Leather breech seals or o ring?
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Leather breech seals or o ring?
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Topic: Leather breech seals or o ring? (Read 6364 times))
JonnyReb
GTA Senior Contributor
Posts: 3759
Where is John Galt?
Leather breech seals or o ring?
«
on:
August 07, 2011, 10:04:27 AM »
I have an issue with an old german break barreled diana and i was wondering if you guys have any thoughts on it. This gun does not appear to have been shot alot and so when i noticed the barrel has reverse droop, i assumed that someone had let the barrel go while cocking and had bent the barrel. Looking closer i now know the barrel isn't bent but rather the breech block sinks too deep into the forks, it goes slightly PAST the place where it should stop.
Thinking that the original seal was probably leather i wondered if that could be the problem as shimming the breech seal helped quite a bit and almost has the top of the breech block now flush with the receiver tube.
The action on the diana 25 is very tight and straight, it's not worn out at all, has no play in it and i can't figure out how the breech COULD be slightly angled upward unless it was designed this way or did the original leather seal allow for different positioning of the final resting spot for the breech? If my shimmed out o ring is holding the breech off the face of the receiver a bit wouldn't this cause POI to change as the o ring flattens out? Is there to be no metal to metal contact between the breech and receiver face? Wouldn't a leather o ring flatten out entirely as it broke in? Any reason for me to try a leather seal? Thanks for your thoughts on this.. J
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Bob P
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Re: Leather breech seals or o ring?
«
Reply #1 on:
August 07, 2011, 02:18:11 PM »
Im not familiar with that rifle + Im no expert! Im still experimenting with this myself. But depending on the rifles lock up, 0.020 - 0.030 protrusion of the O-ring is what has worked for me. I assume, if the elasticity of the O ring is greater than that of the lock up of the rifle, you will get POI shifts until its properly seated/fitted or worn down. Atleast thats been my experience.
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JonnyReb
GTA Senior Contributor
Posts: 3759
Where is John Galt?
Re: Leather breech seals or o ring?
«
Reply #2 on:
August 07, 2011, 09:55:51 PM »
Thanks Bob, and if there were no protrusion of the o ring, would the guns breech face make metal to metal contact with the barrel block? This old gun does and i'm wondering if it were in the design for the leather seal/o ring to hold the metal off the metal? I don't want to try to fix something thats not broken and i just can't much online info on this gun. J
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north caroline
RedFeather
GTA Senior Contributor
Posts: 4741
Re: Leather breech seals or o ring?
«
Reply #3 on:
August 07, 2011, 10:53:06 PM »
How much up-angle are we talking about? More importantly, how does it shoot with the O-ring? I'm not sure how proud the original leather breech seals are in these guns. Most of mine seem to be mushed flush. So long as the gun shoots well and seals, I would not worry about it. BTW, some guys use square sectioned leather boot laces for replacement breech seals. My old Gem (circa 1913) is currently wearing an old auto a/c o-ring. I'll probably do the shoe lace thing later.
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Bob P
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Re: Leather breech seals or o ring?
«
Reply #4 on:
August 08, 2011, 12:04:15 AM »
One thing for sure, if your gonna hunt or eliminate pest with the rig, the metal to metal clash is not gonna be to your advantage! If thats the case, I would replace the leather seal with a poly ring & never look back.. But, if your just gonna plink, id take Red Feathers advice & just see how it shoots.
BTW, if you decide to change to a poly seal,I can probably make you one.
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JonnyReb
GTA Senior Contributor
Posts: 3759
Where is John Galt?
Re: Leather breech seals or o ring?
«
Reply #5 on:
August 08, 2011, 01:49:56 AM »
Nice of you to offer and Bob and thanks Red for joining in. The angle upward was noticable, lets say 1/2 of rise from the breech to the muzzle. When i shimmed the o ring i got no more metal to metal contact and the upward angle was dramatically reduced to almost normal. What i was wondering though is if the design of these dianas called for enough seal to be out so as to hold the breech at the proper spot. The original specs did call the the one shim already in the gun. I added a 2nd. I was just going to try to find a cheap piece of leath on ebay for making a piston and breech seal. Gonna grab some harbor freight hollow punches tomorrow for another project and will try them for making a leather breech seal. J
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north caroline
RedFeather
GTA Senior Contributor
Posts: 4741
Re: Leather breech seals or o ring?
«
Reply #6 on:
August 08, 2011, 01:31:28 PM »
Too bad Tandy is pretty much gone if not defunct. Old belts (solid leather, not pressed) are another good source. The problem with the leather breech seals is they flatten with age and as oil soaks into them. Do some Google searches on making leather seals. I think Gaylord's blog has one and Jim in Pittsburgh who hangs out on the Vintage. If you have trouble finding the links, just ask there and they will point you to it.
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JonnyReb
GTA Senior Contributor
Posts: 3759
Where is John Galt?
Re: Leather breech seals or o ring?
«
Reply #7 on:
August 08, 2011, 02:30:40 PM »
Thanks Red! J
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north caroline
northern lights
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Re: Leather breech seals or o ring?
