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The Trouble With 3-Shot Groups (Page 9 of 12)
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Originally Posted By REDX:
there's a big difference between "purpose built" bench guns and the typical ar so that's like comparing a mustang to a GTO. Molon was not the OP so your argument and comparison are both lacking If you were addressing me you might note that I made no argument, nor did I make a comparison. The only thing one might conclude is that on that day and under those conditions the CTR-02 shooting 69gr SMK's by Black Hills was pretty damn accurate. Had I been shooting from a solid bench on a dead calm day that group would have been even better. I have on more than a few occasions nailed sub .5 MOA, 20 shot groups though I usually use the BH 77gr ammo. It is more a testimony to the quality of the Black Hills product than anything else. No doubt Molon or any number of experienced shooters could duplicate––or better, that performance. The CTR-02 is not a bench specific gun. Have a nice day. |
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Originally Posted By PaoloOrange:
This 3d really helped a lot my shooting technique. http://img201.imageshack.us/img201/7268/gac.jpg Above is the first AR-15 made in Italy (well, a lot US parts). :o) Nice shooting! |
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Over the years I have tried to eliminate my errors in my shooting from the bench so sandbagging both ends of the gun to keep the sights aligned with the target and consistiency in my gropus. I then realized that I really needed to shoot for accuracy in the manner that I would in a SHTF situation. The first target ia a 100 yard, off the bench, with sandbags fore and aft, using the American Eagle XM193 and my original A1 iron sights. Thegun is my first AR....a Bushmaster M4A1.
Aftr making some mods to the SHTF gun setup I decided to try it again with my new frankengun and EOTech sight. I picked the gun up, from a standing position on the gun rack at the range, cycled a round into the chamber and ran around the shooting stalls 4 times to get the heart pumping, then dropped to a prone position and proceeded to empty a 30 rounder into a man sized target at 100 yards. Here is the result using the bipod. Uh sorry for the wrinkled target!!! Just a tip when using the EOTech: A lot of folks say using the dot type sight system makes it impossible to get decent accuracy, at that range with the fuzzy dot, but I have found that turning down the brightness to just where I can barely see the dot makes it much easier. 
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The Advanced Internet Marksman
Move over Internet Commando, there’s a new breed of marksman in town. The Advanced Internet Marksman has arrived and he is not content to merely shoot sub-MOA groups at 100 yards using XM193 as the Internet Commando does; the A.I.M. has his sights set higher. He boasts of shooting ¾ inch groups at 300 yards using 40 grain bullets! The Advanced Internet Marksman doesn’t just make unsupported claims of quarter-minute-of-angle accuracy at 300 yards using his 16” M4, he posts pics to prove it. His target is shown below. 
The 2-shot "group" pictured above was really posted (on another website) as proof that the poster’s 16” barreled M4 had fired a ¾ inch “group” at 300 yards.  . . .  . . . 
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The Crane Naval Surface Warfare Center is involved in developing special munitions and weapons for our warfighters. At Crane, they’re not interested in sales hype and propaganda; they’re only interested in facts. They’re not driven by profit margin; their goal is developing the best tools to help our Special Operating Forces accomplish their missions.
When it comes to evaluating the accuracy of ammunition, what is the number of shots per group that Crane requires? Why, 10 shots per group, of course! 
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Originally Posted By MarkAC:
OK what the heck. JP Rifles CTR-02 18" Barrel ACOG TA31 ECOS Sunny 55 degree day Steady 5-7 mph wind moving directly from left to right Seated on my backyard deck at a shaky 36" plastic Wally World table with the handguard resting on a sand bag Black Hills Blue Box 69 gr SMK's 100 yards http://i28.photobucket.com/albums/c245/MarkChambers/DSC_0126-1.jpg Center circle is 11/2" across 18 shot group Put one shot in the lower right and left hand circles just to do a check I love this gun 
Very nice. What chamber does your barrel have? |
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| Some people will actually laugh at this read and say "I zero my semi auto rifle standing up". I was at the range the other day and a guy zeroed his AK47 at 50 yards kneeing. He said testing accuracy and shooting from the bench was for pussies. |
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The original poster is right on! Three shot groups are very misleading. The trick is to have every shot on center consistently. I'm a benchrest shooter and I shoot for score. Every shot is made at a different bullseye. This type of shooting is difficult because you not only have to keep groups small but you have to change your point of aim on every shot. It has been extremely difficult to get our custom built bolt actions to shoot well. I couldn't imagine competing in something like this with an AR
Here's what my setup looks like: |
Nice set up Tankdriver....Whew! Took me weeks to work through this thread, Boggles my little redneck brain it does. I'm now sold on the validity of 10 shot groups for true accuracy measurement, although I will probably continue shooting 3 shot groups when checking the zero for minute of killdeer using highdollar hunting ammo in my game rifles. On that subject, let me make a pitch. Everything I have read here is about continuous 10 shot strings, target shooting, which is what it is. In the hunting world, and other places where bullet meets bone instead of paper, often the first shot is the only one that matters. The Cold Zero. So I propose a different test; 10 shot groups fired on a cold, clean barrel, the shot you would fire if you had to pick up your rifle and defend your life with it. Take a clean target to the range, stick it up, shoot it one time and put it away. continue your normal range activities. Next time to the range, fire the second shot in the string on a cold clean barrel. and so on, until you have completed at least a ten shot string. Whats your rifle going to do the first shot, everyshot? Any interest? I am prematurely launching this as I have only been to the range one time with my newly built 20" WOA 1/7 .223 AR. I don't even know what it likes to eat yet, so I'm not yet ready to play.....
