Typical Mean Radius for Hunting Rifles?

[Pinnah]

Can anybody point me to a collection of data on the accuracy of different hunting rifles based on mean radius based on 10 or more shots (preferably 20 or more) taken in aggregate to allow for adequate cooling between every shot or 2 or 3?

Thanks to the work by Brian Litz as popularized by a variety of blogs, podcasts and the like (https://precisionrifleblog.com/2020/12/12/measuring-group-size-statistics-for-shooters/) I’ve come to believe that:

1. Individual groups of 3-5 shots don’t provide reliable information (other than the occasional “the combination is terrible and can be excluded”),
2. Groups of 10 or more (preferably 20 or more) provide much more significant (and predictive) information, and
3. Mean radius provides more information than traditional “group size” (aka extreme spread).

As a hunter who wants a very high assurance that my gun is capable of hitting the vitals, mean radius is very helpful in that it can be used to calculate the R95 for a group, which is the radius from the group center that will hold 95% of the shots taken. This combined with the bullet’s trajectory can help me judge the confidence I have at shooting at different distances.

My problem is that mean radius is a new (to me) concept and I’ve not been able to find a listing results for other hunting rifles to help me determine how good or terrible my guns are.

Here are two examples. This is my .223 Varmint gun. A 20 shot string fired at a steady slow fire rate.



And here is my Winchester 94 in 32 WSP. 20 shots fired as a series of 7 different 3-shot strings (last string was 2 shots) allowing 20 minutes for the gun to cool off in-between. Accurate enough for the brush but…

 

[JEFFPPC]

Time to change the channel.

 

[chkunz]

I calculate group size using the “extreme spread” method and also the “mean radius” method. The mean radius calculation values all shots in the test group on an equal basis as opposed to extreme spread which only values the two extreme shots. Extreme spread is more widely used for group analysis, but mean radius is a superior measure of merit and has significant advantages such as reducing the significance of a potential flyer.

 

[chkunz]

Also, It has been shown that for long run averages 20 shot groups can be expected to average 1.79 times as large as three shot groups and 1.45 times as large as five shot groups but only 1.17 times as large as 10 shot groups, therefore, I choose 10 shot test groups for XTC load development.

 

[TominSWNY]

Time to change the channel.

DONE

 

[K22]

I am a hunter too with 50+ years of field experience, these days varmints and predators. Yesteryears, the aforementioned critters plus deer.

Mean radius is not a new concept. I read that during the American Civil War, the Berdan sharpshooter qualification was based on the distance measured from the bull.

Anyway, measuring groups, mean radius, etc. is fine for load development. But once you have a qualified load, if you really want to evaluate your hunting capability stay off the bench and use your range time to practice shooting the way you intend to hunt in the field. Also, develop a target that reflects the vital area of the critter you are hunting. Place the target at varying distances out to the max distance you intend to shoot.

I make my own targets on Power Point using 5x8 cards with concentric circles of 1" to 4". If I stay within the 3" circle, the groundhog is down, the 4" circle, the predator is down. It's that simple. All my shots are from a cold / cool barrel which is the "money" shot for the hunter.

Besides being a lot of fun, testing yourself in real world conditions will quickly reveal your capability. I do 99% of all my range shooting off shooting sticks which is the way I hunt. I grade my performance of every range session and I keep a performance range log.

I have refined my technique and have a very good idea of my capabilities in the field. Also learn to read wind, mirage and learn how your rifle / load responds to changes in air density (cold vs. hot temperatures).

I guarantee you that if you follow the above suggestions, you will be more successful in the field rather than spending your time and money on trying squeeze a few tenths reduction in group size / mean radius off the bench.

 

[CharlieNC]

If you want to know the confidence interval of shots around a mean radius, then you also need to know the SD of that data. You can either measure all the shots to calculate the SD if the target stat program doesn't give that option, or use the approximate SD = 0.5 MR.

 

[coldboremiracle]

I could see this being very relevant to a varmint rifle, as sometimes you are shooting from a cold barrel, and other times you are shooting 10 or more shots within a minute or two.

 

[Pinnah]

Also, It has been shown that for long run averages 20 shot groups can be expected to average 1.79 times as large as three shot groups and 1.45 times as large as five shot groups but only 1.17 times as large as 10 shot groups, therefore, I choose 10 shot test groups for XTC load development.

Have you determined the MR for any of your hunting rifles? If so, mind sharing the results? Distance, number of shots in aggregate, and MR?

Thanks.

