Many tests were conducted in the 1890s and early 1900s on rapid fire techniques with the Krag, with some Krags even being modified for clip loading and being pitted against Mausers in timed rapid fire. A wrist bracelet ammunition belt was even invented and tried but never adopted as standard issue. Loading the Krag with loose rounds from a coat pocket was among the fastest methods, faster than from the belt and very close to a clip loader.
All the tests I have read about were conducted from static positions with no mention of loading while moving where the clip loader has the wider margin of superiority. In my own use of the Krag, the best way for myself that I have found is to grab the rounds by twos, drop the first in the top, close the bolt, drop the other in the magazine, then two and two into the magazine and slap the gate shut.
Whatever limitations there may be with the Krag, I know of no other rifle that is faster to load with loose rounds, so I would consider it to be perfect for GAF shooting.
I always reloaded 220gr jacketed bullets so that I could fire ammunition as close as possible to the original and I have no experience with cast bullets in the Krag, so I must ask, Do cast bullets feed well in the Krag?