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PostPosted: Mon Aug 29, 2016 2:13 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
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Location: United States
A penny isn't going to cut it imo, you need to fill the hole with something.
People apparently have luck with epoxy but if I had to do it I'd tap the hole, thread in a screw with epoxy on threads, cut/grind flush. Could also make a steel plug from a nail or something that has to be pounded in, then ground flush.


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PostPosted: Mon Aug 29, 2016 2:22 pm 
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Location: Somewheres near the Atlantic
Chevota wrote:
A penny isn't going to cut it imo, you need to fill the hole with something.
People apparently have luck with epoxy but if I had to do it I'd tap the hole, thread in a screw with epoxy on threads, cut/grind flush. Could also make a steel plug from a nail or something that has to be pounded in, then ground flush.


1000's of pellets and the penny is still cutting it.


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PostPosted: Tue Aug 30, 2016 12:52 pm 
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Joined: Fri Aug 26, 2016 9:50 am
Posts: 114
Location: Nova Scotia
leadslinger wrote:
Chevota wrote:
A penny isn't going to cut it imo, you need to fill the hole with something.
People apparently have luck with epoxy but if I had to do it I'd tap the hole, thread in a screw with epoxy on threads, cut/grind flush. Could also make a steel plug from a nail or something that has to be pounded in, then ground flush.


1000's of pellets and the penny is still cutting it.

I like the idea of a permanent plug...but, if a penny works, why not use that method?

Sent from my B1-770 using Tapatalk


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PostPosted: Tue Aug 30, 2016 2:29 pm 
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Location: Bradford
JB Weld is your friend ;)

I trust that stuff more than solder.

Image

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When the 425-hp "street Hemi" version hit the street in 1965, it was akin to taking an M230 chain gun to an arcade shooting gallery
Peter


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PostPosted: Tue Aug 30, 2016 11:10 pm 
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Location: United States
I didn't mean the penny will fail, I meant it's leaking. If people take the gun is apart they might as well plug it 100%. How much power is lost I can only guess, plus the penny is likely moving around so the leakage will not be consistent along with power and poi. The effects are likely minor but I'd guess it leaks as much or more than an oem seal which I consider a must fix. I suppose if one used a penny because they didn't want to take the piston out of the gun then I'd say drop in a disc of thin rubber or a blop of silicone sealant, then the penny. Like most anything it's up to the owner if they just want it to work, or work its best, guess which kind I am ;)
airmec: Thanks for posting those pix. I've been trying to explain the barrel angle thing to people in text so that helps.


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PostPosted: Wed Aug 31, 2016 4:09 am 
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Location: Eastern Townships
Chevota wrote:
I didn't mean the penny will fail, I meant it's leaking. If people take the gun is apart they might as well plug it 100%. How much power is lost I can only guess, plus the penny is likely moving around so the leakage will not be consistent along with power and poi. The effects are likely minor but I'd guess it leaks as much or more than an oem seal which I consider a must fix. I suppose if one used a penny because they didn't want to take the piston out of the gun then I'd say drop in a disc of thin rubber or a blop of silicone sealant, then the penny. Like most anything it's up to the owner if they just want it to work, or work its best, guess which kind I am ;)
airmec: Thanks for posting those pix. I've been trying to explain the barrel angle thing to people in text so that helps.


As they say, an image is worth a thousand words :wink: Glad to help, Chevota!

As for plugging the hole, I would tap some threads and use a screw and red LocTite, I wouldn't trust the JB Weld even though it's wonder stuff.JMO.


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PostPosted: Wed Aug 31, 2016 5:01 am 
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Location: Bradford
JB Weld is overkill for such a mickey mouse job..drilling and tapping is beyond overkill. JB will withstand 500 degrees all day long, shock proof, oil and acid proof, etc etc.

Been using it for over 40 years now, most recently on a stripped caliper bolt hole until the helicoil I ordered came in. Needed a breaker bar to remove the old bolt from the JB Weld filled hole.

I would trust your thread locker MUCH less than a plug of JB Weld.

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When the 425-hp "street Hemi" version hit the street in 1965, it was akin to taking an M230 chain gun to an arcade shooting gallery
Peter


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PostPosted: Wed Aug 31, 2016 6:26 am 
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Location: Somewheres near the Atlantic
Chevota wrote:
I didn't mean the penny will fail, I meant it's leaking. If people take the gun is apart they might as well plug it 100%. How much power is lost I can only guess, plus the penny is likely moving around so the leakage will not be consistent along with power and poi. The effects are likely minor but I'd guess it leaks as much or more than an oem seal which I consider a must fix. I suppose if one used a penny because they didn't want to take the piston out of the gun then I'd say drop in a disc of thin rubber or a blop of silicone sealant, then the penny. Like most anything it's up to the owner if they just want it to work, or work its best, guess which kind I am ;)
airmec: Thanks for posting those pix. I've been trying to explain the barrel angle thing to people in text so that helps.