«
Reply #8 on:
August 08, 2011, 04:58:34 PM »
I have rubber o-ring in both the dasiy 250 an diana 25. I think the low vel you are getting is from bad leather pistol seal. Did you put any oil down chamber breech an let it set for a couple of days
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JonnyReb
GTA Senior Contributor
Posts: 3759
Where is John Galt?
Re: Leather breech seals or o ring?
«
Reply #9 on:
August 09, 2011, 12:10:50 AM »
I did oil it with silicone oil and got a few fine sprays out of it along with smoke upon firing it, i really think it's oiled well and i'm not sure why it's so weak but i will open the gun up in the next few days and maybe the problem will be obvious. I hope. J
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north caroline
Bob P
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Re: Leather breech seals or o ring?
«
Reply #10 on:
August 09, 2011, 08:27:44 PM »
No prob, your welcome Jeff.
Bob.
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lloyd-ss
Bob and Lloyd
GTA Senior Contributor
Posts: 3567
Real Name: Lloyd
Re: Leather breech seals or o ring?
«
Reply #11 on:
August 10, 2011, 11:16:10 PM »
Jeff,
I don't think I have ever seen a break barrel where there was not metal to metal contact at full closure. If you remove the breech seal and close the breech on a piece of paper does it appear to give full contact, not tight on the top, and loose on the bottom? You said you are sure the barrel is not bent upwards, correct? If you remove the breech seal where does the detent hold the barrel?
I've made a few leather pistons and had good luck. No breech seals, though. Followed Tom Gaylord's instructions: making a mold, soaking the leather, letting it dry in the mold, etc. I had some leather coasters that were about an 1/8 of an inch thick. Let me know if you need some. I've got plenty.
Lloyd
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Central Virginia
An engineer by nature. The affliction is knowing that everything can be made better. It is easy to make one that works, but it is difficult to make on that works WELL.
My YouTube channel is Airgun Lab
JonnyReb
GTA Senior Contributor
Posts: 3759
Where is John Galt?
Re: Leather breech seals or o ring?
«
Reply #12 on:
August 10, 2011, 11:37:29 PM »
Hi Lloyd. Thanks for jumping in. So far as i can tell, without having disassembled the gun yet, there must be some play in the action or me adding the shim would have made no difference in the slight leveling effect the shim gave, correct? As tight as everything seems, it's hard for me to believe that wear is the issue, and if it was caused by inadvertantly decocking the gun, i just dont see how damage could take place in this particular spot as it would seem to be one of the strongest places on the whole assembly. I'm hoping that when i tear it down in the next day or three, something will leap out at me as the issue, or non issue as the case may be. Also, i put vacuum on the muzzle with everything closed and there was only a slight leakage which i would expect. So the breech/piston seal is doing it's job as it should. If i were to leave the gun as it is and use open sights it would shoot fine. When i mount a scope i'll bet it will be shooting signifigantly high. I'm going to do the tear down first though, and see what i see.
J
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north caroline
JonnyReb
GTA Senior Contributor
Posts: 3759
Where is John Galt?
Re: Leather breech seals or o ring?
«
Reply #13 on:
August 13, 2011, 10:05:54 PM »
I did get the 25 opened up today and never having seen a leather seal i was a bit confused. Looked like an orange synthetic seal to me. Picked at the top ring and it was leather set around some kind of orange synthetic base. It was in fairly good shape and i guess i'll reinstall it after soaking it in neatfoot oil for a few days. Still waiting on the replacement spring although the one installed didn't seem bad. Everything inside is pretty rough though and i spent hours polishing various spots on pretty much every internal part.
Any problem using regular macarri lubes with leather? Should i use something else?
I can't for the life of me see why the breech is sinking in so deep, it truly looks like it's going just where it is supposed to, the detent is not worn and the breech seal lines up fine on the compression tube face. Maybe it came like this?
Now to get it all reblued and reassembled. J
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north caroline
lloyd-ss
Bob and Lloyd
GTA Senior Contributor
Posts: 3567
Real Name: Lloyd
Re: Leather breech seals or o ring?
«
Reply #14 on:
August 14, 2011, 09:16:11 AM »
Jeff,
Regarding the leather piston, if the velocity is low, and you are going to stick with the same leather piston seal, you might try just flaring it out a little, and then lightly breaking the glaze on the O.D. of the leather with some 220 grit paper to allow it to re-seat itself. Sometimes they can be re-rejuvenated, sometimes not. You should have to work a little to get the leather to fit into the cylinder. If the resiliency is gone, its probably shot. But like I said, they are easy to make.
Lloyd
Logged
Central Virginia
An engineer by nature. The affliction is knowing that everything can be made better. It is easy to make one that works, but it is difficult to make on that works WELL.
My YouTube channel is Airgun Lab
JonnyReb
GTA Senior Contributor
Posts: 3759
Where is John Galt?
Re: Leather breech seals or o ring?
«
Reply #15 on:
August 14, 2011, 12:15:28 PM »
Thanks Lloyd, thats just what i'll try and failing in that, did find a leather seal here stateside for sale so i may just order a replacement.
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north caroline
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Leather breech seals or o ring?