I just did that very thing last weekend, breaking in a new gun. Shifted a "stolen scope" from another rifle just to shoot it. Zero'd the scope in 12 rounds at 100, confirmed with 10 rounds on steel at 100, and got first-round hits at 500 immediately.
We took that target out there, and just planted it - distance wasn't a concern, at the time. Get it OUT a little bit. Got back to the firing line, sighted on it through the mil-dot scope... Damn, isn't that thing an even ONE MIL WIDE right now. Sweet, 500 yards, exactly. That target is 18" wide, so when it turned up 1 mil wide in my scope, I knew exactly how far out it was. That's the magic "mil-math" right there. That's all from training, over time.
It's all here, in this link:
That comes down to 2 years on this specific cartridge, knowing what it does, how it acts, how it drops - and shooting it through 4 other different guns of the same caliber at distances to 845 yards before. Even the 12.5" gun get's to 845 yards on this load. Nothing is impossible. It just takes time, practice, and patience.