What's the definition of a "Group" ? (of shots)

[MagnumManiac]

I used to shoot a cold bore shot daily with my precision rifles in the morning and afternoon for a week. Conditions were very very different on some days, but the overall group stayed perfectly shaped throughout. Then I tried this on ONE of my hunting 300WM rifles, a Kimber 8400, and the results were not ugly, but also not what I wanted to see. There were no fliers or outliers per se', but the group over those 14 shots was NOT MoA. I expected MoA from this rifle.
Where I was was at 800 metres, so that elevation isn't a real stretch, but occasionally it would snow and this showed me that that particular rifle was stable with cold bore shots and no discernible shift occurred with follow up shots.

All I can say is this, if you are shooting groups so slowly and cautiously with barrel cooling etc, you are not shooting groups, you are shooting single shot groups. Now, I understand cooling barrels down between strings, but between shots is not a real test.

Cheers.

 

[Phil Rizzo]

Especially a hunting gun.

 

[southpa]

A "group" is whatever you want to call it. I would lean towards anything more than 2 is a group! All this talk about not letting your barrel cool or letting your barrel cool is all subjective. I like to let my barrels cool 5-6 minutes between shots for developement or "groups." It's really the only way you can keep a consistent variable. That being said all my barrels tell me what they need. I've seen some barrels that will shoot 1 hole for 3 shots consecutive all day, every day. If you try a 4th shot she don't like it. But it's killed everything it's ever shot at for years. Does it "group"? Ya for 3 shots until it's good and warm, then it don't. This may be acceptable to some some but others not. My point is, A group is anything you think is representative of your type of shooting.

 

[C.O. Shooter]

So, if you shoot the 1st day at 80° and zero wind, and the next day a cold front comes through, and it is 65° with a 10-mph cross wind and the 3rd day it's 90° with high humidity and heavy mirage, does that really tell you cold bore accuracy?

Ideally if I am planning this I am watching weather conditions prior to. I do very little if any development in the summer months.

I generally don't take a shot without my kestrel. If all is well in the universe and adjustments are correct for conditions, it shouldn't matter what it's doing outside.

 

[Pudgy]

Shooting F-class, how do you time shots and conditions, or any other discipline, with a timed amount to get your shots off in to count?

There is no hard and fast rule to answer this.

I have seen guys shoot a 5 round group in 15 minutes, then clean the barrel and repeat until all shots are fired.
Is this correct?

I shoot my groups in fairly quick succession, no cleaning until all rounds are fired, normally 15-20 shots.
Clean the barrel and proceed with the next lot.
Is this correct?

When I find a load the rifle likes, 10 shots are fired at 600 in fairly quick succession to verify group size AND pattern. YMMV.

Cheers.

F-class 5 or so to warm barrel- them typically 20 shots in 5-10 minutes.
Anywhere from 70-100 rounds between cleaning. Looking for 2" groups at 500 and no more than 4" vertical at 1,000 - sometimes we get lucky and find a barrel that holds under 3

 

[MagnumManiac]

F-class 5 or so to warm barrel- them typically 20 shots in 5-10 minutes.
Anywhere from 70-100 rounds between cleaning. Looking for 2" groups at 500 and no more than 4" vertical at 1,000 - sometimes we get lucky and find a barrel that holds under 3

This is my point, shooting a group or groups is no different to this.
I shoot all of my shots in F-Class with the most identical conditions in the time frame, this generally means shooting fast as conditions rarely stay the same for long.

Cheers.

 

[FireFlyFishing]

I hate complicating things unnecessarily.

Q: What's the definition of a "Group" ? (of shots)

A: A cluster of shots from the load developed for a given purpose, such as hunting, target, competition (timed), etc., to meet the intended goal/parameters.

I couldn't agree more. I've found, a good rifle with a good load shoots a tight group regardless of how long you wait. Cold bore, warm bore, doesn't matter. Auto loader or bolt action.

 

[tim_w]

3 shots in 90 seconds ?
3 shots in 3 minutes ?
3 shots in 30 minutes ?

5 shots in 50 seconds?
5 shots in 75 minutes ?
5 shots in 5 hours ?

How quick do the follow-up shots have to be after the first cold bore shot ? To be considered in that same group.
The barrel is going to be warming up, so all the shots were not shot under identical conditions.

Technically any 2 or more shots (graphed data points). The rest of the parameters could be anything you choose to further define. Obviously, we would typically consider at the same distance to be an expected parameter. As we would the same cartride load. But in the most basic definition it's more than one shot on the same plot. Everything can still have tolerences as well.


