Airsporter RB2 tune

[Oddbob08]

I know this thread hasn't taken a breath for over a year, but just like the RB2, I need to raise it from the dead, because, due to rose tinted memories (of a Mk7 Airsporter and a Superstar) I've gone and bought a pile of bits to make an RB2.

I'm not saying I wish I hadn't, after reading the comments on here, quite the opposite in fact, rather I'm looking forward to having a go, what could possibly go wrong?

I do have some questions though, just out of curiosity.

The barrel is 14" (in old money) and has a hole under the barrel muzzle, was it a carbine and need a muzzle weight if open sights are to be fitted? My eyes are to old for open sights but just curious.

At the breech block end there is a pin which, to a man with a hefty hammer, gives the impression that some brute force will allow the old BSA .2222222 calibre barrel to be swapped out for a .22 or maybe even .177 calibre tube with a slightly tighter breech and a wider choice of pellet. To anyone who says getting a pellet in a .177 breech from a .22 RB will be tricky, bear in mind that my first airgun was a Crosman 766 so that wouldn't put me off.

And then there's that alloy block which sits under the end of the cylinder and is secured by an allen stud, what's that all about? Is it just a bit of support for the underlever? Does it need to be nice and tight or a rattling good fit?

[look no hands]

I know this thread hasn't taken a breath for over a year, but just like the RB2, I need to raise it from the dead, because, due to rose tinted memories (of a Mk7 Airsporter and a Superstar) I've gone and bought a pile of bits to make an RB2.

I'm not saying I wish I hadn't, after reading the comments on here, quite the opposite in fact, rather I'm looking forward to having a go, what could possibly go wrong?

I do have some questions though, just out of curiosity.

The barrel is 14" (in old money) and has a hole under the barrel muzzle, was it a carbine and need a muzzle weight if open sights are to be fitted? My eyes are to old for open sights but just curious.

At the breech block end there is a pin which, to a man with a hefty hammer, gives the impression that some brute force will allow the old BSA .2222222 calibre barrel to be swapped out for a .22 or maybe even .177 calibre tube with a slightly tighter breech and a wider choice of pellet. To anyone who says getting a pellet in a .177 breech from a .22 RB will be tricky, bear in mind that my first airgun was a Crosman 766 so that wouldn't put me off.

And then there's that alloy block which sits under the end of the cylinder and is secured by an allen stud, what's that all about? Is it just a bit of support for the underlever? Does it need to be nice and tight or a rattling good fit?

If I remember correctly the alloy block is to stop the cocking linkage from coming back to far and coming out the cocking slot, as for the barrel, I think they are sweated in as well as pinned, so not easy to get out, you could machine the old one out and thread a new one in.

Pete

[Shed tuner]

as above... but I do think the alloy block adds support / reduces flex during cocking too. firm, but not crazy tight - and defo not loose / rattling.

Is yours the maxgrip raised scope ramp ? If so it may well be designed with an ally muzzle weight fitting, whcih also lifts the foresight arrangement to line up with the open sight that mount onto the maxgrip.

[look no hands]

as above... but I do think the alloy block adds support / reduces flex during cocking too. firm, but not crazy tight - and defo not loose / rattling.

Is yours the maxgrip raised scope ramp ? If so it may well be designed with an ally muzzle weight fitting, whcih also lifts the foresight arrangement to line up with the open sight that mount onto the maxgrip.

Yes I forgot about mentioning the front sight set up, if the barrel is shorter then it is most probably a carbine, the threaded hole underneath will be for the attachment of the barrel weight and the front sights will then attach to that, if it has the front barrel weight then the rear sight will be lifted by a small metal block that screws into the sight mounting and then the sight sits on top of that.

Pete

[Oddbob08]

Thanks for the replies, pretty much as I'd thought for the barrel fitting, not sure I'd want to attempt to drill it out and thread it but that's what I may have to do with a Stingray barrel I have. Glad to say it's not Maxigrip railed, a Lightning I have actually has one of those which was out of alignment with the barrel. I have a block to fit under the rearsight, but tbh, if I do want to use open sights I think I'll be using a williams peepsight or possibly even drilling and tapping the cylinder for the BSA version used on Meteors and Buccaneers.

