Why you're almost certainly measuring your groups inaccurately.
- Thread starter flashman
- Start date
Exactly why `groups`are over-rated.
Or maybe they are over rated cuz you can't shoot any good ones???
First Pete and now repeat. We`ve been over this. I`ve shot many a decent groups. But groups are not my thing anymore.
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It seems the most common, and most accepted, method for determining group size is to measure outside edge to outside edge, and subtract one bullet diameter, as is the specified standard for the MOA challenge threads above.
1.007 - .308 = .699 = .67 MOA
But that's not really the group size. This method has one serious flaw; it relies on an assumption that the hole in the paper is bullet diameter. It almost certainly isn't. It also forces us to do math, when math isn't necessary at all.
Uh oh. .265" That's optimistic by .09" if we measure outside edge to outside edge.
The accurate way is to measure outside edge to inside edge; regardless of hole diameter, that will give us the true center to center, with the added bonus of there being no need to do arithmetic.
Not to open a can of worms, but groups measured outside to outside with a bullet diameter subtracted are almost certainly going to be inaccurate, in favour of a smaller group size than is reality. It always seemed odd to me that the most commonly quoted method is also the most inaccurate one; especially if we're talking precision rifle. Especially if we're talking scoring precision rifle.
That bottom picture is how I have always done it. I don't shout little bug-sized groups, so I always have the two extreme shots to measure.
In BR the group is the goal in and of itself, and you have created a game that values nothing else. Even then I know that conditions are a major component if you plan on winning.
sadly most people measure there groups on the range with a tape measure, yet the same people measure their groups with feeler gauges on the internet, funny how the groups shrink in the truck on the drive home, as the range the group was shot at seams to get longer..............
That is the reason we are a SMALL ELITE group that enjoy the nuances of trying to better the previous group and continue to strive to shoot a smaller agg than the previous. All I do know it is NOT just the group that is valued. There is an entire package that is required to shoot the small groups. Not just any rifle will do it. Not just any shooter. Not just any bullet, barrel, etc...... We value everything in the sport. What I have come to know about our game is there are very few of us who are anal enough to shoot for a weekend or a week doing what we do.
If one does not follow the game one does not know what it takes. Again, the group shooter haters. What I do know is how many IPSC, 3 gun shooters are still winning at age 87? Not likely any. Walt Berger still does win. He shoots a BORING sport but is still able to do it and win. A man who has taken his first love Short Range bench rest, and used that knowledge to create winning bullets for all Center fire rifles.
Anyways, in group we use a Neil Jones measuring device and it is the most accurate way one can measure until they come out with scanning capabilities....
Thanks for the heads up, I think I know what my birthday present will be.
uncledillers
Regular
- Location
- Comox Valley
It's funny that some people are discussing hitting targets or "center" , and shooting groups like they are unrelated things. It's been my experience that if your are shooting small moa targets, your success rate can be attributed to you ability to shoot "groups". If you can't group 3/4 inch at 100 good luck hitting a 7.5 inch gong at 1000.
Its easy to find shooters at the local club range who can hold 3/4" at 100 yards. If we were to take 20 of those out to my little private range and have them try to head-shoot IPSC silhouettes at 800 yards,(6",3/4 MOA more or less) how many of the 20 do you think do you think we would lose? Most of them? I'm going to assume that you can, which is good because you can help with the next part. Lets coach them to the point that they can at least land their hits the body somewhere and call wind for them. Most of them will show that holding most of them in 6" isn't that big of a trick. Putting it where you need it is the hard part.
Brian Litz has done a lot of modelling of hit probability and scores by manipulating the variables of accuracy, wind drift etc. It would surprise many just how little accuracy improves things.
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Hahaha another way over complicated thread on measuring groups. Here's the easy way.
Since most people use digital calipers, this method only works with those.
1) Measure a single bullet hole
2) Zero the caliper
3) Measure the group
4) What you see is the centre to centre measurement that takes into account your bullet hole size in that paper
Since most people use digital calipers, this method only works with those.
1) Measure a single bullet hole
2) Zero the caliper
3) Measure the group
4) What you see is the centre to centre measurement that takes into account your bullet hole size in that paper
I'm not questioning the skills, dedication or equipment needed to shoot BR, nor do I think its boring. I am questioning the actual amount that gains in precision contribute to hits, scores, or converting previously alive things into less alive things.
