The cheapest most effective deflector ive sen used on a ar10 type rifle is one older guy at the range i attend drapimg a thin cotton handtowel sized cloth ove the reciever to cover the ejection port loosely. Seemed to work real well for him. He also had a bathroom type fuzzy handtowel under the gun on the bench to keep the rounds from rolling
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent