Maybe it's time to start reviewing past state-of-the-art in pumpers. Here's a look at one of the lesser known pumpers that I thought was particularly well executed.
The S&W M-77A seems to have used the barrel and pump assembly straight out of the Crosman 1400 parts bins. I'm only guessing since I've never had the need (or the guts!) to break one down for repair.
Note the size of the valve----small wonder that factory pump recommendation was to limit it to 20 strokes. I find 20 strokes on the S&W never exceeds the effort of the 10th pump on a 1400---because of that loooong pump arm perhaps? I suspect the valve could handle a lot more and that the pump arm strength is the true limiting factor.
So what does 20 strokes earn? My ANIB M-77 I acquired last year averages 687.3fps with 14.3 Premiers. That is identical to the output of my bone-stock RWS/Diana M-34 and in the same ballpark as a good 1400, Blue Streak or Benji.
If my health wasn't so bad nowadays I would go to the shop and measure pump arm lengths from the pivot to the end so we would have a baseline but I can't do it. Perhaps someone else who owns those listed above will do so for the benefit of all. Tom