One last OCW question

[ReaperDriver]

Something occured to me while re-reading the OCW link about the what the results are telling you. Given that you are waiting 2-3 min between shots during the round robin testing - each shot is pretty much going to be a cold bore shot. Is this the right data we want?

I'm thinking that if the intent is to find the forgiving OCW - it might be correct for a single cold bore shot. However if you are shooting multiple shots or a match where you are going to be shooting a lot of rounds through a pretty hot barrel - is your cold bore OCW going to still be good for the 5th, 10th, 20th shot in a string like in a tac match or F-class?

Would a latter test, where you typically shoot a bit faster (but not rapid fire), not tell you REAL world results? I honestly don't have a dog in either the OCW or ladder fight - I'm just trying to understand all the pros/cons of each.

Thanks!

 

[jasonk]

Re: One last OCW question

2-3 minutes between shots is by no means a cold bore shot each time. You'd have to wait 20-30 minutes between shots.

 

[Mag 300]

Re: One last OCW question

I agree with Jason just did this yesterday 1 minute apart but it was 5 degrees out, results did come out favorable.
Bill

 

[Mag 300]

Re: One last OCW question

I agree with Jason just did this yesterday 1 minute apart but it was 5 degrees out, results did come out favorable.
Bill

 

[Unsichtbar]

Re: One last OCW question


This is from Dans site, read go shoot

"An indisputable fact about firing long strings of shots during load development is that things that shouldn't change will change. Your barrel will warm and foul. The wind conditions will change. The lighting conditions will change. Your heart rate and other bodily functions will change, affecting your trigger prowess. These are unavoidable variables that can and will skew your load development results--no matter how hard you try to compensate for them.
 
In the conventional Audette or "ladder" test, you fire a string of twenty or so shots at a target 300 yards away. The idea is to look for a cluster of shots on that target which will represent the best charge weight of powder to use. However, during this string of fire the above mentioned variables--either individually or in concert--will certainly skew your results to one degree or another. You might pull a shot or two during the string. Having only one representative shot of each charge being looked at is not the best approach in my opinion.
 
But consider the round robin firing sequence. By firing "round robin" I simply mean that you dedicate one target to each charge weight being tested, and you shoot once at target number 1 with the first graduation, and then once at target 2 with the second graduation, etc., until you've been through all targets three times each, leaving a three shot group on each target. This method spreads the error factor across all groups equally--and you get three shots of each charge weight--rather than the Audette ladder test's one shot. So, if the barrel fouls and becomes inaccurate after 8 or 10 shots, the flyers will be evident in all groups tested. This will yield more meaningful data, and is statistically superior to the conventional Audette method."

 

[Mag 300]

Re: One last OCW question

+1 for that

 

[DaveV]

Re: One last OCW question

I don't think barrel temp is going to make a huge difference in the OCW development. First, higher temps (either barrel or ambient)are not going to show significant evidence at shorter distances. As the distance legs out, velocity changes will obviously effect the results. Lindy can correct me here if need be. Second, you are not looking for tight groups as much as group trends. Even if your MV is changing due to temp issues, the scatter groups will still sandwich your stable groups. If you were at step two with bullet seating and your goal was tighten groups, then you would certainly want to match your shooting cadence to the application you are setting up for. At this point, you are still not going to see major issues until you get out to longer distances.

 

[Mag 300]

Re: One last OCW question

Also if you are shooting round robbin for say 10 samples of differing loads there is normalization of the shots in that every 10th one is on the same grouping
Bill

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DaveV</div><div class="ubbcode-body">I don't think barrel temp is going to make a huge difference in the OCW development. First, higher temps (either barrel or ambient)are not going to show significant evidence at shorter distances. As the distance legs out, velocity changes will obviously effect the results. Lindy can correct me here if need be. Second, you are not looking for tight groups as much as group trends. Even if your MV is changing due to temp issues, the scatter groups will still sandwich your stable groups. If you were at step two with bullet seating and your goal was tighten groups, then you would certainly want to match your shooting cadence to the application you are setting up for. At this point, you are still not going to see major issues until you get out to longer distances. </div></div>

 

[ReaperDriver]

Re: One last OCW question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Unsichtbar</div><div class="ubbcode-body">
This is from Dans site, read go shoot

"An indisputable fact about firing long strings of shots during load development is that things that shouldn't change will change. Your barrel will warm and foul. The wind conditions will change. The lighting conditions will change. Your heart rate and other bodily functions will change, affecting your trigger prowess. These are unavoidable variables that can and will skew your load development results--no matter how hard you try to compensate for them.
 
