So Im relatively new to the whole long range shooting thing. I started about 3 years ago but got more serious about 2 years ago when I started loading. So first things first. I'm not doing this to try to win a contest. I do this mostly to compete with myself and see results. I'm an engineer by profession so I always like making fine adjustments to see improvement. Equipment: .308 Savage FCP-K 3-15x Weaver Tactical FFP Buris Heavy Duty Tactical 30mm rings EGW Picatinny Rail BiPod (Not a Harris but not a super cheapo one they make these days....not sure the model) Rear Bag Loading Supplies: Nosler CC 168 GR BTHP Berger 175 GR Match Burners SMK 180 GR BTHP Varget IMR 4064 Winchester Brass (New Never Fired) - 50 Federal Gold Medal Match Brass (Fired about 5-7 times) - 100 PMC (Various use) - 500 The reason I listed all the supplies I have is because times are a little tougher than they used to be and I'd like to use what I have if I can. If need be I can buy certain items if I have too. So about a year or so ago I went through the process of finding an optimal powder load (Varget 42.2 grains) that seemed to shoot the best out of this gun. From the bench I was usually able to get them 1/4-1/2 MOA at 100 yds all day long. This was using Nosler CC 168 gr bullets and pretty much got the same results with the different brass. At the time I was only really able to shoot it out to 300 yds. It shot not so good at 200 ( I've heard the bullet doesn't really stabilize yet at this distance). About a 2-3 inch group and about a 3 inch group at 300 yds. I have recently been able to shoot out to 500 yards and I wanted to get some more drop data. The way I went about this was as follows. FYI - Im zeroed at 200 yds I shot every 100 yards starting at 100. I used my existing data that Ive already had out to 300 yards and everything pretty much was the same last time I shot the gun. I moved my target out to 400 yards and left my gun dialed in for 300 to see how low it shoots and then to calculate the drop and make the adjustment. I took my 3 shots and went down range and the shots were about 14" low but remarkably it was about a 2-3 inch group. So i thought to myself well thats great Ill just make the adjustment on the scope and itll be perfect. After I made the adjustment and shot again the elevation was "good" but the group went to like 5-6"....... I did the same thing at 500 yards with almost identical results. It shot low without any adjustment obviously with an amazing 3-4 inch group with 3 shots. Then I made the adjustment and Im at like a 6 " group. So I guess my question is what can I do to tighten this up with this gun and what could be causing this? Im not an expert shooter but I do my best to be consistent.....user error? Could it be that my brass has been fired a bunch of time? Maybe certain batches have been fired more? Would this do it? Is this not the best bullet choice? Powder? Primer? Bipod? Could it be incorrect torque on the stock bolts? I feel like there are a million variables and I wanted some advice on really narrowing down the variables. I've shot some Savage 12's that seemed to do better......is this gun just not designed to be shooting 3" groups at 600 yards? I'd appreciate any insight! Im open to any idea.Thank you!