Airsporter.....

[u.k.neil]

My firearms club has had an Airsporter Mk 5 donated to the airgun section for beginners to use. Lovely condition except it had no compression and club admin asked me to have a look.

Stripped it down this afternoon and what has happened is that the piston head has become detached from the piston assembly, but the person who owned it has kept cocking and firing it with the piston head down the bottom of the compression chamber.

Well this has well and truely hammered it in to the bottom and swaged it out, can't move it.

Is there anything that can be done with this or is it a scrapper.

Neil

[Born Again]

If you fixed a hole saw to a long shaft, with a stabilising bush on the shaft near the saw, maybe you could drill the majority of it out, leaving a ring of piston head that might become a bit looser.

[Co2]

Nasty!
I cannot remember off hand if that one is a plain break barrel or tap loader?
This is only a suggestion.
If it’s a tap loader.
You might try getting hold of a long Brass (brazing?) rod as near as possible to the bore size as possible, I think B&Q sell brass rod?
Put it up the entire length of the barrel (Tap closed position) until it hits the piston, then carefully tap the end of the brass rod with a light hammer with any luck you might just shift it.
If you cannot shift it with a light hammer then use a heavy weight job, but you must put a stop over the end of the barrel, as if it does go all of a sudden you might mash the end of the barrel?
Try to keep the end poking out of the barrel fairly short.
Be careful not smack the end of the barrel itself.
You might need two bits of solid brass rod, as it’s quite a length, barrel, tap, and air chamber.
Put some oil (spray grease even better) down the air chamber bore so if and when it moves it has some lubrication to stop it scratching up?
If it just a break barrel then you will only need a foot long bit of brass rod.
I would not try drilling out the piston as you might hit the sides and cause some real damage.
If you cannot shift it send it to me I will have a look for you.
I have had to clear many problems like that usually though it’s an assortment of objects stuck up the barrel.
Ranging from screws, matches, nails, and bits of broken off solid fibreglass fishing rod, amongst other things. and something I can only describe as somebodys tooth filling ;-)

Good luck.

[ora8i]

It’s going to take either some engineering or pneumatic power.

• With a stabilised drill (bush as described above) drill a small hole into the mashed ruin of the piston head.
• Follow up with a stud extractor on a rod and haul it out.

Or Pneumatic.

Huge pressure up the barrel and blow it out, may as well that the opportunity to get the FPE record for an Airsporter

Actually liquid would be best much safer!!!

Regards Ora

[duomatic410]

Niel.
just removed a piston head in same place and condition.

used a coach bolt welded it to a rod, and screwed it into the piston head, which is alloy got it out with a bit of juggling.

tryed the rod down barrel, but outlet port to small, and ofset, it runs downwards,you will probably find the cross head pin has broken, that holds the piston head to the shaft.

good luck and happy juggling. john

[u.k.neil]

It is a tap loader. Have already tried the brass bar down the barrel and even with a big hammer it's not moving, just driving the brass into the piston head.

Knowing how much force I have already exerted on it, I doubt very much if an eaziout would move it.

Ah well, it was a donation to the club, all it's cost me is a couple of hours of my time.

Neil

[ora8i]

Ok time to get nasty.

Aluminium is amphoteric it can be disolved in acid OR caustic, steel however only in acids.

Plug it up, disolved the aluminium in caustic the steel should be relatively undamaged if you do it right.


Regards Ora

[Hsing-ee]

Sodium hydroxide solution (sold as drain cleaner) will dissolve the aluminium but wear thick gloves, goggles etc or it will TURN YOU INTO SOAP and burn your skin badly. God help you if you get it in your eyes. Be VERY careful.

[u.k.neil]

Sodium hydroxide solution (sold as drain cleaner) will dissolve the aluminium but wear thick gloves, goggles etc or it will TURN YOU INTO SOAP and burn your skin badly. God help you if you get it in your eyes. Be VERY careful.

reckon I will try the coach bolt method first though......

Neil

[u.k.neil]

you will probably find the cross head pin has broken, that holds the piston head to the shaft.

good luck and happy juggling. john

Hi John

That's exactly what's happened. There's two impressions of one half of the cross pin embedded in the piston and head.

Neil

[hobgoblin]

I think the coach bolt is the way to go, i had the same problem with a BSA Mercury a few years ago and used a simular method. But i also heated the cylinder up with a hot air gun !
A modified piston assy is available from John Knibbs ,much better quality than the original......Let us know how you get on...Andy.

[JD75]

Sodium hydroxide solution (sold as drain cleaner) will dissolve the aluminium.

Sorry you are the wrong end of the country Neil, as I always have the odd gallon or so of this hanging about.

Just find a nice Landlord as we use it for line cleaning.

[u.k.neil]

Well, tried the coach bolt (actually some long 10mm studding), wouldn't budge tried heat, started with a hair drier, finished up with a gas torch, still wouldn't budge.

Too damned cold to spend any more time in the garage so sod it.

Neil

[duomatic410]

Nial.

You Will Probably Find That The Piece Of Pin That Has Come Adrift Is Embedded In Your Piston Head And Tight
To The Cylinder I Had To Use A Lot Of Heat Which I Forgot To Tell You There Will Be A Lot Of Smoke From The Piston Seal, But Keep At It,it Will Come Out. John

[Jonathan]

I would use the aforementioned drill and bush. Drill an 8.5mm hole, tap it M10 and use that piece of 10mm stud as a sliding hammer (solid end, sliding weight etc.) I have used this method in the past. A bit of heat won't go amiss either. A few minutes should make up the tools required, and hey, you'll always have them for the next time!

Jonathan.