X2! Wow, that man cannot not have been much of a collector, or the condition of the rifle was way overstated. Yes, it is an honest 73 with some reloading equipment - certainly not taking anything away from the gun - but, not worth anywhere near $5,000. More like around the $2,000 ish range for the whole kit maybe?? He should have also known the hole in the buttstock was for the cleaning rod which came with the rifle when it left the factory. Not for ammuntion. Nothing to get excited about there. The weather cover, as you call it, is the dust or mortise cover to keep out dust, dirt, etc.
Nice 73, but not a $5,000 gun. An 1873 in 38-40 would have to be in very high condition to command that kind of money.
Just my 2 cents, hope it is of some help.
Matt