Actually there are only two DIN threads for scuba cylinder use, 300bar or 232bar (iso 12209-2) they are 25x2mm parallel thread with a flat face & rubber seal.
The threads are of a different length (232bar =5 thread, 300bar =7 thread) so that you cannot
accidently seal 232bar equipment to a 300bar pressure vessel, being shorter the low pressure version will leak, 300bar will seal to a 232bar cyl as there is no safety risk.
However
where the end working pressure is below 232bar it is possible to
deliberately include an extra component part to allow a 232bar male fitting to seal in a 300bar female fitting.
My example was the use of the MDE airgun charging kit (for use on sub-surface cylinders which do not include a gauge & bleed as part of the cyl valve assy) where a block including a gauge & bleed is fitted to the cylinder as an extra, this MDE kit is only rated to 225bar swp & is marked as such, but comes pre-fitted with the extension making it 300bar cyl compatible, (although no longer safe on a 232bar cyl
) but the use of these lower swp components is perfectly safe where the SWP of the end use (the rifle) is lower still because the user will close the cyl valve before the pressure builds past those SWP's.
As I pointed out, not very well as it seems, if your rifle is one of the new breed of high pressure fills, you need to ensure
all your fill components are 300bar rated.