Thread: 3 shot groups are useless!

three/five or ten all depends on what you are trying to achieve...

For me, if sighting in I use 3 or 5 shot initially to get a good idea of where the group size is at. Once I know it is shotting a tight group (if it is) I will go to 1,2 or 3 shot groups until I get close to a final setting. Once there, I will use a 5 shot group to confirm the entire group is centred where I expect it.

I consider the size of my group as the +/- variation and the distance from POA as the adjustment measurement ....EG if a rifle does a 1moa group and I am sighting in a rifle an its frirst group is 8 inches from POA then it is 8inches +/- 1 inch. I dont need to fire a 3 shot group to get a bit closer, os afetr I make an adjustment to say 2inches from POA then I know it is 2+/- 1 inch. At that point I would start to use a 3 shot group to get closer. Once I am clustring around 1 inch above the POA at 100m I will wait and fire 2 or 3 two shot pairs atthe sam POA and see what the actual group is doing....and whether I need any further fine tuning..... A 2 inch group at 100m is a 6 inch group at 300 and that is wheel withing the kill zone for a deer or pig sized animal.....

Foster! I can come over in November, should we reconvene at Brian's for a week of shooting? Winner gets the duty free.

Originally Posted by nor-west

Foster! I can come over in November, should we reconvene at Brian's for a week of shooting? Winner gets the duty free.

I'd be in like Flynn!

I wouldn't say useless, however I'd say quite limited in what they can tell you, in many situations.

If you have a genuinely subMOA rifle and shooter system, as in, one that will put 20 or 30 rounds into a subMOA group (therefore if properly zeroed, can hit a submoa target excluding long range ballistic inputs), then a 3 round group will give you a reasonably good measure of your point of impact, within some margin of 1moa at the range you're shooting at.


The problem is that a single 3 round group or even a string of them and measuring the average size, cannot tell you the real dispersion of your system. 3 round groups or an average size of 3 round group is only a very small sample of the distribution of where shots from your barrel will disperse, and by the nature of this, most of the time a 3 round group will be "pretty good" relative to the actual dispersion. They also tend to leave us very open to calling things "fliers" and discounting them. You see this behaviour all the time. Look through recent load development threads.

Multiple 3 round groups do not reliably tell us anything more than a single, unless we actually understand the relative point of impact of all shots across those multiple 3 round groups.

I have seen it time and time again that 3 shot groups will give "wandering zero" where it's a rifle that has a true dispersion of maybe 2moa, but the 3 shot groups average less than 1moa - but don't give a good idea of where zero actually is. Most recently a tikka t3 7mm08 about a month ago - helped the owner set it up, he shot a 3 shot group at 100m, looked to be zeroed - took it out to 400m and it was weirdly low. Back to 100 and yes, the zero was actually low - the 3 shot group checking zero was just a lucky 3 from the upper end of the true dispersion.

Note that you don't have to shoot 10 round or 20 round groups to get accurate data. You just have to plot the relative point of impact of 10 or 20 shots, whether shot in a single group, or 20 days worth of 1 round at a fresh target.

As people have noted, the first round out of the barrel for the day is the important thing for hunting - yes, this is true, however

1. how many actually go out and shoot 1 round over and over again on different days to check that the one round hits where we want?
2. barrel heat is not the factor it is made out to be that prevents the shooting of larger groups. what is happening when you shoot a 5 or 10 round group and it gets larger is often NOT it "opening up" due to barrel heat - you're just getting a more complete sample of the distribution of shots from your barrel.


It is also largely irrelevant for hunting, as I've noted before. As hunters we shoot at large targets at close ranges, mainly. The limiting factor is generally shooter proficiency, by far, not the fact that they are shooting a 1.5moa rifle (that averages .75 3 shot groups, in a slightly different spot each time).

However the converse is also true - for hunting it's irrelevant to have a ".x MOA rifle" so maybe we should stop claiming that with inadequate data

This thread demonstrates the issue clearly.

https://www.nzhuntingandshooting.co....cision-103608/


Average group size across 7x 3-shot groups is .6", however the actual dispersion is 2.7".

You can lie to yourself with 3 shot groups but it's really hard to get the truth from them if you want to.

Originally Posted by gimp

This thread demonstrates the issue clearly.

https://www.nzhuntingandshooting.co....cision-103608/


Average group size across 7x 3-shot groups is .6", however the actual dispersion is 2.7".

You can lie to yourself with 3 shot groups but it's really hard to get the truth from them if you want to.

Exactly. The reason I'm a bit hot on this is that both rifle manufacturers of "factory rifles" and worst, sellers (usually the first owner) of custom rifles pass off rifles as "sub moa". I've bought a few of each. I've spent a heck of a lot of components developing both rifle/load combinations, and my shooting skills. So I'm a bit pissy when I go out and shoot groups such as I have been with the Bergara . . . . With a lot of effort I "might" get it to shoot real MOA. Another really high end and expensive 6.5-06 also springs to mind, since parted out so no one else got sucked in ( and amazingly, the barrel off this rifle fitted to another action later on was a true 0.5 MOA shooter).

The "common denominator" in all this - 3 shot groups with an individual small group, but much higher actual dispersions.

3 shot groups are definitely not useless, but at the same time a single one hole 3 shot groups isn't proof your rifle is a .1MOA rifle.

