There are to many small details to say what you should be getting but...you went with a 5 inch stroke(2100) so you have close to the same swept volume and valve size as my MK1322;My Mk is probably not able to build as much pressure as your flat top...with the pdg .22 Bomb the MK1322 with a 22" barrel hit 560 fps right about 17fpe with you... (with the mk shooting 750fps w/14.3s at the time, it was down 55 fps from normal)so even at equal psi you should beat that because it is easier to accelerate a 25g .25 pellet than it is to accelerate a 25g .22 pellet...but how are the valve and transfer port ported etc... Is the pump tube slot just the right opening (no wasted stoke)etc.BUT...My earlier figures were for a 6 inch stroke (392 linkage)with the 2100's 5" stroke in 20 pumps you are getting about 1500 psi @ 85% efficiency If you can manage two more pumps that goes to almost 1700psi if you stick with .85 for efficiency... creeping up on 1800 psi in 23 strokes and 24 gets 1830 or so...take a look at post 24 in this thread... psi-pressure and you will see .85 is a reasonable expectation...oops here the link...http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.20
I understand it is a 1400 pump tube but you said you used a 2100 linkage... and that determines stroke
Ahhhhhhhh.... so that's the season it's so hard to pump.... you reduced the mechanical advantage to increase the stroke.... Bob
Fixing a leaking piston will just mean fewer pumps before it retains air or gets too hard to pump.... My bet is on the transfer port, or some restriction somewhere.... What is the diameter of all your porting?....Bob
I saw some numbers you got with your 2100 in the mid 1000s, which seems pretty quick (my .177 Uber-Pumper peaked at 953 fps at 35 pumps with no retained air).... If you are getting such wide swings on Chrony readings, you need to find out why.... I use the indoor light kit all the time, even outdoors, with light guards on both sides, between the rods.... Getting the lighting correct is critical to reliable Chrony readings....Bob
Now you're getting there!.... My .22 cal Uber-Pumper hit 25.8 FPE at 20 pumps of a 1400 pump (33cc per stroke = 6.7" effective stroke) with 14.3 gr. pellets (902 fps) and was just retaining air at that point.... At that time I never tried a Disco hammer spring (I was using one from a 2200) nor did I try heavier pellets.... At 25 pumps I was getting two shots of just over 800 fps, for a total of 41.4 FPE....Bob
Glad to see you getting closer to your goal Matt!Keep us posted
Just and