Loads:
4gr reddot under a 150gr wadcutter 850fps
12gr 2400 under a NOE 358429 weighs 177gr 1050fps
Firearm:
4" Stainless GP100
These are very close at 25-30 yds but as the distance grows so does the different poi, the heavier,faster going higher & the lighter,slower lower as it runs out of gas.
Now why, at the muzzle there`s only 200fps difference & the boolits are basically the same shape, the heavier giving more recoil ,but spending less time in the muzzle as it`s rising from recoil, the liter boolit with less recoil, but spends more time in the barrel as it`s rising from recoil. this explains the short distance .
On longer distance (75 yds) the shape comes into play as well as weight , the wadcutter being flat & liter will be shed of it`s kenetic energy from drag faster than the heavier semiwadcutter, plus the recoil thing is magnified at longer yardage.
short answer , you`ll get close , but different loads /boolits will never group the same at 2 distances.
I hunt with my 6" GP & I use the 2400 load by putting the front site level with the rear ,then placing the front site at the bottom of the chest cavity & let recoil & that tuff semiwadcutter do the rest.
When I use the 4"GP I use the same technique but I limit my shots to 50 yds or so, but the 4" is mainly used for back up or if a deer is walkin up on the rite side of me (I just cannot shoot a long gun from the left shoulder) the distance is cut because the boolits hit higher from the 4" than the 6"
I hope this gives some insight to what you wanna do & a chronograph will help more than I can tell ya.
Stay Safe !!
GP
