JM 940 Pro shotgun issues.

[JoeInTucson]

Hello,

So after a year with my JM pro I have noticed a few things.

It does not seem to like heat. It was 106 in Mesa today and that shotgun's receiver was at least that hot by the end of the day.

I was shooting at a Tactical shotgun match.

Which leads me to my first point. 

It seems that as this gun warms up it jams more often.

One of two things will happen.

The shell will not go all the way into the chamber, which you can cure by pushing forward on the bolt handle

Or

It will not let the next shell out of the magazine. The cure for this is to thumb in a new shell on top of the one that would not come out and it starts running again.

I have been running high temperature Lithium grease in it. Last night I thought that it might be a little thick so I switched to Rem Oil.

The first 2 stages everything ran fine.

The third stage saw the bolt handle snap in half.

The location of the snap didn't condemn the gun it just made it aggravating to manipulate.

The 4th stage was when everything that could jam the gun did. 

So when I got home I ordered a new handle from GG&G, and I like Arizona businesses.

I have been running new and reloads that are basically "trap and skeet" ammo.

I think I am going to experiment with roll crimps. That is what Federal does on their "action" 12 gauge ammo.

What else could I do to make a basically good shotgun great?

Thank You

 

 

 

[jrloman]

I have an old 930 that I ran for 5-6 years in 3-gun, I started to have some out of battery issues with it after a couple years.  The issue was a roll pin that is part of the lifter assembly had worked its way out and was rubbing on the trigger group housing.  The lifter was dragging on the bolt keeping it out of battery, hammered the pin back in and dimpled the pawl around the pin to keep it from coming out the direction towards the trigger group solved that issue.

 

Best picture I could find to show the pin that caused my issues, pin circled in red.

 

Depending on how much use the gun has, it might need a new magazine tube spring for the shell not feeding or the shell catch has a bur.