The near-mint CZ Slavia 630 leaves each 4.5 mm / .177 pellet inside the bore .

[Ignition Override]

When there are no holes in a large cardboard box from six feet away, after charging the gun (decent resistance) and pulling the trigger, one then concludes that the pellet never went out the bore.
This beauty looks basically brand new. Naturally I gently use a very narrow cleaning rod to then push each pellet out the bore-before loading the next pellet.
The only ammo came in an old silvery round tin with the gun: " 4.5 mm / .177 euSta , ****(?) Wrage, Made in western Germany". The pellets easily roll downhill on a smooth surface.

Hardly a scratch anywhere on this gun; the bore has a brilliant shine as if it recently was nib. Pellets are gently inserted into the chamber s seen in several videos, but the compressed air pushes a pellet approx. 1/4 -1/3 the distance of the bore.
With (naturally) an empty chamber while feeling whichever amount of air come out the muzzle, I'm baffled whether a gun with so little wear could have an internal leak.

Each of about a dozen pellets (one at a time) were loaded exactly as seen in this video, and of course the barrel locked securely back into place, with the safety button pushed fully fwd. each time before pulling that trigger thingy.
Google searches have nothing about any sort of low gas pressure in the chamber. It only cost me $100.

SLAVIA 630 CZ

Airsoft pelletgun rifle

www.youtube.com

 

[JohnKSa]

It does look like piston and breech seals are available for the gun. I suppose it could be the spring, but I would think you would notice the lack of resistance when cocking if the spring were so bad the pellet goes less than an inch down the bore.

 

[Ignition Override]

The seller offered to refund my money.

Thanks. It seems odd that there are no other related topics found via Google.

 

[Rule3]

Nice looking rifle and that video was well done! I like the spoon spinner pellet trap!

Hope you can get it fixed and not cost a lot!

Here is a manual with schematic.

http://www.vzduchovka.cz/dokumentace/Slavia630-1_manual.pdf

 

[Ignition Override]

Rule3: Thanks, the seller included the manual. That seal is #20 in the diagram.

I would hope that there is either a spare like-new seal available (maybe learn how to oil/lube the seal), and find the best Youtube video (--some are in spoken Czech--) which depicts the easiest disassembly / re-, than to simply accept the seller's offer for the $100 refund.

Finally found a guy with the same issue - pellets aren't pushed through his bore.
Maybe the seal #20 is the same one which surrounds the chamber in his video?

CZ 630 Air Rifle Tear Down - How It Works

We had an old CZ 630 air rifle that wasn't pushing pellets down the barrel. We took it apart to clean and grease then test fired in a bucket of water in slow...

www.youtube.com

 

[JohnKSa]

If you're going to take it apart, be aware that even in a low-powered airgun like the Slavia, the main spring is pretty strong and is significantly compressed even when the gun is not cocked. If it releases when you are not expecting it, there is some potential for injury.

There are three possible issues:

Breech seal. This is the little seal around the opening in the gun opposite the breech (where the pellet is inserted) that you can see when cocking the gun.
Piston seal. This fits on the end of the piston inside the compression chamber.
Spring.

I would guess it's one of the first two, or maybe both of them. A weak spring would result in low power, but it would have to be really very weak for the pellet to go less than an inch down the barrel.

 

[Ignition Override]

Well, guess what...

after carefully taking it apart using two videos (one guy speaks Czech, but clearly show dis- and reassembly) the piston has No plunger/ piston seal on it. Just the metal end and tip.
Poking an aluminum cleaning rod shaft at the forward end of the 'cocking tube', it feels and maybe sounds like hard plastic - not metal. With the flashlight I can see something with concentric rings but don't know what the rear surface of a plunger looks like.

That must be the missing plunger. Sprayed in lots of WD-40 to let the tube sit vertical overnight and soak in.
Maybe that will then allow the tiny shaft of the (.22LR) cleaning rod to manually (kinda gently) be screwed into the tiny hole of what must be a very dried-out plunger, and possibly pull it out. Some oil or gunk must have dried over some years to seal it.
The well-vetted seller used the gun in his basement years ago and then let the gun sit. When I received it and first cocked the rifle, the bolt must have yanked itself immed. clear of the stuck plunger.

The beige-colored plastic plunger or seal at 6:00 is missing. My bolt has only the metal surface and tip on the forward end. This is a widespread problem.
If the WD-40 can easily loosen the stuck overnight, maybe the cleaning rod shaft's screws can get a good grip. If not, maybe there is a low-cost version some sort of extremely long "tweezers" to offer a Plan B and squeeze into the outer circular edges.

CZ 630 Air Rifle Tear Down - How It Works

We had an old CZ 630 air rifle that wasn't pushing pellets down the barrel. We took it apart to clean and grease then test fired in a bucket of water in slow...

www.youtube.com

 

[JohnKSa]

Be sure before you reassemble everything (with a new piston seal, I seriously doubt the old one can be salvaged) you clean the compression chamber carefully and relubricate with a spring-piston compatible lube that won't damage the seals.