I played with this in the past, but just wasn’t completely satisfied. I’m still using the same FP striker I machined from S7 Tool Steel. I just just Cold Blued it. The first time around I experimented with a few ISMI Flat Wire, recoil springs designed for a Glock pistol. They worked, but weren’t sized as well as they could be. I tried them full length, and cut. Ultimately I went back to my clipped & modified stock spring and continued searching. I finally came across an ISMI spring I thought would work better. It’s sized correctly for a 1/4” bore item & turned out everything else was optimum as well. It’s a 22lb. spring made from Chrome-Silicon & still a Flat Wire. Chrome-Silicon outperforms standard music wire for compression springs as one of its characteristics is delivering more energy for the same dimensions. In addition, it does not collapse set at the same rate as standard spring wire & lasts much longer. In rudimentary terms: it just has more Springy-ness!

Here it’s at full length. 30 coils.


It has plenty of space per the OD.



Installed on my S7 firing pin. The proper ID for 1/4” pin, so the coils don’t “snake” badly causing binding on the inside of the Bolt sleeve.


The firing pin set at optimum protrusion. It’s actually at .033”. Now, I’m simply showing something I’ve done. I’m not telling anyone to go get a new spring. In fact, there is no reason unless & until all the other mods are done first. This venture is so I have 100% reliable primer ignition while reducing bolt lift. So I already have everything else making this possible. A longer bolt handle & knob, Lift Kit, all rough surfaces removed/polished for firing pin travel. And I’ve increased Firing Pin travel or “Fall” to the maximum without it hurting bolt lift. There is almost nothing, in terms of space, between the Cocking Pin & front edge of the Bolt Sleeve when in “fired” position. The pin is not hitting the edge, which could be bad, but is maybe a couple Thous away from the surface. Adjusting the Cocking Piece so there is .080” between the CockingPin & the edge would lower bolt lift even more. However, I don’t want to lose the FP travel and am quite happy with the bolt lift like this.