Ladder test interpretation

[cahunter805]

I’d load up 20 at 75.4 (#9) and see how they group.

If it’s crap, back off another ~ .5 grain.

This is what I would try also.
Magnum works great in the 257Wby in my experience. So does H1000.

 

[mevertsen]

Here's my thoughts.

I've been reloading for 20 years.

I have not reloaded a magnum cartridge.

My largest is .30-06.

Obviously, it seems you are dealing with a new gun, but it appears it handles pressure fine. Some guns will show pressure early. (I have to be a bit conservative with my .223 single shot and .30-30).

For my .223, .300 BLK, .30-30, .243 I load in .5 grain increments when testing for pressure.
For my .30-06, I load in 1 grain increments (IMR and H4350), .5 with IMR4895.
For my PISTOLS, I load in .3 grain increments with FAST powder.

I load in groups of 3, 1 for pressure, then 2 for at least an initial group, after checking pressure. I start at the MAX listed charge, go down about 7 to 10 percent and divide it up there. My pressure ladders will only be about 5 rounds.

The trend for me loading that way usually means by the time I am near the top; I know two things.

a. Where is my max? Or is the max load safe?
b. As I go up, those two shot groups should start getting closer to each other, or at least, I'll have a real good idea.

I will also see clear differences in primers, sooting, etc.

I run the single pressure (often without a speed), then check the "group" with the other two rounds. One thing at a time.

When I find something promising, I will then load a few more, check velocity and a 3 or 5 shot group to confirm.

I want all this done in less than 20 shots. If I can't even get close with that, I'm wasting time.

Now, for your .257 Bee?

I'm going down from max in 1 grain increments.

15 shots. 5 to find pressure, and 2 to get an idea on accuracy. Its obvious your gun...

a. is ok with higher pressure loads, so as long as you're not going out in to truly no man's land, experimental bullets, data that isn't available, etc., I would be comfortable with that latter.

b. your gun is reasonably accurate, so space your charges out a bit to see a difference

You are burning a metric shit ton of powder. Your tests are so close in powder wise, you are almost in the area of error on any individual component. The percentages are so small, you are just wasting time and energy.

My bet is if you space things out a little, you will see better patterns.

Good luck.

 

[Wind Gypsy]

Data I am using went up to 77gr but that was off coal of 3.417”. I am at 3.389”.

Who's data is that?