At various times I've read threads regarding the use of reduced charge ammo for use in a semi-automatic, open bolt Mac 10/9mm. The discussion(s) seemed to indicate that a reduced charge would cycle the bolt enough to eject the casing and then strip off and chamber another round but not enough to allow the bolt to catch and stay open as this semi-auto would do. Apparently it keeps this abbreviated cycle going automatically until it runs out of ammo or encounters a fully charged round. It certainly sound possible. The posts I've read mention loading a fully charged round every third or fourth, kinda a burst mode I suppose. Safer too. I do live in one of the few states that don't allow for full auto and this is probably the closest I'm ever going to get. So, my options don't include "buy an auto" or "move".

Now the questions:

I don't intend on modifying the pistol at all. I don't see any state or federal legal problem with adjusting the ammo. Do you? Any thoughts?

I buy commercial ammo and don't reload. There's a local who reloads and I imagine if I asked he would produce rounds. The problem is I wouldn't know where to ask him to start. 5% less, 10% less? What would ask to do?

Any concerns with safety or technical troubles? Any heads-up?

Thanks,

DoubleSun

As far as BATFE is concerned, if it fires more than 1 round with 1 pull of the trigger, it's a MG.  If this burst was accidental, or an equiptment defect, you get some grace, but when you purposely try to do it, it's intent.

Run-away with an open bolt.... be prepared to hang on and control it, as if you not know what to do, somebody get hurt or killed... especially since it is a pistol.

Bad enough when it happen with full power ammo, I have handled a few run-away with properly registered machine gun,  not a good feeling.  

My M11 recently radiused the sear notch on the front of the bolt, and was skipping over the sear when trigger released, fires 3-7 more rounds after trigger release....... went home, and packaged bolt for repairs.



IBTL  

Considering the info you guys provided I think I'll back off and leave it be. I don't relish the idea of federal legal trouble nor is getting hurt high on my list of things to do.

There's a place in Vegas that rents full auto's. Gotta hit a trade show next year there, think I'll give that a whirl instead.

Thanks for the input,

DoubleSun

I get run aways shooting Wolf or Win White Box 9mm in subguns like Swedish Ks and Madsen M50s.  There's no need to reload if you want to 'tweak' your MAC.  Just clip some coils off the spring and use weak ammo intermixed with hotter stuff like +P.  If the ATF really wants your ass, they'll just clip some coils off your gun and use weak ammo to make their case so I won't worry too much about this one pull of the trigger business.  If they want you, they'll make their case regardless of what you own.