Happy Little Group and a Question.....

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AJ

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Shot this group yesterday at the range. Yes, it was the best group out of the five that I shot. Was happy with it, though it did concern me at first as I could only see one hole for the first 4 shots and on the fifth the hole elongated some.

To measure center to center hits, you measure the overall group then subtract the bullet diameter correct?
 

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Yes. Farthest edge to opposite farthest edge, minus bullet diameter equals center to center group size.

Nice group!

Thank you!

With my dial calipers the overall group measures 0.275". I measured a SK Rifle Match bullet and it measures 0.222" at the driving band. Subtracting that gives me 0.053". I am happy! Will hang this one on the wall!
 
Today's Internet "all day long" guys would call a group like that typical of what their gun was capable of "all day long" even if that was the only small group they ever fired.

I've discovered a few things over the years as far as measuring group sizes. Measure the bullet hole diameter in the paper. It will almost always be smaller than than actual bullet diameter regardless of the type of paper. As I recall, .308" diameter bullet holes measured noticeably under .308", so subtracting .308" from your measurement isn't an accurate way of assessing group size even if it's commonly done that way. Your group size will actually be larger than what you record.

Don't use a dial caliper for measuring group sizes. A caliper is only useful in benchrest or similar competition where three or so persons measure with a caliper and then average, because measurements with a caliper are seldom repeatable.

I find it's best to use a ruler with two scales, 1/10" and 1/20". Either is very repeatable and few have a need for any measurements finer than that. It doesn't help boasting privileges, but you'll get a more realistic report of group size. Perhaps the best way to measure group size is to measure across the entire group and subtract nothing.

Not to denigrate the original poster's group size in any way as that's a good group. To be most meaningful, the two groups before that one as well as the two groups that followed provide the best picture of a load's accuracy potential, but few of us go to such trouble.

All this is hair splitting, true, but that's what good groups are about.
 
Nice group AJ ! Couldn't expect any less from an old Devil Dog . My buddies and I were at the range this morning at 0900 , and yup it was cold out there . Not like up north , but mighty cold for a couple of Fl crackers .
 
Best I've ever seen at 50 yards. I'm sure there are Olympians that couldn't duplicate it even with young eyes.

Congrats,

Al

Damn 'flyers'....lol Nice shootin'!

Do you always carry a buffalo head nickel with you?

Thank you both very much!

I usually use nickels to help show the size of the group. There are four Buffalo Heads in the pile ( two 1929's, a 1935 and a 1936). Also I have a Liberty Head nickel (1912) and a Liberty Head Dime (1910). To take care of the "Aw S***!" groups is a Peace Dollar (1923).
 
I have done it several ways, but I usually measure group extreme spread using a small steel ruler graduated in millimeters (about 0.04") measuring actual estimated extreme hole centers. If you really want a statistically reliable measure of grouping performance, it takes firing a minimum of at least five 10-shot groups, then taking the average ES of the groups. A single five-shot group ES tells you nothing reliable. It will require firing at least 25 5-shot groups to give an equally reliable average ES as firing five 10-shot groups.
 
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Today's Internet "all day long" guys would call a group like that typical of what their gun was capable of "all day long" even if that was the only small group they ever fired.

I've discovered a few things over the years as far as measuring group sizes. Measure the bullet hole diameter in the paper. It will almost always be smaller than than actual bullet diameter regardless of the type of paper. As I recall, .308" diameter bullet holes measured noticeably under .308", so subtracting .308" from your measurement isn't an accurate way of assessing group size even if it's commonly done that way. Your group size will actually be larger than what you record.

Don't use a dial caliper for measuring group sizes. A caliper is only useful in benchrest or similar competition where three or so persons measure with a caliper and then average, because measurements with a caliper are seldom repeatable.

I find it's best to use a ruler with two scales, 1/10" and 1/20". Either is very repeatable and few have a need for any measurements finer than that. It doesn't help boasting privileges, but you'll get a more realistic report of group size. Perhaps the best way to measure group size is to measure across the entire group and subtract nothing.

Not to denigrate the original poster's group size in any way as that's a good group. To be most meaningful, the two groups before that one as well as the two groups that followed provide the best picture of a load's accuracy potential, but few of us go to such trouble.

All this is hair splitting, true, but that's what good groups are about.

I have done it several ways, but I usually measure group extreme spread using a small steel ruler graduated in millimeters (about 0.04") measuring actual estimated extreme hole centers. If you really want a statistically reliable measure of grouping performance, it takes firing a minimum of at least five 10-shot groups, then taking the average ES of the groups. A single five-shot group ES tells you nothing reliable. It will require firing at least 25 5-shot groups to give an equally reliable average ES as firing five 10-shot groups.


Gentlemen, I understand about shooting for groups to check the accuracy of a rifle, handgun or the shooter. My Grandfather taught me that over 60 years ago, the Corps reinforced it over 50 years ago and a lifetime of shooting has taught me quite a bit. Have accurized rifles, handguns and developed loads that enhanced the guns capabilities. The rifle that I used for this will consistently shoot 3/8' to 1/4" groups using SK Rifle Match at 50 yards. Some days even better and some days a bit worse depending on conditions and the loose screw behind the trigger. All that said, a group like this is something to behold and marvel at in my book. The fact that I could do it after having the cataracts in both eyes fixed amazes me and makes me very happy...........
 
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I have done it several ways, but I usually measure group extreme spread using a small steel ruler graduated in millimeters (about 0.04") measuring actual estimated extreme hole centers. If you really want a statistically reliable measure of grouping performance, it takes firing a minimum of at least five 10-shot groups, then taking the average ES of the groups. A single five-shot group ES tells you nothing reliable. It will require firing at least 25 5-shot groups to give an equally reliable average ES as firing five 10-shot groups.


I usually have to use a yard stick! And it gets a little tough getting the powder burns off the paper! Nice shooting.
 
A two time national champ once told me. "For every shot the wind blew out of a group, there is a shot that the wind blew into a group!"

My F-I-L was the judge of last appeal at the NRA National Pistol Championships at Camp Perry for about 20 years. The NRA issued him a measuring device That had plugs for 22, 30, 38 & 45. These had a pin sticking out. The device had a "Lasso" that went around the pins. When normal scoring methods ended in a tie, The shortest circumference won!

The NRA owned about 20 of these, they were certified every year.

Using the "Hole minus diameter" method, I once had a Negative .003" group. I've also been known to have groups measured in feet!

Ivan
 
A two time national champ once told me. "For every shot the wind blew out of a group, there is a shot that the wind blew into a group!"

My F-I-L was the judge of last appeal at the NRA National Pistol Championships at Camp Perry for about 20 years. The NRA issued him a measuring device That had plugs for 22, 30, 38 & 45. These had a pin sticking out. The device had a "Lasso" that went around the pins. When normal scoring methods ended in a tie, The shortest circumference won!

The NRA owned about 20 of these, they were certified every year.

Using the "Hole minus diameter" method, I once had a Negative .003" group. I've also been known to have groups measured in feet!

Ivan


I have a couple of the plugs that you mentioned. One is solid aluminum and the other has a plexiglas disc.

Would like to see a "Negative .003" group". That has to be smaller than the bullet making the hole in the target. Mine is a positive 0.053" center to center.
 
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