Philohio's Quick Change 9mm Thompson System

[steeltoe1978]

I read about PhilOhio's quick change 9mm Thompson system in the thread about the new Crosby drums. Any further info is appreciated. Thanks.

[philasteen]

PhilOhio, I'd be very interested to see some pics of your system and also see how it looks with a suomi drum. It sounds like a great way to shoot my Thompson at 1/2 the cost.

[steeltoe1978]

Thanks for the info Phil!! http://www.machinegunbooks.com/forums/invboard1_1_2/upload/html/emoticons/smile.gif

[Frank Iannamico]

FYI...

 

I have some used-VG 9mm 20-rd UD42 mags if anyone is interested. $95.00 each shipped.

 

They look exactly like 20-rd .45 Thompson magazines but they are slightly smaller.

[PhilOhio]

O.K., let's start all over on this one. Merle Bitikofer just called to tell me he's perfected the Thompson boltface conversion for using 9mm Para or 7.62 x 25 ammo, and I got the green light to let board members know. So he won't be surprised if he gets a few calls. (503) 623-8294. This is a big breakthrough for you guys who are not techy do-it-yourselfers. As far as I know, so far, nobody has offered to do these bolt conversions.

 

Merle used his 9mm '28 at subgun matches last weekend and did pretty well. No glitches or malfunctions; used his 70-rd. Suomi drum with rail adapter mount; prefers it, as I do.

 

A big drawback to quick change caliber conversions other than .22 LR (Ciener kit) has been the lack of bolts modified by the Chinese before the 1940s. I have several, but they are now collector items. They brazed in a small steel ring and re-machined the face, also deepening the extractor groove so a standard Thompson extractor could be used. Merle is welding in some stainless steel, also deepening the extractor groove, and also deepening the ejector groove slightly for more positive ejection, using a slightly lengthened ejector.

 

I've been lucky with my gun, getting 100% ejection reliability with standard parts, but it's a near thing. Merle's mod is more sure fire on all guns, through the range of tolerances.

 

Merle also notes that, with 9mm, the Thompson is even more controllable, a big plus in competition. He can tell you about it.

 

We agree that it's easier and better to use a newly made dedicated barrel in the desired caliber. He's shooting both 9mm and 7.62 x 25.

 

So what's required? You need the modified bolt, plus a magazine with an adapter to slide up into the standard Thompson stick mag mounting groove. Sten mags work great, as does the Suomi 50-rd coffin mag and the Suomi 70-rd. drum. All sorts of mags can be fitted. The Thompson digests it all.

 

You may or may not need a slightly shortened bolt spring and non-locking Blish lock, depending on ammo.

 

You need to have somebody do the quick change barrel mod; not difficult, but has to be done correctly and carefully. It does not deface the gun.

 

And you need the 9mm or 7.62 x 25 barrel(s) desired.

 

Cost? Undetermined, but Merle will always treat you right. Compared to eveything else having to do with a Thompson, this process is pretty painless. Time required? Don't know. Somebody here will probably be the first.

 

It's really worth it. Wouldn't be without the setup I made/have. And Merle can help you with improvements to the Ciener .22 kit and reliable non-Ciener mags for it. A .22 shooting Thompson that really works is a barrel of fun. Some of you already know that.

 

Go to it, guys.

[hrt4me]

I used to love caliber conversions (I have various .22lr conversions kits for my MP5, Uzi, M16, Glocks, 1911, as well as a .45 ACP conversion kit for the Uzi), but I've decided to stick with the original calibers. Yet this intrigues me for the TSMG...

 

Got photos of the 9mm conversion?

 

How finicky is the .22lr conversion?

 

[Shattered]

So exactly, what parts is Merle going to make? Are we on our own as far as extended ejectors, barrels, etc?

[PhilOhio]

Guys,

 

I'll have to dig around the computer and see if I still have the pics I posted years ago. It's just another '28 Thompson, but in a different caliber. And my various barrels made it look a little different...several starting out as Stens, so they are shorter. And I made a couple of comps.

 

You've already seen T-man's recent pics of the quick change arrangement. Mine's just the same thing, almost. Except I have a couple different types of set screws and a locking nut arrangement.

