WE/Cybergun M1A1 Thompson Submachine Gun

[renegadecow]

As some of you already surmise, I sold my dignity and purchased something from Cybergun. As the only Tommy GBBR I felt my wallet cornered though to be fair this is not my first CG purchase as I also got the WE/CG Desert Eagle last year so you could say I didn't have any self respect in the first place. So with that, on to the review.

The gun is a truly open bolt submachine gun with select fire capability doing about 330fps (30C) at around 850rpm. When out of bbs the bolt locks to the rear until a loaded magazine is inserted and the charging handle pulled back. It is full metal with the major parts (barrel, receiver) in aluminum anodized in a beautiful parkerized look, however it's worth noting that all Thompson SMGs from 1928s to M1A1s left the factories in a blued or du-lite finish. Parkerization was done at the US armorer level and only when returned guns needed refinishing so completely parkerized guns were rarely ever seen until after WW2. The internals are a cast zinc alloy however the sear and bolt have steel reinforcement inserts where they engage against each other for better wear resistance. It has faux wood furniture in ABS plastic and while visually appealing, has a very hollow sound and feel to it especially when the rear sling swivel rattles about. You could, I suppose, fill the plastic with expanding foam or even body filler/bondo to make it more solid and add some heft as the total weight of the gun with the supplied 50 round magazine (30 in real life) only tips the scale at about 2.8kg. Because of this I've changed the furniture out with real walnut by Black Owl Gear. They are the cheapest commercial kit available though need to have the screw holes drilled out first. They go on without modification however the handguard does not sit completely flat against the barrel and will require some sanding to get it really squared on. Speaking of sanding, the kit is roughly finished giving it a very plain and uniform look. I've refinished mine by sanding it down to 400 grit, re-staining in walnut and coating with a couple coats of clear lacquer for water proofing. Installed, the kit adds about 500g and while still over a kilogram short of the real gun's weight, gives it a much more solid, confident feel to it. There are steel kits available now which brings the gun to true weight however they cost over $900

Before:

After:

 

Internally it has a 270mm inner barrel and of the modified VSR-10 kind which is to say if you plan on changing either the barrel or hop rubber, you have to swap out both. It doesn't shoot bad considering it is a submachine gun, but I did have to correct the crown which was a bit eccentric and was causing turbulence at the muzzle affecting group size. With that sorted it groups within an A4 size sheet of paper at 20m. The sound when firing is fairly loud, but a little different from other GBBRs in that it's oddly similar to a branch breaking. Recoil is very satisfying as the bolt is heavy and traveling at full stroke so it gets a lot of momentum. Because of this, firing in semi-auto accurately needs a bit of practice and I find shooting it in the prescribed old school method (bladed stance, chicken wing) works best. The hop adjustment dial can be a bit loose however and may require tightening using tape or a thin layer of super glue to keep it from walking out of setting. Also because of the massive bolt, gas consumption and cool down are against it. With moderately paced semi-auto fire, a fully gassed 50 round magazine will shoot enough for 70-80 bbs worth which may seem a lot but it holds a lot of gas to begin with and even just going through 50 rounds it already gets very cold.

 

Now, with the basic information done, and having had this for a couple months and working on other units even earlier than I bought mine, below will cover a list of manufacturing problems, as one would expect from WE, and how to address them.

Barrel wobble

The barrel and receiver assembly does not copy TM's AEG design but of Hudson's PFC design which is very close to real steel. The handguard metal is screwed to the barrel and both are socketed into the receiver and a screw at the bottom goes through all three pieces sandwiching them together. This is a very solid design, however WE has some production issues such that the screw installed is way too short. It only really engages the barrel by two turns and it doesn't take a lot of rounds for the threads to get mangled and the assembly starts to wobble. To fix this, it's highly recommended to replace the screw with a longer one right out of the box: flat head, socketed, M5x18mm. For an even tighter barrel to receiver fit, you can glue a strip of aluminum to the receiver acting as a shim much like how you would address barrel wobble on the WE G36 (G39). I used aluminum from a soda can and folded it over making it 0.3mm thick and about 20mm wide long enough to make a letter "C" around barrel.

 

Nozzle breakage

Some units have experience having their nozzle break in two and I found it to be the cause of a short and loose pin. The front and rear section of the nozzle is connected by a pin which, again, with production issues is shorter than it should be. The pin walks out from recoil and because it's short, one side eventually becomes unsupported and the protruding part of the pin hits an area on the receiver which eventually breaks the nozzle. A good solution is to replace the pin altogether with one that covers the full width of the nozzle and preferably from high carbon spring steel. If you can't find/make a pin, you could also just super glue the original pin in place so it doesn't walk out. Also be observant of the pin every so often, checking to see if it's walking out.

