Public Service Announcment: check for fire-on-release triggers

[Ned Christiansen]

Another angle to this on the AR side, that I've seen in classes. For a while Colt was making AR's with larger hammer and trigger pins, to foil Bubba's Big Plan to use M16 parts. Far as I know this was only Colt, but I've seen a few guns that somehow over the years, got put back together with small pins. This is several malfunctions waiting to happen, including fire on release, so-- something else to look for.

It should go without saying, but some people don't appreciate the gravity of it-- don't have any select-fire parts in your trigger group. There are probably a great many guns out there, especially home-builts from twenty-plus years ago, that have some parts in there that ought not to be in there, unbeknownst to the owner. Know the dif and check. I'll try to get some pics up in the next few weeks as I will be looking in on some department guns.

[Helldog]

I want to thank you for this thread. I recently installed a cheapo LPK I ordered from AIM, they claim it was Black Nitride with the FCG machined afterward. well anyway after installation and recalling this thread I function checked trigger and low and behold my hammer fired on release. This would only happen when I slow released it not when I let off the trigger fast. So, as it was a cheap kit, $39.00. I decided what harm could it do to try and fix the problem myself. I took a file to the disconnect or and removed a little at a time. Reassemble and function check. Well after a few times of this I must have passed the sweet spot and completely ruined the disconnect or. Long story short I removed the offending group and replaced it with a nice single stage trigger I picked up from a local shop, https://www.dark-storm.com/dsi-trigg...ess-steel.html and saved myself the grief and possible legal entanglements.
Thank you for making me more aware of such an issue.

[Clint]

Great stuff Ned.

One quick question.

How do you determine 60% engagement?

You can't really see the sear surface, so is it just by feel?

[Ned Christiansen]

Helldog, I would not necessarily blame the FCG or the whole FCG. Could be a combo of things.

Clint, the 60% is a touchy-feely thing. You could do the testing with the hammer spring removed, that would make it easier or easier the first time to familiarize and understand the process.

A person could make a dial-indicated measuring rig but I don't think it's necessary. Due to the pull-each-other-into-engagement geometry of the hammer / trigger relationship, anything over half ought to be good; more is better of course.