I hate to burst your bubble, but the further any projectile goes, the less damage it does. The physics of it is simple, but there is a interesting side effect that may be to your advantage at times. Now, weather we are using a PRB or a modern suppository gun as on your hunt, the further from the muzzle the projectile gets, the more velocity is has lost. The slower it is moving, the less it deforms/expands on impact. This is why you may be able to get more penetration at longer range than at close range with high velocity loads. More expansion means more resistance, and means more damage, but less penetration. This is often seen by people using modern high velocity calibers. For example, you didn't say what caliber you used, but a friend uses a .300 Mag (I am trying to convert him to hunt instead of just shoot, but haven't succeded yet). Due to most .308" bullets being designed for .308 Win/.30-06 velocity levels, out of his gun, he get s alot of bloodshot meat at close range because his bullets act like varmint bullets up close, and don't begin acting like a proper meat hunting bullet until they get out to 250-300yds and have had time to slow down some to prevent the kind of violent expansion that they provide up close. Now with MLs, we tend to not get that kind of meat waste like he does, but in the same way, you may get pass throughs at 75-100yds with the same load that doesn't pass through at 25yds.
Having said that, due to the way a RB slows down and the trajectory involved, most of us limit our ranges to about 100yds or maybe slightly over. This is in part due to the sights, in part due to trajectory, and the way the RB slows, but it is a combination of these factors put together that convinced most of us to keep our shots fairly close. Range estimation becomes CRITICAL and a slight mistake on our parts can mean a missed, or even worse, a wounded animal, so please limit your shots to whatever range you fully trust yourself to make good hits with your ML. This means accuracy first and foremost instead of a pursuit of velocity for the same of itself, as the most accurate load usually isn't the fastest one. This is going to mean that you won't be taking 300+ yd shots with RB like you did with your suppository gun. That's ok though, because it makes the hunting much better. I just say this because I used to do the same thing with mine, and while the long shots were good to be able to make, they just weren't hunting. Now let's see you sneak up and take the next one up close with a PRB. :thumbsup: