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Ancient Cometa rebuild

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AR1911:
Looking for some knowldge here. 
I got this Cometa springer in 1960 for Christmas. It got all the loving attention you can expect from an 8-year old.
Still have it, but it needs some rejuvenation. I'm hoping some experts are hanging around that can tell me how to get this thing apart.

Firstly, the barrel is shot - bend, gouged, and beyond repair. I bought a new barrel from Crosman that looks usable. I need the new barrel in the old breechblock.
Question - how do these separate from the breechblock? Do you press it out? If I have to I can turn it off (the new one) with the lathe and bore the old one out of the breechblock. I'm hoping there is an easier way.


Next issue is how to get the powerplant apart. The rear cap does not appear to be threaded, but I don't see any other way it is retained.

Suggestions welcome !

Toxylon:
Do you have any idea about the model of your Cometa? 1960 is a ways away, but even then, manufacturers usually stamped some info on the gun, usually on the breech block (which appears empty in the pic), but also on the receiver top, sides, front, rear etc. I would go over the gun to try and get some extra info.

Going by the modern Cometa springers, the threaded upright hole in the receiver between the trigger block hole and the cocking hole (where you see the mainspring) should have had a threaded bolt that has a block with an internal thread for a head. This bolt locks an internal rear block that keeps the mainspring in place. From the looks of it, I guess you have taken the bolt off.

Another locking feature is a thick crosswise pin some way back from the upright bolt. Both of these need to come off before the powerplant can be taken out. But, it appears you have taken the crosspin out, as well. At this juncture, the end block should come out, but apparently it doesn't.

I would try heating the end block up, to break any and all extraneous bonding that may be there. Soaking in a solvent such as brake cleaner or simply gasoline would be on the list, as well.

Very old springers have often seized, meaning the mainspring and piston won't move with the normal procedure, due to the parts jamming from lubes turning into glue over time, accumulated dirt, possible rust etc. Oftentimes this means needing to pull the piston, with the mainspring out via the cocking slot, using considerable force (while preventing damage to the gun).

Springer barrels are almost never changed by keeping the breech block and only changing the barrel - that's just too much work, with too many risks. I guess you have tried to locate an actual replacement before going the Crosman route.

Most airgun barrels are pressed in the breech block. I have no experience nor examples of taking the barrel out of the breech block and replacing it with another. But anything that was done at the factory can be undone. It's a matter of cost, skill and feasibility.

AR1911:
Toxylon,
    The tube is marked "Cometa 5" so I assume it is a Model 5. The only other marks on this gun are two "1"s stamp on the rear of the cylinder cap. It is normally hidden by the stock. 
    I emailed Cometa years ago to inquire about parts availability but got no reply.  I'll try again.

    Yes, everything that can come off easily is off, and the crosspin came out easily. It did not seem to be under any pressure.
    I have not tried cleaning it.  I have an ultrasonic cleaner that might be useful, with a strong solvent like Simple Green.  Then follow with a petrochemical solvent.
    I may be able to compress the spring and see if that will push that cap off.  Might take some creative fixturing.
    I expect the piston and spring are toast anyway so I'm not opposed to damaging them in the process.

As for the barrel, I'll make a press fixture and try loading it up on the press.

    Good suggestions, thanks!

AR1911:
I just did a simple Google search for "Cometa model 5" and see that Numrich has a NOS stock for it!   Cool. I'll buy that.
Looks like there is more info out there than there was last time I searched.

TF89:
I know next to nothing regarding how the barrel is mated to the breech.  I once tried to switch out a barrel on an older Chinese springer.  In that case a cross pin was used to secure the barrel to the breech.  It was very hard to see the pin as it blended almost invisibly.  My attempt was not a success, even after driving out that pin, which was hard to do, I could not get the barrel to budge.   I didn't have a press of any kind, and I'm sure it would have made all the difference.  I think using a press will give you the results you seek, just make sure there is not a cross pin.

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