Fallout Weapons

Sometimes I hate Fallout, but I've been a fan since I first played the game, "Wasteland" back in the early 1990s.  Now, I've been getting riled up at the weapon selection in Fallout 4.  The point of divergence happens sometime in the mid 1940's.  Plastics are rare and usually only by the military in the Fallout universe.  The combat rifle in the game seems to be modeled after a PPSh-41 sub-machine gun from the USSR.  Would the U.S. military develop this?  No.  In the "Wanderer" tv commercial the sole survivor is shown shooting a rad roach with a M14 or M1A.  That, to me would be more in line with the lore.  Also, we know from Fallout: New Vegas, Eugene Stoner still developed the AR-15, as the service rifle looks identical to the Stoner testing designs.  Since the military uses plastics, a M16A2 or a M4A3 would not be out of the question.  The combat shotgun also looks like it took design cues from the PPSh-41.  Were the Russians that helpful after WWII in the Fallout universe?

Here would be my substitutions.  Instead of the combat rifle in Fallout 4, there would be a M14.  The assault rifle would change to a M16A3.  The 10mm pistol would be changed to look like an updated 1911 design, or modernized version of the Bren Ten.  I would also add .45ACP 1911's to the game, as well as Browning 9mm pistols.  The combat shotgun would be changed to a Remington 11-87 or a Mossberg 930.  I would also add a pump action Remington 870 or a  Mossberg 590.  The sniper/hunting rifles in Fallout 4 are modeled after a Remington 700, but I would change it to a right handed bolt instead of left handed.  The pipe guns in Fallout 4 just look ridiculous.  I would think there would be enough machinists around to produce higher quality do-it-yourself guns.  Just google "Australian motorcycle gang guns" to see what I mean.