crosman 140 replacement piston head

[--ped--]

I was asked about a replacement piston head for a 140 and as in the UK we have a power limit and sadly the 140 in std form is capable of exceeding it I convert mine to a pressure blow off piston (this is for a non UK gun)
this leaves me with a few std pistons so I set about converting one to an o ring
first I removed the old seal(carefully milling the brass collar in two places to leave the old seal intact so I cam possibly replicate it at a future date) and the washer and felt wiper
I then machined the piston a bit shorter and altered the felt wiper location to take a different size piece of felt
I then threaded the pistom m8 and drilled and tapped a piece of brass m8
the two pieces were screwed together and then the final machining and o ring groove was cut to keep everything as concentric to the piston rod as possible
i could have replaced all the head and made a full brass one but this way enabled me to keep the felt wiper
https://i.imgur.com/dh9IHNC.jpg

[series2a]

I think I have one of your pistons in my 140 it has Belleville washers and a spring ball bearing set up.

[--ped--]

it's based on my design but I didn't make it as I allowed someone to borrow one so he could make one for himself and I believe he later sold you the gun
I use coil springs rather than Belleville's thje ball and seal I supplied though so if you ever need a replacement I can make you one

[series2a]

It doesn't really work very well as it never blows off and I can't be bothered to spend hours setting up.
The gun doesn't go over limit anyway.
Cheers for that.

[--ped--]

if your 140 doesn't go over 12 then it's either working and you don't realise it or it needs re sealing
on mine I set them to blow off at around 7-8fpe as I don't often shoot them and wouldn't pump to full power if I did so