 

The Suomi drum does make a noticeable difference in appearance and handling. It's enough smaller than the "L" drum and handier, and holds 70 rds. "L" and "C" drums are too bulky for me, although they look very neat. The Suomi is good looking and actually functional. And it's totally reliable; no Kahr engineering there. Just load 'er up and hose 'em down. Ask Merle.

 

Frank, thanks for reminding me of the UD-42 mags. I encourage anybody thinking of going with the 9mm conversion to get one of yours while they can. It's a dead ringer for an XX, but holds a couple more rounds. It was clearly designed to precisely fit a Thompson also. Snaps right in and feeds flawlessly. I have one.

 

Barrels? You guys can discuss it with Merle, or PK, or Tommygunner, or Dan or somebody...anybody can thread a barrel for a Thompson and check the headspace.

 

To connect your actuator and bolt on a '28, without Blish locking, Gunmachines made an earless lock. Don't use it on a '28 with .45 ACP, or you may damage the thin rear of your receiver. But with less recoil from 9mm, you probably need this, plus a mainspring clipped about 1" shorter. All that is a matter of tuning to your ammo. I reload, and had to. Merle may know where some of these (I call them Blish unlockers) are.

 

So Shattered, you'll have to talk with Merle, regarding just what he might choose to do, besides bolts. You may not need the extended ejector.

 

Hrt4me, Merle and Glen Whitenberg have worked out what I thought was the last bug in the Ciener mess, getting the ROF down to something reasonable. They machine two steel weights which fit into the recesses on either side of the aluminum Ciener bolt. The added inertial factor makes the rate about the same as a regular military '28 firing .45 ACP. Then feed this from one of Merle's modified Black Dog Machine synthetic banana mags (transparent or smoke) for the AR-15, and you have a .22 Thompson which runs very reliably. And don't forget the Pietta 50-rd .22 drums; hard to find, but they run if you keep them clean. Long time to load, of course. No quick fix for that one. I believe Dan is using one.

[PhilOhio]

O.K., I found a few, but not all, of the pics I was hunting for. Here's the gun with a 50 rd. Suomi coffin mag and my adapter for the Thompson mag groove. The barrel is standard Sten, with some hoaky fins I cut and a small comp I made. The sight shoots 9mm to point of aim with the standard Lyman rear sight. Handles very nicely, and the comp works. You can shoot it two-handed.

 

I have other barrels, but can't find all the pics.

 

http://users.adelphia.net/~cpliechty/PicPark/Coffin&Vert.jpg

 

Below is the gun with the same barrel and one of my ten Suomi 70 rd. drums, held by my adapter; solid steel rib, not cut from a Thompson stick mag. The drum slides up from the bottom, just like a stick mag, so it could be used even in an M1A1 Thompson.

 

Somewhere I have a pic of the thing with a horizontal grip in place. The Sten barrel is so short that half the comp is inletted into the grip. You have to be careful with the fingers, or you'll get your nails trimmed. My quick change screw and lock nut are very visible, which I don't mind, because they are also very easy to use that way. You can make them flush mount, as PK does, but it's a little more work.

 

http://users.adelphia.net/~cpliechty/PicPark/SuomiVertSten.jpg

 

 

Here's a closeup of the open port with drum in place, just to show how beautifully the whole thing fits, to assure perfect feeding. Love those Suomi drums.

http://users.adelphia.net/~cpliechty/PicPark/DrumInPortClose.jpg

 

So that's about it...just to show you it can be done and doesn't look bad. You can use the standard Thompson barrel configuration and length, just bored to 9mm; or 7.62 x 25. Or you can put on a dedicated .22 bbl.; whatever floats your boat. By changing internals like Tinker Toys, it will shoot whatever fits into the mag well. .40 S&W would be a great one.

 

You can get very creative without doing anything to permanently change the gun, except for one little hole for a quick change barrel locking screw. And that can be covered by putting a grip bar on it which has not been drilled.

 

So have fun, but please, don't carve 'em up.

Edited July 9, 2008 by PhilOhio

[Shattered]

I've found large diameter 9 mm barrel blanks that I can turn to very close Thompson specs, however I haven't turned up anything usable in 7.62x25. Is there a Commie subgun barrel out there that might have enough meat on it to carve on? Merle's got too many irons in the fire to work on the M1 caliber conversions as of this moment, not even doing the bolts yet, so if I want to plow ahead, I'm on my own.

