Airsporter RB2 tune

[Oddbob08]

My memory isnt what it used to be 20 years ago, so I measured some seals to verify my statement.
Bear in mind that I find measuring seals accurately difficult, but these were all measured by me with the same cheap digital calipers, so the comparison should be valid:

BSA black seal with some, but not very much wear: 29,15+mm

Maccari BSA seal, has been tried in a gun but not shot much since the tube was too big: 29,2+mm

Knibbs BSA seal, unused: 29,7mm

Useful to know, thanks for taking the time to do the measuring. I went on the Maccari site and he's not listing any BSA seals at the moment, and gives the impression that if you ask him, you're done for.....

[Shed tuner]

Useful to know, thanks for taking the time to do the measuring. I went on the Maccari site and he's not listing any BSA seals at the moment, and gives the impression that if you ask him, you're done for.....

lol - he's a grumpy old git, but he's fine. Ask him.. if a few ask, he does a run.

[Oddbob08]

lol - he's a grumpy old git, but he's fine. Ask him.. if a few ask, he does a run.

[evert]

Useful to know, thanks for taking the time to do the measuring. I went on the Maccari site and he's not listing any BSA seals at the moment, and gives the impression that if you ask him, you're done for.....

I think it has more to do with him being tired of getting the blame when his parts dont work in crappy guns.
If you put his seals in a lightning with bad cylinder and the infamous reverse choke barrel, you will get bad results.
And people who dont know better will blame the maker of the parts they hope will fix a bad gun.

[Shed tuner]

I think it has more to do with him being tired of getting the blame when his parts dont work in crappy guns.
If you put his seals in a lightning with bad cylinder and the infamous reverse choke barrel, you will get bad results.
And people who dont know better will blame the maker of the parts they hope will fix a bad gun.

yeah, all true....

[Oddbob08]

I think it has more to do with him being tired of getting the blame when his parts dont work in crappy guns.
If you put his seals in a lightning with bad cylinder and the infamous reverse choke barrel, you will get bad results.
And people who dont know better will blame the maker of the parts they hope will fix a bad gun.

Airguns are like any mass produced commodity, there will be good ones and bad ones from any manufacturer, people don't get that. I have a Lightning with an out of alignment scope rail, I bought adjustable mounts. I have bought several brand new Weihrauchs and not had one which didn't have a problem of some sort yet any thread where someone asks what people think of a certain gun and there will be several replies saying don't buy one, get a used HWxyz. When people start stripping them and thinking they can 'make it better' many do so with more enthusiasm than knowledge or ability. I probably have more enthusiasm than ability, but am prepared to spend the time getting it right rather than blaming a manufacturer.

Meanwhile, back to the RB2, I just need a bit of tubing to sleeve that transfer port down and I can get started on the rebuild. I may even try the same trick on my Eclipse, another long-length TP rifle, but bought based on rose-tinted memories of reading a test in Airgun World on the carbine in .22 cal, by Rod Lynton. If anyone has a copy of that test they could scan I'd be most grateful, or would even buy the magazine if they wanted to sell.

[Oddbob08]

My last post mentioned quality of mass produced items, then I open my email from Airgun 101 and Andy on Air is testing a nice looking R10 and mentions the same thing, anyone would think I stole his script....

[Oddbob08]

Now I'm stumped.

The slide is not pushing the piston back far enough to latch onto the sear. It can be done by hand (with no mainspring fitted), so there is no binding. A trial fit of a mainspring seemed to push the slide too far forward to get the pin into the linkage.

Did the RB2 come with difference sizes pistons? Is the rod threaded into the piston?

[Shed tuner]

can the slide push it back far enough with no mainspring (or a very weak one) fitted ?

[maximus]

Now I'm stumped.

The slide is not pushing the piston back far enough to latch onto the sear. It can be done by hand (with no mainspring fitted), so there is no binding. A trial fit of a mainspring seemed to push the slide too far forward to get the pin into the linkage.

Did the RB2 come with difference sizes pistons? Is the rod threaded into the piston?

Does the lever travel to the point where it hits the trigger guard? If not its probably that the spring is becoming coil bound or, if you have a top hat fitted as well as a guide they could be touching together before the latch rod engages with the sear. If its the spring you just need to take a one or two coils off, if its the guide just shorten by a couple of mm.

Regards Max

[Shed tuner]

How long is the transfer port on and what's it's ID for the RB2

see my opening post on this thread...

[Oddbob08]

With no spring fitted, the slide will not push the piston back far enough, as if the slot in the skirt was too long, or the rod in the piston is too short. The cocking lever is in contact with the trigger guard.

With a spring fitted (a weak one for testing), the tail of the piston is so far forward that it pushes the cocking slide forward too far to fit the pin in the cocking link. This gives the impression that the head of the piston is too short, but also that a shorter slot in the piston wouldn't work either as it would collide with the cocking link spur when the gun was fired.

Both of these symptoms suggest that the piston is wrong. There must be a different piston available, maybe an export model, and my box of bits came with the wrong piston.

Does anyone know if a piston from a Mk7 would be the right diameter for the RB2? I'm thinking it would be easier to modify one of those to take a later type parachute seal and look at extending the rod than to do anything with the piston I have.

[maximus]

Tho older mk7 Airsporters were slightly smaller diameter pisons than the rb2, 1 1/8" (28mm) so not interchangeable. Maybe the cocking slide/linkage is wrong? I don't think any other BSA had that diameter of piston with a central rod so it should be ok. Other than that you could make a piston head extension then also add material to the slot in the piston to ensure it cocked.

[Oddbob08]

Tho older mk7 Airsporters were slightly smaller diameter pisons than the rb2, 1 1/8" (28mm) so not interchangeable. Maybe the cocking slide/linkage is wrong? I don't think any other BSA had that diameter of piston with a central rod so it should be ok. Other than that you could make a piston head extension then also add material to the slot in the piston to ensure it cocked.

Thanks maximus, that's a shame. I had a spare slide which was a different in design but all the dimensions were the same - it has a slot which runs most of the length whilst the other is nearly all solid with just a short slot for the linkage but other than that, it's the same. I'll send an email to John Knibbs to see if he has seen any different sizes in his stocks.

[Shed tuner]

hmm.. that just sounds like it's the wrong piston - maybe worth sticking up a dimensioned sketch of yours ?