Jim,
You do have a point concerning eastern units & as you pointed out, were better served and the western units would have had a problem with supply due to the long distance of shipping and my interest mainly lies with the western campaign. But the problem with ammunition would occur only with cartridge weapons as with the muzzle loaders & percussion revolvers, there wasn't a problem & the problem would mostly be with cavalry units.
It is interesting but it wasn't until the war was mostly half over before there was a semblance of continuity in arms within regiments. The 1st MO. didn't receive their Sharps & Remington's until 1864. It is true they were issued the Hall's early on, but some companies still carried them at the end of the war. I wonder what the determination was as to which companies got the new replacements?
As some units were being equipped with better weapons, their old ones would be sent to other units.
You just couldn't please everyone.