Mk1 Airsporter not cocking

[ggggr]

been having a play with the Mk1 Airsporter that arreived on Saturday morning. The gun seemed to be in better nick than I thought it would be. THe crack on the stock is not bad at all. run a bit of pva into it and had it clamped over night. The mainspring was one of the worse seen. The piston washer looked like it had stuck to the end of the cylinder at some point so I made another. I also had to make up a tool to tighten the nut in the piston. I got some tube and cut the end to leave two lugs sticking out to go into the slots in the nut. The action would not cock when I tried it although if you pushed the sear up it would. I knew that the gun was not coilbound. I have seen various guns where the cocking slot on the piston is worn and on Airsporters this seems very hard to spot because the piston does not seem to burr like some guns. I took the piston out of the cylinder and pushed the piston rod into its hole in the trigger block. The piston skirt touched the block before the trigger engaged. I then reasoned that the rod was not coming far enough back so I tightened the nut in the piston to pull the rod through a bit more. It still wont cock but it is close. Later I will try removing the fibre washer under the piston washer and see what that does. After that it is either get the end of the rod built up with a touch of weld (favourite I think) or the slot in the piston by about 1/8 inch. I hope this is of some use. I think Barry Eye in New Zealand has been having this problem as well.

[pennineway.fswo]

Hi Guy
I have had similar problems in the past when changing the piston head and also seen the problem where the piston head has come loose during service or a modified type head has been fitted

You seem to have identified the problem and I found that tightening up the piston head a bit more pulled the piston rod further through and allowed the rifle to cock
Removing or fitting a thinner fibre washer should help or as you say just a couple of mms weld deposit on the end of the rod should extend it just enough to trip/cock the sear
Good luck
John

[duomatic410]

Guy.
Did the weld option a few weeks ago with the same problems, worked a treat.
atb. john

[I. J.]

I know someone who re-fitted the piston rod the wrong way round and wondered why it wouldn't cock. (Rhymes with 'PayFun.')


ATB
Ian

[gedfinn 2]

been having a play with the Mk1 Airsporter that arreived on Saturday morning. The gun seemed to be in better nick than I thought it would be. THe crack on the stock is not bad at all. run a bit of pva into it and had it clamped over night. The mainspring was one of the worse seen. The piston washer looked like it had stuck to the end of the cylinder at some point so I made another. I also had to make up a tool to tighten the nut in the piston. I got some tube and cut the end to leave two lugs sticking out to go into the slots in the nut. The action would not cock when I tried it although if you pushed the sear up it would. I knew that the gun was not coilbound. I have seen various guns where the cocking slot on the piston is worn and on Airsporters this seems very hard to spot because the piston does not seem to burr like some guns. I took the piston out of the cylinder and pushed the piston rod into its hole in the trigger block. The piston skirt touched the block before the trigger engaged. I then reasoned that the rod was not coming far enough back so I tightened the nut in the piston to pull the rod through a bit more. It still wont cock but it is close. Later I will try removing the fibre washer under the piston washer and see what that does. After that it is either get the end of the rod built up with a touch of weld (favourite I think) or the slot in the piston by about 1/8 inch. I hope this is of some use. I think Barry Eye in New Zealand has been having this problem as well.

I have seen this a couple of times, Machining 2-3 mm off the piston skirt cured it,
Ged.

[ggggr]

Well it is sorted now OR should be once I get the action in the glued stock. I fitted a thinner fibre washer as the one in it looked pretty thick and that seems to have cured it. Anyhow if anyone is reading this we have a few options, taking a few mm off the piston skirt or welding the slot on the piston or a bit on the end of the rod that sets the sear. Thanks to everyone who has offered up their views and suggestions.

[barryeye]

Thanks Grrrrrr as per usual you have been a great help. Soon as it lands in New Zealand I'll know just where to look.
Thanks again.

[ggggr]

found something else on the latest one. After fitting a thinner fibre washer the gun seemed to be working ok but I was a bit concerned that the trigger spring was moving to one side. I took it off and squared it up and refitted it. I then put some superglue in the slot where it sits hoping that it will stay put long enough to get a bit of memory. This gun will get the rod welded anyway to give the gun another 50 years. Earmarked for my brother this one.

[ggggr]

Just an update on the one above. I asked someone to weld a couple of mm on the end of the rod and did not think to try the piston rod into the trigger block before putting the rifle together DOH! It did not cock. I worked out that because of leverage, too much had been welded on the end of the rod and whilst the sear was pushed back by the rod, the hooked bit in the rod that the sear engages on was not far enough back---ie the sear was just hitting on rod. I filed about 1mm off the welded rod and the problem is now cured. I hope this helps.