I was thinking about how an airsoft electric gun works.  It has a small motor that drives a piston that compresses air to power a little plastic ball. Then I thought about making an up sized version to fire .50 cal muzzleloader balls.

The motor could come from a cordless electric tool or a corded one if it needed the extra power. The piston could come from a 5 liter V8. The cylinder could be machined out of a solid piece of steel.  The values either from an engine or from a maker of high preasure valves.

A tripod mounted gun with 700 to 800 feet per second and 5 to 10 rounds per second could be done.  . If you say you wouldn’t like to line up a row of cans and an old computer at 50 yards and blast them with 100 .50 cal lead balls, you must be spoiled on real class 3 weapons.

Unfortunately a muzzleloader ball will not engage the rifling without a cloth patch but still needs the slow twist of a ML barrel.  Bullets will work with a more complicated feeding mechanism.  They’ll need a loose fit with the bore to account for lubrication oil coming from the cylinder. A .452" 45 cal pistol bullet in a .458" 45 cal rifle barrel is not ideal. But it should work if the bullet engages the rifling.

This would be a fun project and range toy. I guess you could use it as a property defense gun for SHTF.  One 45 bullet at well below 700 fps would not be especially deadly but maybe 10 would.

I have serious doubts about whether this would be legal.  At the federal level it might be.  But I'm sure some states have laws against air guns over a certain caliber.

Anyway that’s what I’ve was thinking about in the shower and the drive in, so I thought I’d share.

%100 legal. As long as you don't use an explosive charge or self contained cartridge to propel the projectile, that means fuel vapor as well. You could use electromagnetics, compressed air, centrifical accelerator. Caliber no issue. They make 9mm and .50 air rifles that are effective for hunting large game.

Fantasizing about big bore and multiple shot capability in the shower?

Why not us a regular compressor and run a hose to a quick connect in the pistol grip?  Higher air volume and you can more easily regulate the pressure.  It would give you up to 120 PSI safely to do what you want.  With a large capacity compressor, you could theoretically get up to 100 rounds at a time easily.

They sell Paintball guns tht run off some sort of propelent. Gas is ignited to send the round down range, and it is legal some how. I say go for it.

Quoted: They make 9mm and .50 air rifles that are effective for hunting large game.

This sounds interesting. Got any examples?

Quoted: Quoted: They make 9mm and .50 air rifles that are effective for hunting large game. This sounds interesting. Got any examples?

Some early examples of airguns packed quite a punch.

"The variety of early hunting airguns reflected the variety of hunting. One 18th century specimen in the Beeman collection is a solid .39" caliber carbine, only 40 inches long, perhaps intended for use in heavy brush or on horseback. Another, made by Hass in Neustadt, Germany about 1750, has a beautiful 33" shot barrel, about .33" caliber, which can be unscrewed and drawn out of the gun to reveal a very menacing .46" caliber barrel with seven extremely deep rifling grooves. In just moments, the owner of the gun could switch from doves to deer! One of the fine-cased English air rifles (made about 1850) in the author's collection was regularly used for deer hunting as recently as 1950. It fires a 265-grain, .44" caliber bullet!

Perhaps the most historically important American airgun of all was an air rifle carried by Captain Meriwether Lewis on the famous Lewis and Clark expedition of 1803-06. The most recent research (6) fairly conclusively indicates that this was a .31" caliber, flintlock-style, pneumatic rifle built by Isaiah Lukens in Philadelphia. It served Captain Lewis well, both for hunting and to astonish the Indians.

Certainly one of the most famous of the butt-reservoir guns was the Austrian military air rifle designed by Girandoni about 1779. Its buttstock also is a detachable air reservoir which could be quickly unscrewed when empty and replaced by a full one. Each reservoir held enough air to fire a series of 20 heavy lead balls fed from an ingenious rapid feed magazine. These formidable weapons could put out their 20 smokeless shots in a minute; it is reported that the .51" caliber (13mm) balls were deadly to 100 yards! A corps of 500 soldiers so armed had a potential firepower of 300,000 shots in a half-hour - incredible for military rifles of the late 1700's! During this same period, and for almost a century to follow, big bore airguns were extremely popular with the wealthy sportsmen of Europe. Among the ancient airguns in the Beeman collection are beautiful specimens of air carbines, about .45" caliber, apparently for boar hunting from horseback, long rifles for deer hunting, and especially beautiful English cased sets with richly engraved receivers and interchangeable rifle and shot barrels for mammals or waterfowl. The ultimate in mechanical airgun development was the fearsome air canes with their jewel-like internal locks. Evidently no well-dressed English gentleman of the late 1800's would be seen without one of these weapons-which ranged from almost .30" to .49" in caliber and had perhaps the power of a modern police revolver!"

www.bit1.com/history/history.html

The BATF only regulates FIREarms, devices which combust a fuel to launch a projectile or devices which launch projectiles which contain their own combustable fuel. The BATF does not regulate airguns at all. FA airguns are perfectly legal.

The downside is that there is no constitutional snag against states or localities making laws of their own against airguns. And I doubt you'd get a lot of power out of such a cyclic-piston setup. A massive tank of compressed air would work, but be not-nearly as portable.
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Quoted: Quoted: They make 9mm and .50 air rifles that are effective for hunting large game. This sounds interesting. Got any examples?

Man, I'm not your Google Bitch!


www.pyramydair.com/

.50 Cal air rifle

9mm Air rifles


Here's a review of the .50, fires 275 gr. "pellets"

.50 Review