Hi,
Few months back I posted a "ladder" test shooting ten single shots increasing in charge by .5gr of powder for each shot. My hope was to develop a load with as little surplus shooting as possible. I wanted to find 3 consecutive shots which grouped close together and use those three charges for further load development. As it turns out, the results were muddy at best and slightly better than useless. Here is a picture of that first 10 shot ladder test.
In the comments which were given to my original post, someone pointed me to Dan Newberry's OCW (optinal charge weight)load development method ( http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134 ). Yesterday, I finally got my act together and went to the range to try it out. I use Dan's method, but shot 5 of each load, not three. As well I shot at 300M, not 100 yrds. Overall, pretty happy with the result, but am not 100% sure which load would be my OCW. So I now look to the wisdom of CGNers for opinions. Here are the details for the picture below:
A) Shot at 300M, 328 yards
B) 300 Win Mag, 180 gr Sierra BT, hornady brass, Fed 215, IMR 4831 (be safe and work up a load for your gun using a published Loading Manual, I am just some dude on the internet)
C) All shots were taken round robin, as described in Dan's article
D) For rough scale, orange stickers are 2 inches in diameter
D) Below I reference charges 1,2,3,4 and 5. They correspond to the following powder charges 1= 71.8gr 2= 72.3gr 3= 72.8gr 4= 73.3 gr 5= 73.8gr
E) In the charge 1 group, my first shot of the day landed significantly right and I figured I was in danger of shots at the far right of the target paper not hitting. So, i adjusted my sight 1.25 MOA to the left and have coloured a circle 4"s left of where the first shot hit, to approximate where it would have landed.
F) In the charge 4 (73.3gr) group my last shot hit right and low- The shot felt good, but I'm pleading fatigue and taking a mulligan on this one in my analysis
Here is a picture of the POIs I plotted on a separate sheet of paper:
Couple general observations about the target. I am most surprised by loads 1, 2 and 3. Despite being only .5gr apart in charge weight, all three charges shoot moa or better but have significant vertical variation on the point of impact, about 4 inches (this goes to show why i believe my original ladder test was pretty much a waste of time). Looking at loads 3, 4 and 5, the groups open up to 1.5 MOAish but are closer to the point of aim in relation to each other.
I have two theories for which is the OCW. Here is the first. Based on my interpretation of Dan's method I should be using charge 4 as my OCW, as there is the smallest vertical variation in the three groups, about 1.25 inches. However, I don't like the way the groups start to open up with charges 4 and 5. So, here is my second theory. I should use 3 as my OCW. Charges 2, 3 and 4 group better (flyer aside) despite there being a 1 inch increase in vertical variation. 2.25 inches vertically is still sub MOA and the advantage of shooting a charge that groups well as a whole is better than gaining a 1 inch vertical variation, since 2.25 inches is still sub MOA. I do realize Dan cautions agains getting "bowled over" by a tight group, but load 3 is definitely the prettiest and I cannot help myself
Originally I was looking for a short cut which required less shooting to develop a load. However after a few failed "ladder" tests or my old method of choosing the best group of a single outing, only to find the next trip to the range the same load did not perform i became very frustrated. I have got to say that from here on out I am going to use OCW method for load development. I feel that the OCW method, specifically the round robin shooting and looking for the closest POI for each charge in relation to each other, makes a lot of sense. I suspect in the long run OCW saves shooting and will develop better loads. While I took some liberties in the method (shooting 5 shot groups and at 300M instead of 100 yrds) I don't see how these changes will impact my final result negatively. Hopefully next weeked I validate this weekends results.
Interested in any thoughts or opinions to which charge is my OCW and comments in general.
Few months back I posted a "ladder" test shooting ten single shots increasing in charge by .5gr of powder for each shot. My hope was to develop a load with as little surplus shooting as possible. I wanted to find 3 consecutive shots which grouped close together and use those three charges for further load development. As it turns out, the results were muddy at best and slightly better than useless. Here is a picture of that first 10 shot ladder test.
In the comments which were given to my original post, someone pointed me to Dan Newberry's OCW (optinal charge weight)load development method ( http://optimalchargeweight.embarqspace.com/#/ocw-instructions/4529817134 ). Yesterday, I finally got my act together and went to the range to try it out. I use Dan's method, but shot 5 of each load, not three. As well I shot at 300M, not 100 yrds. Overall, pretty happy with the result, but am not 100% sure which load would be my OCW. So I now look to the wisdom of CGNers for opinions. Here are the details for the picture below:
A) Shot at 300M, 328 yards
B) 300 Win Mag, 180 gr Sierra BT, hornady brass, Fed 215, IMR 4831 (be safe and work up a load for your gun using a published Loading Manual, I am just some dude on the internet)
C) All shots were taken round robin, as described in Dan's article
D) For rough scale, orange stickers are 2 inches in diameter
D) Below I reference charges 1,2,3,4 and 5. They correspond to the following powder charges 1= 71.8gr 2= 72.3gr 3= 72.8gr 4= 73.3 gr 5= 73.8gr
E) In the charge 1 group, my first shot of the day landed significantly right and I figured I was in danger of shots at the far right of the target paper not hitting. So, i adjusted my sight 1.25 MOA to the left and have coloured a circle 4"s left of where the first shot hit, to approximate where it would have landed.
F) In the charge 4 (73.3gr) group my last shot hit right and low- The shot felt good, but I'm pleading fatigue and taking a mulligan on this one in my analysis
Here is a picture of the POIs I plotted on a separate sheet of paper:
Couple general observations about the target. I am most surprised by loads 1, 2 and 3. Despite being only .5gr apart in charge weight, all three charges shoot moa or better but have significant vertical variation on the point of impact, about 4 inches (this goes to show why i believe my original ladder test was pretty much a waste of time). Looking at loads 3, 4 and 5, the groups open up to 1.5 MOAish but are closer to the point of aim in relation to each other.
I have two theories for which is the OCW. Here is the first. Based on my interpretation of Dan's method I should be using charge 4 as my OCW, as there is the smallest vertical variation in the three groups, about 1.25 inches. However, I don't like the way the groups start to open up with charges 4 and 5. So, here is my second theory. I should use 3 as my OCW. Charges 2, 3 and 4 group better (flyer aside) despite there being a 1 inch increase in vertical variation. 2.25 inches vertically is still sub MOA and the advantage of shooting a charge that groups well as a whole is better than gaining a 1 inch vertical variation, since 2.25 inches is still sub MOA. I do realize Dan cautions agains getting "bowled over" by a tight group, but load 3 is definitely the prettiest and I cannot help myself
Originally I was looking for a short cut which required less shooting to develop a load. However after a few failed "ladder" tests or my old method of choosing the best group of a single outing, only to find the next trip to the range the same load did not perform i became very frustrated. I have got to say that from here on out I am going to use OCW method for load development. I feel that the OCW method, specifically the round robin shooting and looking for the closest POI for each charge in relation to each other, makes a lot of sense. I suspect in the long run OCW saves shooting and will develop better loads. While I took some liberties in the method (shooting 5 shot groups and at 300M instead of 100 yrds) I don't see how these changes will impact my final result negatively. Hopefully next weeked I validate this weekends results.
Interested in any thoughts or opinions to which charge is my OCW and comments in general.
