Yes, you should be shooting tighter groups with that gun at that range. Without knowing more about how your patches look- I suspect you are burning patches with that heavy hunting load---- and how you clean the gun, and how well you see the sights, or the target, or how experienced you are shooting open sights on any rifle, Its only a guess as to what is going wrong here.
It looks like you are using Dutch Schoultz' dry patch recipe. You need to dry those patches or material Flat- not over a line, or suspended from one end. The latter only lets the oil move to the lower portion of the patching, leaving more oil than needed at the low end, and little or no oil at the top. NOT GOOD!
I recommend cleaning between each shot- but I use a cleaning patch just touched to my tongue to dampen it enough to pick up unburned residue. DO NOT run the cleaning jag/patch ALL THE WAY down the barrel. You are pulling the crud out- not shoving it down into the powder chamber. I recommend stopping the jag about 1 inch from the face of the breechplug- or beginning of the powder chamber, then pulling out the crud from the barrel. You will need a bore brush the correct diameter of the powder chamber and a cleaning patch to clean out the powder chamber. I always recommend drying the barrel after you have run anything damp down it. Do this drying in stages, ie., run the dry patch down about 1/3 of the barrel, then pull up on it, to break loose and crud in that part of the barrel; Then run it down the next 1/3, and reverse the direction to pull the patch up that 1/3 of the barrel; then run it down to the beginning of the powder chamber, and pull the patch out of the barrel completely.
This should give you a barrel that is a clean as the barrel was for your first shot.
I found that 60-65 grains of FFg powder is all that is required for great accuracy in my .50 at 50 yards. I then worked up a 100 yd. load, and found shooting 75 grains more accurate- but only slightly-- than the 80 grain charge, and better, the felt recoil was less, and difference in POI was insignificant. Since accuracy is more important than velocity with any round ball load when hunting at that long range, I stuck with the 75 grains powder charge.
Sometimes, just switching to FFFg powder will vastly improve the performance of a rifle's accuracy. its always worth testing it out. For example, a very good friend of mine bought a .62 cal. rifle from another club member, in excellent condition, and began working on loads off a bench at 25 yards, at the club. He was using FFg and could not find a load that would put the ball on paper, much less hit a bang plate that was about 8 inches in diameter. He had forgotten to take a can of FFFg powder to the range, and he was very frustrated by the time I arrived. I immediately offered him my FFFg powder to use, over his protestations that "Big Bore MLers require 2Fg powder"( the old adage). well, the first load he tried- i don't remember what-- he put his ball in the back near center. He fired a couple of more shots and they joined the first. He was both ecstatic, and angry that the gun did not shoot FFg powder well. But, he got over his anger once he found both a target load that was very accurate, and his hunting load, using FFFg powder.
One last thing you can try if you are having trouble holding that front sight on target:
Take a piece of paper, and fold it from one corner to another, forming a large Triangle. Staple this to the target, with the point of the triangle giving your your aiming point. For old eyes, and open sights, this large triangle helps you find that "Point " consistently, even at 100 yds., and you should see your groups reduce in size. I use a business card at 50 yd. targets, because the bullseye is so large, a white business card contrasts nicely with that background. Either have the triangle come up from below, or from overhead. Either works. Some shooters like one better than the other. :thumbsup: :hatsoff: