Dry fire Remington Express result?: totally erratic

[BrianWood]

When I put this rifle away last April, it was shooting nearly as good as my Weihrauch HW95. Somehow the trigger adjustment got off between then and yesterday. I was checking the safety and after cocking without a pellet, the gun dry fired. Then the first pellet went supersonic, maybe from some oil accumulating in the compression chamber over the months? That pellet hit a 15-yard target 6" to the right and about that much low from the months-ago sighting in. After a few more shots equally as errant, I cranked the scope to the left and up but there was just no getting a group. It also looked like some pellets were penetrating the backstop medium more than others (no Chrony).

I disassembled the rifle, expecting some kind of major damage but I don't see anything disastrous. The piston rod is .010" off center at the back of the piston but I don't know if that is out of spec. The seal looks as good as one could expect a factory seal. The receiver/cylinder look okay. The spring isn't straight. It was a little jammed in the piston because of it. That can't be good. I don't know what else I should be looking for. I suppose the weird shooting might be unrelated to the dry firing but the gun can't hit the broadside of a barn now.

[GP2004]

You don't say what scope you are using. I would try iron sights until you get the problem worked out, the scope may be buggered. Is the spring rubbing on the steel sleeve inside the piston? You can try to straighten the spring by bending it in your hands, it might work. The piston seal looks like it got sliced when it was assembled. Deburr the sharp edges in the Remmys tube to prevent further damage to the piston seal during assembly. The piston seal for a Diana D34 fits the Remmy Express, but it needs to be sized. You can adjust the piston rod easily to be centered. Check the crown to be sure that it didn't get any damage in storage. Ask questions here if you think you need help.

[BrianWood]

The scope is an RWS 3-9 X 40 from a Diana 34 Meisterschutze Pro. I will check it on another rifle. Because the reports sounded different from each other and pellet penetration looked different, I still think it is the gun that went bad. Yes the spring is rubbing on the sleeve - to such an extent that it took some effort to extract it on disassembly. I will attempt to straighten the spring as you suggest. I have a new seal left over that was purchased for a Ruger Air Hawk.The crown looks undamaged.

[Doug Wall]

I don't see any lubes on the piston or spring. Did you clean them off, or are they as removed from the gun? If you don't have the proper lubes, things won't be at their best. I use Honda Moly 66 on the sides of the piston seal, and piston, and spring tar (JM) on the spring. Some other people are using some of the synthetic greases (Ultimox?).

[Methuselah]

The scope is an RWS 3-9 X 40 from a Diana 34 Meisterschutze Pro. I will check it on another rifle. Because the reports sounded different from each other and pellet penetration looked different, I still think it is the gun that went bad. Yes the spring is rubbing on the sleeve - to such an extent that it took some effort to extract it on disassembly. I will attempt to straighten the spring as you suggest. I have a new seal left over that was purchased for a Ruger Air Hawk.The crown looks undamaged.

Wow, 12" @ 15 yards?!?

Lots of questions, circumstances, and possible solutions come to mind like a flood!!!

Since you already have it apart, maybe it's more prudent to start over than apply diagnosis, I mean if it was a combination of things, many of the possibilities go away by the time you work through it and get it back together, right?

I'd suggest cleaning the barrel, new seals x2, mind the barrel pivot tension, pay close attention that the fork screw had not come loose, loctite screws, examine ammo just to be sure ... and restart with iron sights at 10 yards.

(Mine has the loose pivot...)

HTH - Happy New Yeay

Steve

[BrianWood]

The spring and piston had lube on them. The photos are after I had wiped them down some.

[BrianWood]

The scope works okay on another rifle.

I have changed the piston seal. It had the exact same factory seal as a Ruger Air Hawk. I straightened the spring, and centered the piston rod. Tomorrow I will polish the ends of the spring, deburr the receiver, and hopefully figure out a way to polish the cylinder wall. It appears to have some surface defects. Maybe I can glue some polyethylene buttons on the piston skirt too.

[BrianWood]

Okay, I didn't button the piston because I didn't know if it was worth the effort if I ended up with a boat anchor anyway. But I am back on track. Using a cheap 4X32 scope from my Ruger Air Hawk, I see potential again. The attached target shows the 31st to 40th shots after reassembly at 15 yards. Thanks for the encouragement and ideas. I still don't know what happened to throw the gun off in the first place.