[PhilOhio]

I've found large diameter 9 mm barrel blanks that I can turn to very close Thompson specs, however I haven't turned up anything usable in 7.62x25. Is there a Commie subgun barrel out there that might have enough meat on it to carve on? Merle's got too many irons in the fire to work on the M1 caliber conversions as of this moment, not even doing the bolts yet, so if I want to plow ahead, I'm on my own.

 

Yep. That's about it. I'm not sure of any of the existing barrels having enough metal to turn to Thompson configuration and add fins. If I were serious about it, I think I'd look for a .30 heavy target configuration blank for starters. I believe 7.62 x 25 is a true .308, or close enough. You might have trouble getting the correct twist rate, as most .30s are 1:10 or 1:12, and I think the pistol caliber would be quite different,...not that it would necessarily make much difference in a subgun.

 

I think Merle had lots of trouble trying to line a TSMG bbl. for 7.62 x 25, and eventually went a different route...forget how.

 

You certainly will have an almost unique, flat shooting, fast firing, high velocity Thompson if you stick with it.

 

[Shattered]

Yep. That's about it. I'm not sure of any of the existing barrels having enough metal to turn to Thompson configuration and add fins. If I were serious about it, I think I'd look for a .30 heavy target configuration blank for starters. I believe 7.62 x 25 is a true .308, or close enough. You might have trouble getting the correct twist rate, as most .30s are 1:10 or 1:12, and I think the pistol caliber would be quite different,...not that it would necessarily make much difference in a subgun.

 

I think Merle had lots of trouble trying to line a TSMG bbl. for 7.62 x 25, and eventually went a different route...forget how.

 

You certainly will have an almost unique, flat shooting, fast firing, high velocity Thompson if you stick with it.

 

My 9mm conversion is almost done. Virgin barrel machined to look the part, Suomi drum done up with a rail adapter on the back. Picked up a fourpack of Suomi 50 rd coffins with a carrying case for $125. Thompson has the quick change barrel already.

 

Got the 7.62x25 barrels figured out too.

 

Picture to follow later on the 9th.

 

Phil, your pics above are dead.

Edited July 9, 2008 by Shattered

[Shattered]

One pic of the barrel on the gun

 

http://www.hunt101.com/data/500/DSC01176.JPG

 

[Shattered]

Another of the parts and the Suomi drum

 

 

http://www.hunt101.com/data/500/DSC011781.JPG

 

 

[PhilOhio]

Shattered,

 

Nice job. You're going to love it. When you add a front sight, make it way too high. Then trim it for the right point of impact before you reblue or park.

 

Who converted your bolt face, assuming that has been completed?

 

I'm trying to find out what happened to my pictures. I think I accidentally deleted them, not remembering what they were there for...think I can replace them.

 

Edit: Got the pics fixed.

 

...just wanted to add, this is a nice way to add a drum to an M1A1. You make no changes to the mag cutout, as would be required to fit a Thompson "L" drum, and you get 20 more rounds drum capacity. Guess you could call the Suomi an "LXXII" drum. They will actually hold 72, but only 70 rounds are normally loaded. I think this is a really nice, good looking rig...whether with the Sten mag, UD-42, Suomi drum, or Suomi coffin. And if you reload your own cast bullets, the lead for one .45 slug makes two 9mm bullets.

Edited July 9, 2008 by PhilOhio

[Shattered]

My buddy Steve from Ares (no, not that one) converted the bolt head about an hour after you posted yesterday. I had a broken M1A1 bolt, the thin lip around the bolt face cracked here and there so if we screwed it up it was no big loss. Just welded everything up and brought the height back down to stock dimension, ran a mill around the inside to match a 9mm case, beveled it a bit, recut the slots for the extractor and ejector and deepened both a bit.

 

Didn't look promising after trying to hand eject a spent round by hand... lot of side to side movement up by the bolt head. So I took a spare ejector, blobbed a pile of tig weld to the tip and recut the ejector 100 thousandths higher. Trial and error got us down to a .560 ejector height. Empty round now punched out of the ejection chamber, but only barely (by hand).

