Ballistic Jell is a medium that is the best thing we have currently.
The US Mil uses it, the FB uses it, the RCMP use it, basically every credible entity I know of uses it.
Live testing is also done in controlled circumstances -- HP White Labs has done a lot of MRI's and XRays from live tests - if you have the friends in low places to get access via an entity.
The reason Ballistic Gelatin is used is because when compared to live tissue impact, it has been found to be the best simulant. And due to PETA and all the other wonderfully nice people in the world - Live Testing cannot be done to the extent that would be preferable.
Personally -- I'd empty prisions and use them as test subjects -- but people dont seem to appreciate my cost cutting methodology.
Sure bullets dont always act the same -- but the Gell showns an AVERAGE effect.
If 5.45 was the devastating killer then it follows that many others would be using it -- and Russian Tier1 assests would not be using 5.56mm M4A1's..
Dosing -- I'm not using it -- its just and extra support weapon in the vehicle.
C-Mags have a terrible reliability record in any platform -- to the point I would not use one for training (the whole train as you fight thing too).