Mossberg 500a not unlocking

[COREY]

I bought a Lakefield Mossberg 500a project gun a while ago. I wanted the action as I had all of the forend assembly (barrel, mag tune and slide assembly) for a Mossberg 590 Shockwave. I had it mounted on a Maverick 88 but wanted the tang safety (I am a lefty).

I just got around today to putt8ng the parts on the 500a action. All seemed to work well until I tried to cycle the action after pulling the trigger. Nada. It will only cycle if I push up on the slide release button. I took it out and compared it to the 88 trigger. The slide release bar will drop down after you pull the 88 trigger, but not the 500a trigger.

Any idea why this may be happening? My local gunsmith is a 45-50 minute fight through traffic so I wanted to see if I can figure it out before I drive over and back twice.

 

[trevj]

Used to be, about every gun part out there came with a standard caution label that read "Some fitting may be required".

Seems to me that by putting together a frankengun (even out of supposedly same models), you are right about 'there', as far as having to do some of that fitting, to get stuff to work correctly.

Sounds to me that the hammer is not disconnecting the lock on the bolt when it falls. You are probably going to have to figure out which parts need to be adjusted, so that it does.

 

[COREY]

Not extremely helpful. The fact that the action has a barrel and stock off of another gun on it should not affect the function of the trigger assembly, especially when I have 2 trigger assemblies side by side. New one works fine out of a Maverick 88, but the Mossberg 500a does not.

Does anyone have any idea what in the trigger group causes the locking bar to drop after the trigger is pulled? If I can figure that out, maybe I can figure out specifically what to fix/replace.

 

[blargon]

Does the 88 trigger work in the 500a?

 

[trevj]

Not extremely helpful. The fact that the action has a barrel and stock off of another gun on it should not affect the function of the trigger assembly, especially when I have 2 trigger assemblies side by side. New one works fine out of a Maverick 88, but the Mossberg 500a does not.

Does anyone have any idea what in the trigger group causes the locking bar to drop after the trigger is pulled? If I can figure that out, maybe I can figure out specifically what to fix/replace.

Well, in that case, sorry to hear that you are way in over your head! LOL!

 

[COREY]

For the ask on if I swapped trigger assemblies, unfortunately no. Over the years, they seem to have e changed tabs on the trigger housing that fit into the corresponding slots in the receiver.

With the trigger assemblies uninstalled, I have cooked the hammers and pulled the triggers on both (with a thumb to stop the hammer hitting the polymer housin). When I do, the locking bar drops down on the 88 but not the 500a. Hence my comment that trevj's comments were unhelpful as it shows that the fit of the rest of the gun should not impact this issue.

Does anyone have any input on what may need adjustments or replacement to get this fixed? I have had 590 triggers apart before to swap springs so I can do the work myself, I am just not sure what may need to be done.

 

[trevj]

For the ask on if I swapped trigger assemblies, unfortunately no. Over the years, they seem to have e changed tabs on the trigger housing that fit into the corresponding slots in the receiver.

With the trigger assemblies uninstalled, I have cooked the hammers and pulled the triggers on both (with a thumb to stop the hammer hitting the polymer housin). When I do, the locking bar drops down on the 88 but not the 500a. Hence my comment that trevj's comments were unhelpful as it shows that the fit of the rest of the gun should not impact this issue.

Does anyone have any input on what may need adjustments or replacement to get this fixed? I have had 590 triggers apart before to swap springs so I can do the work myself, I am just not sure what may need to be done.

Go back and re-read those "unhelpful" comments, esp. the last line.

YOU have the parts in front of you. Thus, YOU have the best chances of being able to look at the function of the parts in front of you, and figuring out what is not working correctly. Everyone else is just guessing (well, except that they are not...).

Find a parts diagram for the 500, and compare to see if you are missing something. You wouldn't be the first guy to not notice a part falling off... Play with the trigger group to see if you can find out what needs to be poked or prodded to unlock the bolt.