I hate to be one of those old guys that talk about "base", but out of curiosity, what is the is the training age of the guys here saying that #315 is a giant weight? How much of that was actually hard, structured training? And how much of that was natural?
If you've only been training 2-3 years, you can't say this isn't possible or that isn't possible because you just don't have enough time actually lifting to understand it. Also if you jumped on the needle early, your vision will be cloudy, because you haven't seen what could be done naturally strength wise.
Go to a legitimate powerlifting board like outlawpowerlifting, etc.... and ask some of the older guys that lifted both naturally and enhanced whether #315 is that big of a number, it is, but it isn't. You'll see that it just takes a decent number of years of low rep training, etc..... for a guy in the #181-220 range. Now, I won't lie and say that you can get to #405 without really packing on the pounds, but low to mid three's is totally possible, especially for a 200lb + man, whose been training multiple years in the low rep brackets.
Now it's hard to show proof of being drug free because the birth of the bench press and powerlifting coincides pretty close to the age of steroids, but you can look up the olympic press results for the non-steroid years, and you'll see that there were a decent amount of guys from the light heavy weights up that were pressing in the #200-275 range during those years. Generally, if a man can stand and press over #200 with no leg drive, he'll be close to, or over #300 on the flat bench, in some cases much more.