I have loaded magazines in an M14 with the stripper clips. Sometimes it was difficult. There is an adapter to load the magazines directly and not use the device on the gun but you have to outsmart it. There is a tap on the clips you need to bend back out of the way before you insert it into the adapter. I would have hated to reload magazines in combat. The M1 Garand at least came with bandoleers with the clips loaded. You had to watch your thumb when inserting them though.
I’ve tried pushing the clips through the guide above the port.
They go in fine but then it takes a mightier man than me to get more than 3 rounds in.
I was looking to save weight but I must have the strength of a newborn baby.