Discussion in 'On Topic' started by thomor25, Jan 6, 2008.
it was getting dark but it was doing 3 shot groups and all were touching at 100 yards.
cool story hansel
The Trouble With 3-Shot Groups
(The distant prequel to The Trouble With Tribbles)
As our story begins, we find our Hero sitting down to the shooting bench at the 100 yard line at his local range. He is a real Internet Commando. He has watched the movie Heat 87 times, is registered on all of the important Internet firearms forums, knows the difference between a “clip” and a “magazine” and attends every local gun show without fail.
His latest acquisition from the local gun show is a 16” no-name Frankengun that originally belonged to a Delta Force operator who was at the Battle of Mogadishu. (He could tell you the name of the operator, but then he’d have to k……well, you know.) The seller at the gun show let our Hero in on another secret too. Eugene Stoner himself helped the Delta operator assemble this AR-15.
Our hero settles into position on the bench and fires his first 3-shot group. (He only fires 3-shot groups because everyone on the Internet knows you only have to fire 3-shot groups to test your rifle and ammo.)
His first group forms a nice little triangle at the bottom of the 10-ring. Our Hero just knew this was going to be a good day. After all, he was using that XM193 ammunition. A former Seal who was selling beef jerky at the gun show had told our Hero that the Seals used ammo just like XM193 in Viet Nam and that a single shot in the buttocks from this ammo would “blow your head clean off!”
At the cease fire the Commando checks his first target. (Our Hero’s targets are NRA High Power type targets reduced for 100 yards. The X-ring measures 1.5” and the 10-ring measures 3.5”). Much to his satisfaction, his first group measures 1.16”, almost minute of angle! Now most Internet Commando wannabees would have stopped right there and gone home and spent the next 3 hours posting threads on the Internet about their great accomplishment, but not our Hero. He makes the decision….to fire a second group!
Our Hero has read reports of other Internet Commandos who have been able to achieve sub-minute of angle groups using XM193. After all, this ammo uses “Full Metal Jacket” bullets and is made to “Mil-spec.”
Our Hero carefully watches the bench-rest shooter three lanes down and only fires immediately after the bench-rester does. He does this for three shots and then checks his target at the next cease fire.
Our Hero measures this target three times just to be sure. The group measures 0.93”! Hooah, a sub-minute of angle group! Our Hero is now one of the few, the proud, the real Internet Commandos who can claim to shoot sub-minute of angle groups using XM193!
There’s just one little problem with that second group our Hero fired. It is centered in a different location on the target than the first one. The group is centered 0.12” above the center of the target and the first group is centered 1.44” below the center of the target. Hmmm…
Well our Hero is a real Internet Commando so he can’t let details bother him. After all, sub-minute of angle is sub-minute of angle!
As our Hero starts to pack up his targets, something in the back of his mind starts to nag at him. He recalls the reports of the other Internet Commandos. They didn’t just shoot sub-minute of angle groups with XM193; they did it “all day long.”
Well, not wishing to be looked down upon by the other Internet Commandos our Hero decides to shoot one more 3-shoot group. After all, if his carbine and ammo could shoot two, sub-minute of angle groups, they could surely do it “all day long.”
So, our Hero settles back into position and again taking his cue from the bench-rester fires a third 3-shot group. Upon retrieving his third target and measuring the group our Hero can not believe his eyes. The group measures 2.5”! How can this be possible? He was using XM193 and not just any XM193. It was the fabled “LOT #3,” the most accurate and hard to come by of all the lots, yet this third group was larger than the first two groups combined! Hmmm… Our Hero wonders how he can ever show his avatar on an internet forum again after firing such a group with XM193.
Then, slowly our Hero starts to recall a word he has heard mentioned many times before on his favorite Internet forum. It starts with an F. F…Fl…Flyer! That’s it, flyer! That low shot down at seven o’clock on the target is a flyer! It’s not the fault of the gun or the ammo, it’s a flyer. It's caused by user error, the loose nut behind the stock, the wind, the sun or any other excuse that can be dreamt of in your philosophy, but not the rifle or ammo.
The flyer is something to be discounted as if it never happened. (Why be concerned with reality when you are an Internet Commando?) Since that shot is discounted, why not discount that whole group as if it never happened? (After all, isn’t that what an Internet Commando does?) Our Hero decides to discount the entire group and throws the target in the trash. He makes a solemn vow to never mention this group to anyone. After all, he is a real Internet Commando.
Upon returning home our Hero makes all the usual posts on the Internet about his sub-minute of angle groups using XM193. True to his solemn vow, he makes no mention of his 2.5” group. At no time does he mention that these groups were 3-shot groups. Nor does he make any mention of the fact that the groups were centered in different locations on the target.
Our Hero ends his day wondering if his grandson, or great-grandson or even great great-grandson will remember the accomplishments of the real Internet Commandos or if their contributions to the shooting world will eventually be lost in time? He even wonders what his progeny might someday be named, James or possibly Tiberius? Hmmm…
Dedicated to DK-Prof for his shining example of "truth in accuracy reporting" in these two threads:
How Accurate is XM193?
Apparently, I suck at shooting
While the fable above is obviously fiction, the examples of targets shown are based on a real target of a 10-shot group fired from 100 yards using XM193. When all of the 3-shot groups from above are overlayed on a single target you see a much truer example of the limitations of the rifle and ammo. The gap made by the so-called "flyer" is filled in by the other seven shots of the whole group. You can see that when the first 3-shot group (which is centered 1.5" below the second 3-shot group) is displayed with the second 3-shot group you are actually seeing a much better indication of the total dispersion of the rifle and ammo combination. Most people fail to mention that their 3-shot groups are impacting at different locations on the target. This is why 10-shot groups are a much better indicator of a rifle and ammo's average accuracy.
Rick Jamison, the author of the Precision Reloading column in Shooting Times magazine approaches accuracy testing in a very scientific manner. He uses a machine rest for testing and fires 10-shot groups. Here are his own words on the subject from one of his articles:
There are stories of a single bullet that for no explained reason flies out of what might have been a tight cluster. This often occurs with a three-shot string and many times with a five-shot string. If you're lucky enough to fire a group without a flier, you can end up with a very tight group. However, usually what happens if another five or seven shots are fired to complete a 10-shot string, other bullets fill in the space between the main group and the flier to make a reasonably rounded group. Ten shots are a more reliable indicator when it comes to predicting what a load is likely to do in the future.
The problem with 10-shot groups is that when you report them, everyone thinks you aren't shooting very well or that the ammunition is not good because the group sizes are so much larger than three- or five-shot groups. Also, when we're firing three- or five-shot groups with a flier, it is only natural to assume that it was caused by a flinch or "pulling" the shot. Therefore, since the flier was our own fault, the tendency is to eliminate it from any reporting of group size.
This is one of the advantages of using a machine rest... The machine rest reduces the human element.
After using this machine rest for several years, I have determined that a 1.5-inch 10-shot group at 100 yards... is a good one.