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is it the seals

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kruzaroad View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2022 at 5:06pm
Just cut out an insert from milk bottle that stops the movement of the piston head so will get thin sheet metal for that tomorrow. The gas tube is thinner, but has that grove around it which would be ideal for a grommet so that's a good idea. Cheers. Aaah a lathe if only, milling machine for stock be handy too. sigh. Solid Bush mechanics for me.
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Billbobnz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Billbobnz Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2022 at 6:32pm
The more you shim those spacings out the more consistent the gun will become, along with new seals. I'm not sure on your gun there but some you can swap the gas piston around so there it less weight firing forwards during the firing cycle thus reducing the recoil further making the gun more accurate (if you do do this you will need to have something in the piston head to keep the rod centralized)
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kruzaroad View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2022 at 6:53pm
I've just epoxyed the plastic from milk bottle to the piston ram head as it's such a good fit and doesn't move as it's always hard against the piston. The gap between the gas chamber and the piston is rediculous. Is about 3mm all the way round. I'm going to expoxy a shim on the gas chamber, piston arm end, to keep the piston level enough to go over the oring/grommet I'll put on, without it just chewing it up. It's Friggin crazy there's no way that gamo makes guns so far out of spec.Something is not right in my opinion.

Edited by kruzaroad - 16 Aug 2022 at 6:54pm
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mercs View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mercs Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2022 at 8:08pm
That galling is ridiculous the whole cylinder must be moving longitudinally.

I googled "gamo igt overhaul" to find some examples and the disassembly I watched did not have any marks on the ram cylinder.

The metal fines from the damage must be getting behind the seal and cutting it out.

I expect the lead flakes are from storing the guns barrel up.  Debris will end up dropping backwards, I would not think the lead would do much damage.

Really interesting, appreciate the pictures, I would expect your supplier to provide some advice or support for such an unusual failure, that has nothing to do with the loading mechanism.

Good Luck
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2022 at 8:38pm
gun is stored horizontal,usually vertical when closing the barrel,I think the bit of lead was from the mag when it was on, it damaged the pellets and didn't push them in very far. The scraping on the gas chamber was at the bottom the piston damage top (except bit of lead). That piston pic is after the brake clean and wiping it! Gun City who sold it know nothing , they recommended young's when asked if they could get seal in. Hunting and fishing tried to order seal but couldn't get one as gun City is sole supplier of that model. I voided the warrenty taking the mag Off.
I'm dealing with vaughans now who are the gamo importer (have been since mag issue, which I decided to not take free replacement) . They sujested might be easier to get whole trigger/gas housing instead of back rubber, and got a quick rundown on what I have to do with it to get it running and I don't need the expense.So they know about it. Their OK he's looking to see if he has it tomorrow.
But saving grace is I have tx, which has been a pleasure. Everything with that process was smooth from enquire to delivery to shooting. When I asked about a tuning kit he recommend not to put one in as they are constantly removing them and turning back to stock.
Live and learn. If I had the machinary to make the parts I'd be in heaven and loving all the faults. For now number 8 wire.
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kruzaroad View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2022 at 8:55pm
I won't ditch gamo for their guns as ppl have good results with them, however as I have to assume this is how the gun is made and I can see major issues with it, I would not recommend the gamo swarm fusion 10x mag (Roadster version) to anybody.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 17 Aug 2022 at 11:37am
May have a found a big part of the issue going thru the schematic . Part number 16080 is totally missing.
It's a spacer that stops the cocking arm from moving up when breaking the barrel.(checked out motion on gun this morning)

I'm now of the opinion that the end of cocking arm has been lifting into the gas cylinder body and sliding along it, pushing it up, causing the ram to lift the piston. This has corrected itself when barrel closed but caused undue pressure on piston seal,
metal on metal rubbing inside of reciever

and probly uneven seating of the piston when cocked. Which would explain some of the peaks and drops in chrono readings as the tolerances would allow it to tilt.
Wether it's broken or worn thru and fallen out, just dropped off as its a clip,out or was never there I have no idea but I've never seen it, or noticed it on my work bench.
Emailed Vaughans for one this morning for new one.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Billbobnz Quote  Post ReplyReply Direct Link To This Post Posted: 17 Aug 2022 at 1:00pm
You will be surprised how good this thing shoots once you've cleaned and polished everything and removed all unnecessary movemen. I'm ordering new piston and breech seal for my Hatsan today as since the rebuild it has become inconsistent. At 40m the goruping was a vertical gorup and after a few shot through the chrony was a high of 728fps and low of 680fps, breech seal doesn't seam to be producing a tight seal.

Thanks to Mercs I have all my guns barrel up so I'm going to check for lead in the cylinder.

My brother in-law brought a Gamo mach 1 in .177 a couple of years ago he is shooting stoger x hollow 10.43gr pellets through it and still shooting 3/4" groups at 40m
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kruzaroad View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 17 Aug 2022 at 1:43pm
we will see. just in town now looking for 3000 grit sand paper. Can't find jb non embeding barrel cleaner anywhere. Of to repco see what valve grinding pastes they have.
it's all fun. if it don't shoot well I'll turf the bloody thing.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 17 Aug 2022 at 7:52pm
Have to laugh at myself.
Went into mitre10 with the receiver tube, poping bits of round dowl in it to find the best size. Got back cut a line down middle feed sand paper into it rolled it around started to polish air chamber. Suddenly dawned on me as I was putting the 2000 grit on,
I could have brought honing tool or sand paper holder for the drill that would have taken 1/5 of time
lol
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