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Alstone · Moderator & Site Supporter

Been busy just lately so haven’t had much time for airguns, plus The farm I had a shoot on has been sold so that’s another loss. But I still have my rat shoot on a farm with several barns.
So with events I have decided to apprise what guns I have and what I need, I always us either my Tx200 or QB-AGS for general shooting and ratting, plus all my guns are .177 cal. When Barn shooting I usually set myself up one end of the barn nice and comfy a beer or two some sandwiches and a straw bale as a shooting rest. But I get the occasion when I need to move around from one barn to another, and what with a rifle plus pistol it gets a bit difficult avoiding farm machinery and junk.

So I have decided to cobble together a ratting gun, the basis for this project is my SA80-QB78, which I don’t use and is not the easiest of guns to handle. One big problem with the SA80 was the barrel which never was much good as far as accuracy was concerned, so this I disposed off and replaced it with a .22 cal Crossman 2240 7.5” barrel, which I had spare from my .177 cal auto feed 2240.
So far I have a very short .22 QB78 with Red Dot sight and stubby silencer, I still have to sort out a butt and tidy it all up a bit and I’m not sure which way to go regarding the Butt.

Al

AirGunEric · Site Admin

That's pretty nitfty!

Did you machine up a collar for the barrel to fit the QB breech?

There does appear to be some extra bits/pieces, however. Mr. Green

Alstone · Moderator & Site Supporter

Your right Eric there are a few extra bits in there. To accommodate the 2240 barrel I needed to make a sleeve to fit the barrel to the breach, this sleeve was heat shrunk on to the 2240 barrel and machined down to fit the breach.
I decided to do away with the O ring seals which are a pain in the a$$ on Qb’s, and use grub screws to hold it in place which gives it a good tight seal with the transfer port.
This has another advantage in that the loading tray is removable and held by a small screw in the breach side, this gives access to the large screw that fastens the breach to the valve tube, so now you can remove breach and barrel together, no more O rings to bother about. This method could be useful on standard QB rifles, as you cannot do anything on a QB with out removing the barrel first and destroying the seals.

Al

Barrel and Separate loading tray

Parts fitted

Small screw holding loading tray

Slavia · Moderator

I doubt it's going to make it on the cover of Triggers and Trollops Quarterly, but a nice job none the less. It shouldn't be too hard to make a butt for it. If it were mine I would only be concerned with weight and parts enclosure, and let appearance evolve from there.

AirGunEric · Site Admin

I like that loading tray idea- the QB breech/barrel setup is a bit of a pain normally- and that certainly alleviates it.

Alstone · Moderator & Site Supporter

I think I’m getting somewhere now? I have shortened the body of the SA80 and I think it looks more in proportion now, done away with the original butt and pushed the new one out and down, and fitted new streamlined side plates.
Just waiting for some high scope mounts to improve the shooting position, and I think I’m about there.

Al

AirGunEric · Site Admin

How did you accommodate what appears to be a relocated trigger?

Alstone · Moderator & Site Supporter

It was simple really ( See first photo on this post ) I just linked the new trigger to the old with a push rod in a tube, then hid the original trigger in a false magazine holder, which indecently will take a NATO 5.5mm 19 round magazine. When you push the magazine on, the old trigger unit pushes the 5.5 rounds down into the magazine, not that it serves any purpose but scares the sh!t out of new guys at the airgun club.

Al

AirGunEric · Site Admin

Alstone · Moderator & Site Supporter

Some of you may remember my QB-SA80 creation, well it never was one of the most comfortable guns to shoot, the weight was mostly toward the butt and I had trouble sighting it. So I decided to rip it down and make a gun especially for Ratting, I do have access to a farm with a few barns where I go rat hunting, usually it consists of making myself comfortable behind some bales with a couple of beers and away you go. But now things have been moved around and the best barn is clutter with tractors harvesters and junk, and moving around with a full size rifle can be difficult, so what I needed was a short gun in .22 cal which I could move around easily.
So this was the out come all my guns are .177 cal and rather than buy a new barrel I used a spare .22 barrel 7.5” long that came with a 2040 pistol, I made a collar to make up the difference between the Crosman barrel and the QB breach this I heat shrunk it on to the .22 barrel and machined down to make a tight fit in the breach, This was grub screwed in from the top, and being a good fit there is no blow past and no O ring seals are needed. The front end of the barrel is fitted with a tube to make up the length to clear the Co2 tube, the end of the tube is threaded ½” unf for a silencer.
As for ratting I haven’t tried it yet but after shooting a tin of .22 fields yesterday I’m impressed with it performance out to 20m and the comfortable layout of the gun itself.