slam fires or no ignition

[blckwlfny]

PROBLEM: Im trying to tune my '42 and it either does a runaway (slam fire) or the primers do not ignite at all
when it does "run-away" it cycles fine. it just wont stop until it there no more rounds to feed (anticipating such a problem, I left an empty spot in the belt every 4 rounds.)

EQUIPMENT: i have one of gordie k's original design bolts with a 2-piece firing pin. It is clean, oiled, de-burred and hand polished as much as i dare without changing the dimensions

DATA:
1) i started with the stock spring on the striker (the pin in the body of the bolt) and added a small spring up on the pin itself. RESULT: runaway fire
2) kept f/p spring and put in a striker spring with 2 extra coils: runaway
3) kept f/p spring and put in striker spring with 6 extra coils (bolt is now held taught by spring pressure): runaway
4) increase f/p spring by 10 coils kept striker spring above: no ignition
5) kept that f/p spring put in stock striker spring: runaway
6) kept that f/p spring put in striker with 2 extra coils: runaway

QUESTION: Am i missing soething here?

THANKS

[drooling idiot]

can you post a pic of the design
seems like you've got a lot of unneeded springs.

[42rocker]

What ammo are you using?

Later 42rocker

[blckwlfny]

(Still working on pic)
Ammo: german surplus blanks which are a green plastic.

[42rocker]

I believe that if you are firing blanks then you are in a whole new world. That said there are a couple of folks on this website which really know their Sh------ stuff (that's the world) on firing blanks. In their MG42's...

Good Luck, some say that it's better to get it running in regular ammo before you switch to blanks.

Later 42rocker

[blckwlfny]

It was running fine live. ...And ran fine with different blanks which became unavailable

[JBaum]

It should work with the German blank firing kit installed. You do have it, right?

[drooling idiot]

so the new blanks don't have the power to reset the hammer? Its following the bolt into battery?
Tighter/smaller booster cone or weaker recoil spring sounds reasonable.

[blckwlfny]

It seems that the problem was that when the feed ramp exerts pressure on the top of the bolt, it flexes the bolt assembly just enough out of true so as to cause the firing pin to bind in the wedge/stryker sleeve. im busy polishing the burrs out

i know that the disconector is holding so its not a problem now, but, if the hammer follows the bolt, can that result in an out of battery detonation?