Well, actually... hmm. I ended up using the shop tab fix, which worked in correcting the "Armor" tab so that the accessories (i.e. optics) are displayed and available for equipping. Problem is, in the editor the weapons' non-rendered portraits disappeared!
Well, a lot of them...
Was the BMP folder supposed to disappear when I used "Patchme.bat" successfully? I noticed that there was no such folder when I applied the fix, so the "BMP" folder only contains an "ITEMS" subfolder, which contains "AMMO-85.E5B," "M18A2.E5B," and "M61-BIPOD.E5B"... curious. I've actually got a folder that contains all of the original post-installation folders and files that would have been overwritten by patch 1.06, and I notice that its BMP folder is of course far more extensive; perhaps I was doing something wrong with regards to the patch and installing Blue Sun in the first place. (My thoughts on having to do a clean install again? BOHICA.)
I do agree, the special M4 stocks are a cosmetic thing, don't trouble yourself too much over it for my own sake, considering that I can't pay you for this.
Thank you for clarifying the issue with the "real" shops; I usually use the editor modifier to check out the various gear combinations.