20 shot test development.

[Benchguy57]

So I gave this a try and have a few questions about it. If you haven't heard if this test method it's somewhere on this site.
Thought it was worth a try.
Basically you take a given powder and bullet combo and load one round increasing by .5-.7 grains until you're are at published max.
Shoot through a chronograph and log fps with each round, the goal is to find 2 rounds with the same or close to same fps.
This is not the end all test, but kinda a starting point to see how the bullet and powder combo work together, they said you don't really have to shoot at paper, cause you're not shooting for accuracy at this point of the test.

So here's what my question; Okay I'm in need of some help.
I really like the idea of shooting less bullets and saving time and money.
I'm shooting a stock Remington 700 bdl 7mm rem mag.
I have been shooting 64 grains of h4831 with 140 grain nosler accubonds velocity is right at 2700 fps and 1/2 " at a 100 yards.
I know I could get this faster, but it's killed deer just fine here in Missouri. I'm happy with this load and I found it using the traditional ocw test.
I was able to snatch up a few pounds of reloader 22 and a couple hundred 160 nosler accubonds and figured I'd like to try this 20 +\- round method out.
Since I enjoy shooting at targets I figured I would shoot at a 1" circle at 75 yards.
The load started at 59.0 grains up to 66.0 grain of re-22 seated at whatever nosler's manual recommended, 3.300" or close to it. I increased the charge weight my .5 grains with each round until I was over .5 published max, which still shows no signs of high pressure btw.
To my surprise all 15 rounds shot inside that circle!!!!
The velocities increased from 2650 upto 2955
But all the bullets are hitting the same place within an inch.
I've never tried this method before and am wanting to get some advice to see if this is normal???
The gun shoots the 140 grain and 160 grain accubonds using diffrent powders and charge weights at almost the same poi.
I'm super excited hoping that I may have stumbled upon a resilient load.
Any and all advice is greatly appreciated.
Regards.
George.

I'm doing this on my phone so any typos I apologize



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[lash]

Well, you left out if any of the velocities grouped together or near enough to be called a velocity node. Isn't that what the 20 shot test is supposed to be about?

While it certainly sound like you might have found a good powder and bullet combo for your rifle, the advantage of having a load range that has similar velocities is that you will get flexibility for differences in temperatures.

Plus, at 75 yds, a 1" circle is more than 1 MOA. Any decent rifle and load should be able to stay in that 1" at that range. It tells you little. Where your velocity and OCW tests will show differences is at distance. Typically at 200 yds minimum or 300 yds is where you'll begin to see the differences in loads and velocities.

 

[Benchguy57]

You're correct I did find the last two shots were within 15 fps of each other.
Thanks for pointing that out.



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[Benchguy57]

That was 5 fps not 15 sorry.
These fat thumbs and a small phone. Lol


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[morganlamprecht]

i had a custom savage that shot 120 amaxs w/ varget, 139 scenars w/ h4350, and 140 bthp's w/ h4350 all at the same POI...i had a custom action build in .260 that did the same thing...my .308 mrad shoots 175 smks and 178 amaxs the same POI at 100 yds with imr 4064 or varget...only time i get a noticable POI shift is when i shoot 110 vmax's...they are moving about 300 fps faster and POI is .4 mil higher at 100

 

[James n TN]

To be quiet honest I'd like to know what groups it holds say at 200 yards with the same testing? As mentioned 75 yards isn't worthy of saying this or that rifle held 20 shots in a 1" circle.

 

[Benchguy57]

Unfortunately the only place I have that's close to my house is only 100 yards.


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[Benchguy57]

Btt


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[Deadshot2]

The "test" you are describing is the old "Audette Ladder" and it really only works when you shoot it at more than 200 yards. The idea is to identify which charge weights cause the bullets to group. What you'll notice if you move out to 300 yards is that shots will spread out but some, often several grains apart, will hit right next to each other. The "group" may consist of several different speeds but because they are exiting the barrel at the same point of it's oscillation they indicate a potential accuracy node.

Here's the write up on the test and how to evaluate it:

Creighton Audette?s Ladder Test | PrecisionRifleBlog.com