Hi everyone. First time posting but I searched and prolly went 50 or so pages back looking for info to no avail.

Question is:

Has anyone gotten this bullet to spit out of a 12" twist, 26" length 12fv or similar savage to any luck? My friend gave me some of his ammo with this bullet but he has a different twist and I don't know what was going on but they were going every which way out of the barrel. Seriously they were just spinning wherever they wanted (6" plus any which way direction). And that really bummed me out because I think the bullet would do great on prairie dogs, which is the main purpose of the rifle. I shot some Wolf Gold also that day and got about a 1.5" or so group @100 yards.

I'm quite new to the reloading side of things but was looking for a couple of starting points to try. The powders I have available as of now are:
1. Varget
2. IMR 4064
3. H380

It will be going mostly in Winchester brass or once-shot PPU brass from the Wolf Gold. I also have Winchester LR primers.

I would prefer to use IMR4064 if possible. Also do I find a powder charge and then start playing with overall length? Because just today I did the whole "sharpie a bullet and push it in the rifle to see lands length(proper term?)" and it was WAY longer than the SAAMI OACL listed on Nosler's website. A little guidance and some rough starting data would be greatly appreciated. Thank you.

Side note: my new favorite gun @ http://imageshack.com/a/img743/5193/XYKloM.jpg