I think if you want to use the TAPCO rails for an AK-74 you do not have to trim the rails. I think it's only for an AK-47 that you have to trim the rails. They are already cut for the smaller case.
I thought that the 5.45X39 cartridge was the 7.62X39 necked down to 5.45. The only difference, what I'm told, is the neck, and also the case walls before the shoulder are straightened out to increase case capacity. If so, why wouldn't the rails be the same?
I also need to get this straight, because I just ordered a receiver from Global Trades specifically to build a 74. They asked me what caliber the mag well needs to be machined for, but said nothing about the rails. I hope I don't have to be a dremeller since I paid the high dollar for the receiver.:help: :dunno: