Will this work? Meteor Mk5

[ggggr]

A MK5 Meteor turned up and I was wondering what to do with it (I should stop buying guns as I will have to move house this year). I have been toying with the idea of leaving the buffer out of a Meteor and hoping someone could turn me up a piston head rather than alter an existing one. Anyway on stripping the Mk5 I noticed it had the piston head held with the circlip rather than the "keyhole" type piston and it got me thinking. I left the buffer off the head and put it on the piston, then thought "Right, I just need a few washers on the inside off the piston on the spigot to make up the width of the buffer and refit the circlip". Not having enough of the right sized washers, I decided to open up the hole on a tap washer, fit that on the spigot, on the inside of the piston, fit 1 washer and then the circlip. I would have preferred a solid washer but reasoned like this----It probably doesnt matter where the buffer is too much for buffering purposes. If the buffer is on the inside of the piston, then I have the benefit of the increased swept volume in front of the piston head, the mainspring is under the same amount of tension when fitted and I still have a buffer washer in the gun. Not tried the gun yet and dont have a chrono but-----Is this theory right or wrong. Get thinking

[lightning22]

The way I'm reading it you will be increasing the preload by spacing the spring at the piston end. You would certainly gain some extra swept volume but I'm not sure what benefit you'd gain from the buffer.

[duomatic410]

Your piston could end up hitting your cocking lever???? john

[coburn]

I think thats what John Bowkett used to do to get 12ftlbs out of a Meteor.

[duomatic410]

Gggr.
Send me your address. John

[lightning22]

I think thats what John Bowkett used to do to get 12ftlbs out of a Meteor.

John did quite a few things to get 12ftlbs out of the Meteor, looking inside mine found a steel piston head with a white square section seal, longer stroke, heavy piston weight, a rather stiff spring and a radiused transfer port.

It's interesting but not very nice to shoot and the rubbish BSA scope rails mean you end up catching the scope as it tries to exit stage left.

My next little project is to make a piston head that will take a proprietary parachute seal and see what difference it makes before increasing the stroke.

Rich

[ggggr]

I would have used washers if I had enough of the right size or one thick one---thinking that these would act as a piston weight. only doing it as a bit of an experiment as I dont do anything other than plink. I haven,t got a chrono so I wont be able to tell really. I actually fitted a new mainspring in this gun as the one it came with was well knackered---AND it was one of those copper coloured jobbies I got from M.A.G. rather than a silver streak so I wanted to see if it would fit ok. This isn,t very scientific either but the spring went in ok using my bit of saddle stem with slots cut in it, without the need to resort to using gloves to protect my delicate hands. I therefore thought that while the spring is longer than a sliver streak, that it must be "softer".
Confession time. The gun was making a horrible racket when cocked(even before), which I put down to the rubbing pad missing from the inside of the stock. I cut a slim piece of something a nice chap had sent me for such purposes and glued it in place, The action wouldn,t go in the stock and I spent an HOUR trying to thin the pad. I ended up heating a bit of flat bar and burning it to the right thickness. It cured it though

[Mike95]

What you really have to worry about is the circlip parting company with the rear of the piston head while cocking and leaving the piston head jammed in the cylinder, a common occurrence with this model. I recommend a new circlip of some type after deepening the groove on the rear of the piston head. Better still, find a keyhole type piston and head.

Mike95

[duomatic410]

FUNNY ANOUGH.
I Have just got a piston key/hole type come in for repair and its sheared off leaving you know what at the breach end.

Never had one of these fail before. john

Have now managed to get it out

[ggggr]

Re the above two posts. Mike the piston head will not go through into the piston on a keyhole type unless you turned the shank/spigot down and machined a new groove in it. I did fit a circlip on a scorpion pistol, which has a similar set up but that was I didn,t fancy paying £4 + £4 postage from Nibbs for a circlip. I did a MK5 Meteor to give to my mates lad and the circlip pulled off that because of the usual sticky old buffer problem. I used a foot pump and adapter to blow it so far back down the cylinder but really you need a piece of tube to slip over the spigot to keep the head as straight as possible until it comes to the cocking arm slot and you can wangle it. Somebody had a problem with an Airsporter piston head about a year or so ago and I would imagine that the same trick would work with a small diameter rod to go inside the piston head.
Dont know about the power but had a quick fun plink with the gun after throwing a Bsa reflex on it to try.

[Mike95]

To replace, you need both the keyhole piston and piston head. The pistons seem to be the same as the earlier type with a small plate welded inside to provide the "keyhole". I tried allsorts and I eventually fitted a starlock type of circlip, after filing the groove on the piston head nub a bit deeper to give more grip. Located the starlock over the piston head nub inside the piston and knocked it on with a small box spanner...no problems since. The "C" type circlips would not fit, mainly because I could only get metric and the nub/shaft diameter is imperial. Might be other suitable fittings about? The original circlip was a Mickey Mouse affair. I knocked out one jammed piston head with a welding rod via the transfer port, plus a lot of WD40...but that one had been in the cylinder for perhaps 20 years!

Anyone handy could probably come up with alternative fittings. I found one Mark 5 with the nub of the piston head flattened out inside the piston, presumably with a big punch/hammer. The piston head can take a lot of punishment it seems! I have also experimented with ptfe heads fitted via a nut/bolt/washer to the piston. I am told that a cut down Supersport piston will fit and can provide a longer stroke. Hours of fun!

Mike95

[duomatic410]

Well, talk about luck.
Just been into my parts bin and first thing i spot is one new keyhole piston head.
How long ive had it i dont know but meteor up and runningjohn