How I have tunned my New Hammer efficiency for Stock Class:
I have switched to the SC configuration after Hamer ~2 years of using my Hammer with siphoned 9oz tank in backbottle configuration. From this reason I do not have velocity graph of stock the New Hammer.
But the performance should be lesser than in case of BE Tigershark (mainly because Tigershark has larger powertube ID, other key parts have similar stats):
On my modified New Hammer was then already lightened hammer - from stock ~50g I have reduced the weight to 28 grams with grinding of the material in middle to reduce the bouncing and get lower sound signature and bette CO2 efficiency. With liquid CO2 it was not problem get good velocity (~285 fps) even with lightened hammer and strong valve spring. For the Stock Class setup it was necessarily use weak Spyder valve spring here to get at least usable velocitz. The results were then:
Not the best - only little better than in case of untunned Sheridan PGP of BE Tigershark. To reduce the losses trought the leaks in the bolt velocity adjuster, I have drillet out the ventury and sealed the threads in the (unused) velocity adjuster. Muzzle velocity has increased for 16 fps in average.
Then I have tested different barrels to find the optimal "paint to bore match". I have testet three 9" barrels: the stock Spyder Compact barrel with ID 17,60mm (.693"), stock New Hammer barrel with ID 17,50mm (.689") and my own "custom" stainless steel barrel with ID 17,35mm (.683"). Best results were with the smallest ID :
Then I have carefully reduced the hammer weight by another 2g (7% of previous 28g) to new 26g - less is imho really not achievable with the stock hammer...
The initial velocity was little lower, but efficiency has increased and already from 8 shoot was the velocity larger.
From 12g CO2 I have no now with this marker 34 shoots above 240 fps. Because he has smaller powertube ID, he has problem to get highter velocities. But if is 240-260 fps enought for you...
From the potential energy stored in powerlet he can transform to the kinetic energy hidden in shoots total 420 Joules. Stock BE Tigershark (which should be better than Hammer because he hat 4,8mm PT ID) can get only 180 Joules from 12g. Most of CCI Phantoms can get between 410-450 Joules. Today SC efficiency records are about 460-500 Joules.
For cheap nelson marker with small powertube ID really not bad...
For far future im planing little mods of powertube and valve nut based on short304 New Hammer PT mods for Redux ( http://www.mcarterbrown.com/forums/r...ml#post2129942