Ovenpaa, I've tried that many Colt / M16 variants I am not sure what a standard one feels like..... :lol:
I shot a custom fully moderated barrel verion in Arizona a couple of years back, whisper quiet but it weighed a ton
The HK style sights on the Sig take a bit of getting used to for an assault rifle, but if you can shoot an MP5 or G3 then you are already there. I find the normal AR sights quicker to acquire however. All training is done with iron sights only (basics and more basics, optics can break or fail) . The cycling seems more robust more "solid" with bog standard mil-surp and being Swiss it will probably run forever and ever - and on time..
The bolt handle is a better idea than that forward assist, easier to clear a stoppage than using "SPORTS" on the AR, also easier to lock open for unloading. Bolt release is the obligatory " slap" with the heel of the hand.
Internally seems like an AR, same take down pin set up etc. The front sight flips up for night use. The newer "civvie Sigs" come with a different sight arrangement and a flat top receiver if I remember right..
I shot the full size and commando (compact) versions, see photo.
I prefer wee lightweight compact rifles for my wee compact arms. Using either version placing head ooops "stop" shots at 35 yards against the clock was a doddle.