OCW testing, better understanding video
- Thread starter dan158
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Originally Posted By: pyscodogWell, I don't know Dan or where he lives but he did a good job posting a video that made sense of OCW testing. Soooo. Good Job!!
Yep it is a decent one. According to his info on his posts Dan is in PA. 2HrLunch has quite a few You Tube videos up.
Oddly the video is not showing up on my computer at this time. I went and hunted it down on YouTube.
Greg
Yep it is a decent one. According to his info on his posts Dan is in PA. 2HrLunch has quite a few You Tube videos up.
Oddly the video is not showing up on my computer at this time. I went and hunted it down on YouTube.
Greg
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Varminterror
New member
I've been doing some permutation of OCW and Ladder tests for a long time. I can generally be pretty sure it hasn't made me any more accurate, since my rifles and ammo are rarely the weak link, but at least it makes me feel like I'm cool for doing some kind of load development.
The funny part to me, disregarding the folks who argue OCW or Ladder tests shouldn't be done at all, are the arguments where guys favor one over the other. It's really doing the same thing - whether you shoot the same POA at a tall, skinny piece of paper at 300yrds or shoot a different POA's moving across a short, wide piece of paper at 100yrds, all you're doing is identifying patterns for vertical (first) and horizontal disparity, identifying a window of charge weights with the least relative disparity, then picking a weight within the window...
The funny part to me, disregarding the folks who argue OCW or Ladder tests shouldn't be done at all, are the arguments where guys favor one over the other. It's really doing the same thing - whether you shoot the same POA at a tall, skinny piece of paper at 300yrds or shoot a different POA's moving across a short, wide piece of paper at 100yrds, all you're doing is identifying patterns for vertical (first) and horizontal disparity, identifying a window of charge weights with the least relative disparity, then picking a weight within the window...
coyotezapper
Member
Here is the problem I have with the way he did this test. Without the use of a chronograph this is not really a true / complete OCW test. He has no idea what the velocity is for each step in the process. Without this, this load is only good for the distance he is testing at. Any velocity spread will cause vertical at longer distance. Just because the POI is consistent at say 300 yards does not mean it will stay consistent further out. He may have ES of 60 fps or more and not know it until he shoots at longer distance. Now if he never plans to shoot out further then he should be fine. Here is my steps to develop a good stable load. Again, this is my way and I am not saying it is the only way it just works for me.
Step 1 - With powder, primer and bullet selected establish OAL for testing. This OAL can be magazine length or whatever you decide upon. I suggest starting no closer than 010" from the lands to begin with for safety purposes. You will test other lengths later.
Step 2 - After sizing and priming cases the next step will be powder charges. I use Quickload for this and most of the time it gets me very close. But if you don't have Quickload then data from companies like Hodgdon will work. Hodgdon gives a starting load of 42 grains Varget and a max of 45 grains for a 308W and 175 MK in Winchester case with fed 210M primer. If you use this data it is important you understand this data is good for Winchester cases and will be different with other cases of different capacities. This is where Quickload is nice because you can measure your case capacity and input that in and it will adjust the load to that capacity. With 45 as max I may go 46-46.5 just in case I have a slow lot of powder. I will then usually start in the middle somewhere and load 3 each of each powder charge moving up in .5 grain increments. So 43, 43.5, 44, 44.5, 45, 45.5 and 46 grains. Smaller cases the increments will be smaller. Now I have 21 cases charged with 7 different powder charges with bullets seated at predetermined OAL.
Step 3 - Range testing powder. Some say this needs to be done at 300 yards but I have found as long as I have a chronograph this can be done at 100 yards. I have no problem seeing vertical ( can be small ) at 100 and usually the velocity and group will mirror each other. I will shoot each charge - 3 each consecutively ( I do not shoot round robin ) and record velocity and watch for vertical in my groupings as shown in the video. As charges increase I am looking for my anticipated max velocity. Hodgdon says max is 2,690 FPS at 48,600 CUP which is 55,775 PSI in a 24" bbl. Once I get to 2,690 FPS - if I'm running a 24" bbl this is where I stop. Just because you don't see pressure signs does not mean there is not unsafe pressures. I use both an Oehler 35 and 43PBL and I have learned over time that the 35 gives me the same info if I just pay attention to the velocity. PRESSURE = VELOCITY. I do not pay attention or very little to group size during this step. What I am looking for is a flat spot in the velocity increase from one charge to the next along with POI - vertical being the same from one charge to the next. For example if 43 - 44 showed on average a 50 FPS increase from one charge to the next but 44 - 44.5 showed only a 20 FPS increase - this is a flat spot. These flat spots can be very wide as much as 1 grain or more, or only in a half grain or smaller window but you will see it. This flat spot should also show up on your target and this is where you want to start your seating depth testing. I usually go to the middle of the flat spot and begin seating depth testing there. The only powder that I have not seen this flat spot with is the new RL26. It was very linear and I was able to pick a charge with good velocity and SD and then do seating depth testing there followed by powder node window testing, testing .1 grain above and below after seating depth testing to verify there was a powder node there but was just extremely small. This flat spot makes your load very repeatable for many rounds down range and limits the load adjustments you have to make as the bore erodes.
