Speed Loading an M1

[MtGoat]

I was watching some 3-gun videos and am wondering how the heck they speed load an M1/M2 like that. They must have modified something as there is no way I could speed load 2 at a time (and still have my thumb attached) like they were.

 

What is modified, how and by whom?

 

Thanks

Pat

[Funjeff]

http://www.c-rums.com/Carriers.html Carrier mod is common, some other threads here about it.