 

Told Steve it was too late to try live fire in my basement (wife hits the sack early) so next morning, (today) loaded 8 rounds in the drum, put it on semi and rapped off two rounds merely watching to see if it ejected. It did, about a foot out and a bit forward, marking and spot about 3 feet to the right and a couple feet forward.

 

Snapped it to rock & roll and emptied out the remaining six rounds... awright.

 

How far out do your empties go in 9mm? Wondering if we need to work on this a bit more? Also did you lighten your bolt? The M1A1 bolt seems to run a bit slow. I don't have a Pact timer, but hoping to run into one at the Eden Vermont shoot in two weeks.

 

Steve is putting the adapters on the 4 Suomi Coffin mags I got from Folke, and has offered up a 4 groove Springfield '03 barrel for the 7.62x25 conversion and wants to do a Ruger 10-22 barrel up for the Swede 5mm practice ammo.

 

Oh, and Steve is a warped bastard. He found a mint condition Poly choke and sleeved it to fit the Thompson threads on the 9mm barrel, complete with gold fill. Yeah, it turns like the real deal and it's only until I find some sort of Thompson thingie for the barrel, but it looks damn different.

 

Now he's got me thinking about the spare HK 91 receiver I have in the safe.... maybe a full auto HK 51 in .410.

[PhilOhio]

Shattered,

 

Good. You did it right, building up the ejector. My stock ejector is shorter than ideal, but it works. Others, like Merle, have extended theirs like you did.

 

The reason your empties are not going far is that there is not as much recoil energy as with .45 ACP. You are already ahead of the game if the gun ejects cases reliably, albeit close by, with a standard spring. I think if you trim exactly one inch from the recoil spring, using a Dremel cutoff tool rather than a snippers, you will get what you want. You may have to experiment with that length, if you use different types of ammo or if you reload. Very hot loads, using jacketed bullets, or military surplus SMG ammo, might run fine with the standard TSMG spring.

 

I very much doubt that you need, or want, to lighten the bolt, although you probably could, if you want to get a high rate of fire after shortening the spring. All of this depends upon the specific ammo used. You just have to experiment.

 

My empties (my handloads) are ejected just a few feet to my right, where I want them. I got it this way by experimentation with spring lengths, bullet weights, and powder charges. I use 4.5 grains of Bullseye, 120 gr. lead RN bullet, mainspring shortened by one inch using the standard diameter of music wire and coils per inch (I make the spring), no Blish locking, standard weight '28 bolt and op handle, and modern polyurethane buffer (from Machinegun Mike, in fact ).

 

I used a Polychoke vented sleeve as sort of a fakey "compensator" to hold the various diameter screw-in restrictors for a .45 ACP blank setup I built a couple years ago. Still haven't gotten around to testing it...once I found out that the opening of the star crimp on my blanks will chew up the forward part of the chamber and bore throat.

[brazos609]

Who will do the quick change barrel modification on a WH? I have a WH currently in .45 and I have an original WH finned/comped 9mm barrel with it. This gun was originally built and registered as 9mm/.45 and was shot in 9mm till the original 9mm bolt broke.

[PhilOhio]

Who will do the quick change barrel modification on a WH? I have a WH currently in .45 and I have an original WH finned/comped 9mm barrel with it. This gun was originally built and registered as 9mm/.45 and was shot in 9mm till the original 9mm bolt broke.

 

You might check with PK. I'm assuming you are talking about a steel frame, right? I would be reluctant to do it on some of the later aluminum semi frames, etc.

[PhilOhio]

Shattered,

 

I just had a long conversation with Merle (the Drum Doctor) Bitikofer, and told him about your project...particularly with 7.62 x 25, which he has successfully done on one of his Thompsons also. He has not been here since the board changed, and I encouraged him to sign on and take a look at this thread and your work. We look forward to hearing how it is going.

 

FYI, Merle has a bunch of jacketed M-1 carbine bullets (90 to 120 grains, I think he said?) which he will be using to reload his boxer primed 7.62 x 25 cases, as the diameter is right. This type of commonly available bullet would probably also work for you, if you reload.

[brazos609]

You might check with PK. I'm assuming you are talking about a steel frame, right? I would be reluctant to do it on some of the later aluminum semi frames, etc.

 

It is an early steel framed gun, 82-83. How do I reach PK?

