That's a very good description, Crowbar --- "with a little love".Originally Posted by crowbar
Sadly, it seems to me that we have to put quite a bit more love into Airsporters and Mercuries than we have to put into other manufacturers guns with a similar swept volume in order to get them running nicely at 12 ftlbs.
As the Airsporters and Mercuries are what I'd call short stroked guns, I've just nipped out to my workshop and measured the Mercury cylinder to determine what stroke it could support, if I went down that route.
The actual compression part of the Mercury cylinder is 95mm long which is a result of the overly long piston head, this equates to the cylinder being 58.5cc in volume, yet the gun was designed to use just 40cc of that space.
By way of giving a little comparison, the HW80 has a swept volume of 57cc, the Mercury could have been built to the same swept volume with the existing cylinder.
Another thing I find a bit strange is that for export market above 12ftlbs BSA seem to have left the stroke alone but increased the piston weight by fitting a steel piston head.
The Airsporter's being the successor to the pre war Standard has the same stroke, when you get to the introduction of the Mercury in 1971, BSA simply used the piston, cylinder and back block from the Airsporter coupled with the barrel from a Meteor for their new Break Barrel --- a logical way to go but they could have gone a little further.
Anyway I'm off to look at my Mercury a bit more before deciding which way to go with it.
All the best Mick
Reply With Quote