 

[JEFFPPC]

I turned the channel back on. I have a question. Did you fire these shots with flags, or not.

 

[chop house]

you will be more successful in the field rather than spending your time and money on trying squeeze a few tenths reduction in group size / mean radius off the bench.

this brings to mind my introduction to p-dogs. i was somewhat obsessed that every varmint rifle/load i took on a trip would shoot 0.5 moa. it did not take me long on the first morning to learn that range and wind estimation errors totally obscured the difference between a 5/8" and 1/2" 100 yard load... ymmv

 

[Pinnah]

I am a hunter too with 50+ years of field experience, these days varmints and predators. Yesteryears, the aforementioned critters plus deer.

Mean radius is not a new concept. I read that during the American Civil War, the Berdan sharpshooter qualification was based on the distance measured from the bull.

Anyway, measuring groups, mean radius, etc. is fine for load development. But once you have a qualified load, if you really want to evaluate your hunting capability stay off the bench and use your range time to practice shooting the way you intend to hunt in the field. Also, develop a target that reflects the vital area of the critter you are hunting. Place the target at varying distances out to the max distance you intend to shoot.

I make my own targets on Power Point using 5x8 cards with concentric circles of 1" to 4". If I stay within the 3" circle, the groundhog is down, the 4" circle, the predator is down. It's that simple. All my shots are from a cold / cool barrel which is the "money" shot for the hunter.

Besides being a lot of fun, testing yourself in real world conditions will quickly reveal your capability. I do 99% of all my range shooting off shooting sticks which is the way I hunt. I grade my performance of every range session and I keep a performance range log.

I have refined my technique and have a very good idea of my capabilities in the field. Also learn to read wind, mirage and learn how your rifle / load responds to changes in air density (cold vs. hot temperatures).

I guarantee you that if you follow the above suggestions, you will be more successful in the field rather than spending your time and money on trying squeeze a few tenths reduction in group size / mean radius off the bench.

Based on your experience, what is the practical range of a 30-30 lever gun carbine for deer sized game?

A standard answer to this question is to calculate the max point blank range with a +/- rise/drop of 3". The thinking is generally that the vitals are a 10" target so a 6" rise/drop error still leaves a bit of room for aiming error from shooting in a field position.

You will note in the picture above, that the first 3 shots from my Winchester 94 (32 WSP) which are circled gave me a group under an inch! Awesome, right? I let the barrel cool completely and shot another 3 shot string on the cold barrel. And then repeated that till I had a 12 shot aggregate target which gave me a MR of 1.6. I changed the scope system and reshot the experiment, this time with 6 3-shot strings and a 2-shot string, all from a cold barrel to generate a 20-shot aggregate with a MR of 1.46. This gives me a R95 = 2.1 x MR = 3.1". Assuming a normal distribution (the common assumption) and assuming a perfectly zeroed sighting system at 100 yards, this means that I can expect that 95% of my shots will hit inside of a 6.2" circle. So, when I'm practicing on a 10" steel plate shooting off hand, I have very little margin of error. And at around 160 yds, the R95 value exceeds 5", which means I can no longer expect that 95% of my shots will hit the vitals even assuming a "perfect shot". Now add the rise and drop of the trajectory, around which the R95 cone of dispersion is moving and we have stacking errors.

So again, what is the practical effective range of a 30-30 lever gun for deer?

In contrast, I shoot my varmint gun (the .223 with the target above) in 200 yd offhand matches. It has a MR of .71 at 200, which gives an R95 of 1.4". That tells me the gun is capable of staying in the 10 ring. So... when I yank a shot out of the black and into 7 ring - as I did in Sunday's match - I know that is all me and not the gun.

So... is my varmint gun accurate enough? For my purposes, yes. But I would love to know what other people are getting for MR out of theirs to be able to compare.

And is my lever gun accurate enough? Or is it a stinker? Or does my load suck? TBH, I have no clue. I can point to a sub MOA 3 shot group and crow about my accurate lever gun. But the MR taken over a 20 shot aggregate tells me that the gun can only be relied on to hold 6" at 100. Is that good or bad compared to other lever guns?

I would love to see MR results for hunting guns from 10 or more shots (in aggregate).

 

[Coyotefurharvester]

Is your goal offhand shooting game?

 

[JEFFPPC]

If your doing these tests, your prerogative, and say it's a light 2.5 mph wind and you shoot a reversal, a net 5mph change, you invalidated your entire test. If you did use flags to try and shot in the same condition , good for you. Just curious. Bake to my regular programming.

