You didnt read all that i wrote did you.
I said there is no point pumping like a mad gorrila... here are the power levels after reworking the rebel
1 & 2 pumps N/A Didn't bother !!
3 pumps 579, 583, 584. 5.6 flbs 178 m/s
4 pumps 656, 657, 654. 7.1 flbs 200 m/s
5 pumps 714, 713, 713. 8.4 flbs 218m/s
6 pumps 755, 760, 760. 9.6 flbs232m/s
7 pumps 789, 792, 796. 10.4 flbs 240m/s
8 pumps 823, 824, 822. 11.3 flbs 250m/s

you can see that itì's very linear so with an increase from 5.6 to 7.1 being 1.5 and the inxcrease between 7.1 and 8.4 being 1.3 and the increase from 8.4 to 9.6 being 1.2 can you see a pattern? the increase from 7 pumps to 8 pumps was 10.4 to 11.3 (0.9 ) so it follows that one extra pump will take you to 12 ft lbs the legal limit....no need for 13, 14, 15. pumps if you want to shoot elephants, get a bigger gun...

When a pellet travels through the air it creates a pressure wave in front that travels at the speed of sound, If you shoot at mach 1+ you will get a loud crack, and no silencer will silence that as it's generated through the flight of the pellet. 4 pumps gives 656 ft / sec that's ample to hit a target with great prescision at 100m if you have set up you scope to compensate. ( use hawke chair gun pro software it's great) At the slower legal power settings 656 ft/sec is quieter and almost silent with my silencer designed specially for the rebel with it's 12 thread.
All I get is a quieit "Teuhh", even when i shoot at 30 meters the sound of the pellet hitting the target is louder than the actual shot fired.. Why alert the target you are shooting at?? why pump over 8 pumps?? what do you thinbk you will achieve??
Look at the mean averages of pellet speed difference for each number of pumps...3 pumps variation is 5 fps. 4 pumps variation is 3fps. 5 pumps variation is 1 fps.-- and 6 pumps is 5 fps. 7 pumps is 7 fps and 8 pumps is 2 fps
The more variation in fps for a set number of pumps means that vertical accuracy is lessened. that leads to poor results. If you only pump at 4 pumps the variation is very little just 3 fps variation. This will drill out the center of the targe very easily...
3 fps variation at 50 meters is 1/4 of an inch...and the 5 pump variation was just 1 fps thats a vertical difference of just 1/10 of an inch at 713 fps.for 50 yards.....yes that's the ballistic precision for pellets with identical performance. The errors above that are down to the shooter.
So why would anyone want to pump 15 or 20 pumps so that the pellet has to go through the sound barrier where it's destabilised, and the pump barrel of the rifle get's twisted under the strain causing side ways errors...Yes that is where the left / right errors come from. Even the innova was not immune to this through forcing hard against the pump handle twisting the barrel in the stock very slightly... Thats why i made improuvements to the securing system and used locktight to stop it from twisting..
If you shoot over 800fps the pellet starts to wobble as the pressure wave is dancing around the skirt of the pellet. All the way up through the point of Mach 1 and up to 1100 fps the change in resistance to the pellet is great . The drag coefecient curve is almost at 45 deg, but flattens out again after 1200 fps and stays flat right through Mach 2 and Mach 3...So why shoot at a speed close to the speed of sound if you want accuracy?
Will the hole in the target be any different if cut at 500, 600 or 700 fps? Will a kill shot be any less effective on a rat or rabbit at 656 or 800 fps ? I doubt that very much.. so why do you want to extract any more power from the rifle??? why pump and pump and pump with a loud "CLACK...CLACK...CLACK" at those higher pressures? with the modified pump stroke and resevoir the rifle pumps silently...shoots silently ( with a silencer) and hits a target at 50 meters with an accuracy of no more than 1/4 of an inch...
Also 4 pumps (656 fps) will drill a hole through 15cm of ballistic clay at 10 meters so why would any sensible person want to go to 15 pumps??? are you hunting elephants??

My detailed page on how to modify the rifle and extract the best performance that will match and exceed any innova is there for everyone to use to get accuracy and easy power quietly...try it and see... use the software available from hawke, learn how to set up a rifle and scope using this software to optimise the "kill zone" and tune in he rifle to get the best results from the scope /pellet type and weight / fps info.
I have fired over 3000 shots through the rifle so far and having done the mods have a far better rifle than when it came out of the box...
Colin