Learning at the Whidden Gunworks Test Range

[ATFIV]

John,
Thank you for sharing your findings.
Respectfully
T Fletcher

 

[Alex Wheeler]

Ready to make the trip. 2 Mullers, Bartlien, and Lilja. Will be interesting.

 

[68Hoyt]

Alex ,
Are the tolerances and tenon timing close enough that barrels can be swapped between actions ? Curious is all

 

[Mg73]

So here’s question about acceptable 10 shot group size at 100 yds you may be able to shed light on given the accumulated data from your testing.

Can you give us your opinion, based on your testing, what is a reasonably acceptable 10 shot group size at 100 yds for a rifle/ammo combo? And even, better, can you give us two answers, one for custom and one for factory.
What I’m looking for is some general guidance from your testing results to help us testing at home evaluate what we should be aiming for in terms of 10 shot group size at 100 yds. Like: our findings show that if you are consistently shooting .75 MOA ten shot groups at 100yds then you are doing well. If it’s 2 MOA or over then something is off in either equipment or technique. Or to remove technique you might say: “Our testing shows good gun/ammo combo’s will consistently shoot x MOA 10 shot groups at 100 yds at our center. If a combo shoots consistently over x MOA, then we would consider that a poor result.”
Am I making sense? Again, looking for some observations based on your testing results to help guide us home testers.

 

[1813benny]

So here’s question about acceptable 10 shot group size at 100 yds you may be able to shed light on given the accumulated data from your testing.

Can you give us your opinion, based on your testing, what is a reasonably acceptable 10 shot group size at 100 yds for a rifle/ammo combo? And even, better, can you give us two answers, one for custom and one for factory.
What I’m looking for is some general guidance from your testing results to help us testing at home evaluate what we should be aiming for in terms of 10 shot group size at 100 yds. Like: our findings show that if you are consistently shooting .75 MOA ten shot groups at 100yds then you are doing well. If it’s 2 MOA or over then something is off in either equipment or technique. Or to remove technique you might say: “Our testing shows good gun/ammo combo’s will consistently shoot x MOA 10 shot groups at 100 yds at our center. If a combo shoots consistently over x MOA, then we would consider that a poor result.”
Am I making sense? Again, looking for some observations based on your testing results to help guide us home testers.

The question is somewhat ambiguous. What is needed vs what is acceptable comes into play along with what is possible.

 

[BowChamp]

Ready to make the trip. 2 Mullers, Bartlien, and Lilja. Will be interesting.View attachment 1664373

I'm very interested in how the Lilja shoots....please keep us posted.

Thanks!!!

 

[Mg73]

The question is somewhat ambiguous. What is needed vs what is acceptable comes into play along with what is possible.

True. Let me be more specific about my intent. What I’m hoping for is that the OP, who has access to a data set that is set up to reduce the human variables, is able to discern some ‘pearls of wisdom’ from that data set to help us reduce the ‘ambiguities’ inherent in our quest for precision. He already did this for me in terms of cleaning schedule, and I’m hoping there’s a pearl or two in terms of groupings.

 

[whiddengunworks]

Mg73, concerning group sizes at 100 yards, let me first give you what we see at 100M then we'll calculate backwards to MOA at 100 yards. It's late, so someone will need to double check this math.

We find very few guns that will shoot an individual group under 20mm at 100M, measured outside to outside. Exceptionally few will shoot an average of 4 groups this small, so let's say this is as good as it gets for custom guns.

From 20mm outside, we subtract 5.6mm to get center to center measurement, so we're at 14.4mm. 100M is roughly 10% further than 100 yards, so to convert for yards we'll subtract 14.4mm-10 % so let's round that to 13mm. A half inch is 12.7mm, so the very best of anything out there will shoot a little over 1/2 MOA at 100 yards. We've maybe seen 2-3 guns reliably average this good.

For factory rifles like a CZ 457 MTR, groups are more like 50mm range, which would convert to slightly over 1.5 MOA or so.

Interestingly, at 100M is where we start seeing velocity variations have an influence on group size. That's not really detectable at 50M.

**edited to correct 100M data**

 

[Mg73]

Mg73, concerning group sizes at 100 yards, let me first give you what we see at 100M then we'll calculate backwards to MOA at 100 yards. It's late, so someone will need to double check this math.

We find very few guns that will shoot an individual group under 20mm at 100M, measured outside to outside. Exceptionally few will shoot an average of 4 groups this small, so let's say this is as good as it gets for custom guns.

