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Testing goals
  • Why doing these tests (some of the reasons)
    • To get the lightest pump stroke without using batteries or pneumatics
    • To get the most possible shots from a 12 gram (averaging 47 at 275 fps right now)
Valve design testing
  • Hypothesis
    • One valve design will provide higher fps per build out (varying dump chamber psi per sweet spot) than all other designs.
  • Test
    • Keep everything with gun the same (except input psi), just change valves and measure average fps of shot string for each after sweetspotting the valve.
  • Test Data
  • Discussion
    • Yep, one valve design is better (smaller input/output diameter). Seems clear, the differences in fps were large.
Bolt internal bore type testing
  • Hypothesis
    • A large and straight bored (no internal down step) bolt will provide the highest fps per a given build out. When take a bolt with an inside downstep and bore that out, will see a noticeable (5-10%) increase in fps.
  • Test Data
  • Discussion
    • This (hypothesis) was not the case. An internal step down seems to not make a difference.
Bolt design efficiency testing
  • Hypothesis
    • One bolt design will provide a measurable and significantly higher fps per given marker build out.
  • Test
    • Change bolts, measure fps of string of shots, keep everything else with marker the same.
  • Test Data
  • Discussion
    • Of the bolts tested one did provide a significantly higher fps, the bolt with three orings. Orings, or a tight seal I am guessing, since that is what they provide, give much higher fps. The tight seal being important was demonstrated by the Black bolt which fits snugger in the top tube and gave high fps scores - also by the Black bolt vs the Green bolt bored out since they are right about the same there except the outside diameter.
Starting spring compression and spring length affect on lbs cocking force required
  • Hypothesis
    • A longer spring that when resting against extended valve pin is uncompressed will require fewer pounds of force to cock for a given fps.
  • Test Data
  • Discussion
    • The hypothesis was confirmed, but with the margin of error the results are not conclusive (+- 2 oz). I expected the longer spring to perform better than it did. I am wondering if the specs of the longer spring are not very efficient (it has very different specs then all the other springs). I am also wondering about efficiency of springs in general and all the springs used in this test, and also (in addition to specs) how age plays on their efficiency.
    • It does not seem to matter much what stiffness hammer spring you use for your pump stroke overall - as in after you add in the pump arm and pump return spring the lbs to cock the whole deal are all about the same. Note - I am not using any of the super stiff hammer springs in this test, they would be too stiff, but the difference between the lightest one used and heaviest is a big difference.
Hammer travel distance & valve pin length testing [have not done this test]
  • Hypothesis
    • A longer travel distance of the hammer will allow for a lighter hammer spring to be used.
  • Notes
    • Thinking that there will be more time for the spring to accelerate the hammer so it won't have to be as stiff to accelerate up to speed in a short distance.
  • Test
    • Compare average fps of a string of shots with a cut valve pin and longer hammer travel from set point to average of same setup without a cut valve pin and shorter hammer travel from set point.
    • I cut a valve stem by a good amount so the hammer travels farther before striking it. The CCM 86 degree frame also holds the hammer slightly farther back then some of the stock grip grams giving a bit extra travel distance there.
  • Test Data
    • Test not completed
Valve pin head diameter testing
  • Hypothesis
    • A smaller valve head pin will require less force from the hammer to open, resulting in a measurably lighter pump stroke.
  • Test
    • Remove excess diameter from a valve pin head and get to 290s fps, measure pounds to cock, compare this to valve pin head that is larger (in same valve) also shooting 290s fps.
  • Results
    • The smaller head valve pin was easier to cock shooting at 290 fps, 2lbs 14oz vs 3lbs 4oz for the valve pin head that was standard (larger) size.
  • Discussion
    • 6 oz difference is major improvement. That cuts my previous record (at this time of writing) by 12%.
Hammer weight testing
  • Hypothesis
    • Did not have one for this, was just curious if there would be a difference.
  • Test
    • Shoot string of shots to get average fps for two differently weighted hammers. Keep everything else the same. Adjust IVG position to match starting spring compression between hammers.
  • Test Data
  • Discussion
    • Changing hammer weight did not change the average fps of two strings of shots. Does not seem to matter what weight hammer you have. Personally I liked a lighter one (after doing this test) because it feels like less of a thunk when shooting, and who likes extra weight? I don't understand why CCM uses such a huge heavy hammer.
    • I have lighter hammers to use and should redo this test with more variation and just to redo it.
Valve spring vs no valve spring on lbs cocking force required testing
  • Hypothesis
    • Using no valve spring will allow for use of a less stiff hammer spring resulting in a lighter pump stroke / less lbs of cocking force required to cock.
  • Test
    • Get a marker shooting 290 fps with a valve spring in, remove the valve spring and get it shooting 290 fps by changing just the spring compression or spring stiffness. If have the use more compression or stiffness then hypothesis is confirmed.
  • Test Data
    • I have done the above test several times just playing with my guns but not recording the data and always had to use a stiffer hammer spring after putting in a valve spring.
  • Discussion
    • No valve spring is annoying if the valve pin slides in too far when the gun is not aired up. Otherwise it is smoother.
  • Hypothesis
    • Reducing the volume of the dump chamber will decrease the fps by 20-60 fps.
  • Test
    • Reduce volume of dump chamber by different amounts and measure average fps of a string of shots for each.
  • Test results
  • Discussion
    • Devolumizing the dump chamber at all at ~300 psi with the build out I was using hurts fps, and so would require a stiffer hammer spring. Not a good thing to do.
  • Question
    • How much would the fps increase if bored out dump chamber?
Pre vertical ASA volume testing [no writeup]
  • Test
    • Add volume below the vertical ASA to see if affects fps for a given gun setup. Was done with a valve that sweetspotted at 225 psi.
  • Results
    • Did not affect FPS

