bsa airsporter mk5 0.22 under repair

[Geezer]

Airsporter barrels of this era were 485mm (19.1”) standard, and 500mm (19.7”) on the S.

It’s interesting that they were round numbers in metric. Supplied from abroad? I don’t know.

The muzzles were indeed counter-bored (larger, non-rifled bit at the end).

The front sight block has a small male lug that fits a shallow female depression cut into in the top of the barrel.

Slightly behind that, a vertical screw running through the front sight block (look at the diagram on Chambers) fits a tapped and threaded vertical hole in the barrel. IIRC, the latter hole is both in and goes through the counter-bored section, not the rifling. The screw either does not protrude inside, or only does a tiny bit, and not enough to impede pellet flight.

I’ve read suggestions that the counter-boring was intended to protect the crown from damage in the field.

It does that, but, if I am right in the para above, I suggest it was primarily adopted to allow the front sight to be screwed on from above as described without having to work with very fine tolerances or risk a random “choking” effect by pushing the top of the rifling down a bit in manufacture.

PS: U.K. Neil retired and sold up his machinery a few years ago.

[stonyat421]

Airsporter barrels of this era were 485mm (19.1”) standard, and 500mm (19.7”) on the S.

It’s interesting that they were round numbers in metric. Supplied from abroad? I don’t know.

The muzzles were indeed counter-bored (larger, non-rifled bit at the end).

The front sight block has a small male lug that fits a shallow female depression cut into in the top of the barrel.

Slightly behind that, a vertical screw running through the front sight block (look at the diagram on Chambers) fits a tapped and threaded vertical hole in the barrel. IIRC, the latter hole is both in and goes through the counter-bored section, not the rifling. The screw either does not protrude inside, or only does a tiny bit, and not enough to impede pellet flight.

I’ve read suggestions that the counter-boring was intended to protect the crown from damage in the field.

It does that, but, if I am right in the para above, I suggest it was primarily adopted to allow the front sight to be screwed on from above as described without having to work with very fine tolerances or risk a random “choking” effect by pushing the top of the rifling down a bit in manufacture.

PS: U.K. Neil retired and sold up his machinery a few years ago.

cheers for that shame would not mind another one of those silencers