This doesn't work as far as i can see.

the step i have done.

1) made a heavy machine gun turret

2) Stored the turret. It has disappeared and when I go to defences > turrets I can clearly see I have 1 item build in my work bench

3) place the turret on the grown The MK. i is still displayed.

4) stored turret a second time

5) Move from heavy MG turret to light MG turret and back and forth no change to the Mk. value.

Remember, the basic and heavy machine gun turrets come in 5 variation each. simply store them in the work bench and place them back down to change each turret's model

With the basic turrets and heavy turrets the scaling is about the same, jus the Heavies are labeled 6-10 rather than 1-5

I - Lameness

II - More health lameness

III - More damage, more health

IV - Incendiary ammo, even more health

V - Even more health, and fire explosive ammunition that deal even more damage.

Look on the front of the ammo container for the version number, and the type of ammo fired.

My game must be bugged because storing a heavy machine gun does nothing and my heavy MGs are all all mk. I not mark V

i have only seen mk1 and mk3 versions at my settlements

never seen any others and tried the build-cancel-build-cancel etc method once i read about it to try get them but its always mk1 or 3 (99% mark 1) im level 45

also i only have heavy machine gun turrets no basic ones and they are all mk1 with the odd mk3 (which sez 10mm on the side rather than 5.56mm that the 1s say)