This post was about mini 14s. How did ARs get mixed in?? ARs jam like an old 3 speed trans.. Mini 14s no jam!
I hope you're joking....
I would assume that poster was joking. If not than perhaps simply misinformed.
I have both an AR(s) and a Mini-14 ranch rifle and have very few problems with either one. Certainly no jamming when shooting .223/5.56 out of my AR(s). The only time I've had feed issues with my AR's was shooting my CMMG .22 kit. And that was due to the kit becoming fowled after shooting several hundred rounds of .22. A squirt or two of Remoil solved the problem and the kit ran fine for another hundred or so rounds.
My Mini-14 ranch rifle is fairly accurate with a scope to 100 yards. Because it's an mid/late 80's version the barrel is thin and gets extremely hot under sustained firing. So hot the wood forearm stock actually started smoke while under sustained firing.