 

Bolt wear

Even with just a couple mags through, many have complained about excessive bolt wear on its underside. You can clearly see the scratch marks and in the worst cases the lower receiver is littered with metal shavings. The cause of this, ironically, are the steel reinforcing inserts WE put on the sear. The edges of the inserts are very sharp and work the bolt like a chisel. To fix this you simply have to dull the edges of the inserts with fine grit sandpaper (800 and up).

Bolt wear shown only after a few mags for testing, but has not progressed after seeing 1.5-2k rounds after being fixed

Dulled edges of sear inserts. You can barely see the difference but I put roughly a 0.12mm radius on the edges.

 

Receiver wobble

While this isn't much of a problem on its own, many have complained about it so I've devised an easy way to address it. Using a wide rounded punch, I hammered a dimple into the upper receiver rails near the opposite ends so that the displaced metal creates a hump. This acts as a spacer to tighten the engagement between lower and upper receiver. You don't have to hit too hard, just repeated light taps will do until the desired tightness is met. Shown are one set of dimples on each side but I later added an extra set of dimples next to the first ones.

 

Double feed

This problem doesn't happen very often but is a pain when it does as the extra bb doesn't always go down the chamber and instead lodges itself between the bolt and barrel causing a jam. I've rooted the problem down to fairly loose feed lips and to fix them I simply heated the feed lips and clamped them to the right width until cool. I used a heat gun, making sure to rotate the mag constantly to heat the lips evenly. When you see the edges of the plastic begin to get shiny, that's hot enough. I then clamped the lips down with a vise grip pre-measured at 12mm and blew on it until it cooled down.

Edited December 18, 2018 by renegadecow

[Sturm]

‘Evil’ Sturm is returning from the dead!

Want to show off my full CNC steel WE M1A1: https://imgur.com/a/2eiALBA

 

[AMPZ28]

On the nozzel halves,where the pin is too short.is one end of the pin seat still plastic sealed?i can only see the pin on one end of the nozzel,so I'm guessing I have to drill the opposite side plastic to reveal and push the pin out

[renegadecow]

I recall mine was drilled through, just that the very end of the hole was kinda obstructed with flash or dirt making it appear like a blind pin.

[AMPZ28]

I've taken your advice and tweaked everything from the post. Great performing gun,just one small concern. Has anyone else experienced on semi fire that it dumps around 5 shots or so randomly?

[renegadecow]

Was happening to me but has pretty much disappeared after doing all the mentioned work so not really sure what was causing it. What I do know is I can make the gun do a burst if I try to pull the trigger too fast or too light and it sort of bump fires. If I make clean pulls with follow through it never happens.

[AMPZ28]

That's a good observation.i remember being a bit light and quick on the trigger. I'll put it to the test tonight.

[3vi1-D4n]

Great review!

 

I bought mine recently, and its a fun gun.  Shoots at 320-330fps at 27*C, which is bit low for my liking.  However gas efficiency is very poor, I get 60 round/cycles out of a full charge.

 

I proceeded to trim the main spring by 30% and stretched + trimmed the nozzle return spring by 40%,  got around 80 rounds/cycles per charge, with a noticeable increase in kick.  

 

I found that the flute valve was being slammed forward during the cycle and hence resulting in low FPS, using an older and stronger WE flute valve spring to keep the flute valve in place , which increased the FPS.  Its now shooting at 430-440fps.

 

Due to the same issues around the hop rubber constriction it is causing a dispersion.  The wobbly and misaligned barrel is also causing a number of accuracy issues.  So I proceeded to shim the barrel, which brought the rifle back to the correct point of aim.  I will be working on the hop rubber later today to get better accuracy.

 

All in all, it does need a heavier barrel and a wood kit, which I will purchase at a later date.

[renegadecow]

Did cutting the recoil spring bring rof down? Been bugging me a bit realizing it's shooting as fast as an M1921 and was thinking of making a weaker spring with thinner gauge wire.

[CatgutViolin]

On 2/21/2019 at 6:53 AM, renegadecow said:

Was happening to me but has pretty much disappeared after doing all the mentioned work so not really sure what was causing it. What I do know is I can make the gun do a burst if I try to pull the trigger too fast or too light and it sort of bump fires. If I make clean pulls with follow through it never happens.

Spitballing here, but on real open-bolt submachine guns, you get the first issue if the sear return spring is too light (so a hard pull 'slaps' it down and the gun is able to cycle twice before it resets), and you can get the second issue if the disconnector is designed to be tripped by pulling the trigger farther than it takes to fire (full-auto is then achieved by blocking the trigger from going far enough to engage the sear- this is how my WE M712 is designed, so I wouldn't be surprised if this uses the same).

