depth of cylinder

[nimrod177]

Bit of help with the depth of the cylinder on an airsporter. Basically i have acquired an airsporter with a seized piston. Pretty sure it is a mk7 but apart from seized piston is in pretty good condition for it's age. So question is i have managed to get the piston rod and spring out however the seal had seized solid. The force needed to get the piston out sheared the retaining pin thus leaving the head down the cylinder. Loads of bits of seal came out but pretty sure not all. My question is from the trigger/action end how deep is the cylinder. From looking down the inside i am almost positive i can see the end of the breech plus transfer port which is clear. i am measuring a depth of 23.5 cm's from end to flat of where transfer port is. It is a bit manky in there as had to quite literally burn the seal out so now needs a bit of work to clean the tube out of burnt plastic. Still rifle didn't cost me anything so a bit of a project. Plus can anyone suggest a new head and seal to replace the now cremated old one please.
Regards rob h

[crowbar]

I have a mk4 in bits and measured the depth at 233mm, so similar to what you have.

[Benelli B76]

Chambers sell all the spares...

Baz

https://www.gunspares.co.uk/categori...87/Airsporter/

[T 20]

I have a mk4 in bits and measured the depth at 233mm, so similar to what you have.

233 mm on a MK4 here as well.

[nimrod177]

Thanks for the help looks like i have quite literally got to the bottom of the cylinder then. Yes had a look at chambers so unless there is any one else out there that can do a good job then looks like chambers it will be. Seems too good a little rifle to chuck in a skip so may as well get the engineering skills back up to scratch and get oily and greased up!
regards rob H

[Shed tuner]

when you fit the new head, don't use the std o-ring seal, as it's far too tight. use something a little smaller, it makes for a more sensible sliding fit. Alternatively I just converted one to take a 28mm diana parachute seal; quite an easy job, and gained 5mm stroke too

[look no hands]

when you fit the new head, don't use the std o-ring seal, as it's far too tight. use something a little smaller, it makes for a more sensible sliding fit. Alternatively I just converted one to take a 28mm diana parachute seal; quite an easy job, and gained 5mm stroke too

You need to get a Meteor O ring as it's slightly smaller.

Pete

[nimrod177]

cheers for the help gents.