How consistent is a multi-pump?
by B.B. Pelletier
Today, we're going to look at shot-to-shot consistency in an airgun many consider inexpensive - the Sheridan Blue Streak. And, of course, anything I say about the Blue Streak holds true for the Silver Streak, as well. This is an experiment I read about years ago, and it's a real eye-opener. It also gives you something to do with that new chronograph you get for Christmas.
Consistency is king!
In the world of airguns, the watchword is consistency, as in how close each shot's velocity is to all the others in a given string. I have known shooters, and perhaps you have too, who get so wrapped up in the quest for the lowest possible shot-to-shot variation that they don't shoot at targets anymore. They just shoot shot after shot through the chronograph, searching for a gun/pellet combination that never varies.
Consistent velocity is an important indicator of the state of an airgun's tune, but it's no guarantee of accuracy. Some very accurate pellets will vary a lot in velocity, while some consistent pellets are mediocre downrange. Still, a number is very compelling.
So, how consistent is a relatively inexpensive air rifle like the Sheridan? Whadda ya think? Ten shots within a 30 f.p.s. spread? 20? 10? Well, before we go try it, there's another aspect to this. Because the Sheridan is a multi-pump, it can shoot on any number of pump strokes between three and eight. So, will the consistency vary with the number of strokes?
And, there's something else. Some guys say that how fast or slow you pump the gun makes a difference in the consistency. So, we have to explore that, too! Didn't I tell you this was going to be fun?
Shot-to-shot consistency with different numbers of strokes
There is no difference in consistency at three pumps all the way up to eight pumps. Shooting Crosman Premiers, my Blue Streak never varied by more than 10 f.p.s. from the fastest shot to the slowest in a string of 10, regardless of how many pump strokes were used. There was a best string on five pumps that varied just five f.p.s.; but the other strings were so tight that, if I tried enough times, I would get the same results on all the numbers of pump strokes.
Even this old Silver Steak from the 1950s is extremely consistent, shot to shot.
I tried this test again with an old Silver Streak I have. Though that gun varied by as much as 12 f.p.s. in one of the strings, it also exhibited the same consistency regardless of the number of pump strokes
Fast pumping vs. slow
This was another walk in the park! The Blue Streak averaged 1 f.p.s. faster when pumped as rapidly as possible, as opposed to taking five seconds to complete each pump stroke. I didn't test this at every number of strokes - but at 3, 5 and 8, it stayed the same.
Are you surprised?
It's been my experience that multi-pump pneumatics are among the most consistent airguns, as far as velocity is concerned. Single-strokes are just as consistent; of course, they're pneumatics, too. Only one spring airgun I know of can equal this performance every time, and that's the Daisy 499 BB gun - the world's most accurate BB gun. But as a class of guns, I have to give my vote to the multi-pumps for consistent velocity.
Try this experiment with your own multi-pumps and tell us what you learn.