Model 12 FTR Accuracy

I have a new Model 12 FTR and I am getting horrible results from it. I initially took some old ammunition that was hand loaded for my grandfather in 1991 to the range and it shot anywhere between 0.75 to 2 inch groups with it. I then took that brass (which was quite old and mixed) and full-length resized it while I waited for my new Nosler brass to come in. I full-length resized and trimmed each case. I am using A-max 155 gr bullets with Win-748 powder. I loaded rounds in 0.5 gr increments from 40 to 43 grains. When I went to the range the next time to try these new rounds out I had groups between 1.15" and 5.5". Most groups were above 2" and most were horizontally dispersed. The 5.5" group was almost entirely horizontally dispersed.

Some additional information is that my scope is a Falcon 5x25-50. I also did not clean the gun between the first 30 shots I put through it and the last test batch that had the bad results. I will be getting another person with more shooting experience then me to see if they can get better results. Any help would be greatly appreciated!!

Don't let that discourage you. Sometimes you gotta try a few different powders. Make sure the scope is mounted tight.

Your horizontal can most times be corrected with bullet seating depth. If you have a flat line across the target take that load and change bullet seating 10-20 thousandths at a time till it starts to get better then go with smaller amounts from there.

My FTR hated 748. Try Varget, IMR 4064, 4320, 4895(IMR or H).

Imr 4064 !

Thanks for all the responses guys!! Powder is really hard for me to get, but we are getting a basspro in the spring. I haven't tried changing the seating depth, so I will try that next. Any opinions on 155gr vs 168gr bullets?

Mixed headstamp brass does nothing to aid accuracy. You should see better results when your new brass arrives.

Do all your ballistics testing with vigilance and know what you are capable of shooting! My Model 12 F T/R shoots 1/2 MOA at 600 yards but it took a lot of testing for the ammo that it likes and then many hours of practice for me to meet the rifles capability and I am still a work in progress!

For me 4064 is money with the 175's and the 12 twist. Somewhere just above 43.3 with Palma brass.

If you get to the point where you're pretty sure you're doing everything right, and your group size just doesn't diminish, try swapping the scope out with a known good one. Many times, bad groups can be traced back to scope internals not doing their part.
One other thing.....that brass is now fireformed to your chamber. Back that sizing die off and neck size only until you can't close the bolt on it smoothly, then just lower the die down enough to lightly bump the shoulder. Full length sizing each time you reload may be contributing to your inaccuracy as well.

Instead of playing around with hand loads, I would suggest shooting factory loads to at least be able to get a baseline, good or bad.

You stated you did not clean the rifle for the first 30 rounds. That could also be a problem. IMHO, I would clean it out thoroughly and then do Savage's recommended break in procedure. It is tedious as hell, but might very well solve the problem after the first 100 shots or so.