ladder test method

[badshotlal]

Hello folks,
Been a while since I visited here. Haven't shot for a while, gettin' long in tooth, but some rifles hollerin' at me to at least try!
Seen some talk about a "ladder test", even dedicated target designs. Know this is old hat to you all, but could somebody point out where I could find some info.
While I got your ear, and although it may be a breach of protocol, I'm 67, fightin' some health issues, but love to shoot dogs and call 'yotes (with my own calls -- no batteries, thank-you). Live in south-central Ks., but am mobile (I get to go to Dillons now, but the boss makes me call when I get there!!)
If you might be lookin' for somebody to pay the gas and carry the guns, I'm your guy.
Hope you and yours are well, and looking forward to a holiday. Fly that flag that represents the very best of what our proud nation has lost, and pray to God that this dismantiling will be stopped.

God Bless

badshotlal

 

[Nodak7mm]

Al,

Hope this is what you may be looking for.. http://www.accurateshooter.com/technical-articles/long-range-load-development/

Sorry I cant help on actual range work, but the commute would wipe out your bait & bullet funds. ;D

Have a great weekend Sir..

Rod in Fargo

 

[MVW]

I haven't looked at some of these in a while, but this is my collection of links that I have gathered related to the topic

Long Range Load Development
http://www.6mmbr.com/laddertest.html
http://thefiringline.com/forums/showthread.php?t=127661
http://www.ar15.com/mobile/topic.html?b=6&f=42&t=256356&page=3
http://www.desertsharpshooters.com/manuals/incredload.pdf
http://forum.accurateshooter.com/index.php?topic=3787603.0
http://forum.accurateshooter.com/index.php?topic=3787663.0
http://forum.accurateshooter.com/index.php?topic=3787632.0
http://optimalchargeweight.embarqspace.com/

The desertsharpshooter is the one I used to start.

I live a long ways from kansas, but it sounds like fun.

Mike

 

[mikecr]

A common problem with ladders directly ties with a common problem using group shooting methods; The guns are producing scattering patterns. Right? Scattering your results.. Even a finely tuned gun shoots a pattern(not perfect).
Now take a gun way out of tune and try interpreting results of a single fine adjustment(powder) within it's patterns?
No
You aren't going to get a pleasant vertical 'wave' from a ladder unless the gun is shooting really well to begin with.
This is analogous to shooting a box with your scope -before the gun shoots well enough to do so.
So you're left with interpreting averages, that inevitably brings sample size to question. This can break down to no method at all.

Notice with a lot of these methods out there, seating depth is kind of 'thrown in' at the end, if even mentioned. Now either they've missed that seating depth alone can double or triple pattern sizes, or they're assuming everyone is/will be jammed. Maybe they assumed we all shoot 6PPCs at 100yds.
The assumption/method can turn out. Seating tests can be run at any time. With some cartridges best load cannot even be achieved without jamming. It's just a matter of how testing of it later would be interpreted, or whether things really turned out best.
Another thing commonly assumed as though insignificant is primers. They say 'pick a primer/powder/bullet' and do this ~. Yet, the primer, seating of it, and especially it's striking, can enlarge patterns.
There is no fine adjustment in changing primers.

IMO, your chances of measuring patterns with powder adjustments, are better with primer performance and bullet seating reduced from pattern first.
Pick a bullet and powder. You have to pick something and it ALL starts with a bullet. While fireforming new cases with a safe load(which needs to be done before load developing), adjust bullet seating for smallest pattern. While second fireforming, adjust primers & primer strike for lowest ES, and/or smallest pattern.
Now size cases as you will, and go to incremental load development, with best seating and primers off the table.

Your ladders should look a whole nother way..

 

[badshotlal]

Hi Mike,
Goodness, thanks for the exhaustive response. Makes sense. With my old hands, I'm never sure whether I'm .005 or .012 or??? off using my tool (can't remember the mfg.)
But I bought a No. 1 22-250 -- always wanted one and now really can't shoot it worth a darn probably -- and I'll be darned if I absolutely can't reach the throat.
Guess I'll try the Weatherby method, but never understood how his guns could shoot.
Thanks again. Hope you and yours are well.

God Bless

badshotlal

 

[badshotlal]

thanks Al

 

[badshotlal]

Wow, thanks so much for all this data. Probably won't get half way through it. Must have taken some time to pull it all together. Thanks again.

God Bless

badshotlal

 

[jlow]

Pick a bullet and powder. You have to pick something and it ALL starts with a bullet. While fireforming new cases with a safe load(which needs to be done before load developing), adjust bullet seating for smallest pattern. While second fireforming, adjust primers & primer strike for lowest ES, and/or smallest pattern.
Now size cases as you will, and go to incremental load development, with best seating and primers off the table.

This is very interesting to me. I guess the part that I have a little problem with, and that this could be due to my own lack of knowledge in this area, is it seems that your advice assumes that optimal bullet seating depth remains the same for different powder weight which is a surprise to me.

My own assumption has been that optimal seating depth basically is a way to tune when your bullet exit the muzzle by slightly changing chamber pressure and thus MV. However, since changing powder weight would change chamber pressure and MV, it would seem that different powder weights would need to be tuned differently in terms of bullet seating depth?

