It's too much space in between the guide rod and cover lock. If you push it down and works better, all you have to do is shim the space underneath to prevent the guide rod tip up and cause the fiction.
Let me see if I'll have time to draw you the diagram tonight.

Yeah it's exacly what happen!!! I'm not sure where I have to shim, but happy to finally find the solution.

terrible drawing but at lease you know what this is.

http://i1285.photobucket.com/albums/...ps4aed2a7a.jpg

I used teflon tape to get a snug fit in that spot and there is a subtle increase in RPM

I use frog lube and I SWEAR BY IT!!! no joke its like magic and you can use it as a sandwich spread too!

Yeah I understand.
I tried teflon tape but doesn't work. The "stick" have to be 3-4 mm lower than it is now. So i really want a shim, but I don't find anything that work... I'll continu searching.

I fixed this issue by shimming from the inside of the top cover. just attached some ikea floor protecting pads (the kind that goes on the bottoms of table legs) and it makes a great spacer. spring guide holds it all together.

Thanks a lot of all of you guys!!!

The gun is perfecly working now with your help. (I places the shim inside the top cover as you refer manchovie).

jai un la meme replique moi aussi le bolt jam meme c jai tres bien lubrifier et tout ya rien a faire si quelqu'un peut maider sa serais aprecier

As you can read, all answer is in this post!!!