Brand new Shield 9 cartridge jamming on striker

The striker return spring should be pushing the striker to the rear as soon as the striker hits the primer. That striker should not be sticking through at all except for the tiny fraction of a second when it is released from the sear and slams forward into the primer. Then the striker return spring pushed it to the rear and you don't see it sticking through.

Just unloaded mine and field stripped it.

The striker cannot move forward unless the striker block is pushed into position to allow the striker to move forward.
Once the striker block is moved out of the way the striker can be pushed forward but immediately returns to the rear once I take my thumb off the back of it. It'll come back so fast/hard you can hear it click as it hits fully to the rear.

If I let up on the striker block while holding the striker forward the striker will sometimes barely catch on the striker block. Meaning the striker stay forward sometimes, not every time and if I barely touch the tip of the striker sticking through the breechface it pops to the rear anyway, overcoming that little bit of friction/drag created by contacting the striker block. The striker return spring is trying to push it to the rear but sometimes doesn't overcome that friction/contact with the striker block without a small touch on the tip of the striker.

That striker block should be staying in position till the striker return spring has moved the striker to the rear. Meaning the trigger bar should be holding the striker block upwards/in place long enough for the striker return spring to move the striker backwards before the slide moves to the rear and the striker block moves downwards again when it comes off the trigger bar.

Does your pistol have a striker return spring in it? If you pull the slide off, remove the recoils spring/guide and barrel, turn the slide upside down, push down on the striker block with a finger tip and the push forward on the striker till you see it protrude through the breechface will the striker pop back to the rear/out of side when you stop pushing the striker forward?

I've got 5 full sized M&Ps and a Shield and all of them do what I just described. They all work the same.

Take a look at yours and see if the striker pops to the rear when you let go up it while holding the striker block down.

Thank you for the replies, particularly the very detailed explanation. That is how I thought it should function. Much like most other striker fired handguns. I have swapped out striker blocks, striker block return springs, verified the plastic dick under the rear sight, swapped striker assemblies. All with the same results of a protruding striker until it resets by contacting the sear and the end of its cycle. I also had a local and very reputable gunsmith take a quick look at it and he basically said it needs to go to Smith & Wesson probably for a replacement slide. I bought a model that was cerokoted by the distributor so returning it also concerned me because S&W wouldn't be able to replace the slide with one of the same color.

I made it to the gun shop where I purchased it yesterday and verified issues by looking at other Shields in stock. After a couple hours of waiting for the owner and the shop disassembling the Shield and verifying everything I said, I convinced them to swap out the malfunctioning slide with another cerokoted one they had in stock. It now works perfectly. Apparently the slide has some sort of manufacturing defect which was not easy to locate or repair and they are going to return it as defective to their distributor and let them deal with it. I give credit to the gun shop, great customer service. They would have been well within their right to tell me I need to send it in to S&W but they helped me out.

Thank you for your help.
Joel

The problem was not the assembly of the striker assembly. Both the original and the spare I purchased were assembled correctly. It could however be the striker spring guide that was missing. I did not see it in the slide that I originally had. Looking in the replacement slide, I do see the striker spring guide in there so I am guessing that's what the problem was.

The shop I used was local to Thousand Oaks, Ca. They have been hit or miss with me in the past. This was a huge win but there have also been some substantial losses. I'll share the info if someone is in the local area and wants to visit them but they don't do mail order and charge more than any other shop around for a PPT so I'll leave it at that.

Thank you all for the help. The missing striker spring guide seems to be the culprit. Something that could have easily been left out when the distributor cerokoted it so I don't feel real bad for the slide to be going back to them.

Joel