Hope this make sense. I would be delighted to be wrong here since it would make my life a lot simpler.

 

[mikecr]

Well jlow, there is potential for tweaking seating 'a touch' after tune, that amounts to small group shaping results.
Now if you were going from jam to OTL(or opposite), you could expect a collapse of tune as pressure significantly changes with this.
You'll find though that if you tweak too much either way despite, the tune still seems to change/fall apart.
But in this case it isn't all tune waving bye bye. It's something independent(and bigger) about a particular bullet seating in a particular finished barrel.

Put another way;
If you load develop to arrive at seemingly best performance with a random chosen seating, then go to adjusting seating(in say 5thou incr), you'll likely find degrading performance right off the bat(unless real lucky). Then you'll likely conclude that your original seating must've been best, and moon walk around like you're all that..
But what if your chosen seating never was the BEST seating? Why would it be? What if your best results are not actually as good as possible? You just don't know, right? And now it's more difficult to verify objectively.

I promise you that tune can be reached at other seating depths. I recommend that you figure out which is really best, and I believe this is best accomplished by testing seating before powder. If nothing else, it let's you see powder results better.
You might go further to test other powders, and guess what? Best seating doesn't change with powders. It's right there where you determined it was (or,, never did).

 

[mikecr]

I should throw in a bit of basis for clarification.
No matter your load, notice that seating depth changes affect groupings more than ANY other single adjustment.
Seriously, take a 1/4 moa gun, adjust seating all over, and watch it go to 3/4moa(or worse) & back.
While doing so, notice that MV isn't changing much, if any.

Then, try to do the same with powder alone. You probably can't..
Even while MV follows directly, a 1/4moa tune doesn't usually degrade so far with powder alone.

Powder is the finer tune, NOT seating.

 

[6BRinNZ]

I should throw in a bit of basis for clarification.
No matter your load, notice that seating depth changes affect groupings more than ANY other single adjustment.
Seriously, take a 1/4 moa gun, adjust seating all over, and watch it go to 3/4moa(or worse) & back.
While doing so, notice that MV isn't changing much, if any.

Then, try to do the same with powder alone. You probably can't..
Even while MV follows directly, a 1/4moa tune doesn't usually degrade so far with powder alone.

Powder is the finer tune, NOT seating.

Mikecr - to what point do you draw the line on this Powder is the finer tune, NOT seating.. this is questioning from an understanding point of view. i.e. would you still apply the statement for .5 grain increments or are you meaning more from 1 or 2 tenths.

 

[mikecr]

From very low to max pressure.
Ask someone with a competitive 6PPC if he could make it shoot as bad as 1/2moa@100yds with powder adjustments.
I know for sure he can with seating adjustments.

 

[6BRinNZ]

hmm, I'm missing something. I found that .5 grain can take me from moa to .2 - .3 moa. But are you saying that is because the correct seating depth is not determined first? I will see if I have some pics to post to clarify better.

 

[jlow]

Thanks for your response. First, the situation is slightly different for me as I am not seating to the lands or jamming but mostly just slightly longer than mag length.

I have not had the luck of finding a great load without tuning seating depths. What I have been doing is going through OCW and picking a powder weight based little change in POI and then based on test temp/predicted working temp, and tuning the load using seating depths to tighten up the group – so I do buy into how effective this method is to affect group size. This has worked reasonably well for me except what I find, at least in my limited experience, loads that seem to be sometimes exceeding sensitive to seating depth i.e. does not tolerate depths that varies 1-2 thousands from the optimal.

In the end, the impetus for my question was to figure out if this optimal seating depth that I have found for the powder weight chosen extends to slightly different powder weights which may be more tolerant of seating depth variation – hope that make sense.

 

[jlow]

BTW, I would have to agree with 6BRinNZ, significant changes in powder weigh at similar seating depth can make a huge difference in group size, was just wondering about very slight changes in powder weight i.e. 0.1 gr....

 

[mikecr]

hmm, I'm missing something. I found that .5 grain can take me from moa to .2 - .3 moa.

This seems normal to me. Can you get .75moa with further powder changes?
You can with seating.

But are you saying that is because the correct seating depth is not determined first?

No, I'm saying best seating and best powder load have little to do with each other, yet mask each other -while BOTH are less than best.

Let's say a gunrag suggests everyone seat 10thou off for load development. This probably wouldn't be best for everyone, right?
Now everyone works up their powder loads incrementally @ 10thou off. But where 10thou off sucked for their combination, did they really pick the best powder load with it?
I say that if they adjust from that 10thou & find best seating AFTER load development, they might as well go back & load develop again to confirm it was best(because they had 2 issues at the same time). So why not find best seating first(eliminating one issue)?
You CAN do it first, and nothing will change best seating, other than a bullet change**.

*If you can't adjust seating due to a mag limit, then forget what I'm saying.
*If you can't reach advantage loads for your cartridge without jamming(as with a 6PPC, 30BR, etc), then forget what I'm saying.
But otherwise you might consider & try it.