print from firefox

In firefox I have a bespoke app to ship items, when I ship an item, a pdf is created and I get  dialogue box asking if I'd like to print, I click yes nad move on, the pdf prints.

The issue, this is an XP computer running older versions of firefox and adobe reader, I cannot create the same situation with W10 and more up to date apps and I really would like to update everything as one day they will break.

The closest I have come is that adobe opens the pdf in the same tab and I can then print and it will close, but it is seconds slower. We're shipping hundreds of items a day so every second counts.

Any idea how to recreate my original experience of a simple dialogue box?

TIA

ALAN