Mossberg 42M (c) 22 issue - The Firearms Forum

Vedeyn · 10-10-2012, 07:18 PM

Hello everyone. My old Mossberg 42M (c) 22 SLLR has recently started firing without me pulling the trigger. When i close the bolt, loading a bullet into the chamber, about 90% of the time the gun just fires on its own. Any ideas what could be wrong with it? Any help would be greatly appreciated. Sorry if my question was not clear enough, I will do my best to clarify if needed.

GunHugger · 10-11-2012, 07:25 AM

It sounds like one or two things need to be done.

First, make sure the bolt is clean and not gummed up with old dried oil and gun powder. Disassemble and clean the bolt.

The other thing to look at when you have the bolt apart is the firing pin. It's not really a "pin", it's made of flat stock. The lower back part of the firing pin is also a sear that is held back by the trigger until the trigger is pulled. I find a lot of these that have been filed down by a previous owner hoping to improve the trigger pull.

Have a look at this page and compare your firing pin to the #R117 to tell if it is worn out or had been filed down by someone.
http://www.wisnersinc.com/additional...22CalFP_1.html

This pic shows the relationship between the trigger sear and the firing pin sear. NOTE: this is not a 42M, just used to as an example.

A new firing pin can be found at Havlin Sales in MO, the best place to find old Mossberg parts. Or Wiseners might have one if Havlin doesn't.

http://www.havlinsales.com/22rifle.htm

Models 42B, 42C, 42M, 42M(a), 42M(b), 42MB, 42M(c), 42M(c), 42TR
Firing pin $18

This might help.

Also make sure that someone didn't over adjust the trigger adjustment screw (Part # R158) in the pic above. (see instruction sheet below)

Redhand · 10-11-2012, 07:25 AM

Sounds to me like an extremely dirty bolt that is gummed up with residue and not allowing the firing pin to function properly. And if you clean it regularly then its probably a broken or worn out trigger sear.

Vedeyn · 10-12-2012, 09:29 PM

I will try giving it a good cleaning and see what that does for it. thank you for your responses!

10-10-2012, 07:18 PM	#1
Vedeyn Member Join Date: Oct 2012 Posts: 2	Mossberg 42M (c) 22 issue Hello everyone. My old Mossberg 42M (c) 22 SLLR has recently started firing without me pulling the trigger. When i close the bolt, loading a bullet into the chamber, about 90% of the time the gun just fires on its own. Any ideas what could be wrong with it? Any help would be greatly appreciated. Sorry if my question was not clear enough, I will do my best to clarify if needed. -->

10-11-2012, 07:25 AM	#2
GunHugger Advanced Senior Member Join Date: Jul 2007 Location: SW PA Posts: 1,161	Re: Mossberg 42M (c) 22 issue It sounds like one or two things need to be done. First, make sure the bolt is clean and not gummed up with old dried oil and gun powder. Disassemble and clean the bolt. The other thing to look at when you have the bolt apart is the firing pin. It's not really a "pin", it's made of flat stock. The lower back part of the firing pin is also a sear that is held back by the trigger until the trigger is pulled. I find a lot of these that have been filed down by a previous owner hoping to improve the trigger pull. Have a look at this page and compare your firing pin to the #R117 to tell if it is worn out or had been filed down by someone. http://www.wisnersinc.com/additional...22CalFP_1.html This pic shows the relationship between the trigger sear and the firing pin sear. NOTE: this is not a 42M, just used to as an example. A new firing pin can be found at Havlin Sales in MO, the best place to find old Mossberg parts. Or Wiseners might have one if Havlin doesn't. http://www.havlinsales.com/22rifle.htm Models 42B, 42C, 42M, 42M(a), 42M(b), 42MB, 42M(c), 42M(c), 42TR Firing pin $18 This might help. Also make sure that someone didn't over adjust the trigger adjustment screw (Part # R158) in the pic above. (see instruction sheet below) __________________ . “There will be a revolution in this country!” “I don’t believe people should to be able to own guns.” ~Barack Obama "Stand your ground. Don't fire unless fired upon, but if they mean to have a war let it begin here." ~Captain John Parker, to his Minute Men on Lexington Green, April 19, 1775. Last edited by GunHugger; 10-11-2012 at 07:32 AM..

10-11-2012, 07:25 AM	#3
Redhand Senior Member Join Date: Apr 2009 Posts: 610	Re: Mossberg 42M (c) 22 issue Sounds to me like an extremely dirty bolt that is gummed up with residue and not allowing the firing pin to function properly. And if you clean it regularly then its probably a broken or worn out trigger sear. __________________ LAMH DERG EIRIN ABU

10-12-2012, 09:29 PM	#4
Vedeyn Member Join Date: Oct 2012 Posts: 2	Re: Mossberg 42M (c) 22 issue I will try giving it a good cleaning and see what that does for it. thank you for your responses!