Zeroing after switching to lead free bullets

Change the bullet and you have changed the load. That is the whole principle, and it applies whether you have moved from lead to copper-zinc, from 150 grain to 130, or from one manufacturer to another. Re-zero every time.

Why the point of impact moves

Several things change at once when you swap to a monolithic, and they do not all push in the same direction:

• Velocity. Lower friction from the driving bands and a different weight mean a different muzzle velocity, which changes the time the bullet spends in the barrel.
• Barrel harmonics. The barrel whips as it fires. A bullet that exits at a slightly different moment in that cycle leaves at a slightly different angle.
• Trajectory. A different weight and ballistic coefficient produce a different curve downrange even from an identical starting point.
• Recoil impulse. A lighter, faster bullet delivers a different push, which subtly changes how the rifle moves before the bullet leaves.

A sensible zeroing sequence

1. Start close. Get on paper at 25 or 50 metres before burning ammunition at distance. A bullet that is off the paper at 100m tells you nothing about which way to turn.
2. Clean, then foul. If you have just scrubbed the barrel, fire a couple of fouling shots first. A clean cold bore frequently prints away from the rest of the string.
3. Let the barrel cool. Group in threes, with time between strings. A hot barrel walks and you will chase it.
4. Adjust off the group centre, never off a single shot.
5. Confirm at your working distance. Once zeroed, verify at the ranges you actually shoot at.
6. Record everything. Load, weight, velocity if you have it, conditions and final clicks.

The first-shot question

This is what matters in the field. You will almost always take your shot at a deer from a cold barrel — so that is the condition you need confidence in. It is worth deliberately testing where your first cold-bore shot lands relative to the group, several times across several sessions, and knowing that number.

Copper fouling and your zero

Copper build-up in the rifling moves the point of impact over a long string. This is one of the practical arguments for the harder copper-zinc alloy — it fouls more slowly, so your zero holds over more rounds. See copper fouling and barrel cleaning.