Some work done, but now the 1377 is much harder to pump

[Tater]

What was done is new barrel, barrel band, solid roll pin, 1389 forearm and lightly oiled (Pellgunoil) the piston. I also used 600 grit sandpaper to smooth out the holes that were widened for the solid pin. The pin and hinges were oiled with Pellgunoil as well. The solid pin is now very snug.
Since then it is MUCH harder to pump. My wife can't even pump the gun at all. It seems to be shooting very strong and it holds air well overnight, even if it's just one pump.
Has anyone had something like this happen?

[cmj21973]

1) which/whose solid pin?
2) which/whose barrel band?

photo requested.

[Crosshairs]

If you dont have a adjustable piston that might be the pboblem, changing the pin can make the piston tighter /closer to the valve.
                                                     Mike

[breakfastchef]

Does the pump arm move freely when fully open? Is the pump stroke difficult only when the piston starts its journey toward the valve?

[Fronzdan]

This happened with one of mine.  Interested to see what people think.  For me, the whole stroke is just tighter.  It feels like there's a lot of friction as the piston slides towards the valve.  I thought maybe I didn't lube it enough??  Or maybe I had rotated the piston from the position it was in for years and its a tighter fit??

[Tater]

If you dont have a adjustable piston that might be the pboblem, changing the pin can make the piston tighter /closer to the valve.
                                                     Mike

I don't have an adjustable piston, just the stock one I had been using.

1) which/whose solid pin?
2) which/whose barrel band?

photo requested.

The barrel band is a new plastic 760 band to accommodate the 12" barrel. The pin was made by a trusted member here, there's two on the right side below:

Does the pump arm move freely when fully open? Is the pump stroke difficult only when the piston starts its journey toward the valve?

Exactly. I moves freely fully open, but tightens up on the "downswing" (piston towards the valve).

[Tater]

This happened with one of mine.  Interested to see what people think.  For me, the whole stroke is just tighter.  It feels like there's a lot of friction as the piston slides towards the valve.  I thought maybe I didn't lube it enough??  Or maybe I had rotated the piston from the position it was in for years and its a tighter fit??

That's an interesting thought. I think mine could have rotated, but I'm pretty sure I lubed it enough.

[WyoMan]

That's an interesting thought. I think mine could have rotated, but I'm pretty sure I lubed it enough.

Tater, It's possible there's something wrong with the pump cup
I would pull the piston and check the pump cup to make sure:
1. the cup has no abrasions that might have occurred when you first removed it
2. the pin that secures the cup is in place and the cup isn't crooked

If none of the above then clean everything, re-lube, re-try (can't tell you how many times I've had to do that!)
HTH - lets us know - thanks,

[PC77]

I have a solid pin in my stock 1377 it works fine. I can't see how changing the pivot pin could make any difference. Maybe some Rem oil got to the o-rings causing them to swell. Did you use any other lubes in the tube? How did the gun work when you first put it back together?
pc

[Tater]

I have a solid pin in my stock 1377 it works fine. I can't see how changing the pivot pin could make any difference. Maybe some Rem oil got to the o-rings causing them to swell. Did you use any other lubes in the tube? How did the gun work when you first put it back together?
pc

Just a little Pellgunoil on the piston itself, none in the tube. I too doubt the pivot pin had anything to do with it, just wanted to mention everything that was done.

[Tater]

Close up of barrel band-

[1377x]

i cant see why the barrel band or the pivot pin would make a difference
the linkage pin could make a difference but how could it fo back into the tube if its out of place
i had a similar problem i linked to the check valve not opening some debris got into the valve but the op said the gun is getting air so its a mystery to me

my suggestion
take the gun apart
clean every part including the valve internals use no cleaning chems just use the pelloil only when done wiping down all the parts
reassemble the gun

[Tater]

my suggestion
take the gun apart
clean every part including the valve internals use no cleaning chems just use the pelloil only when done wiping down all the parts
reassemble the gun

That's what I was afraid to hear. Just got used to it and it's finally sighted in nicely. Well I can live with it, but if it keeps the wife from shooting I'll definitely do that.
Could I harm anything leaving it as is for a while?

[1377x]

That's what I was afraid to hear. Just got used to it and it's finally sighted in nicely. Well I can live with it, but if it keeps the wife from shooting I'll definitely do that.
Could I harm anything leaving it as is for a while?

you might stretch the pivot hole and linkage hole if its really hard to pump

[Tater]

you might stretch the pivot hole and linkage hole if its really hard to pump

The pivot pin went in VERY tightly. I widened it with a 3/16 drill bit by hand but maybe left the hole to small. The really had to pound it in. I doubt it moves in there at all but I lubed it where to linkage contacts it. Is the pin itself supposed to rotate when pumping?