It was probably 5 plates on each side for a total of 450. My mistake. I wasn't there when it happened. I had asked my training buddy why the machine was out of order one day.
Speaking of Smith machines...Did the gym you worked out in during your younger days have smith machines (or your current gym)? When I want to go heavy on bench or squats without spots, I would go to the smith machine, and use the safeties on the heaviest stuff. I know you take out the stabilizers some using smiths, but it's nice to know you can survive a failure and not worry about your spotter paying attention to the hot babe walking by just as you need him (or in my case, worry if my wife is strong enough to get me through that failure enough to return the bar with the assist). She's not standing behind me right now

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I've also use(d) smith machines for tricep presses, shoulder shrugs, and a few types of bicep curls.
We've talked about our shoulders. Let me ask you this? How are your knees holding up? I'm guessing pretty good if your still doing pistols.(?)
Okay, that sounds more reasonable. I didn't even think the Smith machine bar could fit 900 pounds of plates. Yes, there's a Smith machine in my current gym, and I only use it for supinated inverted rows with my feet elevated to bar height. Again, I use the 1.5-rep set for about 12 reps, depending on cadence and pauses. In the previous gym I went to, I used it for bench press because I could no longer do the free weight version due to my shoulders. But, as I mentioned recently, I no longer do that exercise.
When I did barbell squats I used a squat rack/cage with the horizontal safety bars set just below the bottom of my movement. That saved me a few times. Even so, since I tended to go all out, I figured the squat would eventually do me in one day and so I dropped it and only did leg press for years as the upper leg compound movement. I still did extensions and leg curls at the time. Further, although I recognize the myriad of benefits to be derived from barbell squats, I don't think spinal compression is one of them.
I never even tried squats using the Smith machine. I saw, and continue to see, other people do it, but it just never appeared natural to me for some reason. Just a personal observation (and one without even a trial to back it up).
My knees are great. They are perhaps the only joints in my body that have never suffered an ache or pain. If anything, I think the weighted pistols have strengthened them. At first I wondered if the ATG full range of motion would put them at risk, but it has been over three years and the knees are singing. I have to tell you, doing them weighted and slowly (not as slowly as Baron does his exercises!) is as hard a leg movement as I have ever done. And it
seriously works the core.
You should give pistols a try. When I decided to do them, it took about 2 weeks for me to be able to do it without holding on to something. But I was determined because it just seemed so right. And once you get it, it's like riding a bicycle. If your legs are in good shape, and I assume they are, you'll find that doing them unweighted is not much of a challenge. But add enough weight and it changes the dynamic entirely, more so than just adding double the weight to a bar for a regular squat.
The videos you see on the Internet show people doing weighted pistols with dumbbells held in front of them. You can only do that with very light weights. Since I go heavier, I hold the dumbbells down at my sides and move them only slightly forward at the bottom of the movement to prevent them from touching the floor. (And here's a little secret. I still occasionally wobble when I do them unweighted. But the dumbbells act as a bit of an anchor, and counterweight as you ease them forward at the bottom, keeping you upright and stable. But don't tell anyone.

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