the robarms vepr II (20") and 'k' (16") are basically shortend rpk's, the russian squad automatic weapon.
as stated, they are made with a thicker walled receiver that is also reinforced at the front trunnion mounting area to better withstand the intended use of the weapon...full auto supressive fire. the bbl. is heavier, for the same reason.
therefore, the weight is up a bit.
worse, imo, is the 'plasma rifle in the 40 gigajoule range' styling that molot (the russian manufacturer) and robarms (the american importer and installer of the hideous buttstock) sees fit to perform.
however, there is no denying the accuracy and quality built into these fine rifles. at $550 to $600, they are, in my book, a bargain.
if looking at the vepr, i would advise going 5.45 or .223. the russians gave up 7.62 nearly 30 years ago for some very convincing reasons that i will not go into in this post.