twopounder wrote:So, there I was, blob of glue on my turret and a small .50 cal held in a pair of tweezers...
...Is there a trick I don't know? ...

AhhHH YEEsssS, those things.Well first off patience! Carefully cut the MGs off the sprues, inspect them. Looking at the part that goes into the hole in the Cupola (small turret on top of turret) inspect to make sure no extra flash is protruding from it (these usually look like thin skinny lines of metal sometimes folded over) .
Straighten the guns.
Take a needle or pin and CAREFULLY & EVER SO SLIGHTLY enlarge the hole where MG will be glued.
Make small Glob of glue close to where you will be assembling the MG to cupola.
Either using tweezers or fingers pickup MG, dip the part that will go into the cupola
OR taking a PIN dip the pin in your glob and put small amount of glue where the enlarged hole is.
Assemble the two.
Hold for few seconds...this is the part I hate because you NEED to be PERFECTLY still for few seconds (thats why I use fingers sometimes over tweezers)
DO NOT BE DISCOURAGED!!!... the MGs when on will make your M1s look like JEWELS!!