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Broken hammer spring, or "Maybe it worked better on paper"

Posted: Mon Oct 01, 2018 10:42 pm
by WOLF257
I built a CETME from a parts kit a couple of years ago and it worked just like the book said it was supposed to... till the hammer spring broke.

Amazing how quick a rifle converted to fire semi-auto going burst fire will get your attention...

I made several interesting discoveries about the CETME, that hammer spring does a whole lot more than just make the rifle go BANG!

For those unfamiliar with the CETME, the hammer spring is also the sear and trigger spring so when one leg breaks off the spring the rifle starts doing wierd things.

The other discovery was that absolutely NOBODY makes a replacement spring and I was unable to find anything that could be effectively used as a replacement, AR-15 spring is too small and an AK spring won't fit into the trigger box.

I'm a machinist by trade so one of the guys at work said "Why don't you just make a spring?" so I did, and that turned into a real adventure.

I have a small hobby lathe and milling machine so I built a spring winding jig, it took quite a few tries before I found the right mandrel size and then I made 10 or 12 springs that either wouldn't work or failed before I got one that did work.

So here's the question, anybody got any idea how many rounds I need to fire before I can figure that spring will stay together?

I took the rifle to the range this past weekend and fired 50 rounds without a malfunction but it was only 50 rounds, which was all I had, but it seems to me that 50 isn't really enough to call it a success yet.

I know I can replace the trigger group with a an HK unit but I don't have the money right now and .25 cents for a piece of wire is a lot more economical.

For those that have read this far, thanks for letting me rant.

Jim