Yes,
This is what happens to the sleeves after prolonged use, see picture. As far as blowback there is an o ring seal in the breach of the gun.
Looking for Johnson SMG Part's
- Thread starter MarkF1969
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Yes,
This is what happens to the sleeves after prolonged use, see picture. As far as blowback there is an o ring seal in the breach of the gun.
I believe that was how they were were originally designed. Disposable air cartridges, just go to your friendly SMG dealer, Tarpoon Skin Diving Center and purchase another box of preloaded cartridges and toss your old ones. they were made of polyethylene and could not handle repetitive blasts….but they did …and many SMG fishers reloaded their own until they finally broke and leaked water into the air chamber. Now the cartridges used or pre-loaded are impossible to find since they haven’t produced SMGs since the ?? ‘90s ??
Since the ‘blanks’ for the air cartridges are a .22 cal.Ramset construction cartridge and the breach and chamber are immersed in water the blowback is minimal. Or so it was designed. The firing pin and mechanism on these guns are pretty substantial. Mine is, but keeping the cartridge assembly dry in my old one has been a challenge. That is why I seek out reusable metallic air cartridges. I can use marine sealants that will break only when gun is fired and reload the cartridges myself as the original Tapmatic cartridges for the SMG are no longer produced…to my knowledge.
Now if you have a lathe that is capable of producing such a reusable cartridge, You may want to contact MarkF1969, a new Scubaboard member. You can DM him. He showed me what he has. He has some re-loaded and original air cartridges for his SMGs and like myself looking for metallic ones. He does have working metallic ones he made in his dad’s dental lab a long time ago but is trying to find someone who can make a few. I am trying to do the same thing. Please DM me if this is a possibility. If you are able I would like to get maybe 5 as they would be reloadable and reusable. ’James79’ may be able to 3D print, but again, plastic and how many repeated shots would one be able to
Thanks for following up on this thread. I do have a couple of other interested folks. SMGs are ‘ugly as a duckling’ but the most absolutely cool speargun to collect if they work..
Scott G. Bonser
I believe that was how they were were originally designed. Disposable air cartridges, just go to your friendly SMG dealer, Tarpoon Skin Diving Center and purchase another box of preloaded cartridges and toss your old ones. they were made of polyethylene and could not handle repetitive blasts….but they did …and many SMG fishers reloaded their own until they finally broke and leaked water into the air chamber. Now the cartridges used or pre-loaded are impossible to find since they haven’t produced SMGs since the ?? ‘90s ??
Since the ‘blanks’ for the air cartridges are a .22 cal.Ramset construction cartridge and the breach and chamber are immersed in water the blowback is minimal. Or so it was designed. The firing pin and mechanism on these guns are pretty substantial. Mine is, but keeping the cartridge assembly dry in my old one has been a challenge. That is why I seek out reusable metallic air cartridges. I can use marine sealants that will break only when gun is fired and reload the cartridges myself as the original Tapmatic cartridges for the SMG are no longer produced…to my knowledge.
Now if you have a lathe that is capable of producing such a reusable cartridge, You may want to contact MarkF1969, a new Scubaboard member. You can DM him. He showed me what he has. He has some re-loaded and original air cartridges for his SMGs and like myself looking for metallic ones. He does have working metallic ones he made in his dad’s dental lab a long time ago but is trying to find someone who can make a few. I am trying to do the same thing. Please DM me if this is a possibility. If you are able I would like to get maybe 5 as they would be reloadable and reusable. ’James79’ may be able to 3D print, but again, plastic and how many repeated shots would one be able to handle.
Thanks for following up on this thread. I do have a couple of other interested folks. SMGs are ‘ugly as a duckling’ but the most absolutely cool speargun to collect if they work.
Scott G. Bonser
I believe the air/ammo sleeves can be 3d printed. I would like to know the cost of 3d printing one or many would be?
Secondly, another idea I am going to pursue is the caliber of the plastic sleeve/size of the breach to see if another caliber metal (low powered blank) shell will fit as ammo eliminating the plastic sleeve all together.
Thanks,
MarkF
Not a bad idea. I was able to measure as closely as possible .244 o. d. & a 1/4” (.25) shaft was too big.
SubseaSports
Contributor
Going with the rimfire design was clever..elimating the primer leaking issue of centerfire cartridges.
The smallest centerfire I can think of is .25 acp and that would be too big per Scott's post. Also, finding blanks for it would be a challenge (could be handloaded though)
I have a plan in mind already, using the original concept.
The oem sleeves may be physically reloadable, but there is a wall/membrane that seals the muzzle end. Once fired, it is blown out.
Maybe there was a design change?
Also, per design, a shatterable sleeve is used for safety, allowing for expansion while it launches the spear.
I would be hesitant to use metal unless it was soft.
The smallest centerfire I can think of is .25 acp and that would be too big per Scott's post. Also, finding blanks for it would be a challenge (could be handloaded though)
I have a plan in mind already, using the original concept.
The oem sleeves may be physically reloadable, but there is a wall/membrane that seals the muzzle end. Once fired, it is blown out.
Maybe there was a design change?
Also, per design, a shatterable sleeve is used for safety, allowing for expansion while it launches the spear.
I would be hesitant to use metal unless it was soft.
Envious of those Johnson SMGs, what wicked cool guns for the Spearo. I always used pneumatic spearguns from Italy, not in the same league but still kind of Euro-cool. I had a .38/.357 powerhead that I picked up 40 years ago at Austin's in Miami. Welded a SS rod to it to use as a bang stick. Back then we thought every hammerhead and tiger shark was out to eat us.
The original plastic cartridges had two short splits about half the length of the inverted cone-back end of the spearshaft allowing for easy insertion as well as just sealing the tube at the spearshaft interface. A membrane or sealant that can be ejected when fired may also work. What I saw from the homemade steel cartridge was that to was tapered on the inside of the tube so that the spearshafts, inverted interface would seat itself inside of the tapered tube thus sealing the spearshaft in the cartridge. Using a soft sealant such a paraffin or beeswax may also help with the seal on the reusable metal cartridges.
I agree with you about safety. My dad always revealed the sleeves with wax, glue or Vaseline. I believe the length of the sleeve is important and yes allowed for expansion. I am going to grind down the SS casted one I made to allow tube to fit and make it the same length as the oem sleeve. I still will look for a handloadable casing in the right caliber. The offset of the firing pin will strike a centerfire cartridge
I have the bang stick end made for the SMG. It uses the SMG ammo sleeve inside the bangstick tip/tube with an inch and a half aluminum insert that detonates the ammo sleeve on impact. So you get the ammo explosion and aluminum bullet on the end of a spear you can shoot out of the gun.
Oh BTW, I purchased my Mares ‘Bazooka’ from Austin’s in’82. I tried to buy SMG at Tarpoon but they were closed that Saturday. I still have my ‘Bazooka’ used very few times on bigger fish but I prefer shooting my mid-sized mid grip pneumos fo my past hunts.
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