You were shooting the same powder in the same brass with Winchester 240 JHP and the only thing you changed was you went to 240gr XTP bullets and now your groups opened up.
Is that correct?
Are the Winchester bullets round nosed JHPs? I think most of them were.
XTPs are truncated cones.
Did you change the seating stem in your seating die when you started using the XTPs to something that fits the bullets nose profile?
Something had to change in your process. If the seating stem doesn't fit the bullets they will be inconsistently seated. They could be a little crooked which won't hurt them at short distances but you may see something at 100 yds like your seeing with your loads.
I think you said the XTPs were mic'ed at .430 so neck tension shouldn't be an issue unless your already over crimping and loosening your neck tension, which would affect 4227s performance. Not crimping at all would also hurt 4227's performance.
4227 and H110 both need all the pressure you can get to get them to shine.
Do you have an ammo check gauge to check your ammo with after loading? If there are any crooked bullets, bulged cases from over crimping, or any anomalies from the loading process, they usually show up in these minimum chamber gauges. Wilson and Lyman both make them.
I would advise getting a Wilson ammo check gauge and using it.
Almost all of my marginally defective ammo will still chamber in my guns but that doesn't mean they will be as consistent as properly made ammo is.