(Spoilers) Fallout 4, Stuff I Found IV: Turret (Mark) Mk Models?

***SPOILER WARNING: Spoilers may be found in the post below about VARIOUS ITEMS. And I'm going to add in a bit of filler text here to limit how much of the main article gets shown in a preview. That should take care of most of it. Hopefully. And away we go. SPOILER WARNING. ***

Video
Fallout 4: Different Models / Mark MG Turrets?
Fallout 4: Heavy Laser vs Laser Turrets

Different Turret "Mark" Label?
Mark 1, Mark 3, Mark 5, Mark 7... There's a difference?

Let me clarify first: I'm talking about the first two turret models available under the settlement defense building menu. These are the least advanced and don't require any power to be hooked up. The ones with the tri-barrels?

For the longest time, I thought all the turrets within the same model were the exact same in terms of function and damage. Specifically, it looked like the cheaper, weaker turret fired regular projectiles, and the stronger turret fired incendiary rounds.

I feel stupid now because I did notice the marking labels on the sides like "incendiary" and "Mk 3." The question of why some of my second tier, stronger turrets didn't always fire incendiary rounds crossed my mind, but I clearly didn't put much thought into it. They looked like random decals to add some variation to me. Intuitively, there shouldn't have been a difference considering that they cost the same in terms of resources.

Build Them All
While doing some light research, I stumbled on the fact that there was in fact a difference. That obviously meant that I had to build them all. With some help from the DLC that provided cages for trapping things, a bunch of turrets were built at a settlement on the east side of the map.

What I found was that both the weaker and stronger tri-barrel turrets had four different sub-models each: Mark 1, Mark 3, Mark 5, and Mark 7. Maybe I missed some but those were the ones that I managed to built on the east side of the map. Below are the labels I found on the turrets of the corresponding sub-models.

Mk 1, 1000 Rounds, 5.56 MM
Mk 3, 1000 Rounds, 10 MM HE
Mk 5, 1000 Rounds, INCENDIARY
Mk 7, 1000 Rounds, EXPLOSIVE

To reiterate, the same labels were found on both the weaker and stronger tri-barrel turrets (e.g. both Mark 1 turrets were labelled with 5.56 MM). From testing with the cages, the labels appeared to be fairly accurate concerning what the projectiles did. Whether they did different amounts of damage, I don't know. The Mark 3 and Mark 7 sub-models seemed redundant to me -- unless I'm misinterpreting what "HE" means.