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Sweet set-up! Do you use the "free-recoil" method when shooting? |
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hmmmmmmm................. \ that grouping was angle of MOOSE....
MOST INTERNET COMMANDOS DONT POSESS THE INTELLIGENCE NOR START OUT WITH AN IQ THAT ALLOWS FOR FATHOMING ANYTHING BELOW THE SURFACE, MUCH LESS THE ART AND SCIENCE OF BLENDING AN UNDERSTANDING OF QUALITY, SKILL, KNOWLEDGE AND EXPERTIESE IN THE REAL SENSE, about anything... much less...SHOOTING your ....expose on the subject was pretty good! |
| LOL, Seems like you guys should partake in a rifle match and express your skills and equipment abilities. A under 3moa rifle will give you a decent score if you do your part, but will cause some ass scratching after you are done expressing your skills. Of course you would have to shoot " match rifle" with your carbines, and have to show some basic marksmanship abilities @ 2, 3, & 600yds. What the heck, your bullet can go that far. Double LOL |
| For one to truly test the accuracy of any barrel, firearm, or shooter for that matter would need to be tested inside a vacuum environment where there is absolutely no interference such as wind, humidity, or any other natural factor affecting bullet flight. the gun should also be placed in a vice. Also it should be aligned on the target electronically someway that it is aligned in the exact same spot everytime. Then, maybe, just maybe you can see how accurate the barrel and ammo really are. |
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Originally Posted By snipedacoyote:
For one to truly test the accuracy of any barrel, firearm, or shooter for that matter would need to be tested inside a vacuum environment where there is absolutely no interference such as wind, humidity, or any other natural factor affecting bullet flight. the gun should also be placed in a vice. Also it should be aligned on the target electronically someway that it is aligned in the exact same spot everytime. Then, maybe, just maybe you can see how accurate the barrel and ammo really are. By all means, post the results of your tests performed in "a vacuum environment." ... |
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I don't know if the Corps still does it this way, but we used to Battlesight Zero using 10 rounds on the 1000 inch range. Fire 3 rounds, adjust for new zero, fire three more and evaluate, then fire four rounds to check the zero. It worked fine for us.
For a while, they went on the cheapo by having shooters issued three extra rounds at the 200 yard line, and they would fire these in one minute, then dope would be figured off that. I didn't care for that method as much given all the variables that could come into play, but they didn't ask me, they just told me to do it. |
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Originally Posted By clancey2651:
I don't know if the Corps still does it this way, but we used to Battlesight Zero using 10 rounds on the 1000 inch range. Fire 3 rounds, adjust for new zero, fire three more and evaluate, then fire four rounds to check the zero. It worked fine for us. For a while, they went on the cheapo by having shooters issued three extra rounds at the 200 yard line, and they would fire these in one minute, then dope would be figured off that. I didn't care for that method as much given all the variables that could come into play, but they didn't ask me, they just told me to do it. Zeroing at 25 meters using 3-4 shot groups has nothing to do with conducting a statistically significant accuracy evaluation of a rifle/ammunition combination. As I have posted previously in this thread, three shot groups do not give a true picture of the accuracy of a rifle and ammunition combination. That is the point to this thread and that is what the factual data in the first posts of this thread shows. That is why the US Military requires 10-shot groups for the accuracy testing of the ammunition used by our Armed Forces. While zeroing your rifle with 3-shot groups may be expedient and conserve ammunition it is not the most precise method to use. Something better has come along and that is simply using a larger number of shots in your group (specifically 10 shots) to have a better picture of the actual variability of your rifle and ammunition and therefore a much better idea of where the actual center of your group is to adjust for zero. I decided to zero one of my rifles for Federal's XM193. The rifle has a free-floated Colt HBAR and wears a Leupold 3.5-10X40 LR/T. 
The rifle was previously zeroed with match grade handloads using Sierra 77 grain MatchKings. Here is a picture of a 10-shot group fired from 50 yards to give you an idea of the accuracy this rifle is capable of. The target used is an NRA High Power type target reduced for 50 yards. The X-ring measures 0.75" and the 10-ring measures 1.75". 
