How to read Groups
Posted: Tue Dec 18, 2007 11:14 am
G'Day All,
after last weekends, Mexican get-together, i realised that most people dont know how to interpret the info you can get from your groups. So i took some photos to show you what you can see if you look.
This group was 5 shot with a 6ppc at 100yds in an average 10mph crosswind. what it doesn't show is me aiming off by 1 ring (6mm/0.25") left or right to compensate for the wind strength and still continue to hit the centre of the group. Also, this shows the typical 1/4moa vertical that Little River seems to award any shooter when they shoot there. this is what all shooters are usually trying to achieve, a nice round group.
This group was 5 shot with a different BR rifle again in 6ppc, notice there is actually 2 groups in one, each overlapping the other. Why?, miss reading the wind. Also, this barrel has had over 3000 rounds through it and I consider it to be not competitive for BR anymore, notice it looks a bit ragged compared to the previous group. that barrel was rechambered after 1800 rounds so it is relatively fresh.
Now this target sheet has what appear to be terrible groups. These were shot by people who have never shot a BR rifle before. The groups will be called 1-6 starting from top left to right and bottom left to right. Look at grp 1,5 & 6. See any pattern? They all slope from 9:30 to 3:30 across the target. This is a typical wind pattern, most of the shooters said they did not watch the wind flags, if they could and knew how to understand the flags, those groups might have been half the size.
Look at grp #2, better wind reading but it shows 2 distinct wind strengths, bullets are cutting, the rifle wants to shoot. Also notice there is the typical Lt Rvr vertical. But more importantly, they are FLAT. This means the load is a good load and the bench technique is GOOD. Very important to understand that it is not necessarily the load thats crappy, it might be the way you hold the rifle when shooting off a bench or bipod.
Grp #5 is what we call a weather pattern, it looks like a machine gun has sprayed bullets across the target, this shooter did say that he was not watching the flags. We all have targets in our cupboard like that.
What are the lessons:
1. Your reloads should be tested at 200yds or more to see if there is noticeable vertical, if so is it the load or shooting technique.
2. All bullets move in the wind.
3. Most rifles can shoot better than the user.
4. Take more notice of the wind regardless of whether you shoot in the paddock or at paper. The wind does not discriminate, it will punish you regardless!
You may recognise some of these groups as some you have shot, some basic flags like the ones I made and we used last weekend can make a big difference to your understanding of the bullet flight and the forces acting on them.
Hope this helps
Cheerio Ned
after last weekends, Mexican get-together, i realised that most people dont know how to interpret the info you can get from your groups. So i took some photos to show you what you can see if you look.
This group was 5 shot with a 6ppc at 100yds in an average 10mph crosswind. what it doesn't show is me aiming off by 1 ring (6mm/0.25") left or right to compensate for the wind strength and still continue to hit the centre of the group. Also, this shows the typical 1/4moa vertical that Little River seems to award any shooter when they shoot there. this is what all shooters are usually trying to achieve, a nice round group.
This group was 5 shot with a different BR rifle again in 6ppc, notice there is actually 2 groups in one, each overlapping the other. Why?, miss reading the wind. Also, this barrel has had over 3000 rounds through it and I consider it to be not competitive for BR anymore, notice it looks a bit ragged compared to the previous group. that barrel was rechambered after 1800 rounds so it is relatively fresh.
Now this target sheet has what appear to be terrible groups. These were shot by people who have never shot a BR rifle before. The groups will be called 1-6 starting from top left to right and bottom left to right. Look at grp 1,5 & 6. See any pattern? They all slope from 9:30 to 3:30 across the target. This is a typical wind pattern, most of the shooters said they did not watch the wind flags, if they could and knew how to understand the flags, those groups might have been half the size.
Look at grp #2, better wind reading but it shows 2 distinct wind strengths, bullets are cutting, the rifle wants to shoot. Also notice there is the typical Lt Rvr vertical. But more importantly, they are FLAT. This means the load is a good load and the bench technique is GOOD. Very important to understand that it is not necessarily the load thats crappy, it might be the way you hold the rifle when shooting off a bench or bipod.
Grp #5 is what we call a weather pattern, it looks like a machine gun has sprayed bullets across the target, this shooter did say that he was not watching the flags. We all have targets in our cupboard like that.
What are the lessons:
1. Your reloads should be tested at 200yds or more to see if there is noticeable vertical, if so is it the load or shooting technique.
2. All bullets move in the wind.
3. Most rifles can shoot better than the user.
4. Take more notice of the wind regardless of whether you shoot in the paddock or at paper. The wind does not discriminate, it will punish you regardless!
You may recognise some of these groups as some you have shot, some basic flags like the ones I made and we used last weekend can make a big difference to your understanding of the bullet flight and the forces acting on them.
Hope this helps
Cheerio Ned
