Your thoughts on my OCW test?

[SWThomas]

I took my 308WIN GAP-10 out yesterday to conduct an OCW test. I'll list all the specifics and if you could give me your thoughts on what you think that would be great.

Conditions:
Temperature: 54
Humidity: 37%
Pressure: 29.89 in
Visibility: 10 Miles
Elevation: 335 ft

Load:
Bullet: 175g SMK BTHP
Brass: Lapua
Powder: IMR 4064
Primer: CCI #34

Velocities:
43.5: 2604, 2619, 2604
43.8: 2640, 2650, 2619
44.1: 2635, 2619, 2640
44.4: 2682, 2661, 2645
44.7: 2677, 2677, 2645
45.0: 2682, 2699, 2666
45.3: 2699, 2715, 2704
45.6: 2721, 2726, 2726

It started to cool off a few degrees for the third round robin, so the velocities seem to have taken a small hit.

I'm thinking somewhere between 45.3 and 45.6. They seem to be pretty similar in relation to the center, they're tight, and the ES SD and AV velocities look pretty good too.

What do you think?

 

[stool]

how many wind flags...what was the wind like ??
big problem with this silly process is time....how much time from shot one to last shot ?
what was wind like at each shot ?
bbl fouled and up to temp at each shot ? at first shots?

a simple 10 shot ladder takes less time and less components and in my opinion gets you to a loading point quicker.

 

[BoydAllen]

+1

 

[SWThomas]

how many wind flags...what was the wind like ??
big problem with this silly process is time....how much time from shot one to last shot ?
what was wind like at each shot ?
bbl fouled and up to temp at each shot ? at first shots?

a simple 10 shot ladder takes less time and less components and in my opinion gets you to a loading point quicker.

At 100 yards there would need to be some pretty strong wind to throw off shots with a 175g bullet. The wind was about 9MPH when I started and tapered off throughout the test. It took quite a while to finish the whole test, but I'm in no hurry. I fired a couple sighting shots and then ran a bore snake twice. I started the test and waited 5 minutes between shots. After each round robin I ran the bore snake twice again.

 

[halfmoanut]

+1 also. Don't be fooled with your statement about the wind! After that statement, the load even looks better yet!

 

[SWThomas]

So your advice is to do a ladder test? You guys aren't believers in the theory of the OCW test?

 

[mikecr]

I see your testing as simple incremental load development.
I would do Berger's seating depth testing at ~44.7 and further out. Then try your powder adjustment through the range again.
Then, if you're hitting on something good, tweak seating to shape groups. If not, change primers and go through the powder range again, etc.

 

[BoydAllen]

I see a lot of reference to OCW and targets by fellows that don't own any wind flags, and don't realize how important keeping track of what the wind is doing is. This is not the end of the world, but I do believe that the overall approach is flawed. Also there are some basics of shooting that may need some attention, based on the targets (not picking on this one in particular) show. For instance, there are a couple of groups that show promise, but have quite a bit of vertical. This makes me wonder how the rifle was supported and held. The more recoil that a given rifle, caliber, and bullet weight have, and the less like a benchrest stock the stock is, the more difficult shooting consistently becomes. I am personally running into this with a rifle that I am currently working with. Most of my recent shooting has been with a short range benchrest rifle, that can be accurately shot in a wide variety of ways. In contrast with this, the newest rifle that I have been working with has a 40x prone stock, and my most recent loads use 140 grain bullets. The last time I went to the range, I changed up my holding method mid test, and after some thought I decided that the results, while promising, lacked validity because the improvement that my last test showed was likely a combination of the load and a better way of shooting that particular rifle. The good news is that I am making progress, learning, or should I say relearning, and having fun. This is my suggestion. Take your best load, and use it to try several approaches to shooting the rifle, as well as how it is supported. In rifles of your caliber, because of the size of the powder charge, barrels heat rather quickly. Because of this, there is quite a bit of barrel mirage that can confuse the target image. I suggest that I barrel mounted mirage shield be used for all future testing. Also, I believe that too light of a hold can cause issues. Some years back, a friend was having some vertical issues that disappeared when, at my suggestion, he experimented with shouldering the rifle more solidly. These are just a couple of examples of issues that can interfere with load testing, there is a long list.

