https://metroatlantaairsoft.darkbb.com/pictures-f22/completed-vltor-m4-t2550.htmThats my G&P Sentry. The externals are indeed very nice, however a few problems I have had are :
a) the dust cover doesnt close. This is in no way realistic and somewhat annoying
b) the parts are made of steel, and are very prone to RUSTING. You must carefully maintain the grey steel components, wipe them down and when you put it up make sure its oiled, because they will rust very quickly even when exposed to little moisture
That being said, its drop dead sexy and solid as a rock. Out of the box performance wont match the KWA however, I've played a few OPs before using the KWASR12, its one of my favorite weapons in terms of performance.
Pic of KWA SR12 I used:
Both are great weapons and perform well. What you need to ask yourself is what role do you play out on the field. If you are the midrange-longrange kind of player the KWA SR12 will do you better. If you like the midrange-closerange style of play the Sentry will be a better choice for you. That should be your deciding factor.