Valve spring vs no valve spring on efficiency testing


Cocking force - cataloging
  • Test
    • Measurements of the lbs of force required to cock various autococker pumps, while shooting a certain fps (280-300 range)
    • With pump arm and return spring (return spring must bring to full close with marker pointed slightly up)
    • With pump arm and no return spring
    • Without pump arm
  • Data
    • More coming, have about eight guns to take data from
    • For without pump arm see data from "starting spring compression" test
    • Few have done for baseline for the "with pump arm and return spring"
      • Random loaner gun = 8lbs 2oz
      • Personal gun = 5lbs 3oz
Hammer travel distance - investigation
  • Question investigated
    • What determines how far forward the hammer can travel (when not aired up)?
  • Answer
    • The step down in the lower back tube between the threads for the lug nut and the area where the hammer travels. The hammer hits against this step and stops, it does not hit the lug nut or the valve stem.
  • Discussion
    • A hammer that has the front edged milled in will travel farther forward
    • Off all the hammers I tested (about six or seven of them) none of them had their set pin hit the front of the but in the underside of the main body.
    • From testing with cutting off parts of the stock of the valve seal (the part the hammer strikes), the valve does not open very far, with a stock valve in an aired up gun, the hammer travel distance forward will be stopped before hitting the step down.

Measuring smoothness - discussion

CO2 vs HPA regulator output pressure testing
  • Test
    • Measure output psi of a regulator on HPA, then change same setup to CO2 and measure.
  • Results
    • At around the 300 psi output pressure range HPA as an power source results in a higher output pressure than CO2, by about 5%.
  • Discussion
    • This test was done with a 1-1500 1" gauge (not very accurate). But can definitely see dial go up on HPA. I will redo the test with a more accurate gauge, different regulators, and different output pressure ranges.

12 gram efficiency - regulators
  • Hypothesis
    • One regulator over another regulator, each set to same output psi, will give more shots per 12 gram.
  • Test
    • Change regulators, check shot count for each.
  • Test results
    • View Spreadsheet (note, the last three are the ones to look at, the first two was me playing around with other stuff)
  • Discussion
    • Tested three regulators and did not see enough of a difference between them to want to use one reg over another.
    • Was not the greatest test (see notes below), was hoping for more dramatic results so that it would not matter.
  • Notes

    • With leaking, differences in having  balls in and not, me maybe miscounting, different brand 12 grams used, psi not exact on each, slightly different average fps on each -- the results are all really about the same, getting 46 shots
    • The first one did get 4 more shots, want to test that setup again
    • First one was using different brand 12 gram, second ones blew off some co2 as first screwed on since the front of them was not flat/smooth
    • Was using lightest hammer spring I have and turning IVG in a bunch
    • Not sure what spring used on first one, may have used the long one
    • Don't have a very accurate psi tester at this time for anything over 300 psi, using a 1-1500 one that is 1 inch
12 gram efficiency - heavy valve spring vs no valve spring
  • Test
    • Using a valve that sweetspots at around 300 psi, put in a very heavy valve spring and get gun shooting 275 fps. Check how many shots get from a 12 gram. Do this twice, once with a heavy hammer spring, once with a light hammer spring. Then remove valve spring (simulated really light valve spring) and shoot two more 12 grams, heavy hammer spring and light hammer spring.
  • Results
  • Discussion
    • I was hoping to see more dramatic differences. It seems a heavy valve spring is better but too close to be happy with. 12 grams are a bitch to work with - with all their leaking and being inconsistent - the brand I had for this test sucked at the initial seal. I need to get the gauges to do the test with HPA.

12 gram efficiency - devolumizing post reg, pre dump chamber
  • Test
    • Put a devolumizer (plastic rod) in regulator and check shot count vs not having the devolumizer in.
  • Results
    • I did this test but did not record the details. I need to redo the test so can post numbers.

12 gram efficiency - devolumizing pre reg
  • Test
    • Change internal volume of macroline (length and internal diameter) and check shot count per volume.
  • Results
    • Get a few more to a handful more shots when cut distance (volume) off the the pre reg macro line.
  • Discussion
    • Totally worth doing.

12 gram efficiency - devolumizing dump chamber
  • Hypothesis
    • Won't see a dramatic difference, maybe get 1/2 shot difference.
  • Test
    • Put different size devolumizers in dump chamber on vertical ASA side and check shot count for each, and for when there is not one in there.
  • Test data
  • Discussion
    • Did not see a dramatic difference. If dump chamber empties all the way, then cutting the volume in half would only be getting 1/2 an extra shot on a 12 gram - if the physics work like that.