 

[Jay Christopherson]

I see a lot of reference to OCW and targets by fellows that don't own any wind flags, and don't realize how important keeping track of what the wind is doing is. This is not the end of the world, but I do believe that the overall approach is flawed. Also there are some basics of shooting that may need some attention, based on the targets (not picking on this one in particular) show. For instance, there are a couple of groups that show promise, but have quite a bit of vertical. This makes me wonder how the rifle was supported and held. The more recoil that a given rifle, caliber, and bullet weight have, and the less like a benchrest stock the stock is, the more difficult shooting consistently becomes. I am personally running into this with a rifle that I am currently working with. Most of my recent shooting has been with a short range benchrest rifle, that can be accurately shot in a wide variety of ways. In contrast with this, the newest rifle that I have been working with has a 40x prone stock, and my most recent loads use 140 grain bullets. The last time I went to the range, I changed up my holding method mid test, and after some thought I decided that the results, while promising, lacked validity because the improvement that my last test showed was likely a combination of the load and a better way of shooting that particular rifle. The good news is that I am making progress, learning, or should I say relearning, and having fun. This is my suggestion. Take your best load, and use it to try several approaches to shooting the rifle, as well as how it is supported. In rifles of your caliber, because of the size of the powder charge, barrels heat rather quickly. Because of this, there is quite a bit of barrel mirage that can confuse the target image. I suggest that I barrel mounted mirage shield be used for all future testing. Also, I believe that too light of a hold can cause issues. Some years back, a friend was having some vertical issues that disappeared when, at my suggestion, he experimented with shouldering the rifle more solidly. These are just a couple of examples of issues that can interfere with load testing, there is a long list.

I have personally experienced this particular issue. It's one of the pitfalls of learning to shoot light hold/free recoil on a 6MM Open rifle and then switching to a heavier caliber, IMO. Same barrel weight, same action, same stock, same scope, same rest setup - entirely different result.

Anyhow, on the OP's OCW question - I think if I were you, I would re-shoot the test, ideally in a calm condition, and validate your findings before settling.

 

[bow shot]

+1

Oh, the agony I've suffered treating the wind and my form as minor things.

Nowadays, if I have load testing to do (I do my OCW or a ladder @ 400y) it has to be on an absolutely calm day, or it won't happen at all. We get VERY few of those. When they do occur, I'll take work off if I have to! Others do better, but I am NOT good enough to load test with any wind.

Like I said… others do fine, though.

 

[eric32]

44.7-48.0 and work seating depth test move in .003 increments

Look at Erik Cortina's thread on load development @ 100 yards alot of usefull information

 

[stool]

you do not list bbl length, nor Coal.
at 22 inches i get 3000 psi over pressure with your second to last load
at that velocity your 9mph wind moves the bullet about 1/2".......
and i would not use that primer for any accuracy load.
ar bolt and carrier prevents firing pin IMPACT till bolt closed. you can get a dimple from the last bit of movement, and if you drop the rifle muzzle down from 2 stories or so there MIGHT be enough momentum to set off a primer.
i shoot fed match and std rifle in my ar's...do as you wish.

 

[Alex Wheeler]

I see a lot of reference to OCW and targets by fellows that don't own any wind flags, and don't realize how important keeping track of what the wind is doing is. This is not the end of the world, but I do believe that the overall approach is flawed. Also there are some basics of shooting that may need some attention, based on the targets (not picking on this one in particular) show. For instance, there are a couple of groups that show promise, but have quite a bit of vertical. This makes me wonder how the rifle was supported and held. The more recoil that a given rifle, caliber, and bullet weight have, and the less like a benchrest stock the stock is, the more difficult shooting consistently becomes. I am personally running into this with a rifle that I am currently working with. Most of my recent shooting has been with a short range benchrest rifle, that can be accurately shot in a wide variety of ways. In contrast with this, the newest rifle that I have been working with has a 40x prone stock, and my most recent loads use 140 grain bullets. The last time I went to the range, I changed up my holding method mid test, and after some thought I decided that the results, while promising, lacked validity because the improvement that my last test showed was likely a combination of the load and a better way of shooting that particular rifle. The good news is that I am making progress, learning, or should I say relearning, and having fun. This is my suggestion. Take your best load, and use it to try several approaches to shooting the rifle, as well as how it is supported. In rifles of your caliber, because of the size of the powder charge, barrels heat rather quickly. Because of this, there is quite a bit of barrel mirage that can confuse the target image. I suggest that I barrel mounted mirage shield be used for all future testing. Also, I believe that too light of a hold can cause issues. Some years back, a friend was having some vertical issues that disappeared when, at my suggestion, he experimented with shouldering the rifle more solidly. These are just a couple of examples of issues that can interfere with load testing, there is a long list.