[PhilOhio]

You might check with PK. I'm assuming you are talking about a steel frame, right? I would be reluctant to do it on some of the later aluminum semi frames, etc.

 

It is an early steel framed gun, 82-83. How do I reach PK?

 

By going to the FAQs section of this board, up above, and getting all the basic details and contact info for PK, who is Paul Krogh, of Diamond K, in Delta, Colorado.

 

[Shattered]

Phil... I was shooting the 9mm and while it may be a minor problem with the drum having two tight spots in it, some of the rounds were impacting the bottom of the barrel. Couldn't see eggzactly where it was impacting because of the barrel being out of sight.

 

Question is this.... do you have some sort of radius on the bottom of your Sten barrel? Was wondering if I need to open it up a bit. I'm working with a highly skilled machinist and I think the tolerences might be a bit too tight.

 

I was getting two and three round bursts throughout the drum until the final 15/20 rounds which ran pretty good when the drum cleared the final bend.

 

Just trying to figure out which way to go first. Doctoring the drum is a given, just wondering what the breech end of your (or Merles) barrel looks like.

[PhilOhio]

Shattered,

 

Yes, the breech end has to be throated more than for .45 ACP rounds. Much more. It should be done as on a Sten barrel, like a funnel all the way around. The 9mm case is very strong in the base area, even ahead of the groove. It is safe (in my opinion) for the case to be unsupported for about 1/32" ahead of the forward part of the groove. These days, most pistol manufacturers go farther than that, on the lower ramp area, but it makes me uncomfortable. And I have seen competition shooters blow cases, when they go to far with the loading.

 

I do this on a lathe. I believe I settled on an angle of 28 degrees. this is easy to remember, as it's the same as you use for setting the saddle for threading...27 or 28 degrees.

 

It's important for this funnel to run all the way around, because in the Thompson feedway, designed for a larger diameter bullet, you can get jamming at any point around the circumference, not just at the bottom. And the stick mags are two position feed, so it has to work on both left and right.

 

This next part is extremely important, I have found. It also applies, even more so, to making .22 conversion kits run in a Thompson. After cutting that 27 degree funnel, you MUST NOT LEAVE THE EDGE SHARP, where it meets the chamber wall. This is almost certain to cause jams. It has to be smoothly radiused and hand polished. It's hard for me to describe it exactly. But you can get it right by working up to it and testing. Once you understand what has to be done, every one will be right the first time.

 

...but...I first polish the whole angled surface on the lathe, using very fine sandpaper, paper that is almost worn out, and eventually crocus paper, wrapped on about a 3/8" piece of wooden dowel and held by hand against the spinning breech. Then I use a lathe cutter to just break the sharp chamber edge. Then I turn that 45 degree edge into a radius by playing with the sandpaper on the dowel again. The very last step is to make sure you have no steel burrs around the breech, and then use fine sandpaper and crocus paper, held in just your fingers, to blend all that, to feel the radius, and to put a nice final polish on it.

 

Why is all this tedious, obsessive fiddling around necessary? Again, the feedway is big and the 9mm bullet is small. Everything has to be right or you will get a few jams, as you are experiencing now. But you can be sure that, once you have it right, you should get no jams at all. What happens is that, if there is a sharp edge, it will cut into the brass case, try to shave into it, and cause a jam. If the edge is smooth and rounded, this is nearly impossible. You have to be sure there is nothing the bullet can "bump into". It has to encounter all things affecting its direction of travel at some angle, the greater the better. And you want no sharp edge.

 

With a bottle necked case, like the 7.62 x 25, there is much less chance of this jamming, but still some.

 

All I use are my own cast lead bullets, in any caliber. So if I can do that in 9mm, you can be sure yours is capable of the same; and certainly with jacketed bullets of the standard military shape. I.e., if lead will slide across those feeding surfaces without digging in and jamming, so will any rounded, gilding metal jacketed bullet. Just stay away from truncated cone bullets and other oddball shapes. Some work and some don't. They only exist because it is cheaper for manufacturers to make the tooling for them; they do nothing good for you.

[Shattered]

I see... can you snap a pic of the breech of the barrel for a visual reference?

 

The breech end of my barrel is almost totally flat. Steve is very finicky about tolerances and visably shudders when asked to 'open up' something beyond a few .0001. The guns are almost too tight to function.