Hammer Pivot Pin

[Skip D]

Got my wife a M&P 15 22. Finally got out to shoot it. Shoots great. After about 20 rounds it misfired. Racked the charging handle, misfired again. Time to open it up. What I found was the Hammer Pivot Pin had backed out all the way on one side. Pushed it back in works great.
It is obvious that this pin is to short. About 1/8 inch. Does anyone know a source for a longer pin?

 

[Cdog]

If it's milspec length you should be able to pick one up at just about any shop that sells AR accessories.

Again if they follow milspec on the lower parts you can get aftermarket kits that allow the use of external clips.

Hammer Pins | AR-15 | Gun Parts by Gun Make & Model

If you find that you can use a milspec and can't locate one, holler.

I'm sure I have one to spare.

 

[MichiganScott]

There is supposed to be a groove in the center of that pin and a J-spring in the hammer to hold it in place. One of the two is missing.

 

[KarmannGhia]

DPMS Anti-Walk Hammer & Trigger Pins AR-15 Small Pin .154 Matte

I have these pins on a couple of Frankenstein ARs. They do work, just not the best looking (they only cost $5 for the pair).

 

[oneyeopn]

He is talking about a 15-22 so I am not sure!

 

[Skip D]

Sorry guys, I meant to post on MP 15 22

 

[JaPes]

There is supposed to be a groove in the center of that pin and a J-spring in the hammer to hold it in place. One of the two is missing.

Scott is 100% correct. The 15-22 uses a standard AR trigger group. IMO, most likely the "J" spring is broken. Pull the hammer. Look into the pivot hole on the hammer. You should see a spring in there. It's not a coil spring.

I had one break on me, and the firing pin walked constantly.

Shake out your lower receiver to make sure the broken piece of J-spring isn't still rattling around in there.