It's not something specific to a Round Butt 1911, it's something that happens with an 1911 when you install grip panels made of hardwood. Hardwoods don't have as much "give" as a soft wood and also tend to have a high oil content, so they aren't very "grippy" when it comes to holding the screw head. My Ruger SR1911's did the same thing, my solution was to tighten the grip screws tighter.
Since your 1911PC features a Scandium alloyed Aluminum Frame I would be concerned with doing that. It's likely that your frame doesn't feature staked in steel bushings and instead has bosses that are part of the native metal of the frame. In that case tightening the screws tighter might result in your stripping out the threads and an unrepairable frame. That leaves just two solutions, one is that O-Ring suggestion, the other is to use a bit of Blue low strength Locktite on the screws.
Since it appears that the screw heads on your grips are sitting flush with the surface of the grip panels IMO a rubber O-Ring really isn't a viable answer. That leaves the low strength BLUE Locktite as the best remaining option. As much as I dislike using Locktite for something like this I believe that in this case it is the best solution for your problem.
Now, one tip concerning Locktite. The standard low temperature grade Locktites can be "freed" up with the application of a bit of heat. For the Blue Locktite putting your frame in an oven on Warm for 1/2 hour will make removing the grips a much easier task. Because all it takes to get that particular grade of locktite to release is about 135 degrees F. That level of heat won't do any harm at all to your pistol but I would suggest wearing something like a golf glove to hold the frame while you break the screws free. Also work quickly and just break each screw free for 2 turns of the screw, that way you can get to all 4 before the frame cools too much. Once you have 2 turns on a locktited screw you'll find it will come out with minor effort with the frame fully cooled off. BTW, the remaining "gunk" in those threads will probably be workable for retaining the screws for 2 to 3 removal cycles before you have to re-apply some fresh locktite.
As for finding some Blue Locktite, if you can't find it at a local hardware store go online and order it from MSC Industrial Supply or a similar industrial supplier. I would also suggest you get the liquid type instead of the tape because these screws are just too small for most of us to be able to wind on some tape. Finally, don't be shocked at the price, Locktite can run 10 bucks or more for a tiny little bottle.
Yeah, it's going to cost you 15 bucks or more to get those 4 little screws to stop backing out. That sort of thing tends to chap me a bit and I wouldn't be surprised if you feel the same way. However, compare that small cost to the cost of your pistol. Sometimes a bit in insurance is money well spent even when we see no direct benefit from that insurance.
