308 ladder test results

[jsthntn247]

This was done at 300 yards with 168 Bergers seated touching the lands. I mesured and drew dots where the bullet holes were because the target was splintering through the paper creating extra large holes. It looks to me like 44.5 was a scatter node and my best node will between 44.8 and 45.4 grains of Varget. I thought about loading 5 shots at 44.8, 45.0, 45.2, and 45.4 and shooting them at 300 yards. What yall think?

 

[midwesthunter]

Those powder wieghts are too far apart IMO. I would concintrate between 44.8-45.4.

 

[jsthntn247]

Midwest, the ladder test was done in .3 grain increments starting at 43.9 and up to 46.3. Next I think I should load 5 shots at 44.8, 45.0, 45.2, and 45.4 and shoot each one at 300 or 600 yards and stick with which one shoots the best.

 

[green 788]

You mention "scatter node", which is OCW lingo, I should point out...

I do agree that the 45 grain area looks most promising, so the ladder did give you an idea of where to go (but often 300 yard ladder test don't work, for various reasons)...

I have some info on my OCW page you can find linked at the bottom of this post... you cannot identify a scatter node without at least 3 shots at that same charge level, and it's best to shoot the test at 100 yards... the instructions are on the first page.

Read also why the ladder test often fails to yield intelligible results, and the reasons for that; the aforementioned "scatter node," a point at which the acoustic shock wave is at the muzzle when the bullet exits... we identified this event some years back, as the phenomenon generally presented during a properly executed OCW test. And we coined the phrase "scatter node" to describe it...

here's a direct link to that page... http://optimalchargeweight.embarqspace.com/#/ocw-vs-ladder/4529811360

Dan

 

[jsthntn247]

You mention "scatter node", which is OCW lingo, I should point out...

I do agree that the 45 grain area looks most promising, so the ladder did give you an idea of where to go (but often 300 yard ladder test don't work, for various reasons)...

I have some info on my OCW page you can find linked at the bottom of this post... you cannot identify a scatter node without at least 3 shots at that same charge level, and it's best to shoot the test at 100 yards... the instructions are on the first page.

Read also why the ladder test often fails to yield intelligible results, and the reasons for that; the aforementioned "scatter node," a point at which the acoustic shock wave is at the muzzle when the bullet exits... we identified this event some years back, as the phenomenon generally presented during a properly executed OCW test. And we coined the phrase "scatter node" to describe it...

here's a direct link to that page... OCW Overview - Dan Newberry's OCW Load Development System

Dan

I have read your page numerous times and value your opinion greatly. My normal loading procedure is to shoot a couple ladder test 300 and then shoot the same loads in OCW round robin fashion at 100 as you describe on your page. I was trying to save a little time and powder because my first match is not far off and this is a new to me gun. I used your term scatter node incorrectly here as you pointed out, it just seemed that the shots settled into a nice low verticle node about 1% to 2% above the 44.5 which is why I used the term. The day I bought the rifle, the previous owner loaded 5 rounds at the same seating depth at 45.5 grains(his go to 308 load) and shot a 3" group at 600 in a 12 mph cross wind. The group he shot only had .75" of verticle so I new it should be close to a node but since he didn't work it up, I wanted to do some further testing. It appears now that he was at the top end of a node.

 

[green 788]

thanks for the reply...

You may end up being right--that the scatter node is where you suspect.

With a scatter node, you normally at least one shot out of three right on the same POI that the next higher and next lower charges hit. So with a single run up the ladder test, you might get led toward choosing the wrong accuracy node.

As someone else suggested, had you gone in .2 grain increments you may have gotten more definitive info, and a scatter node might be noticed in such a ladder test, but even then it's hard to be sure. The round robin testing of three shots at each charge level gives much better data, in my opinion...

Good luck with the load development, and thanks again for the kind words.

Dan