i truly belive the m&p would cycle shorts if we had the correct magazine.
i ran some through it single shot and it ejects everyone.
would be cool .

I'd be more excited about WMR..

what about a 17mach 2 barrel

This gun is designed for the 22LR. Why would you use a .22 short? Maybe a hot .177 would work too. Have you tried that?

Greetings,

The reason the gun doesn't cycle is because there isn't enough pressure created to push the bolt back after the brass relaxes. I've shot the Aquila Super Colibre' and it works fine...have to cycle each round by hand.

Have fun with what you have.

Happy New Year!

Hobie

__________________
Laissez les bons temps roulez!

Why would it be cool? The ground hogs in my area shrug .22Lr rounds off like rain drops. If I wanted lower noise rounds I would just get a suppressor which is legal in MD, and shoot CCI-SV.
Ejecting and cycling are not the same thing. The bolt only has to travel so far to the allow the case to hit the ejector but about twice as far to allow the hammer and sear to reset. This is the essence of a blowback rimfire design, it has a fairly narrow range of ammo power it can completely cycle through. Too low and it won't reset the hammer, too high and it will likely damage the bolt assembly over time. If the maker says such and such ammo works and such and such does not it may be because of damage it causes as much as something that does not cycle.

B-b-but I want to run diesel in my unleaded car!

I'm certain there are more than a few decent quality rifles chambered in .22 Short that you could choose from. The Smith & Wesson M&P 15-22 is chambered in .22 Long Rifle. For best results, stick with the cartridge that the rifle was designed to shoot.

The differences between a gun designed for lr and short,are significant,far more than just a different magazine.

A gun chambered to shoot Short, Long, and Long Rifle has a very specific chamber with a very specifc tapered rifling arrangement. If not the bullet can end up being canted when it hits the rifling farther down and the accuracy goes to pot really bad or worse. Most multi caliber rimfires are either bolt guns or semis that have actions that resemble shotguns that fire 2.75, 3, and 3.5 inch shells. The unusual chamber I mentioned is designed to get the shorter ammo's slug correctly lined up with the bore when it hits the tight part of the rifling. In a normal single caliber rimfire the lands start right ahead of the bullets correct OAL. In a multi when you put a LR round in it already is into the lands when chambered, just enough to line it up. The lands start just in front of the Short round's OAL. Most multi caliber semis I know of are tube magazine guns, oh gee, just like shotguns, I wonder why. Because of the difference in power they may have the alternate gas port arrangement of shotguns or not. For a semi to work is has to have springs light enough for the Short round to cycle plus a way to bleed off the power of the higher velocity rounds so that they don't slam the bolt into some kind of recoil pad.
Anyway I think if S&W ever found out you put Shorts through the AR15-22 they would likely void your warranty.
You might want to clean that gun as soon as possible as you might have lead pieces on the edges of the rifling that might cause issues with the LR rounds.

no way does a 22 that shoots shorts have the lands set off shorts, that would put the brass of a lr into the lands
pushing the lead of an lr into the lands that far woul create pressure and stuck cases that probably wouldnt eject by hand for unloading.
free bore isnt bad, ive seen worn guns with throats eroded a good inch and they still shoot good enough for hunting