Looking for Johnson SMG Part's

[MarkF1969]

Never put my hands on one..but on my list.

Question about the insert...being rimfire, wouldn't a plastic insert/adapter take a beating from repeated use? (Ok for single use).
Also, is there shell blowback once fired?
From what the picture posted that would be easy to do on a lathe (I have one) .

Yes,
The plastic sleeves do take a beating. A metal washer is added between the 22 ammo casing and the plastic. The plastic sleeve eventually splits down the side.

 

[Scott G. Bonser]

Yes,
The plastic sleeves do take a beating. A metal washer is added between the 22 ammo casing and the plastic. The plastic sleeve eventually splits down the side.

Yes the cupped washer absorbs the impact of the firing pin. The splitting sides are from the shell detonating force when fired.

 

[SubseaSports]

I rough cut one today.
Thats a knarly spent case in there.
It has a 'wall' in the tube like oem. This one is my no washer version.
More to come.

 

[Scott G. Bonser]

I rough cut one today.
Thats a knarly spent case in there.
It has a 'wall' in the tube like oem. This one is my no washer version.
More to come.

View attachment 832070

…looks good Doug. I reckon the best way to test is a ‘live shoot’ to see if it fires and see what kind of ‘dent’ the firing pin leaves in the .22. I did send a quick sketch to Mark F but haven’t heard back yet. I may hear from him on Monday. I can send you a pic of what I drew. Not really detailed but builds on what you and he are discussing. I believe I have your contact info so I will send you one.

 

[MarkF1969]

I rough cut one today.
Thats a knarly spent case in there.
It has a 'wall' in the tube like oem. This one is my no washer version.
More to come.

View attachment 832070

I wouldn't worry about the wall it can be made with glue

 

[MarkF1969]

I own 2 of these great vintage spearguns. Some of you might of seen the one when Richard Dreyfus was loading his gear onto the boat in Jaws the movie. Also the gun was on an episode of Pawn Stars. I have been rebuilding them for over 25 years. I casted an ammo sleeve ( it uses a 22 cal tapcon stud driver shell to launch the spear) in stainless steel to reuse over and over. I would like to try to 3d print one. Anyway I am always looking for parts...ect. I am here in FL and friendly. Call me if you have a SMG or parts for sure.
Mark F
407-703-6195

I now can make reusable ammo sleeves!

 

[Bo123]

I rough cut one today.
Thats a knarly spent case in there.
It has a 'wall' in the tube like oem. This one is my no washer version.
More to come.

View attachment 832070

Hi all. Came across this post online and thought I'd jump in. These spear guns are great. I've found they generally need some going over before going back into use, mainly setting the breach clearance.

I had some metal cartridges re made, and did a number of revisions, basically removing the disposable washer that usually sits between the charge and cartridge. I found them unsuccessful, as the explosion leaks back towards the breach, unlike the plastic sleeve which basically expands and seals, allowing the full charge to push the spear. Different ways of sealing the end I found effected things, ie too tough of a seal, expanded the sleeve.

The charge too, needed to be the paper wadded ones, the ones available here with the crimped aren't suitable. We don't have access to the wadded charges here but I did get some from the US. I have some notes as I worked things out like the charges and so on. Two years back I sent Mark @ Tapmatic an email about them, he didn't have any more info for me for whatever I was asking; I shared a photo of one of mine in use to show his father Allan who designed them. He said Allan was very proud of the SMG spear gun and would be pleased to see one still in use. I'll try upload some images

 

[Bo123]

Yes,
The plastic sleeves do take a beating. A metal washer is added between the 22 ammo casing and the plastic. The plastic sleeve eventually splits down the side.

 

[MarkF1969]

Hi all. Came across this post online and thought I'd jump in. These spear guns are great. I've found they generally need some going over before going back into use, mainly setting the breach clearance.

I had some metal cartridges re made, and did a number of revisions, basically removing the disposable washer that usually sits between the charge and cartridge. I found them unsuccessful, as the explosion leaks back towards the breach, unlike the plastic sleeve which basically expands and seals, allowing the full charge to push the spear. Different ways of sealing the end I found effected things, ie too tough of a seal, expanded the sleeve.

The charge too, needed to be the paper wadded ones, the ones available here with the crimped aren't suitable. We don't have access to the wadded charges here but I did get some from the US. I have some notes as I worked things out like the charges and so on. Two years back I sent Mark @ Tapmatic an email about them, he didn't have any more info for me for whatever I was asking; I shared a photo of one of mine in use to show his father Allan who designed them. He said Allan was very proud of the SMG spear gun and would be pleased to see one still in use. I'll try upload some images

 

[MarkF1969]

Bo123,
Great to hear that you're still using your SMG! When I made the sleeves out of stainless steel instead of brass, i have less problems. Removing the washer is a good idea and now I just make the tube in metal, not the flange part. Aquaseal on the ammo and a little Vaseline in the breach, no problems. Here is a little US history. The SMG is not considered a firearm here in the US. It's intended use is not for bodily harm and has the same regulations as a flare gun. Allen, Valerie and Mark Johnson at Tapmatic had the IRS/ATF look at the SMG in 1968/69. Attached is the ATF response!