[Hectic]

Seemes to be an assembly issue. Could be the cylender head, could be the tightness of the screws (the ones holding the receiver and barrel to the stock) I personally have not had any issues with Deepfire sears however I have had the same issue as you it was caused by tightening the rear screw too tightly and first causing the reciever to be angled in the stock.
What is the base gun a TM or a clone? If it's a clone it could be many fitment issues with the sears that would just take testing filing polishing etc..