I had a problem with a Porter Cable brad nailer, in that the nailing rod/pin would not retract. I have Porter Cable 16 ga. straight finish nailer ... i have the porter cable bn125a and love it. My Cable Nailer FN250 does not fire. Amazon.com. _____ Nails by: Bill 52 Posts . They sell a kit but its is like 30 bucks. i believe i accidentally locked the trigger and can't figure out how to unlock it. – SteveSh Jul 19 at 23:51 If you found that your nail gun wasn't shooting nails, the most likely reason is that the instrument gets jam. Regulator pressure at 80 and tank pressure at 120. A jamming nail gun is a rampant problem, and most owners of framing nailer or nail guns often face this scenario. The Bostitch site says it is the trigger o rings. If you try to fire a pneumatic nail gun or stapler, but only hear air leaking when engaging the trigger, it's likely that your tool's "O-Ring" is not sealing properly.When the trigger is not depressed, you may not hear air leaking, as the valve is probably sealed. They also said that according to my serial number, it has the new design. I have Cable 16 ga. straight finish nailer....it won't fire. There is no jam in nailer. thank you. They say that those parts - Answered by a verified Technician advice would be appreciated. Pull and turn something to change it from single fire to bump fire. problem with pneumatic nail gun - won't fire... Jump to Latest Follow 1 - 7 of 7 Posts. Hey guys, My framing nail gun is about 12 years old. Therefore, the jam occurred when you press the framing nailer trigger, and it refuses to fire. It will fire one time and then if I push the plunger back up into the gun it will fire again but the piston does not retract on its own. When operating, gauges correct…when I pull trigger, it sounds normal with air coming thru hose and gun, but nail not coming thru. Someone suggested one or both of the sealing rings on the air piston need to be replaced, but I haven't done that yet. The gun's die-cast aluminum body is lightweight but strong, and the handle is comfortable to hold, even over long periods of time. Re: Porter Cable DA250B Nailer won't bump fire I called Porter Cable, and they said that new nailers are being shiipped with some sort of combi-trigger. Took it apart, didn't see anything obvious, but the problem is still there. My local dealer says I need part number 893077 or 228506. This Porter-Cable 18-gauge, 1-1/4-inch brad nailer shoots standard brads from 5/8 to 1-1/4 inches long. Discussion Starter • #1 • Feb 28, 2014. Porter Cable FN250C finish nailer .