GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: froggy2x4 on June 12, 2019, 12:04:33 PM
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I bought a refurbished chaser kit from PA not long ago to tinker with and maybe mod it a bit as I'm still fairly new to the game.
works fairly well in pistol form but after looking at the rifle barrel it seems the outer barrel o rings are fairly chewed up..
Now I need a bit of help finding spares. I believe I got the measurements down to 1mmx8mm from the o ring store but not sure the material or hardness, is it possible for someone to confirm or correct me?
Also I was wondering if anyone had any info on opening up the transfer port, I Googled around and didn't find much even with the other rebrands.
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They are an oddball cross section. Not the common size of 1mm, rather 0.8mm instead. M0.8x8
I could not find them on McMaster or Amazon. Theoringstore has a small selection of M0.8 in Buna-N 70D but not this particular size.
I tried the M1x8 size and they would not fit. The way I remedied it was to load the O-ring onto a shank and insert it into my drill press, then use a Dremel with a rubber polishing wheel to carefully abrade down the OD.
I know it sounds crazy but being able to shape an O-ring has gotten me out of a bind many, many times.
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They are an oddball cross section. Not the common size of 1mm, rather 0.8mm instead. M0.8x8
I could not find them on McMaster or Amazon. Theoringstore has a small selection of M0.8 in Buna-N 70D but not this particular size.
I tried the M1x8 size and they would not fit. The way I remedied it was to load the O-ring onto a shank and insert it into my drill press, then use a Dremel with a rubber polishing wheel to carefully abrade down the OD.
I know it sounds crazy but being able to shape an O-ring has gotten me out of a bind many, many times.
I'll give that a try and thank you for the info. Just need to make a micshift drill press and I'll be all squared away.
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Also Jason, did you make your own shank for the o ring? I'm going to attempt to use a hand drill with a drimel to make it all work. Have 100 1x8 Rings coming tomorrow for some trial and error
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I just use a transfer punch as a shank to hold the O-ring. Or you can slip it onto the smooth end of a drill bit.
To get a feel for it, my suggestion would be to experiment first with a thicker O-ring...one that will stretch and hug tight to the shank to help prevent it from slipping when the rotating polishing wheel touches it. Bring the wheel in slowly and give the O-ring a very light touch, otherwise it will try to squirt away. The smaller the O-ring's cross section, the lighter the touch required. Fortunately in this case you're only removing the tiniest bit of material so it won't take much. If you struggle with supporting the O-ring, use an emery wheel to grind a shallow groove in the shank.
Oh and it may go without saying but don't just abrade a flat on the OD. You want to finish up by hitting the edges lightly to round them over so the O-ring won't snag as you push the barrel into the receiver.
Lastly, I don't know how consistent SPA is with their machining tolerances over the long haul but on both my CR600W and CP1-M, the barrel was nearly a slip fit to the receiver. Meaning the O-ring is responsible for sealing only the slightest gap and the 0.8mm-thick OEM O-rings were a super tight fit. If you have to abrade yours down to 0.7mm or something like that in order to keep them from getting sheared off on installation, I wouldn't hesitate for a moment to go with it.
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While waiting for a parts order from SPA, I found I could use The O-Ring Store p/n 80X008.4 Metric Buna O-ring, 0.80mm x 8.4mm, Duro 70 - These work, but they are $0.60 each.
http://www.theoringstore.com/index.php?main_page=product_info&cPath=117_12_2160&products_id=40982 (http://www.theoringstore.com/index.php?main_page=product_info&cPath=117_12_2160&products_id=40982)
According to SPA the actual size is 7.9mm ID x 0.8mm c/s
I don't know if parts can still be ordered from Julie at SPA, but I bought the O-rings there on 7-4-18 for $0.10 each. I also bought other parts so unsure what the cost of shipping for just O-rings would be these days.
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I kinda do the same. The o ring slot in the breech of the .257 that Travis did for me is small, as he wanted it to be tight. However, a bullet will NOT pass thru.
I used a shank form a center punch set to put the o ring on, turned it in the hand drill here at the bench, and held a piece of 400 bench roll to it This allowed me to rock it back and forth which gave a rounded surface and does a fine job now. (It is 90 Duro).
I made a half soz at the same time and now have a fast supply when needed. LOL.
