The stock unpainted mosin does not have any problems.
Its 5 round magazine works fine.

Only after painting black or green will it restrict it to only "chambering" rounds instead of "load"ing them.

same thing for me

I love you Drouz, that worked.
I didnt come across that solution on Google.
It should be an option in game or tie the config file to the steam launch flags.

Further game play indicates to me its about impossible to successfully fire a round from prone position without it being blocked by the ground.

Not a bug.

Read the changelog for the new version, you were never supposed to be able to put bags inside of bags inside of bags, aka BAGCEPTION.
I believe they released a temp fix for current version, new version comes out tomorrow.

Its because your inventory was full.
When you reloaded you took the 10 round magazine which only requires one square of inventory space, the 30 round magazine takes 2 inventory spaces.
So when you removed the 30 round from your weapon there was no room in your back pack and therefore was dropped on the ground by default.
Combine this with the bug thats causes item drops to take up to a minute to show on your screen and you probably never saw it drop.

Not a glitch itself, just a misunderstanding of the game mechanics.

^ Same for me. Depends how long its been since server reset and how loaded it is.

Also, its a magazine not a clip. :)

Have you ensured that you had the canteen equipped and that when in 3PP you were aiming at the well?
If you dont aim at the well and have canteen equipped it wont work, I have had no problems filling my canteen in 3PP.

I agree, both for realism and for DayZ the spread needs to be tightened.
I shot at zeds 100m away and can see the bullets warp almost 2-3 ft away from their torso.
Compare to my real life AR-15 where I can drop 5 water bottles with 5 shots at 100m... and I am by no means an accomplished marksman.