I installed an E2 grip on my new M11A1 along with the replacement hammer strut and seat that came with the grip, using the original spring. The double action felt significantly reduced and I experienced light hammer strikes and misfires about half of the time. I have replaced the new strut & seat with the original ones. I hope to do a range test tomorrow. Anyone else have a similar problem?

Welcome aboard. I think you have to replace the mainspring when you make the switch to E2.

I concur with Yooper. The kit contains the hammer strut and seat; however a new main spring is required to accommodate the new hammer strut. Cost about $7.00

https://www.topgunsupply.com/s...da-sa-new-style.html

Your M11 should already come equipped with a plastic mainspring housing. With that said, the mainspring in the gun can be used in conjunction with the E2 grips and parts. When installing the grips please ensure the trigger bar spring is in the correct spots, it can tend to come off or be damaged during installation.

I was unhappy that there were no instructions with the kit, especially if a new spring would be required. All of the YouTube videos showed the original spring being re-used. Sig’s Customer Service Rep. was not much help but did offer to have me return the pistol for evaluation. He did not mention the need for a new spring and was unsure if using the original strut & seat would be a problem with the new E2. I will shoot it tomorrow.

Let me try to assist:
Remove the grip panels, remove the mainspring house, spring and strut.
Utilize the mainspring seat and strut that came with your E2 grips.
When putting in the strut, apply pressure to the most rearward spot on the hammer. I tend to wiggle the hammer with my left thumb to see if the strut moves up and down. If it moves when you manually press the hammer you are good to go. Keep applying pressure to the strut, slide on the original mainspring and then pop on the plastic mainspring housing.

When applying the E2 grips, separate enough to pass over the screw bushings on the frame but be careful not to disengage or damage the trigger bar spring on the right side.
Sometimes the grips take a solid squeeze to get them firmly in place.

If the strut is in the wrong spot on the hammer or the trigger bar spring is installed incorrectly you wont have much success.

Hope this helps a little. Best of luck!

Puzzling: Re-installed original grips, strut, spring & seat. No problem, Installed E2 with original strut/seat/spring with no problems. Installed original grips with new strut/seat & old spring with no problem. Installed E2 with new strut/seat & old spring with no problem. The original E2 installation had many light primer strikes and misfires but the pistol works flawlessly now. Go figure.