I have found that too fast of a powder under a heavy bullet results is inconsistent accuracy. Secondly, I found that polygonal rifling is detrimental to accuracy in the 9. In fact, the German military requested HK supply the USP with standard rifling for that application because the accuracy was substandard. Don't expect much better than 3" from the Glock factory barrel. You have two variables working against you: loose barrel to slide to frame fit and polygonal rifling.
Sigs have super tight barrel to slide fit and conventional rifling. They are far more accurate off a rest out of the box. You can easily get teeny little groups with the right handloads.
Try some Power Pistol under a 147 in your Glock. It is just right in terms of burning rate. It was designed for 9mm NATO and sold to ammo companies under the Bullseye 84 label. I like 4.5 grains and 1.125" under a JHP and 1.169" under a RN.
Sigs have super tight barrel to slide fit and conventional rifling. They are far more accurate off a rest out of the box. You can easily get teeny little groups with the right handloads.
Try some Power Pistol under a 147 in your Glock. It is just right in terms of burning rate. It was designed for 9mm NATO and sold to ammo companies under the Bullseye 84 label. I like 4.5 grains and 1.125" under a JHP and 1.169" under a RN.