I shot an early (Portuguese, I think) AR-10 full auto once upon a time. My impression is that it is FAR more controllable in full auto than a G3, "standard" M14, or FAL. Not hard to steer whilst emptying an entire magazine. (Not something I would normally do.)
Looks like a Johnson LMG prototype on the wall in the intro. Which would be the direct predecessor of the AR10 (Stoner having consulted with Johnson, it works out)
The early semi auto lowers were available for both the Portuguese and Sudanese parts kits
.years ago. There was also an early wooden butt stock for the Sudanese model as well as an aluminum butt stock for the Portuguese model for grenade launching. Any spare parts are very difficult to find and most upper kits (if found) are missing some key parts.
Back when Australia still had a sense of humour, there were quite a few of the early "Sudanese contract" and later "Portuguese / Italian Marine" contract versions here, "semi-only" of course.
Even the EXTREMELY light early pattern ones were no problem to shoot, the later variants were nicer and slightly better balanced for shooting.
I had one of each at one stage and it was interesting to get out on the range and do "user" comparisons with H&Ks, M-14s, BM-59s, SiG AMTs, FALs etc.
SiG AMT was by far the most "pleasant" to shoot recoil-wise, M-14 for accuracy, early AR-10 for "carry-ability" and L1A1 and H&K pretty matched for "ruggedness". BM-59 not a bad all-rounder