Penny can be removed and drop the gun back to 495 for non pal owners. As for leaking it's +/- 5 fps in chrony test.


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PostPosted: Sat Sep 03, 2016 4:15 pm 
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Location: United States
It may only deviate 5fps, but it may also be 50 lower than if plugged properly. I don't really know what the losses will be other than I do believe it's leaking, plus whatever dead air space the hole is. It's your gun so as long as you're happy, but I don't want others to think it's just as good as a proper plug. If people want to bump power then I assume they want max power, but maybe not.


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PostPosted: Mon Sep 05, 2016 9:55 am 
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Chevota wrote:
It may only deviate 5fps, but it may also be 50 lower than if plugged properly. I don't really know what the losses will be other than I do believe it's leaking, plus whatever dead air space the hole is. It's your gun so as long as you're happy, but I don't want others to think it's just as good as a proper plug. If people want to bump power then I assume they want max power, but maybe not.


I dunno if the 1/8" or less hole would make that much of a difference.


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PostPosted: Mon Sep 05, 2016 2:33 pm 
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Very true, but since I don't know how much it costs it would bug the hell outta me until I fixed it ;)
Picture a engine builder with pistons that all have holes thru them % wise as big as yours, and under the hole is a coin with a spring that may or may not hold that much pressure. Do you think he would plug it or say no biggie? Heck, if you were close by I'd fill it for you and we'd do before/after because I'm getting very curious, but I'm probably >3k miles away..
I do know at least one guy that put a hole in his main seal which lined up with the Xfer port, and he claimed that it acted like an extension of that port to deliver more air to the pellet. I call bs but who knows. If not lined up then I can only see a guaranteed loss just like any other compression loss or leakage.
What is your fps using what pellet(s) now?


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PostPosted: Tue Sep 06, 2016 8:55 pm 
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Joined: Mon Sep 10, 2007 10:56 pm
Posts: 208
Location: North America
I picked up a full power Optimus a while back, tore it down, cleaned it up. It was still too harsh and hold sensitive for my liking. Ended up with the short full power piston and weaker 495 spring. Shoots like a dream. No idea what the fps is like though.

About 7 years ago I had a full power .22 phantom that after the usual clean up and tuning was a fantastic full power tack driver.

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PostPosted: Wed Sep 07, 2016 1:32 pm 
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Posts: 111
Location: Ontario
two part epoxy and some toilet paper mixed together like paper mache, get a fine tipped needle and build up the hole, you can stick some tape inside the piston to stop it from poking out, while you are packing the hole up.

It will never blow out ever if done properly. I have done it to 3 airguns so far and all are shooting full power still and its been years. two part epoxy is one of the best things you can have on hand for airgun modding as it has MANY uses.


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PostPosted: Wed Sep 07, 2016 1:45 pm 
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Chevota wrote:
Very true, but since I don't know how much it costs it would bug the hell outta me until I fixed it ;)
Picture a engine builder with pistons that all have holes thru them % wise as big as yours, and under the hole is a coin with a spring that may or may not hold that much pressure. Do you think he would plug it or say no biggie? Heck, if you were close by I'd fill it for you and we'd do before/after because I'm getting very curious, but I'm probably >3k miles away..
I do know at least one guy that put a hole in his main seal which lined up with the Xfer port, and he claimed that it acted like an extension of that port to deliver more air to the pellet. I call bs but who knows. If not lined up then I can only see a guaranteed loss just like any other compression loss or leakage.
What is your fps using what pellet(s) now?


Using a penny to seal the relief hole and 1 washer. I got Avg 726 FPS with 7.9 ( daisy wadcutters ) and avg 759 with ( crosman 7.4grn competition wad cutters ) W/O I averaged 460 FPS to 475. That's not using a full power spring either.


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PostPosted: Wed Sep 07, 2016 1:59 pm 
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Location: Ontario
I think the spring will put too much pressure on it over time and slowly wear down the bond strength around the penny, because of the helical force of the spring. the hole in the piston will create more volume too and less compression, lowering your potential fps maximization.


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