interest alive. Apparently LeGendre spent so much time "being the baddest kid on the block" and "sticking it to" the conventional gun designers, that he failed to consider the many short comings of his design modifications. The concept of sectional density is lost upon him, and he tends to exaggerate the specs of his cartridges to make for better copy. Unfortunately there is never word of when these rifles or modification services are going to be ready, nor any way of contacting him. The weapons the evaluators actually get are plagued with feeding/reliabilty/durability problems and are haphazardly tested at best. From what I've seen of Tromix guns, they work as advertised and are actually available to the shooting public.

February 15, 2004, 03:05 PM
10mm Magnum sounds compelling - as does using a synthetic stock with a recoil reduction pad.


Starline makes brass for it. ;)

February 15, 2004, 04:05 PM
Back in the late 50's, early, 60's, conversion of M1 carbines to .357 Magnum was done more than a few times. Look for a book entitled "Gunsmithing Tips & Projects" from Wolfe Publishing. There is an article therein, "M1 Conversions", where the author discusses converting to .218 Mashburn Bee, .357 Magnum, .41 Magnum, .22-30 Carbine, and .17-30 Carbine. what's old is new again, hey presto!

Personally, I would love an M1 carbine in either .357 mag or 10mm. I have been keeping my eyes open for sometime for one of the Iver Johnson M1 carbines that were made in 9mm Luger (yep, available over the counter, only I was too dumb to buy one). I think a simple rechamber job would have a coolio .38 SUPER M1 to go with my MilSpec Springfield!

February 15, 2004, 04:46 PM
Go here for more conversion info:

If you enjoyed reading about "Insane M1 Carbine 502 Thunder Sabre conversion" here in archive, you'll LOVE our community. Come join today for the full version!