Why isn't the M3A1 "grease gun" still manufactured?

[LawBot5000]

The M3 works best as a small, cheap machine pistol.

The problems with bringing it back are that:
-there is currently no military market for it, so that means making it for civilians
-which means it can't be an MG
-as a semiauto, it would either have to be a stockless pistol or a fairly long barreled rifle to avoid NFA issues
-as a semiauto it couldn't be open bolt like the original, which makes it more complicated and thus more expensive to manufacture
-as a closed bolt semiauto with a 16 inch barrel, it's a weird unwieldy thing that's very front heavy and has an uncomfortable stock and grip. Trigger pull is probably not great either.
-olympic arms already makes 45 acp uppers that allow one access to the excellent ergnomics of the AR-15
-there are 45 acp carbines in existence already, some of them quite affordable

 

[LawBot5000]

If you got rid of the 86 ban or the NFA restrictions on MG's altogether, the grease gun might make a comeback.

Of course, if you can buy new manufacture machine guns and you want something that uses 45 caliber grease gun magazines, why not get a MAC-10? Same basic idea, smaller size weapon, larger aftermarket.

 

[Bartholomew Roberts]

Very easy to shoot, low cyclic rate, very easy to tap off single shots with one. Roughly half the cyclic rate of a Thompson.

First time I fired an M3A1, we had just been shooting MP5s. I ended up accidentally firing a single shot because I pulled the trigger and then let up before more rounds fired because I was expecting a faster cyclic and thought I had a stoppage.

 

[SharpsDressedMan]

The MAC-10 .45 fires almost twice as fast as the M3A1, but is less controllable. Two totally different guns when you look at performance.

 

[HorseSoldier]

If you got rid of the 86 ban or the NFA restrictions on MG's altogether, the grease gun might make a comeback.

So Alaska is one of those states with a law on the books that states that as long as gun manufacture does not involve interstate commerce*, federal firearms laws based on federal control of interstate commerce do not apply. At least in theory this would mean you could build a Grease Gun or a Sten up here, since NFA, '86 MG registry closure, etc etc etc, don't apply as long as the firearm(s) were not for sale outside the state.

Of course, this more practically means you could be a test case for these sorts of laws and spend the next decade or so possibly incarcerated and certainly tied up in court while your attorneys and the ATF fight it out. (On the plus side, the law also stipulates that the AK state AG's office will provide for your defense, so at least you won't go bankrupt . . .)

(* the AK law states that you can import basic common use sort of items like screws, pins, and such. The real impediment to anyone doing much with this law, as far as I can tell -- besides the above mentioned likelihood of legal apocalypse -- is that no one makes rifles barrels up here, and I think the ATF could make a reasonable case that a rifled 8" 45 ACP barrel is not a "common use" item, etc.)