What are your thoughts on triangle groups. I know most look for horizontal groups and some like round. If you found a good rifle load and it prints triangle groups what direction would you approach to take out the vertical. You have a good powder charge with good ES and groups are in the .4 to .5” at 100 yards. Would you test seating depth testing, or neck tension, primer change or ??
Triangle Groups
- Thread starter trailrider121
- Start date
Record the shot sequence. Many rifles shoot shots into specific areas of the target in order. Like left, right,center, left, high...always or nearly so. So take a video.
tmwinds
Gold $$ Contributor
This...if you only fire 3 shots chances are the group will be triangular.
Yeah I plan to conduct a 5 shot group and neck tension.
TAJ45
Silver $$ Contributor
All 3 shot groups will be triangular. Unless they are. .00000000 groups. Grin
Sry, could not resist.
Sometimes you have to look at the whole picture of groups when testing different powder charges.
If the charge weight before and after have the same point of impact as the group in questing, then you know the charge weight is within a node and can move onto testing different seating depths.
If the charge weight before and after have the same point of impact as the group in questing, then you know the charge weight is within a node and can move onto testing different seating depths.
Shoot 5 at a minimum, preferably 7 round, until you are "pretty comfortable" with the rifle and ammunition, and YOUR ability to use the two to resolve the 0.100" increments we all like to internet about.
At the point you are extremely comfortable on a rifle...like 5-10,000 rounds worth, or equivalent on a similar rifle...then you can get by with 3-round groups for ROUGH development of loads. There, we are looking for the SHAPE and size of the triangle relative to the triangles to either side of it.
But if you really want to see what a rifle--and you--can REPEAT., you need to shoot 10+ round groups, or multiple 5 round groups and agg them.
-Nate
dmoran
Donovan Moran
While I like using 3-shot groups for testing (especially with thin barrels and magnums), and getting confident results from the least amount of shots as possible, doubt could ever get away from not seeing triangular groups using 3-shot testing. The relative efficiency of 3-shot groups (87.9%) is fairly confident. Here are others:
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Thanks for the ideas. I was just wondering about triangle groups and why. Good explanation and understanding of barrel harmonics.
Haha , That one made me laugh out loud until I realized that's all he was shooting .
I jumped in here thinking I was going to see a real abnormal looking group like these . First two are 4 shots but that third one is a 10 shot group firing one shot after the other in 30sec-ish intervals .
Getting two distinct groups in the same string did have my head a spinning for a bit . This was several years ago and has been worked out but at the time I was at a lose until someone suggested I check the action screws . My rear screw was at 5# or 35# less then suggested . Tightened them up and I've not had a double group since .
dcali
Bullet Maker
It sounds snarky, but it's true - all three shot groups are triangles. You can't shoot a round three shot group - it's a triangle. (side note- if your horizontal group is not due to wind, you've got an out of tune rifle).
To add to Donovan's post above, which is totally accurate, the context for it is gaining confidence that a load is as good as you think it is. If you have a load that you think is good, and you want to confirm it and you only have 15 rounds, you're better off shooting 3 five-round groups than 5 three-round groups or 1 fifteen-shot group. That last one may sound counter-intuitive, but it's true. It has to do with the information contained in each group - which is the two most extreme shots that define the groups size (obviously), but also the fact that every other shot landed in between them. So when you shoot 15 shots, you get 2 extreme shots, and 13 in between. When you shoot 3 five-round groups, you get 6 extreme shots, and 9 in between. The math works out that the best balance is around 5 shots/group.
The reason we can get away with three-shot groups when developing loads is that we typically do it in a systematic way - one group per charge, stepped up by .4 grains at a time, for example. There is information in that beyond the size of the groups - there is a known relationship between charge weight vs group size (for example) that adds confidence, so the three-shot groups are better than they would be if they were truly independent. So using three shot groups (instead of 5) for load development allows you to cover a wider range of variables with more resolution. That makes finding a good node easier, and still with acceptable confidence.
You can eke out a little more confidence by measuring each group twice- horizontally and vertically - and taking the average. This is a little dicey, though, because barrel vibrations tend to skew groups to the point where they aren't truly random. (They may string in one direction or another). At least in very accurate rifle they do. This effect gets drowned out by others with less accurate rifles.
And as they say, groups don't get smaller when you fire more shots. The odds of a big three shot group being an outlier are small (but real - which is why we want to confirm what we see), so you're probably just wasting ammo adding two more shots to a big three shot group.
The *best* way to measure groups is not to measure them at all, but to measure every shot. Take the standard deviation of each shot's distance from the center of the group and use that as a measure. There are phone/computer apps that will do this (or something similar), but it's not practical when your groups are one ragged hole.
To add to Donovan's post above, which is totally accurate, the context for it is gaining confidence that a load is as good as you think it is. If you have a load that you think is good, and you want to confirm it and you only have 15 rounds, you're better off shooting 3 five-round groups than 5 three-round groups or 1 fifteen-shot group. That last one may sound counter-intuitive, but it's true. It has to do with the information contained in each group - which is the two most extreme shots that define the groups size (obviously), but also the fact that every other shot landed in between them. So when you shoot 15 shots, you get 2 extreme shots, and 13 in between. When you shoot 3 five-round groups, you get 6 extreme shots, and 9 in between. The math works out that the best balance is around 5 shots/group.
The reason we can get away with three-shot groups when developing loads is that we typically do it in a systematic way - one group per charge, stepped up by .4 grains at a time, for example. There is information in that beyond the size of the groups - there is a known relationship between charge weight vs group size (for example) that adds confidence, so the three-shot groups are better than they would be if they were truly independent. So using three shot groups (instead of 5) for load development allows you to cover a wider range of variables with more resolution. That makes finding a good node easier, and still with acceptable confidence.
You can eke out a little more confidence by measuring each group twice- horizontally and vertically - and taking the average. This is a little dicey, though, because barrel vibrations tend to skew groups to the point where they aren't truly random. (They may string in one direction or another). At least in very accurate rifle they do. This effect gets drowned out by others with less accurate rifles.
And as they say, groups don't get smaller when you fire more shots. The odds of a big three shot group being an outlier are small (but real - which is why we want to confirm what we see), so you're probably just wasting ammo adding two more shots to a big three shot group.
The *best* way to measure groups is not to measure them at all, but to measure every shot. Take the standard deviation of each shot's distance from the center of the group and use that as a measure. There are phone/computer apps that will do this (or something similar), but it's not practical when your groups are one ragged hole.
Lucky Shooter
Gold $$ Contributor
For 100 yd work, use the Poor Man's Gage (PMG)----the PMG costs 41 cents and might have other uses.
The PMG consists of a quarter, a nickel, a penny and a dime.
If you can cover your groups----you pick the number of shots------with a dime, not to shabby for hunting.
As for triangular groups, a tight 3-leaf clover is still a triangle-----and maybe only a gleam in another shooter's eye.
A. Weldy
The PMG consists of a quarter, a nickel, a penny and a dime.
If you can cover your groups----you pick the number of shots------with a dime, not to shabby for hunting.
As for triangular groups, a tight 3-leaf clover is still a triangle-----and maybe only a gleam in another shooter's eye.
A. Weldy
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