Ten Shot Groups?

[denton]

That's a good article, and touches on a lot of stuff, but like most articles, it has some (IMHO) erroneous thoughts and doesn't really nail it down. No disrespect intended, I think that about all of them. Overall I like the article.

It really depends on what we want the rifle to do and what we will accept as proof to ourselves it will do that well enough to be personally satisfied.

My Bench gun is a 1/4 moa or better gun from a vise in a dead calm (Some would say smaller than that), but I can easily shoot groups bigger than that if I miss a pickup in the condition or even worse, a switch.

My .222 Mag heavy barrel varmint gun can shoot 1/4" groups, and has, but it isn't a 1/4" rifle, more like 1/2" in my mind, and again, I can shoot bigger groups with it in a heartbeat.

Some people blame everything on the gun, wind etc, no excuses, and then the other crowd claims all bad shots as fliers. Neither crowd is correct. In competition I always blamed everything on me and tried to focus better, while some people would blame scopes, barrels, actions, brass, anything but themselves, and then wondered why they didn't get better.

I have told this story before, but once the fellow next to me at Riverbend in a registered Benchrest match got mad and threw his brass in the trash. (We had bet a dollar a group and a dollar on the agg) I told him it wasn't the brass, got it out, loaded it, and beat him in the next group with his own brass. He got real mad then and screwed the barrel off. Looking back I should have just left well enough alone and encouraged him.

I think you have touched on an important truth.

There are multiple sources of variation involved in shooting. If the rifle is capable of 1/4", and you're not, you're not going to shoot 1/4" groups.

Variation does not add linearly, and if one source of variation is much bigger than the others, it will almost completely determine total variation. Working on the minor sources of variation is an exercise in futility.

When you're gathering data, you do it because you want to make a decision. Once you have enough precision to make your decision, there is no point in spending the effort to generate more data. If I'm satisfied that my hunting rifle prints somewhere in the 3/4" to 1 1/4" range, that's probably good enough.

 

[MCMXI]

I'm thinking that the commentary on this thread would have been equally interesting - possibly even moreso - if the posters had included the time intervals between shots when firing for group.

Based on quite a few years shooting at public ranges I shoot groups faster than most. The two ten shot groups that I showed earlier were shot in under 3 minutes each (~15 seconds per shot) with one of my AI AW rifles off a front bipod and rear bag sitting at a bench. I've never subscribed to the "shoot one and let the barrel cool" school of thought since there's no real-world situation for me in which that technique applies. With lightweight hunting rifles where I typically shoot 5-shot groups I put all five rounds in the target as quickly as possible. Some will take 30 minutes to put three holes in a target, I'll shoot five rounds in under 3 minutes and quicker than that usually. I can shoot my AIs a lot faster since they're heavier rifles (less felt recoil) with minimal bolt lift meaning that I don't have to reset as much after each shot.

I know benchrest shooters will shoot very fast, and when I competed in F-Class there were some shooters that would shoot as fast as the target puller allowed. I noticed that my scores went up considerably when I had a competent individual pulling my target.

 

[Nature Boy]

So here’s a question on called flyers.

If you know you pulled the shot. No question, 100%

But when you score the target it’s where you were hoping it would go (dead center X ring, through the previous shot’s hole, etc)

Do you call that “flyer”?

 

[Legionnaire]

For me, the only confirmed flyer is a "called" flyer, meaning it's "called" in flight because the sight picture is seen to be off target as the shot breaks. Not the game where we're talking about a low shot count group where one is hanging out by itself, and the guy stands in front of the target and says - "eh, I must have pulled that one..."

Exactly. What was the sight picture when the trigger broke? I was taught to call my shots, good or bad.

 

[MCMXI]

If I'm satisfied that my hunting rifle prints somewhere in the 3/4" to 1 1/4" range, that's probably good enough.

I'd go one step further and say why should we care about the best a rifle/sights/load/shooter will do? What only matters is the worst it will do. If you're hunting you should want to know the greatest distance your shot or shots will land from the point of aim under ideal conditions, and then have some form of data based decision process that you go through to adjust that distance for the given conditions, and then decide if you should be pulling the trigger.

