First off, IMO thinking a factory featherweight barrel with questionable bedding is going to give 3/4" or better "consistently" is a stretch by a longshot!
You have fallen into the trap of fabled internet super accuracy for a factory gun and "all I have to do is keep testing loads" to find the super group.
The barrel is whippy because it is a mass produced factory pencil thin barrel that was never made to shoot 5/8" groups and that is not going to change with forend pressure either.
You have a consistent 1"- 1/1/2" gun and my bet is you have done that repeatedly with multiple loads. We are talking about a lightweight big game hunting rifle, not a heavy barreled varmint rifle.
Just how far do you plan on shooting that the 1 1/4" groups that you probably found dozens of times will not work?
To put this in perspective, you might have even a 1 1/2" group gun that you are not going to shoot over 500 yards absolute maximum with that rifle at a deer with an 18" chest. So you have a 7 1/2" vs a 4 1/2" group on an 18" target and that will not work?
You have shot out half the barrel on each gun at a cost of over $500 (materials cost) between the two and what is the return?
Most factory rounds and rifles pretty much allow you to do a little research on powders and bullets and narrow it down to 2-3 or less on each that will work and give you acceptable accuracy levels for a "factory gun" and light barrel.
First have realistic expectations. Many of the 1/4" internet groups you hear about are one out of 10 groups and not repeatable time after time. Custom guns and barrels different story.
However, if you want to continue testing.
Shoot two rounds at various combos over a chrono to see if they will group and in the desired MV range will do for starters. Minimum of 200 yds and 300 is better.
It is a little known secret that if two shots do not group, shooting three more will not tighten the group up! Do not waste time, powder and bullets.
Take a reasonably working combo and run the seating depth checks (start at max COAL for the magazine) to find the best depth with that bullet and then go back and tweak the powder charge to an acceptable realistic accuracy level at the desired MV based on what the nodes are for that powder and MV as shown by the targets and chrono data.
If you did not use a chrono on the ladder and OCW, and shooting at more than 100 you are just was wasting $ and time. A chrono gives you as much information or more and even Newberry (OCW founder) has come to realize that since he started when he said a chrono was not necessary.
You have so many issues here and the first thing that should have been done has not been (ie fix the bedding). Poor bedding and you will never get consistent groups.
I can go on and on to issues with cleaning, proper torque on actions screws, improper bedding pushing on barrel and action etc.
