Ladder test results

[Thompsonj]

300RUM, retumbo, 215 primer, 215gr berger, 100 yards. Never done a ladder test, know several stretch it out to longer distances for it, but working with what u had available.

 

[Dmagna]

The POI stuff doesn't matter at 100 yards. You will have to use the speed to tell you where to load up an OCW. I would go back and load up 5 of the 89 89.2 and 89.4. Looking for best SD then do a seating depth test.

 

[Jud96]

I would recommend shooting 2-3 shots per charge with the same style test. If you're using a Magnetospeed don't attach it to the barrel when shooting groups or looking for point of impacts shifts. I typically load a course pressure test to find when I hit pressure with the combination I'm using. Then I back off 0.5gr from pressure and work from 3.5gr below pressure to 0.5gr below pressure shooting 2-3 shots for each charge looking for similar points of impact. For example, let's say 90gr was max, I would start the test at 86.0 and work up to 89.5 grains. Same style test you did, but with more shots per charge and less charge weights being tested. I don't really want a max pressure load, and I don't want something that's going to be slow or I'll just shoot a smaller cartridge. So I find a nice window to test in that will meet or exceed expected velocities and have stable point of impacts for several charge weights in a row.

Let me ask, where did you hit pressure with this test? Or did you see any pressure signs like heavy bolt lift or shiny ejectors marks on the case heads?

 

[Mikecr]

If I knew it was all valid, I would work around 86.6gr.
But I don't have a picture beyond 87gr

 

[Laguna Freak]

If you don't have access to longer than 100 yd range, I would move to multiple like loads from 87 to 88.6 in 0.3 gr increments. I would shoot all 6 loads (88.5 becomes max) at the same point of aim 3 repetitions. Be sure to record each poi accurately at the bench. Then you can transcribe each load's number code or color code accurately on target after the session. Then you will hopefully get to narrow the charge range and reduce to 0.2 gr increments if needed, and/or work seating depth in the same manner based on results. As others have suggested longer range will amplify your results more. 300 yd would be good if you can.

 

[MagnumManiac]

Just to clarify what is going on here, this is an invalid ladder test.
What needs to be done is an OCW test at 100, 3 shots minimum per powder weight.
If you want to do a proper ladder test, it needs to be done at 300-600yrds and you map individual shots and see which loads group close to each other at the same height.

Cheers.

 

[Huntnful]

To me, this just shows how inconsistent a test like this really is. Several times almost a grain more powder showed slower velocities. And then jumping 80fps with just an additional .4gr of powder another time. This is just standard dispersion as if you just loaded a bunch with the same charge weight and got a regular ES spread. You can do this in far less shots. Just find pressure. Then back the charge down a little bit and shoot it to see what it's real ES is going to be with that powder and primer and bullet combo. 1% or even less change in powder charge will not find any holy grail velocity node. Especially not once you introduce varying weather conditions and many more documented shots. Your powder, bullet and primer combo are just going to give you whatever ES that combo is good for. You can probably make small decreases in ES with different loading techniques, but nothing magical once you start reaching decent case fill. You'd have to change the bullet, powder or maybe primer to make any discernible difference. That's just my opinion anyways lol.

With enough shots, I'd bet a lot of money you'd see basically no difference in ES or SD with 89, 89.2 or 89.4 or any of the combos. I'd just shoot 10 rounds loaded the same, slightly below pressure signs, and see what the ES/SD of that combination of components is. If it is not acceptable, you'll need to change something other than .2gr in the powder charge.

 

[Thompsonj]

I would recommend shooting 2-3 shots per charge with the same style test. If you're using a Magnetospeed don't attach it to the barrel when shooting groups or looking for point of impacts shifts. I typically load a course pressure test to find when I hit pressure with the combination I'm using. Then I back off 0.5gr from pressure and work from 3.5gr below pressure to 0.5gr below pressure shooting 2-3 shots for each charge looking for similar points of impact. For example, let's say 90gr was max, I would start the test at 86.0 and work up to 89.5 grains. Same style test you did, but with more shots per charge and less charge weights being tested. I don't really want a max pressure load, and I don't want something that's going to be slow or I'll just shoot a smaller cartridge. So I find a nice window to test in that will meet or exceed expected velocities and have stable point of impacts for several charge weights in a row.

Let me ask, where did you hit pressure with this test? Or did you see any pressure signs like heavy bolt lift or shiny ejectors marks on the case heads?

89.8 the bolt was stiff to open. Assuming it was from pressure

 

[Mikecr]

It's not an Audette ladder, but still a ladder, at 100yds.
He uses different targets per shot, so the shots don't stack on top of one another, as they would at 100yds.

Ideally he could shoot it further out, but maybe he can't. The test doesn't hurt to try.

 

[Mike Matteson]

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