Step 4 - Seating depth testing. With powder charge established I then begin seating depth testing. I do this in .005" - .010" increments. This can be started moving in to the lands or away - I move away most of the time. I can usually find a seating depth window of .020" where the accuracy is the same from one depth to the next and with the powder node I seat at the longest OAL which gives me a minimum of .020" throat erosion before I have to tweak seating depth again. Most times it just continues to shoot past this .020" window. With the wide powder node / OCW window the powder charge usually does not have to be changed and only a velocity change in ballistics for long range is needed.
Step 5 - ES / SD adjustments are the last step in my process if needed and can usually be done with primer change or neck tension.
All of this being said, the video has good info but if this method is used as he shows it then I would test at the distance that your farthest shot might be taken to verify you are in a good velocity window.
Step 1 - With powder, primer and bullet selected establish OAL for testing. This OAL can be magazine length or whatever you decide upon. I suggest starting no closer than 010" from the lands to begin with for safety purposes. You will test other lengths later.
Step 2 - After sizing and priming cases the next step will be powder charges. I use Quickload for this and most of the time it gets me very close. But if you don't have Quickload then data from companies like Hodgdon will work. Hodgdon gives a starting load of 42 grains Varget and a max of 45 grains for a 308W and 175 MK in Winchester case with fed 210M primer. If you use this data it is important you understand this data is good for Winchester cases and will be different with other cases of different capacities. This is where Quickload is nice because you can measure your case capacity and input that in and it will adjust the load to that capacity. With 45 as max I may go 46-46.5 just in case I have a slow lot of powder. I will then usually start in the middle somewhere and load 3 each of each powder charge moving up in .5 grain increments. So 43, 43.5, 44, 44.5, 45, 45.5 and 46 grains. Smaller cases the increments will be smaller. Now I have 21 cases charged with 7 different powder charges with bullets seated at predetermined OAL.
Step 3 - Range testing powder. Some say this needs to be done at 300 yards but I have found as long as I have a chronograph this can be done at 100 yards. I have no problem seeing vertical ( can be small ) at 100 and usually the velocity and group will mirror each other. I will shoot each charge - 3 each consecutively ( I do not shoot round robin ) and record velocity and watch for vertical in my groupings as shown in the video. As charges increase I am looking for my anticipated max velocity. Hodgdon says max is 2,690 FPS at 48,600 CUP which is 55,775 PSI in a 24" bbl. Once I get to 2,690 FPS - if I'm running a 24" bbl this is where I stop. Just because you don't see pressure signs does not mean there is not unsafe pressures. I use both an Oehler 35 and 43PBL and I have learned over time that the 35 gives me the same info if I just pay attention to the velocity. PRESSURE = VELOCITY. I do not pay attention or very little to group size during this step. What I am looking for is a flat spot in the velocity increase from one charge to the next along with POI - vertical being the same from one charge to the next. For example if 43 - 44 showed on average a 50 FPS increase from one charge to the next but 44 - 44.5 showed only a 20 FPS increase - this is a flat spot. These flat spots can be very wide as much as 1 grain or more, or only in a half grain or smaller window but you will see it. This flat spot should also show up on your target and this is where you want to start your seating depth testing. I usually go to the middle of the flat spot and begin seating depth testing there. The only powder that I have not seen this flat spot with is the new RL26. It was very linear and I was able to pick a charge with good velocity and SD and then do seating depth testing there followed by powder node window testing, testing .1 grain above and below after seating depth testing to verify there was a powder node there but was just extremely small. This flat spot makes your load very repeatable for many rounds down range and limits the load adjustments you have to make as the bore erodes.
