I have been heavily upgrading my Umarex Elite TAR-21 to make it competitive on the field. However, it is still severely lacking in the rate of fire department compared to similar builds. Troubleshooting this has been slightly irritating. Current Relevant Gearbox/Other Parts: ZCI Hi Torque Motor (22 TPA) Stock 18:1 Elite Force Steel gears *PROPERLY SHIMMED AND LUBED* SHS Lightened (Swiss-Cheesed) poly piston/steel teeth *AOE HAS BEEN CORRECTED* ZCI Polymer Piston Head Stock Spring, seems to be a 110 Stock Microswitch Trigger System OEM Cutoff Lever Stock Cylinder ZCI Aluminum Cylinder head with proper sorbo pad installation Stock Tappet Plate Stock 8mm Bushings, properly lubricated Stock Metal QD Spring Guide Nukefet with 16ga wiring, wired into the gun's original 18ga wiring Rewired to Dean's Parts I am upgrading to after my next strip down: ZCI 16:1 Gears SHS V2 Tappet The battery I am using: 7.4v 1600mAh 20c LiPo. I have 11.1v batteries as well, however I would like to stick to a slightly slower rate of fire due to the proprietary gearbox now being the weakest part of my build, hence the 7.4v. Now the kicker. My TAR-21, with aforementioned upgrades, is shooting at a dismal 13-14 RPS. The trigger response is phenomenal, even though it has a very heavy pull, thanks to the High Torque motor. It fires at this speed with or without the blowback enabled, so it's not the weight of the bolt slowing it down. The same battery in my absolutely stock VFC HK416 (also wired to Deans, however this is pulling a much lighter spring as the stock one shoots about 340) pulls about 18-19 RPS. Mind you this is with a stock motor and their not-so-awesome self-shimming gears compared to a near perfect traditional shim job. I thought this may be due to the fact that the High Torque motor = Lower Speed, as compared to the balanced VFC stock motor, so I plugged the battery into a heavily upgraded G36 (about the same upgrades as the TAR) which contains an identical ZCI Hi Torque motor. It pulled about 20-22 RPS. Things I think may be the culprit: Stronger spring in the TAR compared to the 416, however I doubt this would pull down the rate of fire by 5 RPS, especially since the performance on the G36 with similar specs has a much better result. Length of the wire, as the wiring in the TAR probably adds up to about 3 feet for both the positive and negative sides, equalling a 6 foot circuit. However, this would only affect the trigger response, if it would have any effect at all, since electricity travels lightning fast (sorry, not sorry), and 6 feet (at a maximum) does not add a lot of resistance. Stock Wiring, my weakest suit in tech work is electrical-based. I am confident that my soldering job on the gun was above par, however I do not have much experience with it. The solder used from the manufacturer on the microswitch was not meltable by my soldering iron (450C hottest setting), so I was forced to wire the mosfet into the stock wiring, which is insulated 18ga. I do not know what conductor or insulation is used. Would the transition from 16ga at the battery to 18ga at the wiring to 16ga at the mosfet to 18ga at the microswitch cause an electric bottleneck with the 18ga (thinner wiring)? I have some 16ga wiring being shipped in my next order from the glorious Clandestine Airsoft, however I am waiting to re-do the wiring completely for when I can get different colored 16ga wiring for the negative side. Any help or insight to why the rate of fire is so terrible would be excellent. I can post pictures of my soldering job/wire set up if it would help with any consultation.