Even within DPMS generation 1 bolts, there are two different firing pin tip diameters. There's a standard version, and there's a smaller diameter version often labelled as "high pressure."
I have a bolt carrier assembly which has identical carrier exterior contours, firing pin shape, and solid long firing pin retaining pin as your picture. I got it from Brownells in their packaging, but I don't know who originally manufactured it. Mine has the smaller diameter firing pin tip, and I did just measure it as 0.006" shorter OAL than a DPMS brand reference. But mine hasn't had any light strike issues and has been used in two different barrels.
I don't know if the high pressure bolts have a different protrusion spec.
I did have a problem with the gas key bore being too small, preventing it from closing easily over the gas tube. I returned that original bolt, and the replacement hasn't had any problems. I would check gas tube fitment on your bolt. Possibly the light strikes are from the bolt not going fully into battery.
I would also check headspace in case it's grossly excessive and the round is sitting too far forward of the firing pin. Although that seems very unlikely.
Mine also came with and extremely stout extractor spring setup -- two nested springs and two O rings. Possibly the very stiff extractor is providing resistance to snapping over the round, stopping the bolt from going fully into battery if the charging handle is ridden forward gently. Again, unlikely as an explanation.