4.49 or 4.50 - what should I use and why?

[zooma]

After a gap of over 35 years I am returning to target shooting and find the choice of pellet sizing a little confusing.

Previously all the RWS, H&N and Eley Match pellets I had shot with in the 70's were just generally available as .177 or 4.50mm.

Now various options are availabe apart from the 4.50mm standard gauge - the most popular of which is 4.49mm.

When I ask shooters why they choose to use 4.49 instead of the regular 4.50mm they don't seem to know why - only that they have been advised to buy 4.49 rather than 4.50.

I am hoping I can open a debate with this thread to gain some knowledgeable reasoning for the choice, and in turn help me to decide on the correct gauge of pellet for use in my Feinwerkbau P44 or Steyr L10 match pistols to gain the best results.