btw not saying a tm is bad by any means. Just to bring them up to par vs wha you will usually be playing against it takes a few extra things. That being said I have never had an issue upgrading a tm. They are always reliable and super easy to work on. So far I have done a tm g36 a tm ak47 a tm p90 and a basic maitenence job on a 551. All pleasures to work on.
now this g&g m16 and acm m14 on my bench have been sworn at more than a ship deck.