 

[Jeff Porter]

I understand what you are looking for and see how you are determining that for your own rifles. I use a system more like K22 for determining maximum shooting distance at live targets.

Particularly with new shooters. I will use a target like the Determinator brand.

Effective Range Targets

Easily determine your individual effective and ethical hunting range with Effective Range Targets

www.determinatortargets.com

When I had access to a great open pasture I would set 2L bottles and gallon milk jugs at various distances and angles from 35 to 350 yards. The new hunter ( usually coyote / Varmint ) would shoot from field positions not a bench or prone bagged set up and start near and work out until they missed a target. I would give them one more shot at that target. Two misses and you are done. If you hit it on the second shot you could try the next farther jug but no more second shots.

While not the statistical value you are seeking to quantify for a rifle and a shooter, I find these effective at making a hunter understand just because you see it doesn’t mean you should shoot at it.

 

[chkunz]

Have you determined the MR for any of your hunting rifles? If so, mind sharing the results? Distance, number of shots in aggregate, and MR?

Thanks.

I do not hunt. All of my testing has been for match rifles for NRA high power competition. I develop loads that will put ten shots in the X ring for those targets from 100 yards to 1000 yards. I can give you the numbers that you ask for if that would be useful. I would say it is more challenging than hunting but not as much as bench rest.

 

[K22]

Based on your experience, what is the practical range of a 30-30 lever gun carbine for deer sized game?

A standard answer to this question is to calculate the max point blank range with a +/- rise/drop of 3". The thinking is generally that the vitals are a 10" target so a 6" rise/drop error still leaves a bit of room for aiming error from shooting in a field position.

You will note in the picture above, that the first 3 shots from my Winchester 94 (32 WSP) which are circled gave me a group under an inch! Awesome, right? I let the barrel cool completely and shot another 3 shot string on the cold barrel. And then repeated that till I had a 12 shot aggregate target which gave me a MR of 1.6. I changed the scope system and reshot the experiment, this time with 6 3-shot strings and a 2-shot string, all from a cold barrel to generate a 20-shot aggregate with a MR of 1.46. This gives me a R95 = 2.1 x MR = 3.1". Assuming a normal distribution (the common assumption) and assuming a perfectly zeroed sighting system at 100 yards, this means that I can expect that 95% of my shots will hit inside of a 6.2" circle. So, when I'm practicing on a 10" steel plate shooting off hand, I have very little margin of error. And at around 160 yds, the R95 value exceeds 5", which means I can no longer expect that 95% of my shots will hit the vitals even assuming a "perfect shot". Now add the rise and drop of the trajectory, around which the R95 cone of dispersion is moving and we have stacking errors.

So again, what is the practical effective range of a 30-30 lever gun for deer?

In contrast, I shoot my varmint gun (the .223 with the target above) in 200 yd offhand matches. It has a MR of .71 at 200, which gives an R95 of 1.4". That tells me the gun is capable of staying in the 10 ring. So... when I yank a shot out of the black and into 7 ring - as I did in Sunday's match - I know that is all me and not the gun.

So... is my varmint gun accurate enough? For my purposes, yes. But I would love to know what other people are getting for MR out of theirs to be able to compare.

And is my lever gun accurate enough? Or is it a stinker? Or does my load suck? TBH, I have no clue. I can point to a sub MOA 3 shot group and crow about my accurate lever gun. But the MR taken over a 20 shot aggregate tells me that the gun can only be relied on to hold 6" at 100. Is that good or bad compared to other lever guns?

I would love to see MR results for hunting guns from 10 or more shots (in aggregate).

I have no personal experience hunting with the 30 -30 but my father took 18 bucks with an open sight 30-30 Model 94 Winchester with factory Remington ammo. I don't recall the number of does he took but it was a bunch. He hunted in the big woods of north central PA where shots were typically under 150 yards. Also, the "mountain bucks" rarely got over 150 lbs. He spent very little time on a range, merely 3-5 shot sight in confirmation before deer season and that was it.

As you know, deer hunting is nothing like shooting on a target range. You're dealing with different terrain, shooting positions, light conditions, target presentations, sometimes inclement weather. If you can keep your shots in a field shooting position within an 8" circle at distance "X" I would venture to say you have a high probability of dropping a deer with proper shot placement. Most old timers I knew felt 150 yards was a reasonable distance for an open sight 30-30 lever rifle. Add a scope, and you might extend the range to 175 to 200 yards. These are merely guesses on my part since I never hunted with a 30-30. Members who have should chime in with real world experiences.