I fired some 3-shot groups with the XM193 from 50 yards at an indoor range. Since the shooting was done indoors wind is not a variable in this case. Two of the targets are pictured below. 
The centers of the individual 3-shot groups are indicated below by the blue crosses. 
In order to zero my rifle with the XM193 I would have to come down one click in elevation and left two clicks in windage; that is if I was going by the first target shown below. If I was going by the second target below I would have to come up six clicks and right two clicks. That is a difference of seven clicks for elevation, almost 2 minutes of angle! This shows the problem of trying to zero using 3-shot groups. These two groups are centered in different locations on the target. Which one shows the real center of point of impact? Most likely neither. As the data shows in the first posts of this thread, 3-shot groups tend to impact on different parts of the target and therefore by themselves they are not showing you a true picture of the variability of the rifle and ammunition. Using 3-shot groups you never know where the actual center of point of impact is. Zeroing using 3-shot groups is an exercise in chasing your own tail, down one click and left two clicks for one group and then up six clicks and right two clicks for the next group and so on and so on. I actually fired ten 3-shot groups with the XM193 for a total of thirty shots. Thirty occurences of something being studied is what the statistics types like to refer to as a "large sample." Using the RSI Shooting Lab software program I was able to overlay all ten of the 3-shot groups on each other for a composite target. 
This composite target gives a much better picture of the variability of the rifle and ammunition combination (and in this case particularly the ammunition) than 3-shot groups by themselves do. Two thirds of the thirty shots are within the 0.45" circle of the mean radius (the inner blue circle) giving a much better indication of where the center of point of impact is. The actual changes needed to zero this rifle with the XM193 are three clicks up and one click left. Now, it is not necessary to put together thirty round composite targets to have a very good idea of the variability of your rifle and ammunition. As shown in the initial posts of this thread, 10-shot groups do a very good job of that, (and come very close to approximating thirty shot composite targets as I will show in a future post.) While I wholeheartedly agree that using 3-shot groups to "get on paper" when zeroing is useful in conserving ammunition, once you get close to your desired point of impact, using 10-shot groups provides far superior results than 3-shot groups do. |
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"While zeroing your rifle with 3-shot groups may be expedient and conserve ammunition it is not the most precise method to use. Something better has come along and that is simply using a larger number of shots in your group (specifically 10 shots) to have a better picture of the actual variability of your rifle and ammunition and therefore a much better idea of where the actual center of your group is to adjust for zero. "
Actually, the most precise way to determine a rifle's accuracy is to fire from a fixed vise off a bench. Unfortunately it would be impractical and absolutely useless towards determining how accurate the rifle can be in human hands. As to the way we used for 20 years in the military it worked remarkably well with service rifles, both the M14, and the M16 series weapons. I saw results first hand during the three years I was a PMI at MCB 29 Palms rifle range. And in some cases we had weapons that were so off that had they been fired at 200 yards they would have been off the paper on a standard Able target at that range, so the 1000 inch range was much more useful for determining that, and where the weapons were going to fire to. |
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Originally Posted By clancey2651:
Actually, the most precise way to determine a rifle's accuracy is to fire from a fixed vise off a bench. By all means, post the results of your tests conducted in the above maner. Originally Posted By clancey2651:
As to the way we used for 20 years in the military it worked remarkably well with service rifles, both the M14, and the M16 series weapons. Rough zeroing a weapon at the field expedient distance of 25 meters (1,000 inches) is not accuracy testing. The U.S. military does not conduct their accuracy acceptance testing of rifles/carbines or their associated ammunition at 25 meters and when accuracy testing is conducted, 10-shot groups are the requirement stated in the mil-specs. |
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It seems that this can’t be posted often enough.
As another personal example of the above concept, I fired two five shot groups from a bench-rest at 100 yards using the 70 grain TSX load from SSA using my Krieger barreled AR-15. Those two groups had an average extreme spread of 1.56”. However, when the two groups were over-layed on each other using RSI Shooting Lab to form a 10-shot composite group, the extreme spread of the composite group measured 1.93”. The mean radius for the 10-shot group was 0.63”. Next, I fired a 10-shot group in the same manner as described above. The extreme spread for that group was 1.93” with a mean radius of 0.61”. 
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Still one of the best threads on this site I have read here in almost 8 years. Thanks Molon and others.
Clancy says 3 shots work; Molon says 10 shots works better. I don't see much of a conflict there. What's happening is a definition of acceptable combat accuracy over open sights, clearly a different standard than testing the mechanical limits of accuracy for a given round/barrel. |
| I have a friend who was in the military for 18 years and every time he pulls the trigger it's a "flyer". He also fires his 1911 one handed and pulls every shot low left. Every single time. It took him 60 rounds to zero his M4 at 100 yards. In the Marines during the Jimmy Carter years they didn't get to the range much he said. I can tell. Myself I like 10 shot groups. |
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Shot these two earlier this weekend to tune in my new XTR.