Oddly enough, the Rainstorms have a transfer port in the barrel, with NO rings for or aft. Everyone tells me that the barrel fit is so tight that it is not needed. Wellm mine is apparently oversized in the breech. Ended up using tape with the port cuct out of it. . GRRRR!!!
Knife
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I just use a transfer punch as a shank to hold the O-ring. Or you can slip it onto the smooth end of a drill bit.
To get a feel for it, my suggestion would be to experiment first with a thicker O-ring...one that will stretch and hug tight to the shank to help prevent it from slipping when the rotating polishing wheel touches it. Bring the wheel in slowly and give the O-ring a very light touch, otherwise it will try to squirt away. The smaller the O-ring's cross section, the lighter the touch required. Fortunately in this case you're only removing the tiniest bit of material so it won't take much. If you struggle with supporting the O-ring, use an emery wheel to grind a shallow groove in the shank.
Oh and it may go without saying but don't just abrade a flat on the OD. You want to finish up by hitting the edges lightly to round them over so the O-ring won't snag as you push the barrel into the receiver.
Lastly, I don't know how consistent SPA is with their machining tolerances over the long haul but on both my CR600W and CP1-M, the barrel was nearly a slip fit to the receiver. Meaning the O-ring is responsible for sealing only the slightest gap and the 0.8mm-thick OEM O-rings were a super tight fit. If you have to abrade yours down to 0.7mm or something like that in order to keep them from getting sheared off on installation, I wouldn't hesitate for a moment to go with it.
awesome, thank you again. figured if i could learn some of the tricks to can keep this bad boy working it would be some decent knowledge for either a bandit later or the pp750 when it comes out later in the year
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Recently I acquired a Diana Chaser with a torn barrel o-ring and have contacted two of the GTA posters to find out more info.
Since the O-Ring store wanted a minimum run of 1,030 @ .35, that was not happening.
I contacted Captain O-Ring and wrote: I am trying to locate two sets of O-Rings for a Diana Chaser Rifle/Pistol kit .177 caliber airgun.
One specific size is 7.9mm ID x 0.8mm c/s.
The O-Ring Store offers a close substitute for an excessive quantity of 1,030.
80X008.4 Metric Buna O-ring, 0.80mm x 8.4mm, Duro 70
Jonathan at Captain O-Ring replied: Unfortunately we don't stock either of those two sizes. We haven't worked with the Diana model that you mentioned. The closest thing we have on hand is 8mm ID x 1mm CS, but it might be too thick for you if you need a 0.8mm CS.
Just as I expected. Looks like I will make an order to Bagnall and Kirkwood in the UK and wait...
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I bet you 10 bucks you don’t lose any fps with out the o rings around the barrel. Worry about the breech face o ring nobody likes a blast of air in the face. Don’t run them on 2 Diana chasers cause I couldn’t find any.
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I bought a refurbished chaser kit from PA not long ago to tinker with and maybe mod it a bit as I'm still fairly new to the game.
works fairly well in pistol form but after looking at the rifle barrel it seems the outer barrel o rings are fairly chewed up..
Now I need a bit of help finding spares. I believe I got the measurements down to 1mmx8mm from the o ring store but not sure the material or hardness, is it possible for someone to confirm or correct me?
Also I was wondering if anyone had any info on opening up the transfer port, I Googled around and didn't find much even with the other rebrands.
I have a 177 and opened the barrel tp to match the breach and lost velocity
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I just turned the barrel and opened the grooves slightly to fit the 8x1 oring, lube good and she fits tight.
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I just turned the barrel and opened the grooves slightly to fit the 8x1 oring, lube good and she fits tight.
That makes a lot more sense than chasing the odd sized rings.... the sad truth is that some of us don't have the ability to do that since we are lacking the tools.
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I just turned the barrel and opened the grooves slightly to fit the 8x1 oring, lube good and she fits tight.
That makes a lot more sense than chasing the odd sized rings.... the sad truth is that some of us don't have the ability to do that since we are lacking the tools.
+1
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I just turned the barrel and opened the grooves slightly to fit the 8x1 oring, lube good and she fits tight.
That makes a lot more sense than chasing the odd sized rings.... the sad truth is that some of us don't have the ability to do that since we are lacking the tools.
I'll turn it for you if you want, just send it to me post paid for return. Takes all of 5 minutes to check for run-out and widen the groove.
I honestly don't know why they designed the groove like that, it's not really doing a lot, most the air will stay in the TP area even with damaged rings.