Step 4 - Seating depth testing. With powder charge established I then begin seating depth testing. I do this in .005" - .010" increments. This can be started moving in to the lands or away - I move away most of the time. I can usually find a seating depth window of .020" where the accuracy is the same from one depth to the next and with the powder node I seat at the longest OAL which gives me a minimum of .020" throat erosion before I have to tweak seating depth again. Most times it just continues to shoot past this .020" window. With the wide powder node / OCW window the powder charge usually does not have to be changed and only a velocity change in ballistics for long range is needed.
Step 5 - ES / SD adjustments are the last step in my process if needed and can usually be done with primer change or neck tension.
All of this being said, the video has good info but if this method is used as he shows it then I would test at the distance that your farthest shot might be taken to verify you are in a good velocity window.
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Keeps people thinking of creative ways to work up their loads.
I will say that when I am working with a wild cat with no known loading data in print, that much can be learned by shooting two shot groups to initially find out what kind of grouping you can get with various charges, especially used in conjunction with a chronograph.
Custom barrels will often put the bullets in the exact same bullet hole, which is what you want to see. Then verify on later occasions, even better if you can reload right at the rifle range.
It is nothing short of amazing how a primer change or seating depth change can alter groups.
I will say that when I am working with a wild cat with no known loading data in print, that much can be learned by shooting two shot groups to initially find out what kind of grouping you can get with various charges, especially used in conjunction with a chronograph.
Custom barrels will often put the bullets in the exact same bullet hole, which is what you want to see. Then verify on later occasions, even better if you can reload right at the rifle range.
It is nothing short of amazing how a primer change or seating depth change can alter groups.
204 AR
Well-known member
Having the range right at home has changed my load development style. It saves time of course and loading unnecessary rounds. I agree with ackleyman on the 2 shot group to begin with, especially when getting a baseline for velocity and pressure signs and grouping. If the first two shots are not close, a third, fourth or fifth will not make it any better. And if that powder won't give the speed you're looking for no need to go further either. I'm looking for a speed plateau like has been mentioned, where the groups are good at that weight and on either side of it and in the same vicinity in relation to aiming point. Load 5 of them and check it. Adjust seating depth if needed. If speeds are erratic try a different primer.
I like testing at 200 yds because that's as far as I can shoot at the house. Calm days are the hardest part, any wind will destroy varmint bullet results. Not quite as bad with long sleek target bullets.
I like testing at 200 yds because that's as far as I can shoot at the house. Calm days are the hardest part, any wind will destroy varmint bullet results. Not quite as bad with long sleek target bullets.
Ackman
New member
So he has 7 different 3 shot groups. But shooting one of each load, each time, somehow turns this into a special way of arriving at an "optimum charge weight"? What a load of crap. Of course the groups move around in relation to point of aim. That's what happens when doing a load workup. And this is nothing more than shooting groups for load workup.....which is finding the "optimum charge" if you want to use that term. Trying to make it into something more than it is and calling it OCW, is making a lot out of nothing. That whole website is a load of crap.
Ackman
New member
Originally Posted By: ackleymanI have tried the ladder test at 300 yards. Found the clump of bullets. Then shot groups with various loads in the clump, not one of them was worth a darn when I went to 3 shot groups.
Same here. Doing a ladder I'd get groups much tighter than with 3 and 4 shot groups of the "good" loads. The ladder test never worked worth a crap for me.
Same here. Doing a ladder I'd get groups much tighter than with 3 and 4 shot groups of the "good" loads. The ladder test never worked worth a crap for me.
coyotezapper
Member
OCW, Ladder, ILDM and all of the other methods like this have been around forever. They all have similarities and they all work. Someone just has to decide what works best for them. Most if not all long range competitors use these methods or something similar. I know some who do seating depth testing first and then tweak powder charges - to each his own and I am not going to say their way is wrong, that is just the way they do it.
Those who say it does not work but do not give a reason why are those who have never really tried the process or do not understand it and are unable to compile the data properly. I see guys all the time that are so inconsistent at the bench in their shooting there is no way they will get good results. Their loading process may be sound but their execution is poor. Everything you do from priming the case to rifle set up in testing shows up on the target down range. If you don't have the discipline or the proper thought process your results will be crap.
Those who say it does not work but do not give a reason why are those who have never really tried the process or do not understand it and are unable to compile the data properly. I see guys all the time that are so inconsistent at the bench in their shooting there is no way they will get good results. Their loading process may be sound but their execution is poor. Everything you do from priming the case to rifle set up in testing shows up on the target down range. If you don't have the discipline or the proper thought process your results will be crap.