In the conventional Audette or "ladder" test, you fire a string of twenty or so shots at a target 300 yards away. The idea is to look for a cluster of shots on that target which will represent the best charge weight of powder to use. However, during this string of fire the above mentioned variables--either individually or in concert--will certainly skew your results to one degree or another. You might pull a shot or two during the string. <span style="font-weight: bold">Having only one representative shot of each charge being looked at is not the best approach in my opinion.</span> 

But consider the round robin firing sequence. By firing "round robin" I simply mean that you dedicate one target to each charge weight being tested, and you shoot once at target number 1 with the first graduation, and then once at target 2 with the second graduation, etc., until you've been through all targets three times each, leaving a three shot group on each target. This method spreads the error factor across all groups equally--and you get three shots of each charge weight--rather than the Audette ladder test's one shot. So, if the barrel fouls and becomes inaccurate after 8 or 10 shots, the flyers will be evident in all groups tested. This will yield more meaningful data, and is statistically superior to the conventional Audette method." </div></div>
See... the bolded part above is what really throws me off. I've read Dan's website numerous times and he is making it sound like the ladder people are shooting ONE shot for each charge weight, where as I normally would shoot 5 of the same charge weight at a single target and then move onto a fresh target for the next 5 of the next charge wt step and so on.

Also, he makes the case that flyers, bore fouling, breathing techniques, wind effects and so on are statistically compensated for in OCW. But if you shoot 3-5 rounds of a single charge weight and wait 2-3 min between each shot - how is THAT also not as statistically accurate as shooting a round robin?

Now if Dan's argument REALLY IS that people are shooting a SINGLE round of each charge weight step - then obviously his method is superior. But I don't know anyone that is doing that. Who shoots 20 shots at a single target like he describes?

As I said, I'm not defending any one method over another - I'll use whatever works best. I just simple don't see any difference statistically from shooting 10 steps of a powder/bullet combo round robin style vs shooting 10 steps of a powder/bullet combo 5 rounds in a row at one target and then moving onto the next fresh target with the next charge weight. The ONLY thing I can think where the round robin method would help is if the environmental conditions (winds, temps, etc) changed over the course of the total range session - THEN I could see RR style spreading some of those effects out across all the charge weights. But the rest of the reasons that Dan argues (breathing, flyers, etc) will be statistically the same whether you do 5 shots of one charge weight all together or spread those over the whole day. The shooter fatigue and error is still possible - regardless or not the current shot I'm pulling the trigger on is 44.0 grs of Varget or 44.6.

 

[Shady_Jay]

Re: One last OCW question

Cold bore is really not an issue. Clean bore versus fouled bore make more of a difference.

 

[DaveV]

Re: One last OCW question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ReaperDriver</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Unsichtbar</div><div class="ubbcode-body">
This is from Dans site, read go shoot

"An indisputable fact about firing long strings of shots during load development is that things that shouldn't change will change. Your barrel will warm and foul. The wind conditions will change. The lighting conditions will change. Your heart rate and other bodily functions will change, affecting your trigger prowess. These are unavoidable variables that can and will skew your load development results--no matter how hard you try to compensate for them.
 
