The effect of barrel heating can be different in each rifle. It can be a combination of barrel heating and the amount of movement of the barrel in the stock. Yours is already bedded so any heating will probably come from the barrel.
On my 6.5mm CM, with a bull barrel with aluminum pillar bedding, the PIO drops down at 6 o'clock about 1/4 inch after the barrel gets to 113 to 122 degrees and stays there.
I admit I don't let it get too much warmer than that.
The internal barrel bore temperature may actually be higher than that because the LCD strip isn't calibrated and it measures the outside of the heavy barrel not the bore.
But the effect is repeatable so it is a good indicator for me on when to stop shooting and let the barrel cool.
On my .270 M70 hunting rifle with a standard hunting barrel, the POI moves out at 2 o'clock 1/4 inch on the 3rd shot in a group and then goes another 1/4 in the same direction with each successive shot. To see that, I don't stop and let the barrel cool within the group.
That really opens up my group sizes from two touching to being barely able to stay under 1 MOA at 100 yards after 5 rounds.
For hunting, it is very accurate but as a group shooter, it's a bust.
I assume you can see the bullets on your target at 100 yards with your scope set at 10X magnification.
(A white background helps and the targets in your previous posts would work fine.)
You will need to see each shot because you need to determine if there is a trend in movement due to increasing temperature.
I use a 5-14X 56mm VX-L Leupold (with the crescent shape cut out in the front optic to allow the big front optic to mount closer to the barrel) on my .270 and I can easily see the bullets on the target using 14 X magnification. I use 5X for hunting.
I suggest you set up with 5 rounds in your magazine, and adjusting your position as little as possible, shoot each shot (checking for natural point of aim if you're comfortable doing that).
Watch the results after each shot to see if you can see a trend in movement as the barrel get hotter.
One last bit of advice.
If you have trouble seeing the reticle you may have the reticle out of focus (that is not focusing on the same plane as the image).
If the reticle focus is not in the same plane as the image focus plane, it means your eye will have to change focus to see the reticle and then refocus to see the image of the target.
When the reticle is focused on the same plane as the image, your eye won't have to refocus and both the target and the reticle will be clear all the time. You will have less eyestrain and fewer problems.
The rear objective rotates to focus the reticle for your eye to get the two planes focused on the same plane. The rear objective sometimes has a small dot and mark to allow you to see how far you moved them off the initial setting. The initial setting is for perfect eyes and I know I don't have them.
The best way to adjust the reticle focus is to point the scope at a white wall. The reticle should be instantly in focus when you look into the scope. Rotate the rear objective and see if it gets better or worse and pick the best position.
With my old eyes, I have to do this with every scope. If I didn't do it right, I find that after about 15 rounds, I have trouble seeing the reticle when focused on the target image. Then I know I didn't adjust it quite right.
If you wear glasses or contacts:
I used to shoot with progressive prescription glasses rather than contacts because I use monocular vision contacts so I can read without reading glasses with the weak prescription on my shooting eye.
Turns out that the progressive grind and most bifocals have the least effective grind on the edges of the lens and when I am shooting through a scope that is the part of the glass that I am looking through.
A wise optometrist who was also a shooter suggested that I get shooting glasses with just the normal prescription, without the progressive grind.
They work much better and I had the plastic lenses in my shooting tinted yellow to help in the dim morning light.