A few years ago I bought a 2nd type Crosman 160 via this forum.
I wanted to improve its efficiency, as it is a "gas guzzler"/"gas hog" in standard form.
I got about 20 consistent shots per two powerlets. For a Dutchman, that's a nightmare!
After many unsuccesful attempts at improving efficiency by using stiffer valve return springs and preload washers in the valve, I concluded that the massive hammer was the culprit. Plus the hammer spring hole in the hammer was too small for my other hammer springs (QB78).
So, frakor was kind enough to slim my spare 160 hammer down. Ped did this with my QB78 hammer previously, and that worked well.
The 160 hammer now weights 56 instead of 76 grams. That's a 25% reduction. It also has a bigger hammer spring hole so that I can now test with various other springs.
Original hammer on the left; diet type hammer in the middle; diet type QB78 hammer on the right
I tinkered using this Sheridan type seal in the tube cap. This way I can use the gun with one powerlet, in an efficient way:
an empty powerlet pushes against the seal. This way the pressure in the cylinder remains high for longer.
End result:
50 consistent shots, at 15.5 degrees Celcius, with 15.89 gr JSB
Between 525 and 545 ft/s. That's about 10 ft/lbs.
It's easier to cock (shorter hammer spring), quieter, and the shot count is much better.
The S331 comes from a friend in the USA.
Cheers, Louis
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Originally Posted by louisvanhovell