For varmint hunting (eastern groundhogs), my standard in a field shooting situation is the ability to hit a 3-inch circle at the maximum distance I intend to shoot. In the past I would often practice in the field using 3x5 cards mounted on a makeshift holder placed at various distances. If you can hit the card mounted vertically, you have a high probability of taking a standing hog. If you can hit the card mounted horizontally, you have high probability of taking a crawler. Over the years I just settled on using 5x 8 cards for range practice with concentric circles to simplify scoring both vertically and horizontally. I am only interested in performance shooting, not bench shooting.

The bottom line is after you have a qualified load, the real measure of your field capability is to make a shot in the vital area in a field shooting position at the maximum distance you intend to shoot. I use the 95% rule, over several practices sessions I strive for an average a 95% hit rate both vertically and horizontally. I should add that I use a field shooting aid, cross sticks while sitting on a portable field sportsman's chair which give a relatively stable shooting platform.

Addressing your mean radius measurement question, I do not measure mean radius but my ability to hit the vital area. I don't think you can apply an absolute measurement system to hunting because of all the variables involved. In my experience it is significantly different and more challenging than target shooting which is why I like it so much. I have inexplicability missed ground hogs at 100 yards yet taken them at over 250 yards with much more difficult profiles. The point is nothing is absolute when it comes to hunting. However, with enough practice, in my experience, you can obtain a fairly accurate understanding of your maximum effective range for the critter you are hunting that will result in success most of the time but never 100% of the time.

 

[K22]

this brings to mind my introduction to p-dogs. i was somewhat obsessed that every varmint rifle/load i took on a trip would shoot 0.5 moa. it did not take me long on the first morning to learn that range and wind estimation errors totally obscured the difference between a 5/8" and 1/2" 100 yard load... ymmv

Yes of course, plus air density changes due to temperature changes. Add in different terrains, different distances, different target presentations, bugs biting you, sun in your face, etc., well you get the idea, it ain't shooting at a nice, covered range at a fixed distance usually flat.

 

[Pinnah]

As you know, deer hunting is nothing like shooting on a target range. You're dealing with different terrain, shooting positions, light conditions, target presentations, sometimes inclement weather.

IMO, hunting performance is closely tied to range performance in an important way. Hunting performance is worse than range performance. There is a YouTube video making the rounds of a guy taking an elk with a 30-30 at 300 yds. IMO, he got lucky as (IMO) that's way out past the accuracy limit of the gun. Range testing helps us understand that.

In similar manner, it makes no sense to me to practice 200 yd shots in field positions even with a scoped 30-30. Again, (IMO) that's pushing that system beyonds it accuracy potential.

If you can keep your shots in a field shooting position within an 8" circle at distance "X" I would venture to say you have a high probability of dropping a deer with proper shot placement. Most old timers I knew felt 150 yards was a reasonable distance for an open sight 30-30 lever rifle. Add a scope, and you might extend the range to 175 to 200 yards. These are merely guesses on my part since I never hunted with a 30-30. Members who have should chime in with real world experiences.

I generally think of a 10" vital region for deer but agree largely with what you've written here to a point. I too have heard many old timers say the same thing about 30-30 lever guns. "The gun will take deer out to 200 yards if I do my part." But, I discount the "real world experiences" which are anecdotal stories about successes with misses explained away as being the shooter's fault. Off the bench, my gun exceeds a 4" R95 at somewhere near 130 yds, which means beyond that, no matter how good of a shot you are, you can't have high confidence on staying on your 8" plate. Which is to say, I think the old timers aren't right.

Reversing Whelen's famous quote, in this thread, I'm only interested in the accuracy of the gun & ammo system. It's the outer bounds of what I, as a hunter, can aspire to with that system. And, it's a way to consider the pros and cons of different systems.

I'll not belabor the point. I've asked if people have or can point to MR values for hunting rifles based on 10 or more shots. I think the answer is "no" which is fine.

 

[Eagle Six]

About 15 years ago I was with the range owner as we were scouting for a training area. At the same time we both pointed and called coyote, which was about 200 yards at out 2 o'clock just below the civilian crest. I stopped the Jeep dismounted and circled around getting my eyes on the yote that was running as he fired with his range gun. A beat up scarred and patinaed 94 30-30. The yote was down and out. I grabbed the rangefinder it was 340 yards! It sounds to others like a wild story, but I witnessed it. Calculators and ballistic programs as well as paper targets on the range were a bit foreign to him. There is a moral in that story and others like it for those that read between the lines.