My gun had the same symptoms with the only thing different from stock being the omw spring. I added a few thin layers of tape to the top of the blaster where the catch spring hit, since it was stock and I thought that may be the issue. Sure enough it now acts like stock but with the added boost of the omw spring. Since you already have a better catch spring I don't know if this will help you at all but as I found this thread having the same symptoms this may help someone else.