In the conventional Audette or "ladder" test, you fire a string of twenty or so shots at a target 300 yards away. The idea is to look for a cluster of shots on that target which will represent the best charge weight of powder to use. However, during this string of fire the above mentioned variables--either individually or in concert--will certainly skew your results to one degree or another. You might pull a shot or two during the string. <span style="font-weight: bold">Having only one representative shot of each charge being looked at is not the best approach in my opinion.</span> 

But consider the round robin firing sequence. By firing "round robin" I simply mean that you dedicate one target to each charge weight being tested, and you shoot once at target number 1 with the first graduation, and then once at target 2 with the second graduation, etc., until you've been through all targets three times each, leaving a three shot group on each target. This method spreads the error factor across all groups equally--and you get three shots of each charge weight--rather than the Audette ladder test's one shot. So, if the barrel fouls and becomes inaccurate after 8 or 10 shots, the flyers will be evident in all groups tested. This will yield more meaningful data, and is statistically superior to the conventional Audette method." </div></div>
See... the bolded part above is what really throws me off. I've read Dan's website numerous times and he is making it sound like the ladder people are shooting ONE shot for each charge weight, where as I normally would shoot 5 of the same charge weight at a single target and then move onto a fresh target for the next 5 of the next charge wt step and so on.

Also, he makes the case that flyers, bore fouling, breathing techniques, wind effects and so on are statistically compensated for in OCW. But if you shoot 3-5 rounds of a single charge weight and wait 2-3 min between each shot - how is THAT also not as statistically accurate as shooting a round robin?

Now if Dan's argument REALLY IS that people are shooting a SINGLE round of each charge weight step - then obviously his method is superior. But I don't know anyone that is doing that. Who shoots 20 shots at a single target like he describes?

As I said, I'm not defending any one method over another - I'll use whatever works best. I just simple don't see any difference statistically from shooting 10 steps of a powder/bullet combo round robin style vs shooting 10 steps of a powder/bullet combo 5 rounds in a row at one target and then moving onto the next fresh target with the next charge weight. The ONLY thing I can think where the round robin method would help is if the environmental conditions (winds, temps, etc) changed over the course of the total range session - THEN I could see RR style spreading some of those effects out across all the charge weights. But the rest of the reasons that Dan argues (breathing, flyers, etc) will be statistically the same whether you do 5 shots of one charge weight all together or spread those over the whole day. The shooter fatigue and error is still possible - regardless or not the current shot I'm pulling the trigger on is 44.0 grs of Varget or 44.6. </div></div>

You make some interesting arguments. While being a big fan of OCW, I think a case<span style="font-style: italic"> could</span> be made for ladder shooting providing a more consistent platform because of NPA. Once you are settled into a string, I think you will shoot more consistent than coming off the rifle to load/engage each target in OCW.

Here is an interesting article about the "magic" number of shots in a string:

Testing Loads

 

[Downzero]

Re: One last OCW question

Load for consistency, not for something you see on the paper. If the bullets are leaving the bore at a similar speed, they'll hit the same point on the target.

I load for single digit SDs and go.

 

[ReaperDriver]

Re: One last OCW question

Testing Loads[/url]

Ahhhh, that stats link hurt my brain!

What's "NPA", btw?

 

[308sako]

Re: One last OCW question

Deleted in protest!

 

[DaveV]

Re: One last OCW question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ReaperDriver</div><div class="ubbcode-body">

Testing Loads[/url]

</div></div>

Ahhhh, that stats link hurt my brain!

What's "NPA", btw?

Natural Point of Aim

 

[DaveV]

Re: One last OCW question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 308sako</div><div class="ubbcode-body">Wow something that made sense and I could almost understand all that too! Good link
J </div></div>

Yea, I dropped math in my Sophomore year. Fortunately, there are guys out there that dig this stuff. The article didn't really change the way I was doing things, but it did reinforce that a 5 shot string is better than 3.

 

[Grump]

Re: One last OCW question

It would be interesting to aggregate all of the two-shot groups into one master target and compare that method's use of the T-test with the results of running a mean radius method.

I *think* there's a freeware program called "CompareTarget" or something that lets you calibrate your mouse and computer screen on X and Y axes, then click circles into the bullet holes on your target as you hold it on the screen. It then automatically calculates group center and a whole bunch of other stuff.

I might have it on one of my computers here somewhere...