IZH-46M Stuck Sear Repair

Gwhite · Post by **Gwhite** » Wed Nov 27, 2013 4:30 pm

I help coach the MIT collegiate team, and do a lot of their pistol maintenance & repair. We have about fifteen IZH-46M air pistols, and they are old enough that we have quite a battle keeping most of them working well. I've been trying to document some of the more common failures. Some of them are just normal wear & tear, but we also have a lot of variations in how careful the students are in using them, which can create additional issues.

I've attached a PDF of my latest discovery in the hopes that it might save someone else a lot of head scratching. The inner workings of the IZH's are a bit complex, and I'm still developing some detailed drawings of all of the timing and relative motion of the pieces, especially during the cocking process.

Spencer · Post by **Spencer** » Wed Nov 27, 2013 7:00 pm

Congrats - a nice job - looking forward to further chapters.

slofyr · Post by **slofyr** » Wed Nov 27, 2013 7:25 pm

The spring that lifts and positions the sear [15] may have become weak. Replacement, or a little tweak might help.

Gwhite · Post by **Gwhite** » Wed Nov 27, 2013 7:50 pm

It's not the spring. These things are jammed solid. It think it's only an issue with some pistols. I just fixed a leak on another one, and I pushed as hard as I dared, and it wouldn't lock up. The ones that jam work fine if you cock them normally with the pump lever. They can also be dry fired just fine as long as you only pull the breech lever back until it meets some resistance.

There are always a few students who seem to think that if cocking things is good, cocking them harder must somehow be better...

heli_av8tor · Post by **heli_av8tor** » Wed Dec 04, 2013 8:27 pm

My IHZ had 60 pellets fired and likely as many dry fires when it failed in this manner. It happened with normal cocking between pellets and not dry firing. It could have poorly fitted parts, but not from wear.

I got it unjammed by using the procedure described but it occurred again after three pellets.

At this point, being a new gun, I boxed it up for warranty service.

Without more dis-assembly I couldn't figure out what actually rotates the Trigger Sear (#15) CCW in the cocking process or why it would over-rotate. Maybe someone could explain the cocking process in detail.

From the drawings it appears that if the tip at the top of the Trigger Sear (#15) was taller it could not get under the Valve Sear (#14).

I suppose I could be extending the cocking arm with too much vigor (?) but I don't think so.

Gwhite · Post by **Gwhite** » Thu Dec 05, 2013 5:08 pm

The exact sequence of things in the cocking process is something I'm still a little fuzzy on. I think the top of the trigger sear gets rotated by the back of the notch in the breech lever. It's possible there is a burr there, or a piece of debris stuck in the wrong spot that is moving the sear to early or too far forward.

heli_av8tor · Post by **heli_av8tor** » Sat Dec 07, 2013 10:03 pm

I got my Izzy back from warranty service today. (Sent Monday, received Saturday.) Faster than I expected and in time for tomorrows match.

I shot 120 pellets or so without a failure today.

The gunsmith who did the work wrote the following note:

Refit cocking lever to prevent #15 from getting stuck. Lube, test fire. All ok.

Thanks Gwhite for the pdf's and the work you put into them. I too look forward to more.

TargetTalk

IZH-46M Stuck Sear Repair

IZH-46M Stuck Sear Repair

New Izzy Failed this way