I have enjoyed sitting back and watching the exchange of information on this subject - All good stuff gentlemen.
I agree 100% with CJS06, my standardization of ammo - and firearms - centers around the MAG's agreed upon loadout. With that written, I like Jackalopes approach to buying a firearm too.
I will use a recent acquisition as an example.
I had a hole in my personal firearm preps. In my case, it was a heavy semi auto rifle that could reach out there and touch someone or lay down some series suppressing power. I opted for a PTR FAL Clone in 7.62x51. Before I bought it, I did my research, e.g. optics, sling, cheek rise, ammo, etc. etc., and added those costs into the purchase of the rifle (Review to follow when of those days when I have time to write it-LOL). Then I saved up my nickels and dimes till could afford the whole setup. Once I had the money saved, I pulled the trigger, sort of speaking, on the whole enchilada.
To me, a firearm is just a tool and ammo are the nails. I do not own a lot however, like a hammer used for specific jobs, I own a selective series of firearms for specific tacks. No more no less.
My fun guns not my everyday tool guns, tend to span past history from lets say, 1750 to 1869.
Good stuff gentlemen...Good stuff.