There are a lot of factors that go into being confident of the shot’s results, although confidence provides no guarantee.
For me, confidence starts with a firearm and load I can consistently shoot well, whether at the range or in the field.
The range involved plays a big part – is it a known factor (e.g. lasered) or is it an estimate? Close range engenders higher confidence but as the range increases confidence drops accordingly. Inside 300 yards, confidence is very high. At 400 it starts to drop, with lack of a steady rest increasing he rate of drop. Beyond 500 yards everything needs to be perfect before I would attempt a shot. Past 600 yards, the limit of my practice, confidence drops to zero. My longest shot to date is 487 yards with passes on all longer opportunities.
Knowledge of the cartridge plays a part, too. Regardless of the bullet, I wouldn’t choose a .223 Rem for elk at 600 yards. A .300 WM, yes.
Then there is confidence in the bullet, the thing that does all the work. I have a strong preference for mono-metal and bonded bullets for my bolt guns as I trust them to hold together and penetrate better than cup-and-core bullets after high velocity (i.e. close range) impacts. For my lower velocity hand and lever guns, cup-and-core or hardcast are acceptable and sometimes all that is available.
Then there is the angle of the particular shot. Even a good bullet at the wrong angle gives me pause. For extreme angles I would want a bullet like a TTSX that has proven its worth in the penetration department. Not only have my hunting partners and I never recovered one on broadsides, I’ve taken facing shots and driven them lengthwise through mule deer with exits.
