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PostPosted: Mon May 09, 2016 4:37 pm 
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Joined: Thu Mar 24, 2016 7:33 pm
Posts: 240
Location: Yukon
So I have been given a 1968 model Slavia 620. It was pretty rough but I am bringing it back. The previous owner had swapped the original spring for a heavier shorter one. Since it was shorter he added a separate 3 inch chunk to fill the gap. Anyways after ordering the heavier spring for my phantom 22, I took the Phantom 500 fps spring and installed into my 620. Also added 10 pennies for good luck. Anyways it is old but still shoots like a 620. Deadly little groups and Im guessing about 500 fps.
My issue it that I am missing the original screws (2) that install onto the barrel where the breaking action takes place. The action may simply be worn or perhaps the original screws would fix my problem. I have a single one now though do not know its pedigree.
The problem is that the gun over closes. If you can follow me the barrel ends up pointing slightly too high, and above the line of the air chamber. While I simply use a bit of pressure to re-align the barrel before shooting it is an issue I would like some advise with.
What mechanism keeps this pointed level?
Anyways love this little 177 as it makes me 50 years younger to when I bought a 620 from Woolco for 13 bucks. I have seen quite a few 618 and 622 around, where are all the full sized 620's.?
I would love to find one in better shape for the right price.


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PostPosted: Tue May 10, 2016 12:02 am 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1271
Location: United States
I wouldn't shoot it like that, it'll only pound the loose parts looser and/or pound the breech where the top of the barrel block meets the receiver. Plus without a tight breech seal it'll leak air and pound harder.
So I'd get the oem main screw if you can and see if that fixes it, if not go from there and figure out how to make it right. If you keep shooting it you're lessening your chances it'll work with a new screw. If you can't find one I'd imagine one from some other gun would fit, problem is figuring out what gun. Otherwise I'd just make one. A home made one that is tight is certainly better than what's in it.


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PostPosted: Tue May 10, 2016 10:08 am 
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Joined: Thu Mar 24, 2016 7:33 pm
Posts: 240
Location: Yukon
The only new OEM parts are for 630 and beyond. The screw I have seems to work (tightens) but the original had a second screw that worked as a lock I suppose by. One of the 2 had a notch on the head, though not sure which one. I am checking my old Husky chain saw parts box for something that may work, but am uncertain if the screws alone were the fix. Perhaps a thicker O ring on the barrel with help tighten things up.
Even with this issue it shoots hard and accurately.
Its not worth spending much money on this rifle due to stock and metal condition, so a simple fix would be my only sensible option.
t


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PostPosted: Tue May 10, 2016 8:21 pm 
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Joined: Sat Jan 25, 2014 9:16 pm
Posts: 1271
Location: United States
It shooting well is a good sign, but that barrel pointing up part makes me nervous. If the screw is too small in diameter at either the barrel block or the side under the head, then the gun will pound on that like a hammer.
Or could it simply be a bent barrel? They do bend upwards if you let them slam closed under spring pressure. You said you move the barrel back a bit so that's what makes me think the screw fit is loose.
Don't worry about the second smaller screw right now, it's just to prevent the bigger screw from loosening. You can either deal with that later or simply use loctite.
The reason the guns can hammer themselves is because inside they're kinda like a spring loaded slide hammer, but with a pneumatic cushion to greatly reduce impact.
Here's a couple vids that can help if you aren't familiar with what goes on inside:
http://arld1.com/pistonpelletdynamics.html and click the "second stage" dot to actuate the animation.
http://tinyurl.com/p5r8h5z at ~ the 10sec mark you can see the gun recoil, which is the spring launching the piston. Then you see the gun jump forward rather harshly, which is the piston hitting the end of the stroke.
In the animation you can see the piston move down the tube, then the red is supposed to be the high pressure generated for launching the pellet. I don't think it's an accurate representation but certainly better than nothing. Point is that if you have air leakage then the piston will hit the end of the receiver tube harder than normal, and it is capable of breaking things, even ripping the gun apart. What you said about moving the barrel before firing makes me worry you're opening the breech and letting air escape causing the piston to hit harder. If the bolt is loose it likely means the breech seal is not sealing anyway. Even if it was sealing perfectly, the gun still hits hard enough to pound on loose parts. For example if the stock screws are not tight the gun can pound on those and break the screws or elongate the holes in the wood, even break the stock. So the stock, and barrel, has to be tightly attached to survive.
This is why springers have trouble with scopes btw, especially dovetail rails. That piston impact hits the gun so hard it pounds the gun out from under the scope even tho it's rather securely clamped to the rail.
If you can, remove the screw and post pix of it and the holes with measurements. Or at least just inspect it for tightness and decide for yourself if it's ok.
If your screw is unsat, I'd assume the 630 screw would be your best odds. Other people here have the 630 and I'm sure one will be kind enough to remove his and measure it along with pix so you can see if it will work.
So let me/us know....


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PostPosted: Sat May 14, 2016 9:31 pm 
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Joined: Thu Mar 24, 2016 7:33 pm
Posts: 240
Location: Yukon
Just back from the mountains and no internet. Beautiful out there. i will watch the videos but want to thank you for the time you've spent so far responding.
I will keep u posted.
cheers
tango


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