When I did my electric pistol build, I decided on these 4666kv generic FK130 motors that redditor /u/Meishel found on ebay a while back. However, what arrived in the mail was not in fact the same motor.
It turns out there has been a substitution across multiple sellers, perhaps at the supplier level, of a vaguely similar motor and I was one of the first to receive the new ones. At the time, I was oblivious to the difference, because I hadn't used the original Meishel motor. It wasn't until I put the thing together that I noticed anything remotely amiss (the high speed and noise of these things compared to what I was expecting them to do), and then after redditing my blog post, Meishel commented. Further research blew the can of worms wide open. So here's the deal.
This is a true "Meishel" FK130 motor. Note the SQUARE vent hole in the can, the standard zincplate finish on the can, and the standard length FK-series shaft end which is exactly like the one on the Mabuchi FK180SH-3240 and other Mabuchi FK motors you may have seen.
Proper specs for torque and current draw are maddeningly nonexistent on these, but what we know is "28000rpm @ 6.0V" which gives a kv of 4666.
These motors are well tested with 2S lipo batteries. They turn at ~34500rpm unloaded giving nominal performance, and have response and torque noticeably inferior to the Falcon WFK130SZ-2190, but pretty damn good for a 130 motor, especially for one that uses a simpler and more space efficient 2 cell battery and is thus well suited to pistols where fitting in a 3S pack with enough guts for Falcons would be difficult.
Now this motor is the new one people are getting from former Meishel listings which is NOT a Meishel motor. Note rectangular vent hole, longer shaft (only a good feature for flywheels) and can that appears hot galvanized or plated with heavier zinc.
This motor is rated at 25000rpm @ 4.8V, giving a kv of 5208. It is wound substantially hotter than a "Meishel".
On 2S lipo, this motor turns at circa 38000 rpm. This is not an optimal setup, speeds over ~35K are not helping with velocity and might decrease accuracy and consistency. Plus the obvious noise. Durability and reliability are not well known for this combo but I don't expect trouble out of these from how mine have acted so far.
Some comments about reliability concerns, brush gear, LiFePO4 batteries, and such for this 5200kv FK130 "banshee" motor in this reddit thread.