MAC Owners Rejoice: New MPA Hammer fixes Trigger Slap

Trigger slap is a phenomenon present on a number of gun designs, but most commonly encountered on semi-automatic AK-47, AK-74 and MAC-10 clones. In some of these guns the trigger “slaps” against the operators trigger when it resets. It can range from a mild annoyance to bad enough to numb or hurt the operators finger. In the case of MAC-10 clones, it is the result of the BATFE rules requiring them to fire from a closed bolt. This design problem was not as much of a issue with the original open bolt MAC-10 machine pistols.

Masterpiece Arms has developed a hammer/disconnect that completely eliminates trigger slap. It will be installed on all their MAC-style guns starting in January next year. They will also be selling it separately for $39.99. It woks with both MPA’s own guns as well as MAC style guns manufactured by Cobray/Leinad.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Esh325

    You’ll be hard pressed to find many semi auto only AK’s that have trigger slap today.

  • Jeff M

    So it does it work with the full-auto cobray?

    • The MAC machine pistols fire from open bolt. The bolt slams forward with a fixed firing pin to strip a round from the magazine, load it into the chamber, and fire the round.

      No hammer.

  • chs

    They stole my idea!! Hahaha, I’ve been thinking of a floating disconnector for the closed-bolt MAC’s for a while now. Only I was going to put it on the actual disconnector bar inside the receiver instead of the hammer. I’d say that this is actually a more elegant solution to the problem though.

    • macmechanic

      MPA had a floating hammer design in 2006 or 2007. Much simpler, less parts & cheaper to manufacture than this new design.

      Buyers didn’t want it, only a few were made for T&E.

  • Lance

    For a MAC-10 this may help. For Aks a Tapco will do too.

    • Or you could just cut the tab off the rear of the disconnector. Century Arms used a full-auto pattern disconnector for some of their early AK FCGs. The tab at the back of the disconnector serves no purpose in a semi-auto only rifle. When the bolt travels back, cocking the hammer, the hammer hits that tab on the back of the disconnector and it kicks the trigger forward – trigger slap.

      G2 trigger kits don’t have the tab on the back of the disconnector.

      • Wait. I didn’t get that quite right. The hammer hits the disconnector, which rocks back, causing the tab on the back of the disconnector to pivot down, causing the trigger to rotate into your finger.

  • gunslinger

    where’s the gif of what’s happening, and how this fixes it?

  • macmechanic

    There goes bump firing! The new design will change the little guns well known characteristic (bump fires so easily, as if designed to do so) to a boring, unwieldy target pistol. Carbine sales used to account for under 1% of total sales, maybe this is where the improvement is intended.

    Way to go, guys, since late 2008, MPA still doesn’t understand their market or their heritage.

    Also, installation of the hammer alone, in any other manufacturers’ firearm is not recommended unless accompanied by the rest of the fire control, malfunctions may result from different specs & tolerances between Vulcan & Leinad.

    • Cozmo

      It is kind of funny that the feature that makes the gun cool (bump fire) is also what causes the last fun part about shooting it (the trigger slap).. If I had to choose between the two I’ll keep the bump firing. 🙂

      • Cozmo

        LEAST fun part of shooting it rather.

  • Mike Knox

    I thought it was called ‘trigger snap’..

    • Sam Suggs

      interchanglable terms l

  • camosoul

    “The disconnect is a consumable item and will need to be replaced. The
    life of the disconnect depends on the length of barrel of your MPA
    model, caliber and type of ammo. Life expectancy will be in the 600-1200
    rounds range.”

    I think I’d rather put a piece of rubber fuel line on my trigger to absorb the slap, than have a disconnect that falls apart every few hundred rounds…

    Why even make the thing?