So I actually had this exact same thing happen to me before, I spent 2 weeks going crazy over it lol.. Prior to the light strikes starting on the second to last stage of the match, I had always used the exact same Norma 124g ammo and never had so much as a single light strike in practice even with around 15,000 rounds since getting a shadow 2 and going with a 10# CZC main spring. I figured surely the spring was just needing swapped as it had around 15k through it and popped in another 10# spring but the problems did not go away I was light striking in SA sometimes even.. So I went up to 11.5# cgw spring, still light strikes practicing. At this point I was like there is just no way this is the spring, but at the same time I was thinking there is no way it’s the ammo as the ammo has always ran absolutely flawless I’m not even exaggerating that I hadn’t had a single light strike or even a single malfunction for that matter in the first 15k rounds I put on my shadow 2.. Owner of my club is a top 10 open nationals finisher for over a decade now and is almost always right, he was saying it has to be the ammo it’s possible they had a bad batch. So I do some researching and find that there are multiple other people complaining about Norma 124g suddenly light striking for them when it never has before. Turns out there were some lot#s that Norma issued recalls on, but the 1000 round case I had was not on that list. Figuring it’s totally possible there are effected lots that they don’t even know about, I bought a different ammo for the first time in like a year and it ran flawlessly through 2 straight mags of me putting the hammer down between every shot so they were all DA pulls as this is when your hammer will be hitting the lightest. I gave it a month for the bad batch that was manufactured to be resolved/all sold and the next case of Norma I bought was back to running good as gold.
So yea, moral of the story here is that I drove myself crazy writing off that it was the ammo because I knew the ammo to be great and reliable in my gun, but bad batches/boxes totally happen and I am willing to bet it was a short stretch of rounds that something was off on. If you are running a 10# spring like me, you have to be extremelyyy careful with factory ammo that it will reliably run, here are a few I have found to run reliably you can test with: Norma 124g(the best), federal 124g, PMC 124g, and of course blazer brass but I would try using another kind just in case there’s a few bad batches currently.. Never ever ever get fiocci it is pure garbage and gets stuck going in battery and when it does go into battery you’re likely to have a light strike lol I will never waste my money on that crap again.. Good luck!