 

[Danoobie]

JMHO- if you don't have a bull barrel, 10 shot groups are mostly a waste of time. Any (or most) sporting barrels
are going to heat up, and around shot four will either start to string the shots, or throw them all over the target.
That said, 10 shot groups are fun and challenging. If you have either the heavy barrel, or the time to cool one
off enough to maintain accuracy.

 

[Steve S.]

My perspective is that bench shooting, sighting, groups, etc are predominately a test of the rifleman and not the rig. Unless there is a known/ discovered problem with the equipment or the rifle is a (rare) lemon, banging away regardless of the number of rounds, has been a test of me. I cannot say that any of my equipment over all my years of shooting has ever had a problem that could be attributed to bad groups. I have had bad groups, but I have always been certain that it was me as the next session down the road with the same equipment would magically shoot just fine.

 

[wally]

JMHO- if you don't have a bull barrel, 10 shot groups are mostly a waste of time. Any (or most) sporting barrels
are going to heat up, and around shot four will either start to string the shots, or throw them all over the target.

Disagree, I want to know how bad my gun might get when I'm fighting off the zombie invasion! Mag dumps required.

 

[Varminterror]

So here’s a question on called flyers.

If you know you pulled the shot. No question, 100%

But when you score the target it’s where you were hoping it would go (dead center X ring, through the previous shot’s hole, etc)

Do you call that “flyer”?

I "call" it Lucky...

The whole point of calling your shots is to derive a differentiation between your wobble area and shot break timing vs. your group size. If you're shooting a low right group and call one high left, and it finds the X ring, you're in business. If a guy is calling a shot low right, but it flies high left, he should be adjusting his zero for elevation and adjusting his wind call for hold.

I learned "shot behind" as a kid, so my paradigm is to call, then observe. If I mark a no-call, I don't reserve the right to call a flyer. If my impact doesn't match my call, it's either group size or incorrect correction/hold, and I can't claim shooter error to exclude it.

In my book (literal data books), only when the call and the impact agree can a guy call a flyer.

Now - if there's a "WTH was going on with that shot?" impact in a group, I do one of two things: 1) send more shots at the same POA to see if I can replicate the error. 2) Go back to the drawing board, as there's something wrong in the system, whether it's the rifle, the ammo, or the shooter... I don't cover it with a penny and claim the rifle capable of the rest of the group.

 

[Walkalong]

I'd go one step further and say why should we care about the best a rifle/sights/load/shooter will do? What only matters is the worst it will do.

To bad Bart isn't here, he is a big proponent of whatever the worst it will do is what its accuracy level is.

 

[Walkalong]

I "call" it Lucky..

Sometime shots blow into the group despite us, it isn't always the other way around.

 

[Laphroaig]

Years ago I was walking down the firing line before a highpower match, and wished one of the best shooters on the line "good luck".

He looked me in the eye and replied "luck has nothing to do with this."

I must admit I've probably gotten lucky a few times, but its still some of the best advice I've ever received

 

[_N4Z_]

10 shot groups @ 100 yards are the standard course for the MBAR rifle matches I participate in. 5 strings of 10. First two are for CtoC group size, next three are for score. Iron sights.

 

[Walkalong]

He looked me in the eye and replied "luck has nothing to do with this."

For the most part he is right, and there is a reason why the top shooters are almost always at the top at the end of the day, but even the best shooters will take a little luck when they can get it.

 

[Walkalong]

Oh, and I used to tell people I hoped they shot well.

 

[_N4Z_]

luck is the residue of skill.

 

[old heeler]

10 shot groups @ 100 yards are the standard course for the MBAR rifle matches I participate in. 5 strings of 10. First two are for CtoC group size, next three are for score. Iron sights.

You did leave something out. A ten minute sighter string may be shot prior to beginning record strings, but the sighter may not be left hanging.

FC and BR has sighters.

 

[_N4Z_]

You did leave something out. A ten minute sighter string may be shot prior to beginning record strings, but the sighter may not be left hanging.

FC and BR has sighters.

I don't shoot sighter string. Too damn lazy to load the extra rounds.

 

[MTMilitiaman]

I use ten shot groups on semi-autos. In fact my BZO confirmation on anything that might be used SHTF is to put an entire standard capacity magazine into a group at the distance the round is sighted in for. So for my M1A, I confirmed BZO @ 200 yards by firing 20 rounds of 147 gr WWB FMJBT into a softball sized group at 200 yards.