All this is based on the assumption I can get it shooting as sweetly as I remember my Mk7 did. When I had that, it took more rabbits than a Theoben gas ram, not because it was more accurate or powerful, but because it was so much quieter both to cock and to fire than the far-more expensive Theoben, so rabbits nearby weren't spooked. And another thing I'd like for it is a walnut stock, I've seen a used one for a Mk7, but I'm not going to polish a turd, if it won't perform it won't get it.

[Shed tuner]

yeah, good to not have the maxgrip, stupid thing it is !

Tuning as per earlier in this thread - reduce the port a bit, and lighten the piston.

[look no hands]

yeah, good to not have the maxgrip, stupid thing it is !

Tuning as per earlier in this thread - reduce the port a bit, and lighten the piston.

Jon, did you ever try the Maccari piston seal I sent you?

Pete

[evert]

Jon, did you ever try the Maccari piston seal I sent you?

Pete

He mentions swapping for the Maccari seal in the first post
The Maccari seal is in my favorite Supersport, and performs well.

Talking about piston seals for the 29mm Supersport/Lightning/Superstar/RB BSA's, both the original and Maccari/ARH seal are too small for some of the oversize Superpsort/Lightning tubes I've seen. I have a couple of Knibbs' seals, and they seem to be a bit bigger, but have not tried them yet.

[Shed tuner]

He mentions swapping for the Maccari seal in the first post

yes indeed

There's always some variations in tubes, so it pays to have some slightly tighter seals around. Especially so when you have guns which tend to be harsh anyways, as they benefit from a tighter (slightly power robbing) seal to calm them down. Using a weaker spring doesn't have the same affect.

Useful to know the Knibbs seals are even larger...

[Oddbob08]

I just went to the Knibbs website, just a random search on Google, and the very first image it brought up was an Airsporter Centenary.

Does he have his own supplier for the seals as it was mentioned they are a little tighter? To get my project started I'd robbed a seal of a Lightning I have, built it and never used it much, so thought the seal would be fine. I don't remember where I got the seal, probably Chambers, but it was a loose fit in the piston, not sure how it compares to other seals. I'm still waiting for a few bits I ordered from John Knibbs last week so can't say for sure how the piston seal is going to do.

[evert]

Useful to know the Knibbs seals are even larger...

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

[Shed tuner]

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

excellent, many thanks...

[Jimny4x4]

Something to do with barrel resonance and the trigger? Big Seth had one back in the day and did everything he could to make the RB2 shoot straight and it ended up in the bin I think.

My BSA Firebird PCP with the same breech type arrangement had an accuracy problem, and after a phone call to John Bowkett (gosh I actually spoke to him, and got free useful advice!) I reseated the barrel and it shot very accurately.

Is it a matter of seating the barrel on a 'Sporter?

The BSA Stutzen RB2 is a truly beautiful rifle but horrible to shoot and inaccurate. My old 1973 BSA Meteor can outshoot it.

Nothing wrong at all with the performance of any Airsporter , especially an RB2 , especially a tuned RB2
Stunning in a word .

[greenwayjames]

I know this thread hasn't taken a breath for over a year, but just like the RB2, I need to raise it from the dead, because, due to rose tinted memories (of a Mk7 Airsporter and a Superstar) I've gone and bought a pile of bits to make an RB2.

I'm not saying I wish I hadn't, after reading the comments on here, quite the opposite in fact, rather I'm looking forward to having a go, what could possibly go wrong?

I do have some questions though, just out of curiosity.

The barrel is 14" (in old money) and has a hole under the barrel muzzle, was it a carbine and need a muzzle weight if open sights are to be fitted? My eyes are to old for open sights but just curious.

At the breech block end there is a pin which, to a man with a hefty hammer, gives the impression that some brute force will allow the old BSA .2222222 calibre barrel to be swapped out for a .22 or maybe even .177 calibre tube with a slightly tighter breech and a wider choice of pellet. To anyone who says getting a pellet in a .177 breech from a .22 RB will be tricky, bear in mind that my first airgun was a Crosman 766 so that wouldn't put me off.

And then there's that alloy block which sits under the end of the cylinder and is secured by an allen stud, what's that all about? Is it just a bit of support for the underlever? Does it need to be nice and tight or a rattling good fit?

There is no need to swap the barrel out in your RB2 it doesnt use the loading tap of the Airsporter range, as you will have noticed

[MartynB]

I had a .22 RB2, wish I still had it, OK not most powerful but was good enough for me. very nice handling with 4x32 scope