Help with Benjamin Marauder Tuning

I need some help with a basic Marauder tune that will get me at least 30 good shots in the 880 fps range with a 16 grain pellet. I've had a couple of gen1 Marauders years ago and was able to get 35 to 40 good shots. 30 shots with an ES of 12 and SD of 3.3. Today I was helping a friend do a basic tune on his new Marauder (unregulated) and was barely able to get 20 shots with 16 grain pellets. The transfer port was set to two turns out and the hammer spring preload was set to 2 1/2 turns out. The average fps was 875 fps. I was only able to get 20 shots before the fps started to drop of sharply. Have they made some kind of drastic changes to the air delivery system or am I missing something. Oh, I left the hammer throw at the factory setting. Any help or suggestions will be greatly appreciated. Thank you.
 
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I think you are probably pretty close to average with 20 shots at your power level and ES. Maybe with some more chrono time and tuning adjustments you can get shot count up a little. There were a few differences between the Gen 1 and Gen 2 Mrods but didn’t think the changes they made affected the tuning or power levels, but could be wrong. About 5 years ago I set up my unregulated .22 Gen 2 Mrod for Field Target Competition and got 25 shots at just under 20 ft lbs with an ES of 10, from 2350 to 1900 psi, using JSB 15.89 pellets. My adjustments were TP: 1.5, HS: 3.25, and HT: 7.75.

I primarily used the “A” team Marauder Tuning guide and used Method #1. Here is the link to the guide: https://www.gatewaytoairguns.org/GTA/library/A_Team_PCP_Tuning_Procedures 20090601.pdf

A couple years ago I converted that same .22 Mrod to a .177. and added a SSG kit from Airgun Revisions. It really helped with shot count. Here’s the link: https://www.airgunrevisions.com/product/tuned-ssg-hammer-kit-for-gen12-marauders/