For bolt actions, especially magnum hunting rifles with sporter weight barrels, I never saw need to go over 5 round groups. Typically still allow barrel to cool between shots.

But one of the basic principles of statistics says sample size matters, so shooting larger strings will never give you a less accurate impression of a given rifle/ammo's accuracy.

 

[Offfhand]

I took this photo of a competitor's 10 shot group fired during the 100 yard Unlimited stage at the SuperShoot last year. Despite the obvious "flyer" at top of group it still scored .121" and won him some money.

 

[Walkalong]

I never had an unlimited gun and had to shoot my 11 Lb bag gun (Didn't have a weight for the stock) against them. It was a real challenge, but I enjoyed it. Never shot anything that good in unlimited class.

 

[DeadFlies]

I shoot ten round groups because my 10/22 has a ten round magazine. And it’s more challenging than just 3-and-out.
Here’s my best 10-round group, at 50 yards, with bulk Winchester ammo.

 

[Nature Boy]

@DeadFlies that’s some nice shooting

 

[NWPilgrim]

OK... just one objection so far:

When you're dealing with Z scores (Normal Distribution) you need about 30 observations minimum. That's because tests with the Normal Distribution assume that you have the population mean.

But nobody uses Z scores. Everybody uses the T Test, and that only assumes that you have an estimate of the population mean based on a sample.

For some reason, the 30 observation requirement sticks in most people's mind. In reality, there is no such requirement for the test almost everyone uses.

Characterizing variation is a lot harder than characterizing the mean. You can often do a meaningful T Test with two samples of 4-5 items. Testing variation takes a lot bigger samples.

I think the problem though is a representative sample has to be a random selection from the full population. You can't shoot five shots and claim that is a "5 shot sample" of 30 shots or 500 shots. No, it is a total population of 5 shots. If you want to sample, you need to have at least 30 shots to randomly select samples. If you were generating shots anyway, then you could randomly (somehow?) select say 7 from that population and have a true sample. This works in manufacturing because you are manufacturing 1 million units to sell, and you want to sample a tiny percentage that will give you the statistical probability of compliance to a standard. But when you try to apply that to shooting, you find you still have to create those 30 shots anyway, so sampling less than what you have actually shot does not make sense. Now if you had 100 targets of 3-shots then I think you could sample by randomly selecting the proper percentage (I forget how to calculate the exact size the sample should be, but essentially any more or less is less valid then the exact proper number) of say 7-10 targets and overlaying them on POA. The resulting overlay of say 21 shots would then be a valid representation of all 300 shots.

As you point out, there is no getting around doing extensive testing to arrive at a valid statistical model. 3 shots or five shots tells very little on their own. Most guys shooting these I think mentally "overlay" a long series of 3-shot targets as they shoot the same load over the years. But claiming a load is a sub-MOA load after only shooting a couple of 3-shot or even 5-shot targets is nonsense. You MAY be able to say that load is likely more accurate that one shot with two targets of 2" groups but not necessarily. Shoot how ever many shots will ring your chimes, but be aware that you are not basing your decisions on enough information, and comparing your 3-shot results with some else's 10-shot or 30-shot results is meaningless.

 

[NWPilgrim]

For a hunting rifle, the only shot that counts is the first shot from a cold barrel. Why shoot 10 after you have zeroed for your chosen load? For my target rifles I usually just staple new targets over the last one so at the end of the day the bottom target shows my total group. Maybe 20-100 rounds depending on which rifle. That exercise would be a real eye opener to SOME of the "MOA" shooters.

I agree completely. For hunting, I think it would be better to shoot ten targets with one cold bore shot each. Or perhaps a couple of shots as that is typically the most you will get in one game sighting. And again, the "group size' is not what you are interested then, but the average distance of the shot from the POA.

Shooting large number of shot groups is for comparing different ammo loads to determine which shoots better statistically. And there is no law that says a 10-shot group must be fired so fast your barrel heats up much. But if you are going to buy, or can only buy, one type f ammo, say 150 gr Rem CoreLokts and don't care how they compare to 180 gr load or Win or Federal loads, the I think the 10 targets of one cold bore shot each is more informative.