From 20mm outside, we subtract 5.6mm to get center to center measurement, so we're at 14.4mm. 100M is roughly 10% further than 100 yards, so to convert for yards we'll subtract 14.4mm-10 % so let's round that to 13mm. A half inch is 12.7mm, so the very best of anything out there will shoot a little over 1/2 MOA at 100 yards. We've maybe seen 2-3 guns reliably average this good.

For factory rifles like a CZ 457 MTR, groups are more like 50mm range, which would convert to slightly over 1.5 MOA or so.

Interestingly, at 100M is where we start seeing velocity variations have an influence on group size. That's not really detectable at 50M.

**edited to correct 100M data**

Thanks, so much. Just to be clear, we’re talking 10 shot groups, right?

Assuming it’s 10 shot groups, then the take home messages are:

Under ideal conditions, clamped in a vise, no wind, premium ammo, the very, very best 22LR guns will achieve around 1/2 MOA at 100 yds consistently for a 10 shot group.

For a factory 22LR gun under the same optimal conditions, 100 yard, 10 shot groups of 1.5 MOA or better would be considered a good shooter.

Is this correct?

 

[whiddengunworks]

Yes, those are 10 shot groups and you're understanding it right. These would be the average of (4) 10 shot groups, a very different thing from one good group!

 

[drewh]

Do you, or could you collect velocity data when the tests are run?

 

[linebaugh]

Mg73, concerning group sizes at 100 yards, let me first give you what we see at 100M then we'll calculate backwards to MOA at 100 yards. It's late, so someone will need to double check this math.

We find very few guns that will shoot an individual group under 20mm at 100M, measured outside to outside. Exceptionally few will shoot an average of 4 groups this small, so let's say this is as good as it gets for custom guns.

From 20mm outside, we subtract 5.6mm to get center to center measurement, so we're at 14.4mm. 100M is roughly 10% further than 100 yards, so to convert for yards we'll subtract 14.4mm-10 % so let's round that to 13mm. A half inch is 12.7mm, so the very best of anything out there will shoot a little over 1/2 MOA at 100 yards. We've maybe seen 2-3 guns reliably average this good.

For factory rifles like a CZ 457 MTR, groups are more like 50mm range, which would convert to slightly over 1.5 MOA or so.

Interestingly, at 100M is where we start seeing velocity variations have an influence on group size. That's not really detectable at 50M.

**edited to correct 100M data**

THANK YOU FOR THIS. ^

 

[Mg73]

Yes, those are 10 shot groups and you're understanding it right. These would be the average of (4) 10 shot groups, a very different thing from one good group!

Thanks so much for sharing your data. You’ve given us some data driven benchmarks to help us interpret our home results. A couple of further thoughts:

Given your results are under optimal conditions, when we shoot at our homes or ranges where we have more variables, ie wind, shooting technique, untested ammo lots, we should use .5 MOA and 1.5 MOA more as goals to strive towards and accept that being ‘in the ballpark’ may be the reality of home testing. At least now we have an optimal benchmark to guide our interpretation of our home testing groups.

The importance of using 10 shots: shooters need to know that using your .5 MOA and 1.5 MOA for benchmarks only works with 10 shot groups. Fewer shots per group or even more shots per group will give you different benchmark values.

That’s just basic statistics. If you shoot only three shots and get .10 MOA you might have just been lucky. Shoot another 3 shot groups and the probability is very high those results will not repeat. Same thing if you shot a 3 shot group and got 5 MOA. Shoot another 3 shot group and the probability is very high it won’t repeat. It’s so few samples that confidence that your gun will do that consistently will be very low. Consider this: statistically, the more shots you take in a group, the larger your group size will grow (up to a point). It makes sense because the more shots you take, the more opportunities you have for every little variable to influence the result. The great thing is that this effect decreases after a certain predictable number of shots. So what happens is your group size will tend to enlarge most up to about 10 shots. After that your group size will grow but at a much slower rate and tends to stabilize and max out somewhere around 30 shots. Again, just basic statistics. 10 shots seems to be a sweet spot that gives you reasonable confidence in your results for your money. In keeping with our narrative, take another 10 shot group and the probability is pretty good the results will be similar.

So the take home message on number of shots per group is: 10 shots per group is the sweet spot.

The more shots you take per group, the greater the probability that the results between groups will be similar. In other words, that’s what that gun/ammo combo will consistently do under the same conditions. That’s important info to know.

The result of a three shot group is really not much better than chance. A five shot group is better but still doesn’t give you great confidence that’s what your gun will consistently do. 10 shots is around the sweet spot for being reasonably confident that’s what your gun/ammo combo will do under the same conditions. You can gain more confidence in your results by shooting more shots in a group but you spend more money for decreasing gains in information.

