Scorpiosxs. UKSF do not use the M4. They use a L119A1, very similar but not the same gun.
They USED to use M16s back in the 1980's/1990's but not anymore. There's probably a few kicking about in armouries still but they'll train on the L119A1 or whatever weapon they're taking into combat.
With regards to camo, they have more freedom (not complete) of choice while they are away on operation. Basically it has to be a NATO pattern and they only bother with US or UK stuff. Anyway nowadays its redundant as they're all using multicam.
As for kit they have some freedom of choice but not as much as people seem to make out. As said beofre if they are usign anything not endorsed or issued by the army (even a belt rig) they will need separate insurance to cover any injuries occurred if they were wearing it. For instance you break your ankle wearing non-MoD approved boots and it ends your career or you need time off the Army might not give you any compensation for it as they did not approve you wearing them.
Also you will only see people in non-British camo on operation or about to go on op as in base they have to wear DPM/MTP (depending on era) at base etc.
If you do go on Google images of say SAS in Iraq, Task Force Black, most recent and abundant UKSF pictures you'll notice its only the camouflage and what/where their pouches are that changes. They all use L119A1s, RAVs, Sig P226s, Blackhawk! CQC serpas MICH 200 helmets.
The rule with any SF loadout is that there's so much "my mate's friend said this" that only pictures count. An even then positively IDing the pictures is difficult.
Also SFSG are not the same as UKSF. UKSF consists of SAS and SBS. The SFSG is their "support group" not actually in the SAS or SBS. They are formed mainly out of 1 Para but with elements of Royal Marines and RAF Regiment. They are the equivalent of the US Army Rangers, they were even going to be called the rangers at one point.
But with regards to your question which I replied to earlier but you seemed to miss it:
But back to the question as to why you see more US.. basically its different and there more options. Also Asian companies make US parts for the US market whereas the UK market is usually to small for them to make a replica Mk.7 or SA80 bayonet for instance.
The fact the US is different is probably the biggest reason. No one really wants to wear DPM as they can be considered a noob and MTP is all over the place that its nearly as common if not more common then DPM.
I went for African loadouts are finishing my US and UKSF loaoduts as it was something different.
But why do you find people wearing US loadouts "Tacky and *pretentious"?
And are you talking about specifically American loadout or do you just not get the whole why people replicate real forces?