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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 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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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 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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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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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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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2022 at 4:49pm
Hmm, I would fabricate something on my lathe if it was mine. You might find something like an o-ring that is a tight enough fit to stay in place or beer can shim with tabs behind the ram?
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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 4:09pm
Have just got ahold of vaughans for new rubbers.Piston and barrel seal arivved yesterday. But will rember that for next time thanks.
I'm currently looking at piston which has so much space between it and the gas plunger it's been rubbing on the gas housing during cocking.

Need to make spacer. (sujestions appreciated)

The gas ram end has play where it sits in the rear housing.
Noticed that one of spring clips on trigger (previous pic) is broken.
I have nothing against gamo but I'm starting to think I scored a rifle made from parts taken off other rifles that didn't make the grade.
Sigh.

Edited by kruzaroad - 16 Aug 2022 at 4:13pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 16 Aug 2022 at 3:14pm
An air arms seal should fit if you want to use a better seal or get one from https://www.customairseals.com
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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 2:25pm
So pulled the gamo open and had a good look. Not impressed. Done a bit of sanding to inside of stock as had rub points but at irregular intervals. It has ribs under it to hold bottom of receiver. All along one side and just front and rear on other side. Can't see that helping an even shock vibration pattern. But I may be wrong.

Had a worn rubber on one side, where pin that holds trigger housing/piston housing to receiver.

Piston seal was embedded with a chunk of lead right at seal edge.(bottom of pic)

Seal Edge crap too

Sprayed with brake clean to see what came out, metal filings and brown crap I assume is protectent for metal when shipping.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 13 Aug 2022 at 11:41am



Here's the last 2 digits of next string weighed and sized pellets, seated approx 3mm in barrel.Under the same shot as yesterday's mixed for comparison. (only 15 shots)

mixed
79,90,94,84,94,70,66,71,68,87,73,54,64,
weighed/sized
68,51,58,50,55,59,55,26,77,71,39,58,48,

mixed
58,50,68,59,68,55,60,64,65,56,57,62
weighed/sized
41,67
Good drop in power over all, possibly bit more stable but some weird drops and spikes. Have to check for metal rubbing,and how much that piston can freeplay I think. Cheers Billbob that was well worth doing. Appreciated.
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