Ok I'm going to take it easy here because you are genuinely perplexed, which tells me you are new to this. So here goes.
Let's assume for a moment that the 123 scenars are indeed at velocity on the box of 2950. With a g7 of .263, and density altitude of 2500, you will have 284 inches drop (7.9 mils) and 7.9 inches of drift for every 1 mph of crosswind. If you are aiming at the center of a 16 inch square plate, that means a 1 mile per hour crosswind error will move you off the plate even if you were shooting .3 in groups at 1000 yards. Respectfully, if you are asking these kinds of questions you are not experienced enough to judge wind to 1 mph, which would be world class performance, especially in an 18 mph wind day. So that's the first issue.
Next, let's consider the rifle. Let's assume for the sake of argument that the rifle truly is a consistent .3in rifle, which is fantastic performance. Your group size grows in proportion to time of flight, not linear yards. At 100 yards, TOF is about 0.1 sec. At 1000 it is 1.43 sec. The best your rifle would consistently do then will be 1.43/.1=14.3 times the 100 yard group. 14.3 times .3in is about 4.3 inches. At 100 yards aiming error is minimized because we have the magnification and relative target size to precisely place the crosshairs in the same spot, of course at 1000 we don't have that luxury so we will always have aiming error which will make that 4.3 in group grow significantly, easily 2-4 inches or more with most tactical rifle scopes. A tactical rifle consistently producing 8 in groups at 1000 yards is doing great even if it were locked in a vise.
We haven't talked about the scope. Have you validated the click values? Are the clicks giving you the true elevation the label says they are, and is this true across the range of adjustment? This rifle needs 7.9 mil or 27 moa to get to 1000. If you have one tenth moa elevation clicks, but they are only giving you .09 instead, you will be off 270 times .01moa, or 2.7moa. A measly ten percent error in click value is a whopping 28 inches at 1000 yards. If it were ten times better than that (99% accurate) that is another almost 3 inches.
Let's talk your yardage. Are you really at 1000 yards? At a public range it may be surveyed but if you are using a rangefinder in field conditions a 3% error in rangefinder resolution is common even if the laser hits the plate. That's 30 yards, so you could be at 970 or 1030. For your load, that would amount to over 20 inches of drop alone, clean off the target.
Have we talked velocity variation? A factory load producing extreme spreads of 30 fps is excellent performance. At 1000 yards, that is worth about 7 inches, the edge of the plate, even if everything else is perfect and these other sources of error weren't present.
How was your shooting position, natural point of aim, trigger pull?
I don't mean to burst your bubble, we can make hits at 1000 on small targets and do so often. But as you can see there is a lot to it. That's why the internet claims of "this gun (or shooter) shoots 6 inch groups at 1000" get taken with a grain of salt around here. We know what goes into repeating, over and over, that kind of performance. A shooter who is consistently a 1 moa shooter at 1000 in field conditions every time would truly be world class and likely doesn't exist. So don't feel bad if your 16 in plate lives as much as dies until you get a handle on some of these variables, the main ones being your shooting fundamentals and the wind call.
