Ladder testing...? anybody prefer just shooting groups?

[6BRinNZ]

Hi Guys,

awesome thread, and very timely for me. I have a new rifle that I am working up loads for.

Until now I have shot 3 shots at .5 grn increments (different POA for each group), until I hit pressure. I then looked at the groups to see which had the least verticle and then tuned from there. I have always ended up dissappointed as i haven't been able to repeat the "good" groups next time up. Even though this is quite coarse I can see the groups shrink in and out as I move up through the ladder, it just seems hard to keep it consistent.

So,

my new rifle (Barnard P action) can handle significantly higher pressures and my recent ladder test has left me somewhere around 1-1.5 grns away from a max load.

Should I change tact and try the 1 shot ladder test (same POA) through to max load (for the remaining 1-1.5 grns) and maybe use .2 grn increments? I have started graphing the powder vs velocity as well

 

[BoydAllen]

Give it a try, and let us know what you find.

One more thing, I have found that simply taping a weight to the end of the barrel will slow the swing enough to hit the next higher node with slightly less powder. I stretched two layers of electrical tape around a cylindrical piece that was about 5/8" dia, and 2 1/2" long that I positioned on a strip of tape, on the underside of the barrel, flush with the muzzle. It allowed me to hit the same node in a 6PPC with .2-.3 less powder, when I was in a situation where powder space was at a premium.

 

[RonAKA]

Lynn, I appreciate your detailed response to my admitted "devils advocate" post. I'm about to test a new gun and am sweating the exact same issue that the original poster raised. How should I do it without burning the barrel out before I find what works.

I agree that the ladder test is the perfect tool, in theory. But, that "in theory" bit has me worried. Bryan Litz which I believe may be a contributer here has an excellent quote on his website. "In theory, there is no difference between theory and practice. But in practice, there is. - Yogi Berra"

With the exception of shot #6 I would agree that your numbers represent the perfect and theoretical ladder test. #6 at +18" must have been shot by that teenager just finding out what sex is, or an old fart like me with their first prescription of Viagra.

The problem I see is that the nice +1/4" increment in the bad non node zone areas are not likely to happen in real practice. A 30-06 hunting gun for example is lucky to get 1 MOA accuracy. If you overlay this with the fact that this is happening out of the sweet spot it is very optimistic to expect 1 MOA. But, even if we stay with the optimistic view, that +1/4" is really +1/4" +/- 1". Now all of a sudden with this +/- effect then we can have the appearance of what looks like nodes.

Now if one ladder test produces these fake nodes, then they are not likely to occur if you do a second ladder test. I wonder if anyone has done a ladder test one day, and then tried to replicate it another day, without success? This could be the reason.

I appreciate the need (conserve the barrel and ammo costs) to I get to a good load quickly, but I wonder if it really can be done on the fast track.

My current thinking is that the ladder test, but with 2-3 shots per load step may be the quicker way to the end point. Yes, it takes more shots up front, but I think it saves you going down rabbit holes chasing fake nodes.

 

[BoydAllen]

One little thing that needs to be said....doing intricate load testing without making sure that the rifle is as good as it can be is a waste of time. Attend to the bedding, trigger, and scope first. Don't be one of those guys that has an untouched factory rifle, shooting off of a bad rest setup with no flags, that is trying to put together data using a method that is to subtle for the conditions of the test. The "noise" will be too loud for valid results to be seen.

 

[tripcrow]

Of late I’ve become suspect and question those nodes my crony and I found using 1-3 shots per load ladder tests. I’m now thinking Quick Load may be right and they wouldn’t have been there if I was running 7-10 shots per load tests instead. Heck it even seems that loads found using a 7 or 8 shot group comparisons method aren't always the best load come match day.

Has anyone retested around their nodes using 8-10 shot groups and come up with the same velocities and bullet placings?

 

[Phil3]

As a newbie to load development, I like the idea of the ladder test, but I too am concerned about lack of inherent accuracy in the gun (or shooter) being so much noise, you can't see any meaningful results. I am looking for an accurate bolt action, but right now am looking to develop loads for an AR15, something that may produce too much "noise" for meaningful results. It has shot well under MOA 5 shot groups, with cheap ammo...is that accurate enough for a ladder test to be meaningful for 223 at 100 and 300 yard ladder test?

- Phil

 

[CPorter]

I've found the ladder with 3 rounds per load works well, the results are repeatable and most accurate for factory guns. Barrel vibrations for nodes are not just up and down and won't tell you about residual stresses in hammer forged barrels. It also works with ARs, bolt actions, or whatever other action.

One thing most people forget about when shooting a ladder test is barrel fouling and the need to fire enough rounds to properly foul the barrel. To short cut the process when using uncoated bullets you can use "Lock-ease" to treat the barrel after cleaning.

Maybe the others will pipe in about their experience interpreting results but I have found that the results are variable with changes in atmospheric conditions and barrel heat to some degree. Also chronograph readings will change slightly with lighting conditions as well as temperature so the numbers may not match exactly. Still the node center will be +- a few tenths of a grain provided the seating depth remains constant, same primer, etc.

 

[RonAKA]

I would suggest two things for anyoner not familiar with a Ladder test.
First would be to increase the range you are testing to so that you are at the limit of your scopes ability to see bullet holes.
I don't think you will get good results with a straight 4X scope with heavy duplex crosshairs.If you had a 20X scope and a 223 then 200 yards would be fine.
With a 6BR and no experience 300 yards and a 32X scope would be better.
Second thing I would recommend is using a different rfle and doing several Ladder tests to get yourself familiarised with it.I always recommend the highest magnification scope you have along with a lightweight trigger even if you need to borrow them just to do the testing.
Once you have a couple practice tests under your belt your set for life.

Lynn thanks again for your detailed response. Your advice is very helpful. I will be shooting this Savage LRPV 6BR with a 24X scope, but I have never shot targets beyond 100 yards. I agree that increased distance is helpful in discriminating the elevation point of impact as a result of velocity variations. It is not linear where differences are double at 200 yards compared to 100. It is more. The trigger will be 6 oz. or possibly less, so I don't think that is a big issue.

I will be shooting at a new range which I have never used before. The longest range is 300 meters. So depending on wind etc. I will have to decide which distance to use. Believe it or not, we have forest fires so bad right now that visibility is limited, and 300 meters may be out of the question just to see the target clearly.

 

[Phil3]

Phil
I would let your daughter do the shooting as her targets looked very good while you sit next to her and record what she is calling out.Put a orange sticky disc on a target stapled up backwards at 200 yards.Make sure your weakest load hits about one inch above that.
Now let her fire your next round and have her call it out by saying 1/2 inch higher or whatever she sees through the scope.Tell her ahead of time you are not interested in left or right just the vertical element.
Do you have a rest set-up for it now that fits it well?

Lynn,

OK, rub it in, my novice daughter shoots better than I, at least on that one day! I am not sure I understand the test procedure you are describing. Afix an orange sticky disc to a blank cardboard target, and keep aim point the same on center of disc, and she calls out where each round went (vertical only). Correct?

No front rest, yet. I wanted something high quality but the price tags put a damper on that, especially while acquiring all kinds of reloading equipment and a replacement car this year. A friend is a long time machinist with a robust shop, and said we could make a very good rest without much trouble. Maybe, or just buy.

- Phil