Good call on replacing the extractor spring. Also check the extractor for damage & wear.

It's also possible the shoulder of the reloaded ammo has been pushed back too far. Extractor loses control of the ammo and the ammo fits too deep in the chamber for a solid strike from the firing pin. It could also be from the shoulder length being too long.

Your problem could be caused by the extractor not snapping over the rim on chambering. This could be caused by too much extractor pressure.

It could be caused by a weak hammer spring.