After ignoring lots of advice and being told that I was "building a bomb", I'm happy to report that my 18650 powered Stryfe is fully functional! : r/ Nerf
TUTORIAL] How to make a DUMMY BATTERY for your Nerf Gun - YouTube
Amazon.com: NERF Pro Stryfe X Dart Semi-Auto Blaster, Rechargeable LiPo Battery, 30 AccuStrike Half-Length Darts, 15-Dart Magazine, 150 FPS, Eyewear, 14+ (Amazon Exclusive) : Toys & Games
Amazon.com: NERF Ultra Select Fully Motorized Blaster, Fire for Distance or Accuracy, Includes Clips and Darts, Outdoor Games and Toys, Automatic Electric Full Auto Toy Foam Blasters : Everything Else