by B.B. Pelletier

Part 1

It’s been over a month since the first report, and we’ve heard from many Viper Express owners in that time. What they say pretty much agrees with what I reported in part 1, though one reader did have some success with the pellet insert, while another reader actually saw some skilled shotgunners break clay pigeons from station 8.

Many were surprised by the small amount of tiny shot in the shotshells. They reported penetration at 10 yards in cardboard boxes, and that lines up with what Gamo says. Today, I’ll tell you what kind of ballistics are behind that performance.


Twenty No. 9 birdshot fill about half the Viper Express shotshell. The plastic cup is the base wad.


Looking inside the empty shotshell, we see the breakaway plastic retainer that holds the shot inside the shell until firing.

Starting with the shotshells
The black plastic shotshells hold 20 No. 9 lead shot. I think the picture speaks for itself. The shells are only loaded about half full, but that’s because of the cumulative weight of the shot, which is 15.3 grains. The shotshells do not break apart in firing, as one reader reported, so they can be reused for a long time. This is good, because the price of $7.50 for 25 is too high for a lot of use, which is exactly what this gun requires for proficiency. Trap and skeet shooters all reload (nearly 100 percent of them!), so you’re in good company. All that’s needed now is a good reloading procedure, which I’ll work on along with some of you.

Shotshell performance
The shot charge averaged 562 f.p.s. at the muzzle, with a velocity spread of 21 f.p.s. This equates to 10.73 foot-pounds of muzzle energy, but this small shot sheds energy fast. This is a very close-range airgun with shot.

Pellet performance
The Viper Express is a .22, so the following numbers represent more power than they would if this were a .177. RWS Hobby pellets weigh a nominal 11.9 grains and exit the muzzle at an average 666 f.p.s. with a spread of 13 f.p.s. That’s a muzzle energy of 11.72 foot-pounds. Daisy Precision Max pointed pellets weigh a nominal 14 grains and average 595 f.p.s. for an energy of 11.01 foot-pounds and a tighter spread of just 9 f.p.s. RWS Superpoints weigh 14.5 grains and average 626 f.p.s. That produces 12.62 foot-pounds, so the Viper Express needs an FAC in the UK. The spread was only 6 f.p.s., which is remarkable for any spring gun – especially one that hasn’t been broken in! The final pellet was Crosman’s .22 caliber Premier. It weighs a nominal 14.3 grains (boy, am I glad I wrote the posting about pellet weights! Now you know what I mean when I say nominal weight.) and averaged 638 f.p.s. That’s a muzzle energy of 12.93 foot-pounds. The spread was 10 f.p.s.

So, what do we know?
We know that the Viper Express is very well-behaved for a new spring gun. We also know that it has power in the 12-13 foot-pound region. It isn’t rifled, but the diabolo pellet doesn’t really need rifling to be reasonably accurate. I’m guessing this gun will shoot 1″-1.5″ groups at 10 yards with pellets.

Next time I’ll show some downrange performance.