MK1 VS Mk2 .25 heavies

How can I buy a specific lot of pellets? I bought some mk1 from AOA and they were the perfect fit for my impact. When I placed the order they were 4 tins and out of 4 there were 2 tins that were shorter and they fit smoothly into the berral. The other to were a tighter fit and shot terrible. Can I just call AOA and tell them I want these specific pellets will that work? They were all mk1 pellets just 2 different sizes?
 
At PA, you only have to buy 4 tins to get the 4th free (I.e. You only pay for 3 of the 4). 

On the question on pellet sizes, no two are the same which is why some people that compete in BR and FT spend time weighing and sorting all of their pellets. 

They don't usually claim that some shoot well and some don't (once damaged ones have been removed). It's more that pellets of different weights have a different poi. By grouping all of the pellets by weight and only loading a mag with pellets of similar weight, they get better groups. They will literally spend hours sorting pellets into different baggies to match their weight.

They also like to clean and lube pellets too. Pellets aren't usually one of the things in life that I like to use lube for but I keep meaning to try it to see if it makes me into a world-class marksman. 
 
Unfortunate part of commerce is as demand increases quality usually drops forever or at least till the growth "spurt" is ended. It is being seen across the board in the USA now since there are literally millions of "new" people here who have lowered expectations because of the conditions and supplies in the lands where they originated from. This cost us all since they will buy substandard products and never complain! Those of us accustomed to a higher standard are left out in the cold because the manufacturers stock holders only respond to $$$ PROFIT margins. Few if any care about quality in a sellers market. These of course are generalizations to apply as you see fit.

Thurmond