Decided to tune my stock Marauder rifle for shooting JSB Exact Jumbo Heavy 18.13gr pellets @ 880 fps by only tweaking the hammer spring tension, hammer throw, and transfer port screw settings. I went for slightly above ~880 FPS with lowest standard deviation and decided that I would stay within the hammer spring and hammer throw values of 60-85% to find the most efficient power tune without shooting 10,000 pellets for all positions. I very carefully aired up the rifle to ~2600psi (+/- 50psi) before each test and then shot 5 rounds across the chrono from a bag. I refilled the rifle after each test to make sure there was consistency and recorded my numbers. If this copy pasta edited text sounds familiar I posted my P-Rod tuning adventure in the Air Pistols topic but have also included those results here as well. Hope this helps others more quickly find a good tuning combo and realize that it's not that hard to do and all it takes is a little organization, focus, and Gatorade (I was hand pumping). Here are the results and I couldn't be happier.
Note: These values are with the transfer port wide open 5 turns. Final numbers were found after fine tuning down the transfer port from wide open (5 turns out) to about ~4.1 turns out (0.9 turns in).
P-Rod Tune Post: https://www.airgunnation.com/topic/tuning-stock-marauder-pistol/
View attachment 1565512343_7404059955d4fd29701c770.11820060_Tuning Record.xlsx
Note: These values are with the transfer port wide open 5 turns. Final numbers were found after fine tuning down the transfer port from wide open (5 turns out) to about ~4.1 turns out (0.9 turns in).
P-Rod Tune Post: https://www.airgunnation.com/topic/tuning-stock-marauder-pistol/
