Another ML question and I really am asking for a friend. He and I both rookies at ML. He has shot it 20 or 30 times and each time it felt about the same as he pushed the ramrod down. Then one time it was a lot harder to push down and that particular shot was about 10" lower than expected(as compared to other shots at same distance.) He shot it a few more times without issue. Any idea why it would be hard to load and would it cause a 10" drop?

First shot clean bore, after that ya pushing excess degree back down barrel.
Might not have fully seated bullet, left out one of the pellets.

Put ramrod down muzzle, mark end muzzle, take pellets & bullet, measure, mark it off on ramrod.
Heavier weight bullet, longer bullet..

The experts will be here shortly... just my lots of verables...
Stay Safe

The best solution is clean between shots.

Low humidity can make it hard to load after the barrel is dirty.

I know that he runs a wet patch(or two) and then a dry patch(or two) between every shot but not sure how often he cleans more than that.

The cleaning ritual sounds correct, could be his patch lube, not enough.

I agree with a Colt 45. Lots of variables. Goex BP causes the bore to tighten a lot faster than synthetics. Black Horn 209 is very clean.
Is he shooting a patched ball ,conical or saboted bullet?
In 50 years of ML hunting , I’ve never run a wet patch down the bore between shots. Usually only a dry patch every few shots.

Pappybear, thanks. He uses sabot.

Possibly the sabot twisted going down the barrel which would cause both the hard to load and inaccuracy you described.

What would cause it to twist. Inconsistent pressure? Bad sabot?

Bullet Improperly seated in sabot when started in the muzzle or defective sabot would be my guess.

Unless you are using BH209 powder you need to moist swab the barrel after each shot. I expect the shot that was low was not firmly seated on the powder. Put a witness mark on your ramrods to make sure your bullet is firmly seated on powder.