New Crosman 1377 are under power - here's how to fix them.

[Antoni]

No-one has mentioned adjusting the dead volume of the pump.

I got one these pistols in the 70s after covetting my mate's one - I only had a crappy break-barrel at the time. I simply used the piston position adjustment to change the dead volume at the end of the pump stroke. The trigger was never very nice and it was certainly less nice after the adjustment. My point is, that indicates that an "adjustment' had indeed been made.

[Biker_Bob]

No-one has mentioned adjusting the dead volume of the pump.

I got one these pistols in the 70s after covetting my mate's one - I only had a crappy break-barrel at the time. I simply used the piston position adjustment to change the dead volume at the end of the pump stroke. The trigger was never very nice and it was certainly less nice after the adjustment. My point is, that indicates that an "adjustment' had indeed been made.

No adjustment option on the new pistols. The pump is a moulded plastic part.
This is why the "flat top piston" mod is popular. But as I mentioned above, mine is getting perilously close with the standard pump - don't need any more.

[ratbuster2240]

Thanks for sharing your findings. These are great fun and almost impossible to leave alone
in standard form. I have two, one converted with a 2250b barrel I think 14.5" long with flat top piston and and valve and makes 11fpe. I cant remember how many pumps might have been 15. Again this thread makes me want to revisit my 1377.

[--ped--]

a good ftp set up with a 14.5 .22 barrel should do ten on ten pumps but you have to set hammer strike so the valve retains air to keep under limit

[ratbuster2240]

That's some very healthy power for something that weighs nothing!

a good ftp set up with a 14.5 .22 barrel should do ten on ten pumps but you have to set hammer strike so the valve retains air to keep under limit

[Alan's]

Hi I've had a 1377 and 1322 for years that are the old type with the hammer knob at the back the 1322 I've converted to air to run of my raped bottle when it got down to 1000psi with steel breach and scope and stock like rat catcher and the 1377 steel breach of a falcon fn19 flat top
Piston stock scope and silencer then everything had to be bigger but as you know now bigger is not all was best and you have a limit on pistols the valves in them had spacers in or a loneg PTFE inlet valve taking up volume witch I took out then . but you have to much on standard barrels and the pellets gone time the rest of the air comes out . so know I've put a small spacer in to reduce volume so now with ftp 7 pumps 5.25 flb and you struggle to pump it more . there was one of these that had a different valve witch I sold way back but made the trigger much better it cocked when you pumped it and the valve split to release pressure has any one got one or seen one . any way I've found out now the pump has a mane part in the workings and I do not want to be pumping 20 + times I've a bull worker for that any way the first write up was good