I have personally experienced this particular issue. It's one of the pitfalls of learning to shoot light hold/free recoil on a 6MM Open rifle and then switching to a heavier caliber, IMO. Same barrel weight, same action, same stock, same scope, same rest setup - entirely different result.

Anyhow, on the OP's OCW question - I think if I were you, I would re-shoot the test, ideally in a calm condition, and validate your findings before settling.

Don't want to hijack, but I think that is something that has been plaguing me since I have started shooting heavier recoiling rifles again. I always want to not influence the gun, but that has not been working out too well.

 

[timeout]

a simple 10 shot ladder takes less time and less components and in my opinion gets you to a loading point quicker.

This. I have tried OCW and find that a simple ladder test performed @ 300 yards, followed by seating depth testing for groups, gets me to the best accuracy load for a rifle faster, with much less waste of components. Not to mention a waste of barrel life. I don't claim to be an expert. What works best for me certainly may not work for yourself.

 

[SWThomas]

Thanks for the input fellas. I'm gonna go testing again Monday. As far as seating depth goes, I can only go in. The rounds are magazine length and there is no more room to go further out without single loading them... Which I'm not going to do.

The barrel is 18".

I can see a ladder saving components, but how would it be quicker??? I've tried ladder and OCW is quicker. Walking back and forth to a 300 yard target 12 times or so to mark your shots is pretty time consuming.

 

[SWThomas]

44.7-48.0 and work seating depth test move in .003 increments

Look at Erik Cortina's thread on load development @ 100 yards alot of usefull information

Have you ever tried to load 48g of 4064 in a 308 case? It won't fit. It's already compressed at 45.8g. Besides, that would be extremely hot.

 

[Jay Christopherson]

Thanks for the input fellas. I'm gonna go testing again Monday. As far as seating depth goes, I can only go in. The rounds are magazine length and there is no more room to go further out without single loading them... Which I'm not going to do.

The barrel is 18".

I can see a ladder saving components, but how would it be quicker??? I've tried ladder and OCW is quicker. Walking back and forth to a 300 yard target 12 times or so to mark your shots is pretty time consuming.

You could try marking your bullets with colored sharpies - they leave a trace on the paper when they punch through. If you use a different combination for each bullet, it should be pretty easy to see which is which. I know it's been discussed here a couple times and I think Jason Baney wrote up a ladder test article on the main site about it.

Also, at 300 yards with a good high magnification scope OR a spotting scope, you should be able to see the holes in the paper as you make them, and keep a plot sheet to track them. Especially if you use white or light colored targets.

 

[allenn]

Now you know what is wrong with the OCW test. Or any test done at 100 yards. They are very hard to interpret.

 

[stool]

you take a similar target and simple mark the shots on it from the rifle scope or a spotting scope....
no brainer
its quicker because it is typically only 10 shots...and then you look at the target.
best to start with 2 foulers off the target
circle shots
1/2
1/2/3
2/3/4
3/4/5
4/5/6
5/6/7
6/7/8
7/8/9
8/9/10
and 9/10

look at those GROUPS..
and pick a spot or two to work from.

quite simple....

Thanks for the input fellas. I'm gonna go testing again Monday. As far as seating depth goes, I can only go in. The rounds are magazine length and there is no more room to go further out without single loading them... Which I'm not going to do.

The barrel is 18".

I can see a ladder saving components, but how would it be quicker??? I've tried ladder and OCW is quicker. Walking back and forth to a 300 yard target 12 times or so to mark your shots is pretty time consuming.

 

[rminut]

Why can't new shooters just copy federal gold medal match (42.2gr/4064), which shoots incredibly well in more rifles than not, and focus on trigger control/sight alignment before they test loads that will never shoot well with someone that doesn't know how to shoot?

am I being a silly high master (one that's never done a ocw)? OCW's taken to the level of OCD do not overcome bad shooting. IF you have to ask how to decifer a 100 yard test then you don't have the shooting skills to see the difference in .2 grains of powder. plain and simple.

known good 308 loads are that way for a reason.