jandbn
10-13-2009, 08:33 PM
definitely adds up! After 20+ years of being away from shooting/reloading, I finally started working up a load for my new Ruger Bisley .45 Colt using H110 and 325 gr LBT style PB boolits. Off a rest at 25 yards, I had a 4-shot group @ 1 1/8” measuring center-to-center with one of the loads. The remainder of the 5-shot group was just about 2” inches from center of the 4-shot group. I was tickled that after 20+ years of not shooting a handgun that I was able squeeze off that 4 shot group. The “flyer” made the group the size I used to get with my .41 BH and .44 SBH years ago (unfortunately I no longer have them).
Anywho, after I got home, I started thinking IF the Bisley was capable of shooting consistant 1 1/4” - 1 1/2” groups, how far would I have to mis-align the iron sights to cause a 2” ‘flyer’. I had never sat down and did the math before and I was rather shocked that it didn’t take much misalignment to open up a group.
To put the distance measurement in perspective, I thought about using hairs. A common measurement for a hair is .001. According to my calculations (please correct me if I am in error) in Excel, I would have had to mis-align the 7 1/2” sight radius (in this case, 2” longer than the barrel length) by about 17 hairs to put the ‘flyer’ where it landed. If a person were to line up 17 hairs side by side, it ain’t all that much!! Then think about if the front sight is 17 hairs above the top of the rear sight. That would move the POI 2” high.
Needless to say, I have a new-found respect for an absolutely solid rest. When I toss a grip change that can cause POI shift during a string of shots into the equation along with shooting off hand, no wonder I can’t shoot worth a ****! I have a very healthy respect for those folks that use iron sights off hand and can keep ‘em on a paper plate. After another 500-1000 shot, maybe, just maybe, I can keep ‘em all on a paper plate off handed at 50 yards? I didn’t try, but I bet I couldn’t keep ‘em all on a plate off handed at 25 yards. Half worn out 50-year-old eyes are not going to help matters any either. I don’t know how you old fogies with your ‘elderly eyes’ can shoot like you do!! I guess maybe I should think about using a scope for load development to remove a lot of my influence from groups. I just don’t want to tote a scope around while hunting. The Bisley as it is looks and feels just right!
For those that have never thought about misalignment of iron sights by a few “hairs”, see the 25 yard table below. (Take POI change times 4 for 100 yard shift in impact.)
Anywho, after I got home, I started thinking IF the Bisley was capable of shooting consistant 1 1/4” - 1 1/2” groups, how far would I have to mis-align the iron sights to cause a 2” ‘flyer’. I had never sat down and did the math before and I was rather shocked that it didn’t take much misalignment to open up a group.
To put the distance measurement in perspective, I thought about using hairs. A common measurement for a hair is .001. According to my calculations (please correct me if I am in error) in Excel, I would have had to mis-align the 7 1/2” sight radius (in this case, 2” longer than the barrel length) by about 17 hairs to put the ‘flyer’ where it landed. If a person were to line up 17 hairs side by side, it ain’t all that much!! Then think about if the front sight is 17 hairs above the top of the rear sight. That would move the POI 2” high.
Needless to say, I have a new-found respect for an absolutely solid rest. When I toss a grip change that can cause POI shift during a string of shots into the equation along with shooting off hand, no wonder I can’t shoot worth a ****! I have a very healthy respect for those folks that use iron sights off hand and can keep ‘em on a paper plate. After another 500-1000 shot, maybe, just maybe, I can keep ‘em all on a paper plate off handed at 50 yards? I didn’t try, but I bet I couldn’t keep ‘em all on a plate off handed at 25 yards. Half worn out 50-year-old eyes are not going to help matters any either. I don’t know how you old fogies with your ‘elderly eyes’ can shoot like you do!! I guess maybe I should think about using a scope for load development to remove a lot of my influence from groups. I just don’t want to tote a scope around while hunting. The Bisley as it is looks and feels just right!
For those that have never thought about misalignment of iron sights by a few “hairs”, see the 25 yard table below. (Take POI change times 4 for 100 yard shift in impact.)