Ladder testing at 1k- Detailed article and video

Buckreed

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Here is a ladder test question for everyone. If I do a ladder with one powder, say H1000. Then I want to switch to another powder. Do I need to do a ladder test or can I just work up to the same velocity? I assume the node would be the same velocity for all powder, but maybe the harmonics change?
 

Buckreed

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different harmonics with different powder so need to retest.
Good to know. I suspected that. Just out of curiosity, how far does if move? 100 FPS, 300? I’m sure it varies, but curious what your experience has been.
 

Alex Wheeler

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1000yd ladders are the best way to be sure your tuned for that range. Over 10,000 rounds fired at that range, and I have yet to beat it. Other than I do recommend 3 shots per powder charge. I call this a long range sine wave test but its all the same at the end of the day. Single shot ladders can really trick you. Do 3 shot groups at one point of aim. Even with thin barrels, just let it cool between groups and pick the right day. Its harder, but you will end up with a tune that actually works at 1k every time.
 

Bart B

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A given barrel's harmonics, actually its resonant (lowest, several dozen Hz) frequency and several harmonic (higher, up to several thousand Hz) frequencies, are fixed and don't change from the shock of firing. The rigidity of the steel doesn't change as it heats up from firing a few dozen shots fired once every 20 to 30 seconds. Or 10 shots once every 5 or 6 seconds.

If your shots start walking away from point of aim as the barrel heats up, it's not stress relieved or fit correctly to the receiver face.

Buckreed, you'll need to do another test. Different powders can produce the same velocity but bullets will probably leave at different angles on the muzzle axis due to barrel time changes. Ideally, the slower ones will leave on the muzzle up swing at a slightly higher angle from the LOS than faster ones. Shoot at least 5 shots per charge weight.
 
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Alex Wheeler

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I agree, good barrels dont walk. But even with a stable powder you will get velocity increase when the barrel gets too hot, especially if the case cooks in the chamber, and you will increase throat erosion.
 

Bart B

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Alex, yes, hot powders shoot bullets faster.

I like to fire 10 to 15 seconds after loading. I come down 1/4 MOA click on the sight every 20 or 30 seconds of chamber time at 1000 yards depending on charge weight.

My data on 308 Win barrel life is about 3000 rounds for all shots fired in it at10 per minute compared to another fired once a minute. Same life with one fired ten times as fast for all shots.
 
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Don A Parsons

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We do 3 simple ladder test up here in the North for F Class.

7 to 9 varying loads to shoot at the dots at 100 meters...
3 cartridges for each of the 7 to 9 varying loads...

To lesson the variance between the targets we shoot the lowest charge and work our way across the target dots at 100 meters using the 0.3gr powder charge... Once we find the tightest vertical at that distance we move out to the 600 metre...

Now we have about 4 or 5 loads to test using 3 cartridges per load...

We set up the big chunk of card board to find the tightest vertical at that distance...

Now we're down to 2 or 3 test loads,,, same idea of shooting at a clay bank at 1000 meters...

If our calculations are correct from 100 and 600 meters,,, they should be on par at 1000...

We only shoot our ladder tests on calm days late in the evening...

Simple easy and fast...

Of course we have a mobile reloading set-up that we bring to the range,,, the control center saves alot of time since we can change loads on the fly...

1 to 2 hours to find loads for all rifles that come out to the range...

We test these loads over a period of days to make sure that they are a go...

Different temps and elevations along with low to high humidity days...

Cheers from the North
 

Alex Wheeler

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Alex, yes, hot powders shoot bullets faster.

I like to fire 10 to 15 seconds after loading. I come down 1/4 MOA click on the sight every 20 or 30 seconds of chamber time at 1000 yards depending on charge weight.

My data on 308 Win barrel life is about 3000 rounds for all shots fired in it at10 per minute compared to another fired once a minute. Same life with one fired ten times as fast for all shots.
A .308 is a very mild round. Do that with something like a 28 nosler and I think you will find a very different result.
 
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Bart B

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28 Nosler is a 65K psi round.

308 Win is a 62K psi round.

If 308's are very mild, a 28 Nos. is just plain mild. Either ones limits will overlap the other.
 

Alex Wheeler

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Im pretty sure you understand the difference in throat life between the 2 and why. You'll need to find someone else you argue with. Good day.
 
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Bart B

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"Mild" means lower peak pressure to me.

Of course, the 28 Nosler has about one fourth the barrel throat life of a 308. It's about the same as the 7mm Rem Mag.

Both those 7mm charge weights are about twice the bore capacity. The 308's charge weights are about at bore capacity.
 
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TOM H

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Alex, yes, hot powders shoot bullets faster.

I like to fire 10 to 15 seconds after loading. I come down 1/4 MOA click on the sight every 20 or 30 seconds of chamber time at 1000 yards depending on charge weight.

My data on 308 Win barrel life is about 3000 rounds for all shots fired in it at10 per minute compared to another fired once a minute. Same life with one fired ten times as fast for all shots.
Bart, your testing load and I'd like come up where your testing and watch you. I'm not that far from Byers
 

Almondgrower

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That is one of the best write ups I have seen for Ladder testing.

The problem I always have is keeping up with where each shot went. Glass good enough to spot a .204 hole at 4-500 yards is well out of my price range! It never occurred to me to color the bullets and use that as a way to keep track of which one went where. I think I will try that as well as set up a video camera next time to see what works best for me.

The wife will really like the idea of the video camera sitting downrange next to the target.:rolleyes:
See: ladder test must have in reloading forum , I just posted about this problem 5 min ago .....simply awesome !!!
 

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