You could for instance take many different targets over a large period of time (say months and 20 or 40 targets) Shot from the same distance at the same range and overlay them based on target orientation and point of aim. This could be considered a type of group. It actually can be quite informative when considering actual accuracy to the point of aim. You could take one shot every hour for 4 hr for 30 days and overlay to get a good data on your true cold bore shot accuracy on a hunt. After all we all usually are taking cold bore shots but I rarely if ever would choose to take a clean bore shot. It's why I prefoul my bore

You could shoot the same POA on a target but move to varying distances angles etc. Can still be a group.

 

[crkckr]

I let the rifle dictate how often I shoot. It depends on how quickly the barrel heats up and how hot it's getting. Generally, if I see stringing it's time to check the bedding, although that's not the end all be all. If a rifle doesn't get too hot to touch after the first shots and I'm working on load development, (I shoot 3 shots initially) then I'll go on to the the next batch of loads. Those that seem promising will get another round of 5. Once I settle on a load I will do the one shot per day thing at the same target to check cold bore POI over at least a 5 day period. I've even gone so far as to leave the rifle outside, in a case, if it's going to be cold when/where I hunt. I can do that at my private range. Probably leaving the rifle in your truck is just as good and more secure. If it's cold, I want the rifle completely cold soaked when I touch off that first round.

Back to bedding, I did a nice job of glass bedding a Win Model 70 that shoots pretty decent groups. After the bedding cured, I took it out and it barely kept 3" groups! I was in a panic, what have I done?? I remembered I had taken down a "shim" of wood at the end of the stock, so I built up a new shim of of layers of aluminum sheet (pop cans!) and it the went back to it's normal .5," 5 shot groups. Whew! First time I've ever bedded a rifle and it got worse. Scared the bejesus out of me, too!
Cheers,
crkckr

 

[FrogFire7]

The definition would be all rounds sent downrange at the same point of aim.

The time between can vary wildly. When I was a new member here I remember a guy shooting essentially two shot "groups", but like half a day apart, and at a rock 1,000+ yards away to show that his rifle and load wasn't shifting elevation with change is temperature and humidity, etc.

Some of the competition guys shoot as fast as they can get rounds in their gun to try to minimize changes in the wind... Just depends. The important part is that the rounds are being shot at the same point of aim (or rather, trying to get them to hit the same spot).

 

[ncwg2boatguy]

This is definitely not a PRS question.
10-***** 90-120 seconds. But normally during testing for load development and data I do 5 shot in 3-5 min

 

[jrock]

I test rifles for their thermal capacity. I shoot 5+ shots in rapid secession, similar to a hunting situation. I see when the POI starts to change. I'll then know when to let the barrel cool. Maybe that limits the gun to 3 shot groups vs 5. Here is an example. A magnum sporting rifle would reach it's maximum temperature stability at 4 shots. The barrel 6" in front of the chamber would be 150 degrees. If I kept that temperature below 150, it shot to the same POA.

For larger stings of load testing, I always use artifical cooling. I run a barrel cooler 1 to 3 minutes between shots. That is enough time to stay under the maximum stable barrel temperature. Of course if it's well over 100 degerees, cooling takes longer, or I use other means.

Comp guns are a little different and I usually do thermal group testing on those based on the type of competition they are being used in.

 

[Philward]

Maybe: any number of rounds of identical specification fired from a single firearm while aiming at the one POA with said firearm being held in same position for each round. Regardless if offhand, sandbags, leadsled, bipod etc. Don't think time between shots is a factor, weather could be though i.e. hot weather groups, cold weather groups, rainy weather.

 

[Rabid Fish]

3 shots in 90 seconds ?
3 shots in 3 minutes ?
3 shots in 30 minutes ?

5 shots in 50 seconds?
5 shots in 75 minutes ?
5 shots in 5 hours ?

How quick do the follow-up shots have to be after the first cold bore shot ? To be considered in that same group.
The barrel is going to be warming up, so all the shots were not shot under identical conditions.

3 shots in 90 seconds ?
3 shots in 3 minutes ?
3 shots in 30 minutes ?

5 shots in 50 seconds?
5 shots in 75 minutes ?
5 shots in 5 hours ?

How quick do the follow-up shots have to be after the first cold bore shot ? To be considered in that same group.
The barrel is going to be warming up, so all the shots were not shot under identical conditions.