Monday, April 4, 2011

Variation On A Theme

Tam throws out a "modest proposal":
... I think that you could drive a half-dozen gun companies to the brink of bankruptcy if you sold a sealed, non-reloadable, disposable, 10-shot pistol ... Discus.

The comment thread is entirely too predictable though.

For added context, JayG posted this video back in February about the Girandoni rifle carried by Lewis and Clark during their trans-continental expedition.

Back to Tam now. She proposes a disposable handgun, but sticks to the traditional bullet, powder, shell casing, primer model. My alternative is to build an air gun having the same general terminal ballistics performance of the historical Girandoni rifle.

Since unit cost is going to be perhaps the principle consideration, I propose using an established bullet in a widely available caliber; .45 acp in 185 gr. JHP configuration. Please note that no gun powder, shell casing or primer are required, thus allowing savings in materials as well as design and safety considerations.

Using the 1911 platform as illustration, by placing the compressed air cylinder in the same location as the return spring and guide rod occupy in the traditional gun (along with the area occupied by the ejection port and firing pin mechanisms) ought to permit sufficient volume to project 15 bullets at a muzzle velocity of ~900 fps. The upper portion of the same volume of 1911 slide also becomes usable barrel space of course, with a fixed, bead-type front sight in the traditional location.

Making the trigger assembly/grip portion of the frame a separate item makes penetration of the sealed compressed air cylinder impossible until the user unpacks the gun and assembles the two components which assures an extensive shelf life for long-term storage.

The bullets are factory stacked into the rear of the grip with a plunger below them which receives compressed air pressure to advance each round into the breach end of the barrel. A simple view port showing the number of bullets remaining is inlet into the grip also. Pulling the trigger releases a mechanically metered volume of compressed air to fire each bullet. Unlike the JMB design, this gun would have a DAO trigger that cycled a cambered block from top-of-the-magazine into breach (and back again after discharge either by means of a simple spring or by air pressure). Also unlike the JMB design, the two sub-assemblies would go together by means of an open hinge and pivot pin arrangement similar to that used by SKS/AK magazines instead of sliding together along grooves.

By appending a hinge pin to the bottom rear of the grip, a hinged frame can be revolved to meet the rear of the grip assembly and onto the top rear of the upper (barrel/compressed air cylinder) portion of the unit to achieve several things, 1) lock the two sub-assemblies together, 2) provide a rear sight and 3) mechanically engage the air cylinder needle to charge the unit and make it an operable gun. While it would not be impossible to remove the hinged frame from the upper portion, there would be no mechanism provided to do so (you could use a file or saw to cut it out of the upper, but you couldn't do it by hand). Once the 15th bullet has been shot, any remaining compressed air is released around the trigger telling the shooter the gun is now a flimsy hammer.

As should be obvious, this concept easily converts into a carbine-type rifle having a factory loaded under-barrel tube magazine and the compressed air cylinders in the detachable butt stock. Unlike the pistol, this configuration would lend itself better to an LED-type laser sight as both hands when in the normally used in shooting position(s) better allow the fore-hand to activate the laser as required without altering the grip to do so.

Regarding packaging, I think a preformed "sardine can" containing the disassembled sections in a nitrogen gas-rich mixture would make for better (ie: more stable) storage. This could be pressed into a PVC outer shell which is sealed with a glued-on top having a wire embedded into it. To open, lift the pull ring on the wire and cut the top off by pulling the wire through the glue material (if the wire should break, I presume there will be a knife of some description present). Once open, pop the "sardine can" top, lift out the sub-assemblies, latch and lock them together and - viola! - you're armed.

Based on the reported terminal performance of the Girandoni rifle, this concept would permit 15 shots from a .45 acp hand gun using 185 gr. JHP bullets and a carbine holding between 25 and 30 of the same bullet. Reserving the hand gun for targets within 25 yards max, the carbine ought to be effective out to 100 yards. Even though air powered it won't actually be "silent", but it will certainly have a much quieter sonic signature than traditional gun powder weapons have.

It also occurs to me that a concealed carry defense model ought to be fairly straight-forward too. The gun (think Colt "Officers" model - barrel long enough for six bullets max) comes in a kydex-type "holster" pre-assembled, fully loaded and charged with air. Pulling the gun from the holster punctures the gun's air cylinder. Some mechanism for releasing the air pressure (without pulling the trigger :)) ought to be crafted that a gunsmith/armorer could use to safe the gun and replace the air cylinder (not just by re-holstering though). Specialty market option maybe.

If the pistol could be MSRP'd for under $50 and the carbine for under $100, I think Tam's target market would be vulnerable.

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