If you increase the tension on the sear, it will typically fix both issues. Assuming what I described above is what's going on.

[renegadecow]

You might be on to something with the weak sear spring. As for the mechanism for select fire, it has a disconnector that's tripped by the bolt.

[DiscoBiscuit]

On 3/14/2019 at 5:05 PM, 3vi1-D4n said:

Great review!

 

I bought mine recently, and its a fun gun.  Shoots at 320-330fps at 27*C, which is bit low for my liking.  However gas efficiency is very poor, I get 60 round/cycles out of a full charge.

 

I proceeded to trim the main spring by 30% and stretched + trimmed the nozzle return spring by 40%,  got around 80 rounds/cycles per charge, with a noticeable increase in kick.  

 

I found that the flute valve was being slammed forward during the cycle and hence resulting in low FPS, using an older and stronger WE flute valve spring to keep the flute valve in place , which increased the FPS.  Its now shooting at 430-440fps.

 

Due to the same issues around the hop rubber constriction it is causing a dispersion.  The wobbly and misaligned barrel is also causing a number of accuracy issues.  So I proceeded to shim the barrel, which brought the rifle back to the correct point of aim.  I will be working on the hop rubber later today to get better accuracy.

 

All in all, it does need a heavier barrel and a wood kit, which I will purchase at a later date.

Which is why I didn't buy this thing despite the Thompson being super cool, the fixes seem so simple to engineer (from a commercial point of view) that I can't give WE my money because they can be such half-a$$es. Add 15% to the price and just do it right.

Edited March 17, 2019 by DiscoBiscuit
big balls!

[3vi1-D4n]

On 3/15/2019 at 10:45 PM, renegadecow said:

Did cutting the recoil spring bring rof down? Been bugging me a bit realizing it's shooting as fast as an M1921 and was thinking of making a weaker spring with thinner gauge wire.

Yes I did, ROF is lower.

When you do it however, you gotta remember that on an open bolt, the impact force releases gas. So if you lighten that too much FPS will be affected.

1 hour ago, DiscoBiscuit said:

Which is why I didn't buy this thing despite the Thompson being super cool, the fixes seem so simple to engineer (from a commercial point of view) that I can't give WE my money because they can be such half-a$$es. Add 15% to the price and just do it right.

Funny you say that, pretty much Most WEs I would have to do the same sort of fixes to them anyways. 

It actually makes the WEs more flexible.  For example because I need to do that tuning, I can max out  gas efficiency, recoil, reliability, and power output where I would have trouble with say a GHK or a Marui.  For cheaper, a WE get better performance overall.

 

 

 

[DiscoBiscuit]

4 hours ago, 3vi1-D4n said:

Yes I did, ROF is lower.

When you do it however, you gotta remember that on an open bolt, the impact force releases gas. So if you lighten that too much FPS will be affected.

Funny you say that, pretty much Most WEs I would have to do the same sort of fixes to them anyways. 

It actually makes the WEs more flexible.  For example because I need to do that tuning, I can max out  gas efficiency, recoil, reliability, and power output where I would have trouble with say a GHK or a Marui.  For cheaper, a WE get better performance overall.

 

 

 

But you are a tinkering Jedi, I am a mortal, ham-fisted fool. 

[AMPZ28]

On 3/14/2019 at 4:05 PM, 3vi1-D4n said:

Great review!

 

I bought mine recently, and its a fun gun.  Shoots at 320-330fps at 27*C, which is bit low for my liking.  However gas efficiency is very poor, I get 60 round/cycles out of a full charge.

 

I proceeded to trim the main spring by 30% and stretched + trimmed the nozzle return spring by 40%,  got around 80 rounds/cycles per charge, with a noticeable increase in kick.  

 

I found that the flute valve was being slammed forward during the cycle and hence resulting in low FPS, using an older and stronger WE flute valve spring to keep the flute valve in place , which increased the FPS.  Its now shooting at 430-440fps.

 

Due to the same issues around the hop rubber constriction it is causing a dispersion.  The wobbly and misaligned barrel is also causing a number of accuracy issues.  So I proceeded to shim the barrel, which brought the rifle back to the correct point of aim.  I will be working on the hop rubber later today to get better accuracy.

 

All in all, it does need a heavier barrel and a wood kit, which I will purchase at a later date.

Interesting spring adjustments. What effect did the shortening of the nozzle spring cause? I'm going to try your fixes

[3vi1-D4n]

The rationale behind that is to decrease gas consumption in the blowback cycle.

 

There are two springs which control the amount of gas which result in net rearward movement of the bolt carrier;  the main recoil spring, and the nozzle return spring.

