Ancient Cometa -disassembly help?

Jump to latest Follow Reply
AR1911

AR1911

Member
Oct 23, 2021
11
1
TX, United States
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.
1685755189145.jpeg


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.
1685755291201.jpeg

1685755328205.jpeg


Suggestions welcome !
 
Triglav said:
It kind of looks like the mainspring is soldered or welded shut. Cometa has always used "wonderglues" in the production of their guns, I know that from my 300 that exploded. The cylinder wouldn't have ruptured, if the damn thing would've been soldered together properly; Note it wasn't :cry:
Click to expand...
I see no evidence of solder in the joint between tube and rear cap. In 1960 I don't think there was a wonderglue othre than epoxy. There is brazing on a couple places but none around that joint.

I did find a couple of witness marks, which indicates it may be threaded. I sure don't see a hint of threads in there though. Normally there would be one or two threads exposed.

Edit: I clamped it in a vise and put quite a bit of torque on the endcap. It did not budge.
Next step is probably the ultrasonic tank with heat. See if I can shake something loose.

IMG_4477.JPG

This thing is crudely built by modern standards. It's like it was hand-made with hammers, files and hand drills.
 
Last edited:
Upvote 0
AR1911 said:
I see no evidence of solder in the joint between tube and rear cap. In 1960 I don't think there was a wonderglue othre than epoxy. There is brazing on a couple places but none around that joint.

I did find a couple of witness marks, which indicates it may be threaded. I sure don't see a hint of threads in there though. Normally there would be one or two threads exposed.

Edit: I clamped it in a vise and put quite a bit of torque on the endcap. It did not budge.
Next step is probably the ultrasonic tank with heat. See if I can shake something loose.

View attachment 361654
This thing is crudely built by modern standards. It's like it was hand-made with hammers, files and hand drills.
Click to expand...
Hey,
First of all, I was referring to epoxy by commenting "wonderglue", it's kind of a slang for that where I live, we've got a ton of germanic technical slang words in my country, we're bordering with Austria to the north after all; Although I agree, I should've written epoxy instead, as folks'd probably interpret that as JB, I'm sorry about that.

...And yes, I completely agree on the fact that this thing was crudely, almost hand-madely built in a way, there's a ton of tool marks on the metal of that thing. A friend of mine has 3 Cometas, an old, not anymore in production model 200, a new production 220 Galaxy and a model 400 Fenix (a standard model). The old model 200, that he bought around the year 2000, which is now some 20+ years old (and still works, although it's been rebuilt a few times), also shows signs of crude manufacturing, not everywhere of course, but in some areas it sure does, like for instance where the two pieces of the cylinder were stitched together - they've separated a little bit, but haven't come apart entirely, the two portions are still sticking, but if you'd go down the cylinder with your fingernail, you'd catch that gap/extrusion of one part of the receiver sticking up. That's also where the receiver/cylinder of my model 300 ruptured. I was luckily OK, as was my friend spotting for wind, right next to me.

I wrote all about that Cometa 300 here (the review comes in three parts - this is a link to the first one):

An in-depth Cometa Model 300 review; Plus a couple of technical quirks about it... <PART ONE>

This is my very first airgun review, which is going to be about the Cometa Model 300, chambered in .177 / 4,5mm caliber. I will describe the entire journey, that I've had with this particular airgun, from the first impressions by the unboxing part, to the gun's unexpected, outrageous and almost...
www.airgunnation.com www.airgunnation.com
 
Upvote 0
So, I made a press fixture for support and also a piloted pusher. I loaded up the old barrel/breech-block and pumped up to 3 tons. I was afraid to go much more because the breech face and the end of the barrel are not 90-degrees to the barrel, so the load was a bit unbalanced to one side. Nevertheless, I added some kroil and heat while it was loaded, and then added more pressure (back up to 3-tons plus a little more). It finally popped and I was able to push it on out easily.

The Crosman barrel was slightly bigger at .5-7" OD, so I had to ream out my fixture a little, then loaded it back up. Using the same technique - pressure, Kroil, Heat - it would only give up about .015". I took it out of the press to look it over and saw there acually WAS a crosspin. I guess the slight movement was enough to make the joint visible. I drove the pin out and the barrel came out without further drama.

Now I just need to turn the new barrel down to fit, press it in, and then dress the breechface to match the angle of the original.
I'll need to cut the pivot bolt hole into the underside of the barrel

One thing I need to determine is how much to allow for the breech seal. As I have it now, the breech seal would need to be:

13mm OD
8.8mm ID
2.5-3mm deep/long
Is that anywhere close to a standard size? Is there a list or table somewhere I can use to fit this to a standard size?
Barring that, I guess I could turn some from teflon or delrin. Is there a better material?

IMG_4482.JPG
 
  • Like
Reactions: fishing43
Upvote 0
Turns out the ID of the breech block is almost identical between the old Cometa and the new Crosman barrel. I'll just need to shorten the breech end of the barrel about 1/2" and press it in, It will not be a tight press-fit, so I may have to fine some of that afore-mentioned WonderGlue. Then I'll need to cut the recess for the pivot screw in the underide of the barrel. That looks like it will take a 7mm endmill. Hopefully I have one at the shop. It will be tricky to cut without enlarging the hole.
Then dress the barrel to match the angle of the breechface. Probably will handfile that.

Still scratching my head over that powerplant disassembly. You don't suppose they assembled it from the breech end, then Wonderglued that breech cap on?
 
Upvote 0
Rich_B said:
Judging by the witness marks on the back of that receiver, I’d bet it is threaded together. I could be wrong. I would try a little heat back there and see what bubbles out. I had to heat the heck out of a Chinese gun to get their glue to break loose. It stunk up the whole basement for a week.
Click to expand...
I think that is most likely. I’ll take it to the shop for some heat and ultrasonic.
 
Upvote 0
You must log in or register to reply here.
Top Bottom
Back
Home
Forums
Resources
Menu