Loads ready can't decise ocw or ladder test?

[jca57jd]

Good evening! I hope everybody had a good day and there holidays are off to a good start! I want to start off by saying that I have developed some rounds that are consistent 1/8 moa (out to 300 yards) for my some off my longrange guns, however they are I developed them in warmer seasons (70+ degrees). These loads never do good in cold but are always great when it's above 60 out.

I'm currently working on a new load development for a new 243 I built. It has a 26" Krieger barrel on it. I read a lot about ocw and the ladder test to develope loads that are better for all year purposes in temp change. I am working with Berger 105 hybrids. The powders that I currently have in stock are imr4350, imr4831, rl17, and rl22. I was leaning on going with the rl22 because it was slower burning but then I read about pressure spikes in warmer (90 degree +). After further research on what my best powder to start with was I saw that one of Dan newberrys pet loads for 105's in a 243 was 40.7 gr of imr4831. I have also read about getting loads to the proper speed wear the barrel harmonics are right. I found this link below but I am trying to figure out how to use it if I don't have access to quickload?

http://www.the-long-family.com/OBT Table.pdf

As of now I have 3 shell loads (10 total loads 30 shots) going from 39.1 - 41.9 of imr4831. I'm trying to decide if I should do the ocw or ladder test?

- I have a chrono and a 300yd flat range behind my house
- no access to quickload for barrel harmonics comparison

Which method would you use if it was you and at what range?

***my main goal is to produce a good, all season, longrange (1000yds and under) accurate load for hunting and shooting in some groundhog and egg shoots***

Many thanks for listening to me ramble on if you get this far lol!

 

[justgoto]

I use the Audette Ladder Test, because I usually can identify a load within 7 shots. But some loads still don't shoot well with extreme temperature spreads. I wouldn't think the load development method would have an effect on that.

But... I do have a load using IMR 4064 and the Lee C309-150-F, (150gr FN cast bullet,) that doesn't have a problem with POI or precision with extreme temperature spreads at out to 350 yards. I did identify a large node on the ladder test target; something I would think the OCW would also identify.

 

[bill123]

This is a topic that I have always been interested in. I've had great success with OCW but because I don't have access to 300 often, I've never tried Ladder. I would think that there should be a correlation between ladder and OCW results but from what I have heard, that's not always so.

 

[dsculley]

I use the OCW method and have had good results with it. Try it with the loads you have and it will show you where the nodes are. Once you find a node with the OCW, you can use a ladder test in the node range to verify and fine tune the load. The basis for the OCW is that if you have found a true OCW node, minor variations due to differences in case volume, changes in temp, small errors in powder weight, etc, will not cause a major change in point of impact.
If you do some research on Practical Riflery Forums... techniques and equipment of the practical rifleman... Forums you will probably find a lot more info on loads that have tested well with the .243.

FWIW,

Dennis

 

[royinidaho]

I use one of two methods.

1. Ladder test followed by OCW with 3 loads around the ladder test selected round.

2. Load to max acceptable pressure (slight extraction and/or extractor mark however slight.

Back off on powder a couple of grains in RUM sized or larger cases and OCW around that. Back off a little less in smaller cases.

If the rifle is fully custom #2 works well.

If factory rifle #1 works better.

Just my thoughts.....

 

[jca57jd]

Thanks for the advice everybody! I think I am going to do the ocw test at 200yds to start out. Then I will move back to 300 and see how everything works out by shooting 3 rounds at the ocw optimum and then verify the theory by shooting with one shot of the lower and higher end powder charges in the node.

Does this sound like a good plan?

I also wanted to ask for your thoughts on weather I need to do a test on 10 different loads (30 shots) or if I could refine it down to 6 or 7 loads (18-21 shots)?

Here is a picture of a spread sheet that shows my loads and I'm thinking about starting at 40.3 and going up. What's your thoughts?

 

[justgoto]

Thanks for the advice everybody! I think I am going to do the ocw test at 200yds to start out. Then I will move back to 300 and see how everything works out by shooting 3 rounds at the ocw optimum and then verify the theory by shooting with one shot of the lower and higher end powder charges in the node.

Does this sound like a good plan?

I also wanted to ask for your thoughts on weather I need to do a test on 10 different loads (30 shots) or if I could refine it down to 6 or 7 loads (18-21 shots)?

Here is a picture of a spread sheet that shows my loads and I'm thinking about starting at 40.3 and going up. What's your thoughts?

I would start with a middle of the road load and slowly work my way up. If your min/max data is correct, 39.2 would be my starting point.

 

[bill123]

Thanks for the advice everybody! I think I am going to do the ocw test at 200yds to start out. Then I will move back to 300 and see how everything works out by shooting 3 rounds at the ocw optimum and then verify the theory by shooting with one shot of the lower and higher end powder charges in the node.

Does this sound like a good plan?

OCW is supposed to be done at 100 yds.

 

[Topshot]

Don't get confused with these methods when looking for a good "Long Range" load.
Although you may get very good close and medium range accuracy with these methods.
You will not get good, consistent, vertical grouping beyond 800 yards unless you have a low SD in velocity.

 

[jca57jd]

Well I just got done cleaning my gun and putting it up? Here are the results from the ocw at 200 yards. I Hope doing it at 200 yards doesn't make it worthless! I feel that if I had of been at 100 then the results might have been to tight to compare. What is your opinions of what you would do with these results?

Starting conditions 3:00 pm Ending conditions 4:33 pm
Altitude 804' 804'
Barometric pressure 29.92 29.92
Temperature 49* 40*
Relative humidity 33% 57%

Imr4831gr Velocities
40gr - 2668, 2702, 2676

40.4gr - 2653, 2697, 2732

40.7gr - 2726, 2794, 2700

41.0gr - 2723, 2802, 2740

41.3gr - 2811, 2781, 2753

41.5gr - 2802, 2828, 2788

41.7gr - 2847, 2828, 2778

41.9gr - 2832, 2812, 2795

I'm a little bit depressed that my sd is so high with all of these loads! This is a custom Krieger barrel, all new Hornady cases devided by weight (all 3 strings were within .5 grains of one another), each powder charge was individually weighed on a electronic scale, and all the loads were measured to exactly 2.20" oal to the ogive.

 

[jca57jd]

Next picture.

 

[Tones]

41.3 looks pretty good, seems to be in the middle of the 'high' righters. I'd start around there.

 

[Dr. Vette]

41.3 looks pretty good, seems to be in the middle of the 'high' righters. I'd start around there.

I would agree. I believe that Dan now recommends adjusting seating depths a bit to see what happens.

 

[dsculley]

Did you shoot this in "round robin" fashion? You were shooting in the late afternoon. I assume there was a large change in ambient light from the time you started until the time you finished. What kind of chronometer were you using? There are lots of variables that can account for the recorded change in muzzle velocity other than an actual change in velocity. 100 yds is better because it virtually eliminates wind drift. Any shooter error is magnified at longer ranges.

If you can get the average case volume of your cases (in grains of water) and provide me all the other pertinent data I will run this load in Quickload. PM me if you are interested.

Dennis