Note that the OP based his .5 MOA and 1.5 MOA benchmarks on the average of four 10 shot groups. So those results are rock solid.

 

[CharlieNC]

Thanks so much for sharing your data. You’ve given us some data driven benchmarks to help us interpret our home results. A couple of further thoughts:

Given your results are under optimal conditions, when we shoot at our homes or ranges where we have more variables, ie wind, shooting technique, untested ammo lots, we should use .5 MOA and 1.5 MOA more as goals to strive towards and accept that being ‘in the ballpark’ may be the reality of home testing. At least now we have an optimal benchmark to guide our interpretation of our home testing groups.

The importance of using 10 shots: shooters need to know that using your .5 MOA and 1.5 MOA for benchmarks only works with 10 shot groups. Fewer shots per group or even more shots per group will give you different benchmark values.

That’s just basic statistics. If you shoot only three shots and get .10 MOA you might have just been lucky. Shoot another 3 shot groups and the probability is very high those results will not repeat. Same thing if you shot a 3 shot group and got 5 MOA. Shoot another 3 shot group and the probability is very high it won’t repeat. It’s so few samples that confidence that your gun will do that consistently will be very low. Consider this: statistically, the more shots you take in a group, the larger your group size will grow (up to a point). It makes sense because the more shots you take, the more opportunities you have for every little variable to influence the result. The great thing is that this effect decreases after a certain predictable number of shots. So what happens is your group size will tend to enlarge most up to about 10 shots. After that your group size will grow but at a much slower rate and tends to stabilize and max out somewhere around 30 shots. Again, just basic statistics. 10 shots seems to be a sweet spot that gives you reasonable confidence in your results for your money. In keeping with our narrative, take another 10 shot group and the probability is pretty good the results will be similar.

So the take home message on number of shots per group is: 10 shots per group is the sweet spot.

The more shots you take per group, the greater the probability that the results between groups will be similar. In other words, that’s what that gun/ammo combo will consistently do under the same conditions. That’s important info to know.

The result of a three shot group is really not much better than chance. A five shot group is better but still doesn’t give you great confidence that’s what your gun will consistently do. 10 shots is around the sweet spot for being reasonably confident that’s what your gun/ammo combo will do under the same conditions. You can gain more confidence in your results by shooting more shots in a group but you spend more money for decreasing gains in information.

Note that the OP based his .5 MOA and 1.5 MOA benchmarks on the average of four 10 shot groups. So those results are rock solid.

Yep that's why group size is a poor statistic, although it is universally treated as an observation. The individual shot distance to center can be used as observations to determine not only the mean radius, but also the SD for a more robust and useful statistic.

 

[whiddengunworks]

drewh we can (and sometimes do) collect velocity data. We've about solidified our plan for doing this, and will offer this service very soon to everyone.

 

[Mg73]

Yep that's why group size is a poor statistic, although it is universally treated as an observation. The individual shot distance to center can be used as observations to determine not only the mean radius, but also the SD for a more robust and

Agree that mean radius and standard deviation give even more accurate results, but only by a degree. Labeling group size a ‘poor statistic’ just goes too far, in my opinion. It gives us a good solid place to start that can be honed even further by mean radius and standard deviation. I suspect that, on further reflection, you might agree that ‘poor’ might not be the appropriate adjective. That being said, I think your overall point to include mean radius and standard deviation is a good one, and I do include them in my own analysis.

 

[67gt350]

Give me a lot that will shoot 13mm for 5+ groups over one that has 9mm,12mm IMO what most don't understand is consistency is what produces the better scores.

Lee

More importantly is when you overlay 4 or 5 - 10 shot groups what then is the total group size. Olympic standard was a 40 shot group < or = to 14mm at 50 meters

 

[Alex Wheeler]

Alex ,
Are the tolerances and tenon timing close enough that barrels can be swapped between actions ? Curious is all

Its supposed to be but I have not been tracking it over enough time to know if its always that way.

 

[TRSR8]

Its supposed to be but I have not been tracking it over enough time to know if its always that way.

Eck did a large number of them and they mostly are.
A couple instances required somewhat of a “butterfly” extractor cut, not a real big deal.

 

[Dave Way]

I understand the whole mm thing since the ammo is from overseas and the Olympics are international but maybe it’s time to measure 22 groups in inches here in the United States!? After all, we are the country others wish they were.


Lapua Super Long Range

Dave.