When to change breech O rings?
I’ve just got myself the 1K4 PSI regulated tank and the 48 CU bottle but It seems to be eating air up. About 1 bar a shot. The shots are all 639-642 FPS so to me that’s a hell of alot of air for that power? TBH I thought even with the 12″ barrel I’d have more power too?? to me the rifle seams quite loud too but perhaps that’s just going from my S400 to the SS and having the valve and hammer right next to my ear.
Anyway I’ve been In contact with a member off here for a while who has been helping me with the reg and all other problems (Cheers mate 😉 ) and he mentioned putting some tracing paper over the breech and If It moved, I’m loosing air. I tried with a single ply piece of toilet paper pushed tight around the cocking bolt and breech area, fired a shot and It got pushed right up Into the carry handle 😆
My valve hasn’t had the O ring mod on but still should I be loosing that much air?
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The plastic washer that fits around the cocking knob stem it there so you don’t have metal to metal contact when cocking the gun.
If you take out the cocking knob out you’ll see the hole is not drilled/tapped all the way through.
Thanks Lang. So that should improve the seal then, Strange 😕 One of my valves has gone off to be O ring modded anyway so I’ll try it after that.
Plastic washer thing you say Brutus? I’ve had the breech out a few times so I’ve taken the bolt off and can’t say I’ve noticed the little plastic seal bit?? Are you saying that air can come out of the hole that the cocking knob screws In to then?? Will go double check about the washer anyway……
Just been looking at the position of the paper after your test shot and come up with yer another possable area to look at.
You have a cocking knob on your breach slide. If you remove the rubber cover you will see that there is a bolt holding it in place.
If you undo this slightly the cocking nob will raise. When it does you should notice a plastic washer thing – I think this plastic bit ensures an air tight seal.
Check if it is there and that it is not damaged.
Again this is guess work now but worth a check as it will only take a minute to do.
Sorry, can’t remember his name.
Believe it was sawtime
There was someone on here selling packs of them quite recently…
Sorry, can’t remember his name.
I need new o-rings for my breech. Where is the quickest way to get them?
Tried the same on the TH, Blocked the 2 side ports and blew from the barrel end. No air escaping again as I expected as this Is a tight seal on the TH. Then I tried my MK1 valve (airforce O ring modded). I opened the spring retainer so the derlin seal wasn’t coming In to play, plugged my finger over the hole In the TH and blew from where the bottle would be and the air escaped. Leads me to think that the MK1 O ring modded valve Isn’t doing It’s job?? correct?
Sounds correct to me, unless the air was getting through the spring-retainer’s thread? My memory is a bit fuzzy on how that old setup looks. Better off completely removing the spring-retainer, so there is absolutely no other way for the air to go except out the tophat or up alongside it’s stem.
The other o-rings (breech ones), the higher the air-pressure the better the o-rings seal, or so I believe. The pressure forces them to deform and create a tighter seal.
That’s that idea squashed then 😆 Cheers Lang. I’ve just stripped the rifle down and tried a quick test. Breech on the barrel the correct way round and making sure only 1 O ring Is sealing on the barrel I plugged my finger over the muzzle and tried to blow down the TH end of the breech. No air was getting out at all. I know there’s a hell of a difference between my puff power and 1400 PSI hitting them but the barrel O ring seemed a good seal even If It Is a very light seal.
Tried the same on the TH, Blocked the 2 side ports and blew from the barrel end. No air escaping again as I expected as this Is a tight seal on the TH. Then I tried my MK1 valve (airforce O ring modded). I opened the spring retainer so the derlin seal wasn’t coming In to play, plugged my finger over the hole In the TH and blew from where the bottle would be and the air escaped. Leads me to think that the MK1 O ring modded valve Isn’t doing It’s job?? correct?
I don’t know what durometer my O rings are but I got them as a direct replacement. Don’t know If the hardness will make much of a differance either as Sot says but worth a try?
Thanks for measureing your TH. Good to know mine Is OK but I didn’t expect that was the fault anyway.
Is It possible to get some slightly fatter O rings to give a good seal?
It was only the actual top of the top hat Brutus that I was going to get changed but only slightly. Still doesn’t explain why the barrel O ring Isn’t very tight though. I wonder If during manufacture they cut the o ring grooves slightly too deep hence why non of them are giving me a decent seal?? I guess the fatter O rings will fix the problem If you can get them to fit??
The o-rings on all stock rifles are a looser fit over the barrel than the one at the top-hat end. Given that the breech is a straight cut through the bore it has to be that the barrel is slightly thinner than the top-hat’s nozzle.
A fatter o-ring won’t fit, as it’ll be too fat to go into the groove. If it does fit in there’ll be no room for it to move under pressure.
Cheers Buzz, Will drop you a PM In a mo….
I don’t know what durometer my O rings are but I got them as a direct replacement. Don’t know If the hardness will make much of a differance either as Sot says but worth a try?
Thanks for measureing your TH. Good to know mine Is OK but I didn’t expect that was the fault anyway.
Is It possible to get some slightly fatter O rings to give a good seal?
It was only the actual top of the top hat Brutus that I was going to get changed but only slightly. Still doesn’t explain why the barrel O ring Isn’t very tight though. I wonder If during manufacture they cut the o ring grooves slightly too deep hence why non of them are giving me a decent seal?? I guess the fatter O rings will fix the problem If you can get them to fit??
If you increase the size of the TH too much, where yours measuerd 12.23mm, you will not get the breach slide to fit correctly.
I had this problem with a TH measuring 13.00mm and the breach slide recess measuring 12.48mm.
this very small difference stopped the rifle from fireing.
FYI Buss, durometer refers to the hardness of a material, or it’s resistance to permanent indentation. Tony changes to 90 from 80 (stock).
The breech uses #11 O-rings
I measured my tophat at .309″(7.849mm) and the barrel at .308″ Good seal all the way around
You definitely need the bigger o-rings, 90 durometer, I believe. I thought you already had them?
I got a few of the 90s, shoot me a PM and I’ll post a couple of them to you.
Well It made no differance. Looking at the pics on talon tunes I see Tony uses a fatter O ring so guess the after market O ring mod will help seal up better than the budget version airforce give you! Looks like I’ll be looking In to getting the O ring mod done.
Are those measurements for the top hat about right? I was thinking of getting another TH made up but slightly wider to create a better seal but still there’s the barrel to seal up tight 😕
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Sorry, can’t remember his name.
Hey Fusion & Pablouk
I got my O-rings from RHIGHZ (real name Royce). Very nice guy and easy to deal with.
Here’s his original post: http://talonairgun.com/forum/viewtopic.php?p=61382&highlight=#61382