Hi John,
First of all

to TIG!
I looked at your imperial blasters (nice macro shots BTW!) and compared them to the ones listed in the weapon guide.
http://www.imperialgunnery.com/imperialblasters.htm
I think your first blaster is version V1A, it has both the dent as well as the micro circle on the magazine.
Imperial blaster: Version 1A
The second blaster is less clear to me.
At first glance I thought version V1C: no dent, no micro circle and a thin rear end.。
Imperial blaster: Version V1C
But on closer examination, the clip on the magazine looks much more detailed in your gun. Also in your gun the little circle and horizontal bar (at the end of the barrel) are closely connected whereas there is a little space in the V1C version.
I therefore think it is the V4 version: Thin rear end, no distance between the little circle and bar at the end of the barrel, trapezium side clip. You can even see the slight circle indent on the magazine here.
Would be good to have some input from other members on this one.
Imperial blaster: Version 4
I hope this was helpful for you.
Cheers
Marco