Well, you wont get both. Our Mk IX is a late -42 model and they only got .50s in early -44..
The Mk IX is in reality at least 4 different versions. The Brits are bad at a lot of stuff, soccer, food and proper naming different versions of fighters so there are room for a lot of confusion. The Mk IX we have is pretty much just a Mk V with a new engine and a few other modifications while the
Lf Mk IX that is our Mk XVI have a different engine, different wing, different tail etc so when talking about the Mk IX you need to know which variant of it you are talking about....