The Armalite AR5 was accepted as a replacement for the M4
which was a wire-stock, bolt action that fed .22 Hornet from
the same magazine as the Savage bolt action rifles.
The M4 action was adapted from a Mossberg bolt IIRC.
Now, the AR5 introduced the same style stock and takedown
as the AR7, but was not procured in any significant numbers
because SAC was well-stocked with the M4 and M6 survival
guns. AR5 had to fit within the 14" space under a bomber seat,
so if any AR5s are around, they are a rare NFA short barrel rifle.
AR7 is based the AR5, but AR7 itself was never adopted by the
Air Force as a survival rifle. AR7 has been used by Australia as
a military, silenced weapon; again that is limited use.
As others have pointed out, AR7s have probably seem more
issue in the movies (Firestarter, From Russia With Love, etc)
than in the military.
The AR7 has a pretty heavy bolt for a .22, and premium high
velocity ammo does improve reliability; also the feed lips of
the magazine and the feed ramp on the front of the magazine
are subject to deformation. I have a Cosa Mesa Armalite AR7
rifle and a Charter Arms Explorer II pistol. The rifle works best
with CCI Stinger, but the pistol is more accurate with Winchester
Super-X, for whatever that observation is worth. Given the
minimum and maximum chamber and cartridge spex, you will
find optimum combinations of gun and make of ammo. Rarely
will a gun work equally well with all brands of ammo, especially
.22 rimfire.
I had a Winchester 69 with the barrel bobbed at 17",
stock forearm trimmed back, scope mounted to barrel,
that could be taken down with a coin to fit in a 21"
carry case. That to me is a better option, since that
allows use of everything from .22 short CB to Stinger.