XDM light firing pin strikes

[blaster]

like the tittle says, I occasionally get a light firing pin strike with my new XDM. when I re-chamber the round, it always goes off. no problems shooting the same ammo out of my Witness. I thought that I might have gotten oil or dirt in the striker channel but even after totally cleaning & de oiling the striker mechanism, it still happens. I know very little about striker fired guns. (my first one) would a heavier striker spring help? do they make a heavier striker spring? and will a heavier spring affect the trigger pull? thanks in advance for the replies.

[sqlbullet]

Ammo specific?  I know eastern block ammo is known for hard primers.

As far as trigger pull, yes, but in the XD/XDm guns it will be negligible since the striker is fully compressed by the slide. 

[Azrckcrawler]

I use S&B primers, Xdm runs them fine. I get light strikes with the same S&B primers in a tuned S&W 625 revolver.

[blaster]

the ammo is all my reloads using the same lot of lg. Winchester primers that I have been using for a while with no problems.
good to know a stronger spring won't affect the trigger. I forgot about it being compressed.