100 yards BCM 16" M4 carbine upper LAR lower Prvi M855 2008 production Burris XTR 1-4X at 4X Bench rested First 
Second; 3 clicks left windage 
I'm pretty happy with the set-up. 
Now it's time to take on some grapefruits. 
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| On youtube I heard stories about the AK47 and the 3 shot groups. I sent them a link to this thread but they pass it off as heresy. The AK47 youtube commando said his rifle was getting 3 shot groups around 3-4" using brown bear ammo. He seemed to think that was good. |
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I have an AK-47, a Saiga in .308 Winchester that does alright. I shot it a while back at a Pizza Hut box that I had put a dot on. 100 yards, and, I admit, I only shot 5 rounds. I was checking the Remington 150 gr Core LOKT PSP bullets to see where I might need to adjust the scope. I had a 3 x 9 x 40 Simmons scope on it. Shot from a "box" rest. I was just trying to see if the rounds were good since I paid only $14.99 for them at Dunhams. http://vernsdidj.com/pictures/guns/Saiga308/308_saiga_rem150psp.jpg I'll have to try some more shooting when the weather clears. I live on 10 acres and my range is in my back yard. I'll give it some more shots with 10 rounds each unless I have it sold by then. |
at 100 yds if u cant keep it under 10 inches offhand stay home!
from a bench with a bipod and rear monopod at 100 maximum two inches !
if you use a mechanical rest and rear bag one inch max as long as the ammo, weapon and shooter are capable, but if you don't carry all that into the field its not a good test just what you can hump on your back
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Originally Posted By ekrall:
but if you don't carry all that into the field its not a good test just what you can hump on your back Get a clue. The subject of this thread has nothing to do with "what you can hump on your back." |
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Curses on your 10 shot groups Molon! After reading this thread I am covinced of the validity of your conclusions, which has caused me great misery trying to achieve a sub one inch 10 shot group. Why didn't I take the blue pill and remain blissfully ignorant, happy to shoot sub moa 5 shot groups! On the other hand, I think I might have progressed far enough to try the grapefruit......maybe if I could afford the krieger.....Thanks for all the useful data and inspiration to improve.
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Not an AR-15 question, but what about groups for magnum rifles?
My 7mm Rem Mag heats up QUICKLY. I have always shot 3 shot groups with it because after 3 shots the barrel is very warm. I open the breech, leave it open, go check the target, piddle around a while and then repeat. Any quicker than 10 minutes between 3 shot groups and the barrel gets HOT. I guess I should just use the same paper and go with 9 shot groups. Of course at $2+ per round on some of the premium loads and this is gonna get expensive. |
| One solution for you guys complaining about barrel heating is to bring more than one gun. I usually bring at least three and sometimes five rifles to the range. Shoot one round, open action set gun on the rest, pick up next gun do the same. By the time you shoot each rifle once, the first one will be cool and you can start all over again. I'm a hunter more than a target shot and I'm more concerned with where the first shot from a cold barrel goes. I also like to know how closely the first three rounds out of a cold barrel will group and also the first five rounds. This tells me if I have a bad barrel that walks as it heats up. Keeping track of the rounds in the order fired can tell a lot about the rifle. On a different subject, have you done any testing to see if there is any difference in point of impact between rounds chambered manually and rounds chambered by the action itself. I have a Ruger 44 mag carbine that consistently throws a manually chambered round 3" right of the following rounds in the magazine. Never been able to figure out why. I haven't seen this tendency in my LR-308 yet, but I haven't fired it extensively. I follow a fair number of shooting forums and have to say this is the best discussion of how to determine the accuracy of ammo that I have ever read. Thank you for your time and willingness to share with those of us who are interested in learning something new. |
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I'm sorry I didn't find this thread months ago. Been using 5 shot groups to figure ammo and load. Just put 200 rrounds together, and now don't feel as confident as I did when I developed the load. Guess I'll have to call that ammo "plinking rounds."
Will pray to the ammo god for a 10 shot group that will be 1.5 or better.
I did notice in some of the taget pix, the center of the sepatate groups was not in the same place from taget to taget. Is that human error?? |
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This guy loves his 3 shot groups. He even says you don't need special training to shoot this well.
http://www.youtube.com/watch?v=Pk6NOvENefE |
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Originally Posted By PR361:
Almost  http://i933.photobucket.com/albums/ad172/sureshot31/80grnnoslercomp.jpg"Almost" what? |
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The Trouble With 3-Shot Groups (Page 9 of 12)
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