MKIII Sear pin

azkmd · Post by **azkmd** » Mon Nov 23, 2009 5:41 pm

First off: New to this forum and I must say the info here is second to none, you guys are great. I've been lurking for a while now.

I have a MKIII that I put a VQ kit in and it took care of my creep, but I wasn't inpressed with pull though the gun functioned fine. When I got home I decided that I was going take the VQ kit out and see what I could do with the factory trigger, I found the sear pin was sheared on the left side just past the spring. I made a new pin out of a broken drill bit that's the same size, 1/8", and now I have a perfect trigger, no creep and a nice light pull.
Any ideas on what I possibly did to break the pin? I assume it was something I did? Called Ruger and they requested the broken pin sent to them, of course replacing it free of charge. Great customer service.

Post by **Bullseye** » Mon Nov 23, 2009 8:59 pm

Welcome to the forum! Was you pin for a 22/45 model or a regular Mark III?

R,
Bullseye

azkmd · Post by **azkmd** » Mon Nov 23, 2009 9:21 pm

Sorry, regular MKIII.

Post by **Bullseye** » Mon Nov 23, 2009 9:41 pm

It may have been defective with a flaw in the casting or improperly heat treated. If you call Ruger they will send you a new one. A drill bit is a good temp fix but the right pin is best overall.

R,
Bullseye

bigfatdave · Post by **bigfatdave** » Mon Nov 23, 2009 11:18 pm

I also had a broken sear pivot pin, also replaced by Ruger (although they didn't want the broken one)

Might have been a bad batch of them at the factory, or I might be reading too much into two isolated failures.
Good thinking with the drill bit, it wouldn't have occurred to me that I actually DO have a set of bar-stock samples in various sizes, located in a cheap set of drill bits.

greener · Post by **greener** » Tue Nov 24, 2009 7:03 am

The drill bit is a great idea for a temp fix.

Curmudgeon · Post by **Curmudgeon** » Tue Nov 24, 2009 7:28 am

Couldn't you get a proper pin at Lowe's or Home Depot? Drill bits are a real bag of heat treatments. While the tip of a drill bit is heat treated for hardness and less toughness, the shank is much tougher and softer.

A file test comparison will make you want to replace the pin soon.

blue68f100 · Post by **blue68f100** » Tue Nov 24, 2009 9:25 am

I do not think this pin comes in the VQ kit, if so Call VQ they will send you a replacement free. If not Call Ruger as previous suggested.

If you have access to a good industrial supply house. The should have pins that are hardened and polished. Where I use to work had a kit with all sizes. These are used to pin some collars to shafts.

If it's a 1/8" pin a SS tig welding rod may do the trick.

azkmd · Post by **azkmd** » Tue Nov 24, 2009 7:10 pm

Thanks for the replies, a new factory pin is on it's way courtesy of Ruger.
I've had good luck using drill bits for TEMP fixes in the past, I keep those smaller bits that break just for such an occasion to get by until the correct factory pin can be obtained.
Ruger requested the broken pin back because the tech I talked to was curious and we have a history, we used to duel it out on the range quite frequently at one time.

Post by **Bullseye** » Wed Nov 25, 2009 6:13 am

As previously mentioned there have been a rash of these breaking recently. The folks at Ruger are privy to how many customers are calling in for this problem and may have thought the number of calls warrants a closer inspection for defects. Or, the guy doesn't trust you because you two have a history!

R,
Bullseye

blue68f100 · Post by **blue68f100** » Wed Nov 25, 2009 9:42 am

Looking at the part will give them an idea as to what is causing the failures. Either it be in the manufacturing process, heat treating or fatigue. Heat treating parts can leave surface stress cracks which can lead to failure. Normally if your getting fatigue failures it indicates a part is being stressed, repeatedly below the yield modulus. Which is very unlikely since this part does not see a lot of stress, all should be in shear. If surface defects are present that aids in causing part failure. In most cases it is due to improper heat treating, a bad lot of material (not in spec) or just a bad design.

At least Ruger are taking care of the problem.