Oh and forgot to mention this as a frustrating thing with airguns. Thayne Simmons was there at the UFT match - score 26, as well as Justin Welch - score 31, two of the winning-est airgun shooters in the US, both shooting slugs, neither scoring all that well, and I highly doubt their skills were the problem.
Airguns are somewhat finicky anyway even using pellets and "can" be worse using slugs. As usual POI shifts happen more than rimfire and it's one of those aspects that aren't fully figured out yet.