Yeah was shooting at 400fps when I first tested it.
The mag was just a spare high cap I had laying around so I pulled the internals out and superglued the pin back in to give some rigidity to the top of the mag. Wiring is still into the mag as it's just the better place for it tbh. If I wanted to make the profile smaller, I could get a short mag and put a peq box size battery in there.