Struggling to Achieve a Zero at 100 yards.

[Lawnboi]

Just to add more to the 6.5 tikka thing. My gun likes 140 Berger the most, plus you get Lapua brass. The round is significantly hotter in my rifle than any of the hornady stuff

 

[HighUintas]

What is it with tikkas and the 6.5 cartridge? The consistent easy accuracy is mind boggling. It makes me want to get one

 

[KYKRAZEE]

I am having trouble getting a good zero at 100 yards (3-shot groups, 3 MOA) and have a few questions related to that. First, I'll lay out some facts and assumptions:

Equipment:
1) Gun: Rem Model 700 .30-06, wood stock, adjustable cheek rest, LOP=13.25
2) Scope: Leupold VX-3i 4.5-14x50mm
3) Ammo: Rem Core-Lokt's 180 GR PSP
4) EGW $40 Pic Rail 0 MOA

Rail Bedding/Scope Mounting:
1) Rail Bedding: used Jeff Broz method
2) Scope Mounting: Used Formidilosus' post as guidance
3) Leveling scope to barrel/gravity: Used scope level resting on flat iron sight (see image of gun) and put the reticle flush to a de facto plumb bob with a DFAT on there.

Description of Zeroing set-up: from a bench rest using front and rear caldwell sand bags (can't get prone at 100 yards at my range).

Here goes my assumptions:

1) I need to shoot more than 3 shots to get better data to see where the group is and confirm zero
2) I am not a great shooter, and am probably not using great trigger control, proper breathing, and otherwise introducing more error into the rifle than a competent shooter would be.
3) I plan to buy some better ammunition and collect data on it prior to hunting this Fall (see question 1).

Here is my question:

1) How much would better ammo (e.g., federal premium nosler accubond 180 GR) decrease MOA (given no human error to the system)?

I would not only try different bullet weights but different brands of ammo as well.