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Johnson Submarine Gun (SMG) cartridge powered

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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popgun pete

popgun pete

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Jul 30, 2008
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These SMG spearguns first came out in the late sixties and I remember checking out the single barrel version at Alcock & Pierce which is/was a sports store in Melbourne. The ammo that they used was a limitation as although based on the range of Ramset .22 cartridges for power tools like nail guns, you needed the "Sub Ammo" plastic sleeves that waterproofed the rimfire cartridge and which the tail of the spear stuck into at the front end in order to stop the spear falling out of the speargun's barrel. They were non-floating after the shot weapons and more suited to scuba divers conducting spearfishing at depth. Tapmatic Corporation in the USA manufactured them for about ten years, then at some time Crocket and Co(?) in New Zealand bought the rights and the remaining stock of speargun components and subsequently produced the SMG in New Zealand. Being banned nearly everywhere but the USA destroyed the market for such guns. Tapmatic told me that they produced about 2500 guns, but how many more were made or assembled in New Zealand is unknown. I have seen a couple of the New Zealand guns and they are identical to the US guns being the twin barrel versions. These guns turn up every now and then on auction sites and are generally in good condition as they could rarely be used if you did not have the plastic ammo sleeves.
SMG brochure.jpg


smg1.jpg



SMG Reel.jpg


Johnson SMG patent.jpg
 
popgun pete

popgun pete

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Jul 30, 2008
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If you look carefully at the patent drawings then you will see that the SMG trigger mechanism is just a pull down sear lever mechanism, as was used in the first French Arbalete, which fires a long captive bolt that acts as a firing pin. Until I found the patent the innards were a mystery to me, but coincidentally in my own cartridge gun I used a similar mechanism based on a spring gun trigger mechanism which operates the same way. Unfortunately when the rules changed I had to destroy it, however it was not a very practical weapon, but seemed a good idea at the time.
SMG handle and trigger mechanism

Ramset 22 spear pistol 2

My ramset pistol for underwater hunting, built in the early seventies. The bolt is cocked by drawing the top lever back and then moving it sideways in a dogleg gate which acts as a safety. You inserted the shaft, which was retained by an internal collet at the rear of the stainless steel tube barrel, and then put a ramset cartridge into the breech. The breech was then screwed shut with about 3 turns of the barrel, the line was rigged and once you were ready you flipped the lever upright and you were then ready to shoot.
 
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Dickbillhill

Dickbillhill

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May 22, 2021
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This time you gave me one double barrel I still have it on Craigslist right now and some dude wants to buy it for $5,000 how much are they really worth oh my God so far I've seen it up to $10,000 somebody tell me what they are worth please double barrel smg-e made in California
 
popgun pete

popgun pete

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Jul 30, 2008
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Worth depends on who wants to buy it, with no ammo and banned in many places there would be few people who want one bar collectors.
 
popgun pete

popgun pete

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Jul 30, 2008
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Some photos of the ammo showing the washers and sleeves. On these examples you can see slots in the front end that may have helped pushing the spear tail in the front end if the plastic used was not compliant enough to stretch and allow trapped water out of the front cup.
Smg sub ammo photos

Sub Ammo

SMG Sub Ammo
 
popgun pete

popgun pete

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Jul 30, 2008
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Note that Ramset .22 cartridges are/were colour coded by a dab of paint on the crimped front end of the wadded blanks; you just selected a plastic sleeve of the matching colour so that you could identify which load you were using as once glued into the sleeve you otherwise would not be able to tell.
 
popgun pete

popgun pete

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Jul 30, 2008
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This image shows a comparison of the long barrelled MAGNUM model and the standard MKII, the MAGNUM being able to use the more powerful ammo grades with the extra barrel length allowing more gas expansion inside the confines of the barrel to drive the spear.
SMG MK II MAGNUM and Standard model
 
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