12 June 2016

Enlightenment

Marv has been buying optics for his ARs.

Because he's cheap, he's on his third round of buying the things.

This time he's buying what I've already researched and own.

But he still hadn't listened about mounts, so yesterday's trip to the range has resulted in him buying new mounts as well.  Hecho en China doesn't have to mean crap, but...

During the zeroing process his 6.8 started to barf.  Failure to extract.  Only with Hornady 110gr V-Max.  The 90gr Federal XM68GD worked fine and got him zeroed.  Later examination shows an old blue insert extractor spring.  Black inserts ordered.

While we were trying to figure out the failure to extract, the trigger stopped resetting.  Slow clap, Marv.

Marv had modified the trigger in this gun.  The first thing he did was to add some polish to the trigger nose and hammer notch.  Then he found a web page showing how to lighten the trigger by cutting one leg of the hammer spring and bending the legs of the trigger spring.  Finally he got a screw-within-a-screw grip screw that pre-loads the trigger to give a crisper break.

Playing with the trigger on a bench I noticed that the hammer could be caught by the disconnector even with the trigger released.  The safety selector also dragged against the trigger.

Because the trigger adjustment screw works by essentially pulling the trigger slightly, we backed the set screw out a half turn at my place after we got done at the range.  Better, but it didn't fix the problem.

So I took the guts out and looked harder.  While there's some evidence of accelerated wear because Marv might have polished through the hardening, it doesn't appear too advanced yet.

The weakened trigger spring, though, is not strong enough to lift the trigger all the way to its rest position.  Marv un-bent the legs and suddenly the reset problem was cured and the safety selector stopped dragging!

We've got to go back out when his extractor springs and new mount arrive.  Fingers crossed!

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