 

A quicker rearward movement is a result of lightening of the mail recoils spring and the nozzle return spring.  That will result in less effort and gas used to push the bolt carrier rearwards, shutting the gas release valve sooner, using less gas without changing the rate of gas flow in the system.

 

But of course, as an open bolt system, the main recoil spring determines the striker force on the gas release valve, which will affect initial gas release impulse and will affect FPS if trimmed too much.  Over lightening of main recoil spring may also result in cycling and reliability issue.  

 

Recoil will definitely be harder, and will affect the structure and buffering at the back of the receiver.

 

So it is all a balance.

[AMPZ28]

1 hour ago, 3vi1-D4n said:

The rationale behind that is to decrease gas consumption in the blowback cycle.

 

There are two springs which control the amount of gas which result in net rearward movement of the bolt carrier;  the main recoil spring, and the nozzle return spring.

 

A quicker rearward movement is a result of lightening of the mail recoils spring and the nozzle return spring.  That will result in less effort and gas used to push the bolt carrier rearwards, shutting the gas release valve sooner, using less gas without changing the rate of gas flow in the system.

 

But of course, as an open bolt system, the main recoil spring determines the striker force on the gas release valve, which will affect initial gas release impulse and will affect FPS if trimmed too much.  Over lightening of main recoil spring may also result in cycling and reliability issue.  

 

Recoil will definitely be harder, and will affect the structure and buffering at the back of the receiver.

 

So it is all a balance.

Great explanation. Less tension= less work(gas) needed. I'm going to trim the nozzel spring down 30% and increase the tension on the flute valve spring 10%..see if I can gain fps that way. 

On a separate note.any ideas on why the sear isn't locking after each shot on semi? I follow through with each trigger pull,but the gun cycles 4-5 shots quite often.

[AMPZ28]

On 3/15/2019 at 2:39 PM, CatgutViolin said:

Spitballing here, but on real open-bolt submachine guns, you get the first issue if the sear return spring is too light (so a hard pull 'slaps' it down and the gun is able to cycle twice before it resets), and you can get the second issue if the disconnector is designed to be tripped by pulling the trigger farther than it takes to fire (full-auto is then achieved by blocking the trigger from going far enough to engage the sear- this is how my WE M712 is designed, so I wouldn't be surprised if this uses the same).

If you increase the tension on the sear, it will typically fix both issues. Assuming what I described above is what's going on.

Do you know of a possible higher tension spring? the sear in my mind seems pretty weak to be honest.I can't get rid of this random cycle issue. 

[renegadecow]

It's a fairly simple compression spring with lots of tolerances so finding a suitable replacement won't be too hard. You can also insert a smaller diameter spring inside it to bring the tension up, maybe from a ballpoint pen. One other modification (if you could call it that) which I now remembered after going over my internals is polishing the top and edges of the disconnector (#62) where it engages the trip (#67).

[renegadecow]

So I tried lowering my ROF today by making a new spring instead of cutting coils. New one on top just shorter by 3-4 coils, but made of 0.8mm wire vs 1.0mm on the original. ROF dropped to 660rpm and so did muzzle velocity to around 300fps, but I also encountered occasional light strikes and a very strange condition where it would consistently disconnect the sear in full auto making it fire in semi unless I put forward and upward pressure on the handguard while firing. I put the original spring back and it was shooting normally although the magazine valve got stuck forward. Opening the valve apparently the brass housing isn't one piece like the usual. Inside it is a separate brass ring that's press fitted which can get stuck forward causing the valve stem to stay open.

[3vi1-D4n]

How have you made springs?  They look very well made.

 

I have wounded my own springs with an electric drill and a steel rod which the spring can coil around.  I have tried to use a lathe but can't get it right.

[renegadecow]

Thanks. I use a metal rod as a mandrel with a vise grip holding one end of the spring and a flat piece of PVC with sized holes and a screw on the edge as a wire guide. I turn it by hand, going slowly to make sure the coils get the proper tension and negative angle so they're compressed tightly against each other. After the needed number of coils is reached I reverse is slowly to ease off tension then cut the ends. For compression springs I stretch it out by hand, sometimes using a rod or screwdriver shaft as a spacer towards the ends then temper.

Edited May 10, 2019 by renegadecow

[renegadecow]

The stiffer floating valve spring works great! I didn't need all that much of a boost so just modified mine instead of buying after market ones. Stretched out an extra 30% in length and retempered yielded a good 10% increase in muzzle velocity, just enough so the bbs aren't as easy to dodge at a distance.

[3vi1-D4n]

Yeah isn't it?

 

How much more weight does the wood kit add to the silly light thompson?

[renegadecow]

With BOG's kit and a sling mine weighs 3.08kg.