i agree... but there is some thing with the later weapon also...

There seems to be a not that good line on the upper part of the arm... try to get that line on the inside of the arm because then it can look like seam ^^
He is holding the weapon bad >.<.. It looks like he is really concentrating on holding it in a special way far from the body or something (I can’t real describe it)... you should not have a totally strait arm like that while holding a rifle. it looks weird.. especially if he not is aiming in eye height with it. If you know what I mean? ...
I don’t know what you should do to get realistic poses with the weapons.. because you had something little that was not that good with the pistol too.
But try search on internet to get a better image of how you should hold weapons ^^