Receiver rail guide.

[sheepherder]

Originally Posted by 1969goatman

And how are you pronouncing that AM BUT ment???

It's abutment -

Abutment - Definition and More from the Free Merriam-Webster ...
the part of a structure (as an arch or a bridge) that directly receives thrust or pressure

Now, as to the recoil spring...Yes, if it is weak, the breech block will slam into my abutment...and it it does, it will leave an imprint on my abutment...kinda like the one on your abutment...The breech block has thin walls, they weren't designed to be slammed around...The breech block (in a perfect world) should stop just short of that abutment, or just barely kiss it...while still ejecting & feeding...

You are trying to tailor your Luger to your cartridges...I don't use Fiocchi; I handload...and tailor my loads to my pistols...So in your case, yes, I would get a Wolff Springpack and try the weakest spring first...and see if I still get good ejection & feed...If not, move up to the next spring...and try again...etc...

Or you could do it the easy way, and mail your Luger to one of the real experts here to tune for you...(Mail the ammo you will be using too)...

Some here will say you can get an incremental 'tune' by clipping coils off a certain spring...For instance, if the toggle obviously doesn't go all the way back...and it stovepipes or doesn't feed...

I'm surprised none of the really knowledgeable people haven't jumped in here...I'm just a dummie...