Reading a ladder test

[Blackdirt Cowboy]

Today I did a ladder test with my 338 RUM and N570 powder under 250 grain Berger's. I want to see what the masses suggest that I do next. Here is a picture of the target:

And here are the velocities:
#1 - 98 gr 2957 FPS
#2 - 98.5 gr 2979 FPS
#3 - 99 gr 3014 FPS
#4 - 99.5 gr 3034 FPS
#5 - 100 gr 3034 FPS
#6 - 100.5 gr 3055 FPS
#7 - 101 gr 3066 FPS

I ran into pressure at 101 grains, flattened primer and ejector swipe. I planned on going up to 103.5 grains but had to stop. What would y'all do next? I'm thinking of loading up 5 shot groups of 99.2, 99.5, 99.8, and 100.1 grains and shooting groups to narrow my load down. Then I'll adjust seating depth if need be. Or should I load up 99.7 grains and try that? Let me know if you need any other info to determine where to proceed from here.

 

[odoylerules]

You've got a dandy node around 99.5-100 ish grains. I think you're on the right track with double checking it by loading the 99.2-101.1 ish area. I'd load a 101.5 as well. If it's still good after that, the next step is to check groups by tweaking seating depth "if" needed. Anything half MOA or tighter and I'm good personally.
Nice shooting!

 

[Canhunter35]

I agree, shot 4-5

 

[L.Sherm]

What distance was this ladder shot at?

 

[L.Sherm]

Why try 101.5 if he hit pressure at 101?

 

[odoylerules]

Why try 101.5 if he hit pressure at 101?

Nice catch. I missed that detail

 

[Blackdirt Cowboy]

Lsherm, it was only shot at 100 yards, as I was mainly just looking for the velocity node and it's hot as hell here today and I have a 100 yard range off my back porch. I shoot here on my ranch and plan on stretching it out to around 500 yards on the next go round.

 

[L.Sherm]

I hear you I shoot at 100 to get things started but anymore 500 tells a true story. I would repeat your ladder at 500 and see if you get the same results, maybe not the lower ones or 101 if you hit pressure.

 

[Blackdirt Cowboy]

Yes sir, longer is better. Honestly, I feel like loading a group at 99.7 and seeing how it groups at 100. If it's good, then shoot that same load at 500 to verify. If that works, that would be a load development in 17 loads. Can't beat that!!!

 

[L.Sherm]

I did some group-primer testing last weekend with a 6.5x06AI at 500 between H1000, RL26 cci250 and Fed 215 primers
H1000 and 215 won out the vertical was obvious.

 

[User4302021]

I'm gonna bet you settle somewhere around 99.5 grains. I usually find the widest tunable spot around 2% off of where I found pressure:
101 x .98 = 99 grains.

However, you said it was "hot as hell that day". So, to put you at the top of that node (so it hopefully holds up in cold weather), I would reduce that to 1.5%. That brings you to 99.5 grains.

 

[Remmy700]

I always take that into account when I am looking at nodes. Man U will hit a sweet spot that hammers but it's only .2 gr wide that is trash unless u shoot in those same conditions all the time. Usually a real good node will hold for .5 gr atleast and that gives u room to play with outdoor conditions also. Been there and done that chasing nodes around the seasons. No matter the temp stability they all have some flux with temps so unless u want to chase your tail with the weather u have to figure that out based on your powder and environmental conditions!

 

[Blackdirt Cowboy]

So what are you suggesting Remmy? Looks like the node is at least .5 grain wide. Should I load in .2 or .3 grain increments around that node to see how wide it truly is?

 

[Remmy700]

Yes sir by the info u gave I would load around the 99.5 to 100 range in atleast .2 gr increments. Find that sweet spot on SDs and then play with seating depth as needed brother