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is it the seals
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xyon View Drop Down
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Posts: 135 		Post Options Post Options   Thanks (0) Thanks(0)   Quote xyon Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 2:27pm
Originally posted by kruzaroad kruzaroad wrote:

Ive sent the pics to gamo distributor and asked if this could be the issue with accuracy and will gamo replace the barrel. They also put a 5mm washer behind the gas ram (as standard) which I'm probly going to take out.It reeks of a gun that has just had a spacer put in to upgrade the power and I suspect that the piston is hitting the end of cylinder harder than it should, increasing recoil and doing the seal no good. I'd rather a lower power rifle (providing its not to big a drop) that hits where its aimed more than a faster rifle that puts pellets into the rear of animals your aiming to the front of.
This gun has been a major pain in the arse, but worth its weight in gold as a learning curve that's for sure.


Hi, make sure the gas spring still has a few mm of preload after you remove the washer - otherwise it will kill itself as the internal parts slam together. BTW changing the pre-load on a gas spring won't change the spring force as much as a steel spring.
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kruzaroad View Drop Down
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Posts: 2284 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 4:54pm
Cheers Xyon. All ready dropped it and retested it by time read this.But have filed that info away for future. Guessing as still had to use gclamp to compress it to put pin in that holds it all in I fluked that one. whew.
With washer out back in 600fps range. Last 2 digits 10 string group as follows 89,94,79,95,85,93,89,91,82,86.
AVG = 690fps
A lot less erratic and a lot less thump at end of stroke.
25m groups:with baffle and washer in 4.55cm,x 3.51cm
baffle out / washer in 3.4cm x 3.7cm -Baffle out washer out 1st group 3cm x 3.4cm. 2nd group minus flyer ( really I pulled trigger to early coming onto bull) and a totally pulled it, leaves a 8 shot group at 2.3cm x 2.5cm
20m groups: (didn't shoot one earlier with baffle out)
Washer in baffle in 4cm x 3.15cm
washer and baffle out 2cm x 2.5cm

now if I can get that trigger adjustment screw in ten or prefablable 12mm length I'll be able to take out the rediculous amount of travel in the sear without filing it back any more. Get that machining mark sorted.clean up the baffle, I might have what gamo should have sold me.
Cheers for advice. Any more fire away it's all been good so far.



Edited by kruzaroad - 23 Aug 2022 at 5:25pm
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Billbobnz View Drop Down
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Posts: 867 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Billbobnz Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 6:42pm
Good evening, one thing to check is how much play is there in the breech? If you have a feeler gauge, remove the breech bolt that the barrel piviots on and feel for any gaps down beside the breech shim bushings. If there is even the slightest gap as the breech bolt is tightened it squeezes the front of the shim bushes and allows a MIT of lateral movement at the rear (hard to explain but you may know what I mean) a gazillion of a nanometer of movement here will throw your accuracy out.

You will be able to get shim washers from a engineering firm near you to replace the factory ones to help remove any gaps in this area.

Just another thing to check :)
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Billbobnz View Drop Down
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Posts: 867 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Billbobnz Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 6:47pm
I had this really crazy idea the otherday that I have no idea if it could be engineered. Is somehow fit a highflow regulator between the piston chamber and breech to regulate the pressure to allow more constant pressure behind the pellet for greater accuracy - almost had a brain aneurysm over the idea - if it's possible we all will patent it lol
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Billbobnz View Drop Down
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Posts: 867 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Billbobnz Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 6:48pm
Patent pending - Kiwiairgunners

Hahaha
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kruzaroad View Drop Down
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Posts: 2284 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 6:51pm
I had to read that about 4 times but yep I've got it. I'll do that in the morning and get what I need tomorrow in town. Excellent timing on your behalf. Great advice cheers.
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Billbobnz View Drop Down
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Posts: 867 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Billbobnz Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 7:06pm
I have a habit of explaining things in a way that usually ends up with a WTF expression from the listener.......
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kruzaroad View Drop Down
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Posts: 2284 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 7:12pm
It was all good. worked for mee
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kruzaroad View Drop Down
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Posts: 2284 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 7:45pm
chamber in front of end of piston stroke. one way valve to chamber (think flap of metal on inside, for example)
air gets forced into chamber it seals from back pressure. that then goes to valve system above the chamber. Look like a pcp but be a single shot.
A release button or forward trigger to release the piston.
piston fires, high pressure chamber full. gun is loaded. firing separate to piston release.
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kruzaroad View Drop Down
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Posts: 2284 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kruzaroad Quote  Post ReplyReply Direct Link To This Post Posted: 23 Aug 2022 at 7:46pm
oh under or side lever
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