Micromag won’t fire

[nak81783]

Can you post pics of your sear pin and where it goes in the body?

Does anyone have a pic of a factory Micromag sear pin?

Just trying to get a good image of it all. If the sear is out of position, I can see it doing the things you’re describing.


Can you blue up the top, back end of the sear to see where the on/off pin is hitting on the sear, and the valve assembly around the on/off to see if/where the rear sear nub is hitting the valve assembly?

[oats944]

Hey fellas, I got it working, but I didn’t do anything new to it that I didn’t do at the beginning so no real a-ha moment.

Dropped the .742 on/off pin from my classic rt back in the Micro valve. Lengthened the sear rod so it’s just barely not touching the trigger. Level 7 bolt. As described before it would leak down the breach, it would shoot when pulling the trigger, and with the trigger held the leak would stop. I could repeat this over and over until the tank was empty.

With the trigger held and no leak I started leaning towards the power tube as the culprit. I pulled a level 10 bolt from one of my classic automags and put that on in place of the level 7 just to see what happened and it works perfect. Shoots, RT’s, no leaks, and is shooting 280 fps. I had the same level 10 in it previously and it wouldn’t shoot even with the reg turned all the way up.

I can take some pictures and measurements if it helps anyone tomorrow, gotta go watch my Phillies get eliminated from the playoffs now lol.

[StaticShocked]

nak81783
I don't know if it's factory, but mine is a pin that is 0.188" diameter, 0.625" long, with a 0.020" x 45 degree chamfer on each end. I would think just a dowel pin might work as an acceptable replacement.

Dowel Pin Alloy Steel, 3/16" Diameter, 5/8" Long
https://www.mcmaster.com/product/98381A507

Photos below for you.

oats944, glad its working! I will keep messing with mine in the hopes i get it working as well.

[oats944]

Forgot to mention one thing I did do for the first time tonight based on Meglomachinist’s advice was take the bottom on/off oring out, oil it, and put back together.

[Meglomachinist]

Yeah I've had that same thing happen to me before a few times just pull the whole on off out with the bottom ring reassemble and pop it back together then it works. Maybe that was it...can't explain why it would make any difference but for some reason it just does.

[nak81783]

I'm going to link this here, as it's relevant to Micromag pin length that's been discussed in this thread. Tuna knows his stuff when it comes to Automags.

https://www.mcarterbrown.com/forum/p...566#post746566