The air rifle comment is seemingly correct.

People claim the Scar has a "forward recoil impulse" similar to an air rifle. A $30 BB gun from WalMart will ruin a $1500 NF in short order.

Standard scopes are not built for forward g-forces.

Newer ACOGs are allegedly strong enough, but I've heard of at least one unsubstantiated claim where a Heavy broke a bottom end ACOG. I asked for proof, but none was proved and the claimant disappeared.

JYD #123 The great one formerly known as Architect.

I am now a fictional British television police officer (currently a Detective Sgt) at Thames Valley Station. My governor is Detective Inspector Fred Thursday and it’s 1969.