OK. If you know someone with the Rocket or the Wolf one, try them out. I think they do help in taming the roughness of the Glock triggers. I know that you have posted in the reloading section with some other questions, but let's address the group size with "good" ammo.
I'm air quoting it, because, once you master the trigger control, and have your reloads where you want them, then the ammo really doesn't change much at 7-8 yards, where we are shooting. Ammo will show differences at 25 yards in group size (benched), but for informal off hand shooting at 7-15 yards, not much IMHO.
The groups I mentioned above, and the targets at the various ranges can be duplicated for me regardless of the ammo - my reloads using plated, lead round nose, lead cone, or fmj. Federal, Blazer brass and aluminum, Wolf, Tula, Silver Bear, and who knows what else.
Back to the other questions:
How good is your trigger control? Does the break surprise you? Do you keep the group at your point of aim? Or are they somewhere close?
If you have a good shooting coach/mentor you can work with, it may help. But there are some tips I can suggest that helped me.
1 -- trigger control
2 -- trigger control
3 -- trigger control
4-9 -- trigger control
10 -- sight alignment/sight picture
11 -- any thing else
One trick that I use to help me zero in -- is a small area/point to aim at. I find that if I have a set point on the target to aim for instead of a broad empty area, then it helps me stay tighter. Sometimes I use the small paste circles from the shoot and sees.
Get a couple of dummy rounds made up or buy some snap caps, have a buddy load your mags and when you shoot, see what happens when you hit the dummy round. Do you flinch, jerk, anticipate the recoil or otherwise mess up the trigger break?