It is an odd one really - they have vast stores of AK pattern rifles, in varying condition, no shortage of small arms ammo, etc. despite many of the what were essentially conscripts being deployed to Ukraine with little more than 3 magazines and 3 days worth of supplies. They could retool production of AK12s for a much cheaper, quicker to make and more material efficient design. I think people underestimate what could happen with a large scale general mobilisation in terms of getting mothballed and reserve hardware back into service.
Logistics is a big problem for them despite having a lot of light trucks still as almost anything beyond light equipment still relies heavily on rail and as noted earlier in the thread Russia doesn't tend to make effective use of things like pallets for loading, etc.
Training seems to be a huge issue for Russia and may be more prohibitive on several levels than almost any other factor - especially they seem to lack the military institutional structure, knowledge, experience and mindset for conducting large scale complex combined arms operations against near peer adversaries.