A MICHIGAN guy asking that question?
There's absolutely NO REASON what so ever, that his Encore won't shoot accurately to 200yds and even beyond. I shoot that distance quite often when my range opens up (corn gone) and can group them under 2".
It appears that your father maybe caught up in the pellet craze and powerbelt bullets. His rifle is capable of better shooting with a different propellant and bullet. I've owned many Encore platform rifles and they can be outstanding shooters. Actually never had one that wasn't. Way to many people IMO get caught up in the "easy way" and are told that pellets are the way to accuracy. I disagree...
Now he could go right to the Lansing area and order an Ultimate but, he'll spend $3,000+ for it. But he can change up propellant and bullets and make it shoot accurate. For around $35 and shipping, it can be turned into an excellent rifle with a few rifle modifications. However.... for cost savings this close to the season, I'd change up propellant and bullet.
He should try loose powder and I would highly suggest BH209, which will require him to measure his powder with a VOLUME measure.
NOTE: 120grs VOLUME IS A MAXIMUM CHARGE and NOT 150grs as with other propellants. He should purchase CCI209M or Federal 209A primers, as his muzzleloader primers used with pellets are not hot enough to reliably ignite BH209. As for a reliable and accurate bullet, I would suggest he use either the 250gr TMZ or the 290gr TMZ Barnes bullets. He should find that the neighborhood of 105grs to 110grs VOLUME of BH209 will group that rifle excellent. SEAT THE BULLET HARD ON THE PROPELLANT. After that, its the shooter.........
Using the above combination, I took two last year, one at 191yds and one at 203yds. Both were pass thrus and dropped in 35yds. His rifle is very much capable of shooting much better.