Reply With QuoteI think it may be new piston time then. As it seems an alloy head with no buffer washer is going to be a recipe for disaster.
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Sounds like a good idea, you will get more swept volume but with their design of having a hard piston head it there will be no shock absorption when smashing against the end of the chamber. Most new airguns have a polyurethane piston head for impact resistance and resilience. I would make a completely new design piston head from polyurethane rod.Originally Posted by copperjacket
Baz
BE AN INDEPENDENT THINKER, DON'T FOLLOW THE CROWD
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I think it may be new piston time then. As it seems an alloy head with no buffer washer is going to be a recipe for disaster.
may also be employed in conjunction with a drawn reciprocation dingle arm, to reduce sinusoidal repleneration
I tried acetone and pulling-bolts ... in the end battering it with a large diameter punch got it shifted but needed hammering all the way out. The piston head looks non-standard it has an extended nose with a strange metal clip or ring 4mm in front of the 'O' ring. Why would anyone make a piston like that I do not know. I am going to dissect it further. The buffer washer is cheese, but this head seems to be made of PTFE or something. Is it a standard BSA head I wonder? Going to get to use my endoscope to see if the cylinder is scratched as the metal ring/clip whatever looks like it might have been pushed out to the cylinder wall.
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If I were making a new nose, I'd think I'd just make one to take a 28mm diana seal. Solves a number of problems, and very easy to make.
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.
Even better looking than a HW35
Been there, done that and washed the T shirt many times, it's just getting someone to make the adapters which is the problem, if I had a lathe I'd be making them and buying a house in France with the profits
Pete
Far too many rifles to list now, all mainly British but the odd pesky foreigner has snuck in
may also be employed in conjunction with a drawn reciprocation dingle arm, to reduce sinusoidal repleneration
You have got a shed, which is the first step to lathe-ownership. You could swap your Chinese Weihrauch for a Chinese lathe ...If I had a lathe I'd be making them and buying a house in France with the profits
Pete
http://www.americanmachinetools.com/...se_a_lathe.htm
Mushroom Man
I seem to remember coming across the same a couple of years ago but cannot remember rifle or model number ... but it was an Airsporter or a Mercury. Hillers diagram of the Airsporter Mk5 shows something but Chambers diagram does not show any extra part but examination seems to show some sort of groove in the piston head.
Update: referring to The Golden Century there is reference to the time when an Airsporter nylon piston head gave problems due to swelling because of absorption of oil (GC p. 172). To try and cure this, an extra groove was put in the piston head into which was fitted a steel scraper ring designed to remove any build up of nylon in the cylinder. It did not work very well and was abandoned in the mid 1970's in favour of a new aluminium piston head.
So this seems the likely explanation.
Cheers, Phil
may also be employed in conjunction with a drawn reciprocation dingle arm, to reduce sinusoidal repleneration
That is exactly the case Phil, it looks like a scraper ring and it is a horrible idea/thing.To try and cure this, an extra groove was put in the piston head into which was fitted a steel scraper ring designed to remove any build up of nylon in the cylinder. It did not work very well and was abandoned in the mid 1970's in favour of a new aluminium piston head.
So this seems the likely explanation.
Cheers, Phil
Even better looking than a HW35
You need somewhere secure and damp free (preferably with a decent electric and heat source), otherwise the lathe will soon get a layer of rust on it, I don't have my Chinese Weihrauch anymore, I sold that when I swapped a BSA Spitfire for a HW95 and that's replaced it.
Pete
Far too many rifles to list now, all mainly British but the odd pesky foreigner has snuck in
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Method i used once was a length of m16 stud bar. Drilled a hole in one end to 1-1 1/2" ground one side of the thread flat around this hole. Drilled and tapped a hole for a m6 grub screw. This will go over the bar. if extra force needed can always put penny washers over the thread bar and a nut and use this to pull the piston back by tightening the nut up. Acts like a pullers then.
may also be employed in conjunction with a drawn reciprocation dingle arm, to reduce sinusoidal repleneration
That is an elegant solution. I just battered it with a punch until it shifted, probably lucky I got away with minimal damage that can be fixed with a file. BSA Mercurys are strong implements.
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I've always got away with soaking it in WD40 & drifting it out through the transfer port, I think reading the posts I've been quite lucky. I've read that Acetone or Cellulose Thinners are better than WD40 but I've never had to find out.
Almost all my BSA's are converted to do away with the buffer washer, it's a simple job & I don't believe the buffer washer is needed anyway I've got a single Scorpion Pistol that's still got one in, but it's just a matter of time before it doesn't.
Long stroking - you can use a shorter spring, what's not to like?
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I use an electric heat gun to heat up cylinder and wd40
Down transfer port
Works every time
I get it hot and it'll start to move a bit
At a time till eventually you can cock and fire it.
Then strip it quickly
may also be employed in conjunction with a drawn reciprocation dingle arm, to reduce sinusoidal repleneration
The piston and cylinder are going back on the auction site. I bought them so I had a spare for when I long-stroked my Mercury-S, but I have decided to leave it standard and sell it on. Thanks for the help chaps.
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