I use 4 shot groups during load development, idea being if a 3 (or 4) shot group is over an inch then I'm not interested in it, it's more a way for culling out bad charge weights rather than finding the right one.

After I've decided on my load I'll then load up more rounds and confirm them again at 100m and take them out to longer distances.
I have had groups grow from that first 1 or 2 4 shot groups, but never go from say a .5" to a 1.5" group, more like .5" to .75".

My recent load development was the same and my 4 round groups during load development shot just as well when I increased them to a 6 shot verification group.

Yep, a true sub MOA rifle is generally not a rifle picked off the shop shelf and bunged onto the range. I have a Rem M700 that was a shocker, fussy as hell with ammo (even a change in lot number would piss it off - I called it my girlfriend rifle for a while). On the other hand, a Rem700P from the custom shop with a HS Precision bedding block stock is one of those that if you feed it good ammo it will shoot all day into one hole - boring as. Those are both roughly the same platform and tech, so it doesn't really make sense that one is that reliable and the other is crap. As an experiment, I swapped the stock off the P onto the SPS (shitty plastic stock) version. Instantly tightened the groups up with an honest average group of well less than 1.5" with the odd group slightly larger when I cocked up (this with either my hunting reloads which were made for another rifle so not tuned or using FMJ milsurp 7.62mm ammo).

I've replaced the plastic floppy handle on that rifle with an aftermarket heavy urethane stock (what fell into my hands at the time) and that improved the groups to around 1.75" without a bedding job. I have a stock from a rem mountain rifle there and when I'm able to resume shooting the bigger gear I'll bed that in and set it up on the rifle. It's lighter and stiffer and also a lot nicer profile and I have a factory spec limbsaver recoil pad for it which should be nicer on my slowly sorting itself out shoulder!

Prior to doing this work I was able to get a fluke or four of 3-shot groups that were nice and tight, say 1.5" but the issue with it is that the mean point of impact wasn't reliable for those three groups. As others have mentioned, the odd decent three shot group is not what you want - you want a repeatable pattern of groups where the size is reliable and you know your aiming and shot technique is good enough to call the shots and know where to look for them on the target. If you have that, you can be confident in the rifle - even if the groups are 3" or bigger at 100m but - that means they are all within 1.5" of your aiming point!

If you shoot 0.5" 3-shot groups, that's great but if the odd group is 4" and the mean point of impact of the groups is wandering over the page you actually have a not very reliable rifle there and I would not have much confidence in it. I recently had this with my fruit tree protection device (.177 air rifle) as these are bloody notorious for shaking the snot out of scopes. I was able to shoot nice good 20m groups (minute of rosella) but the groups one day to the next were anything up to 5 or 6" different to the point of impact from the last time. That's a clean miss on a rosella... A quick change of scope and grouping sorted, until this one fails anyway.

Setting up my son n laws 300wm.Could only get a 2 shot group at 400yds,but it's not a useless group either.

Thru the winter-spring,about twice a month i go out to the range and just fire 1 or 2 shots and go home.Dont touch the zero on scope.You really get to know the personality of yr rifle-scope set up and yr good and bad habits when shooting.

I'm more interested in that initial cold clean barrel shot. The only one that practically matters.
I absolutely hate that i must leave some carbon in to keep the rifle hitting in the same spot reliably (for hunting).

But there it is. Gotta hunt with the rifle you have, not the perfect world POI you get after sending 40 downrange.

Useless for what?

Im not saying anyone is wrong, but it would be helpful to know how you are using your rifles. I have a suspicion that many of you are in the 5 or less % who are really looking to use all of a rifles potential. Potential that comes from likely spending more money than alot of hunters can realistically afford.

For what I wish to use a rifle for, 3 shot groups are absolutely acceptable. Yes as long as they are repeatable and checked before each trip.

Originally Posted by whanahuia

Useless for what?

Im not saying anyone is wrong, but it would be helpful to know how you are using your rifles. I have a suspicion that many of you are in the 5 or less % who are really looking to use all of a rifles potential. Potential that comes from likely spending more money than alot of hunters can realistically afford.

For what I wish to use a rifle for, 3 shot groups are absolutely acceptable. Yes as long as they are repeatable and checked before each trip.

Im inclined to agree. Most hunters just sight in with a few shots and then shoot a series of one shot groups at animals. Thats not to say that the theory in this thread isn't correct, and I fire a lot of bullets at paper myself. But as my mum used to say; "sometimes we can be too heavenly to be of any earthly use". Bless her.

Originally Posted by gimp

1. how many actually go out and shoot 1 round over and over again on different days to check that the one round hits where we want?

Not many, though you'll recall that @R93 did take the time and effort of doing this and mentioned the results in more than one thread, none of which I can find for a link at the moment sorry.

Originally Posted by Tahr

Im inclined to agree. Most hunters just sight in with a few shots and then shoot a series of one shot groups at animals. Thats not to say that the theory in this thread isn't correct, and I fire a lot of bullets at paper myself. But as my mum used to say; "sometimes we can be too heavenly to be of any earthly use". Bless her.

Doing time on a range as a NRO is quite informative, have seen the 'wandering group' scenario a few times now. Most people never suffer from the effects of it even if they know it's there, others ignorance is bliss.

An average animal has a larger kill zone than the usual amount of error anyway. Edit: at the ranges most hunters work with...