[ShelledPants]

Originally Posted by dragwindsor

OK. I'm ordering a Systema drop-in.

Which model do I get for 1200 rpm @ 375 - 400 fps with .20's.

What motor would work the best?

It has a Prometheus M4A1 (363mm) 6.03 TightBore inner.

I was thinking of a standard box with standard motor running off a 9.6v battery.

I'd like to achieve those figures with an 8.4v battery, as I have to build a custom battery because I have a DD 9.0 front R.I.S. and I'm getting a Magpul UBR RS stock which has no room.

I plan on placing cells wherever I can, linking them, and just having the connector somewhere I can access. I'll just plug the gun in.

Thanks for your help. I'm gonna get this thing done.

You will be hard pressed to get 1300rpm at 400fps with an 8.4v large battery, but it's not impossible.

I would recommend a Systema Magnum motor. They simply are the best motor's on the market, pricey, but tried and proven.

If you can put a mini sized battery in your setup, go for lipo, 1300rpm at 400fps can easily be achieved with a 11.1v lipo and a magnum motor. 7.4v will probably put you at around 1100 or 1200rpm at 400fps but is 2/3rds the thickness of the 11.1v.

This is all speculation though, as I've never used a Systema drop in mechbox.