Best way to shorten hot end assembly by 1mm?

[NHSA_Rainer]

If it is brass then take a file and file it down. Should be done in less then 10 minutes. Clean it up well afterwards ...

[Titan]

If it is brass then take a file and file it down. Should be done in less then 10 minutes. Clean it up well afterwards ...

The heat break's made from a polished steel. To be honest I was hoping there'd be a simple solution that I was missing, but having done more research it seems Monoprice have just created an annoying and fiddly issue using non-standard sized parts. Even getting a compatible replacement heat break is proving a problem, and I'd like to buy a spare so I can return the machine to standard if necessary (GigDigit sell them but only deliver to the US and Canada, and I'm in UK). I think filing away the top/entry section of the metal throat is the best solution as it's the only part that doesn't 100% need a perfect seal.