I know a guy who shot himself in the foot, no joke it really happened, and blames it on a problem with his 742 rifle. He claims it is a common problem with the 742 rifle that is well known and documented. So now with half his foot gone he continues to bad mouth Remington rifles instead of acknowledging his improper handling of the rifle which cause the incident.
I'd never heard of any problems with the 740 model series other than when the chamber is dirty the bolt locking lugs cause excessive receiver wear. My Dad bought a 740 when they first came out in 1955 and I bought a 742 in 1970 and neither one of us have had any problems.
Does anyone know of any "safety" related problems with 740 series rifles?

I have never hear of remington semi auto accidental discharges. This as you stated seems to be improper handling. Peolpe are always trying to blame others for there own problems. It's a shame. Anyhow the mod 740 is noted to be the best. The 7400 is in the middle and 742's are the worst. That being said i have two 742's 308 and 30 06. They work flawless but the 742 receiver is made of soft metal that will wear out. Keep the round count down and they are great. Typical ounce a year hunting trips will almost never hurt a 742 but i have seen them chewed all to hell fom guys that moose, bear, deer and wolf hunt hard core. Usually dirty chambers and bent box mags will cause cycle issues that's about it. Safety is in the hands of the shooter.