For the members of the forum that have been tracking the various firearms used throughout the series, I have identified one that may have been missed, and noted which character used the weapons I'll be mentioning here, I hope it helps!
The character Aiden Monroe was weilding an FN SCAR assault rifle while leading the supply run during the episode "Remember". Also, on his final, fatal run during the episode "Spend", Aiden Monroe was armed with the MAC-10.
I figured that the people tracking the various firearms in use are quite busy with their own lives outside the forum, which is perfectly understandable. So I thought I might help out by watching the series, identify weapons, which episodes they were in, and which character(s) had them in their possession.
Finally, some other site had listed Dale Horvath's rifle as a Ruger M77 Hawkeye. Could it have been misidentified by them, knowing how accurate the list here is?