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#6821315 - 07/13/17 07:41 AM Fast and efficient ladder test.
FiremanJG Online   content
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Registered: 12/16/08
Posts: 21142
Loc: Wolfe City, TX
Randy obtained a new DPMS LR-308 G-2, with 20" Barrel. He decided on 165 gr Hornady boat tail spire point, and I said let's try IMR 8208, since it worked so well in my rifle that is similar. Simmons 4-12X with a duplex reticle. I checked zero at 100 with a copy of the lowest charge, then held the point of the heavy post on steel at 300 yards, since that distance from center of the reticle was exactly equivalent to 1.0 Mil. The bullet impacted low from center, but I knew it would keep us on paper, so that was my hold, on the "+" every shot.

I do have a Razor 85mm spotting scope with a fixed 30X Mil eye piece. Randy stayed on the spotter while I shot 3 rounds through his rifle. Then I would get behind the spotter and "map" where each one landed, POI vs. POA in tenth of Mil. And write the powder charge next to the impact on the map. Photo below explains it well. We never drove to the target through 15 shots. We stayed parked in the loading room, in the shade.


.
.
After the shooting, I drove out and retrieved the paper target. The bullets had been colored and labeled accordingly, so we knew what color bullet hole was which charge. We had a clear node at 40.0, 40.3, and 40.6 gr. Those three grouped 2".




.
I told Randy usually the one in the middle of the node is the winner of the group shoot, but let's not skip a charge. Well 40.0 shot 1 1/2" tall and 4" wide at 200 yards, then I shot 40.3" gr.

200 yards.


Height is more important to me, but it was .58" wide. I just loaded the wrong photo here. That's 1/4 MOA in a plain vanilla DPMS. Will it do that every time? No way, but we did find the BEST powder charge after having shot only 22 rounds. This process took a grand total of 2 hours. Since Randy brought his press, and components prepared to load a group within the node, immediately after shooting the ladder test.


Edited by FiremanJG (07/13/17 07:48 AM)
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#6821394 - 07/13/17 08:49 AM Re: Fast and efficient ladder test. [Re: FiremanJG]
patriot07 Online   content
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Registered: 11/06/11
Posts: 1571
Loc: Royse City, TX
Very nice!

What distance would you do this for on a 223? 200 yards?

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#6821403 - 07/13/17 08:55 AM Re: Fast and efficient ladder test. [Re: patriot07]
FiremanJG Online   content
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Registered: 12/16/08
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Loc: Wolfe City, TX
My personal minimum distance for a ladder test is 300 yards. And I have performed a ladder test, with a .223, at 300 yards. It worked perfectly.

I'm fact I have ladder tested the following cartridges at 300 or 500 yards, and every time it has given me the perfect powder charge. Frequently there will be a slow node (light powder charge) and a fast mode (heavy powder charge). The .308 AR, above had a clear winning powder charge, in the middle of the charge weights.

.223
.22-250
.243
6.5 Creedmoor
.260 Rem
7mm-08
.308 Win (bolt action, and AR)
7 Rem Mag
.300 Win Mag
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#6821408 - 07/13/17 08:59 AM Re: Fast and efficient ladder test. [Re: FiremanJG]
patriot07 Online   content
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Registered: 11/06/11
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Loc: Royse City, TX
Good to know, thanks.

Do you have a chrono available for public use? Or do you not even worry about a chrono until you find the right load?

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#6821413 - 07/13/17 09:04 AM Re: Fast and efficient ladder test. [Re: patriot07]
FiremanJG Online   content
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Registered: 12/16/08
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Loc: Wolfe City, TX
I've got a cheap-o Shooting Chrony. It's fairly accurate, but I get real velocity by working DOPE backwards into the calculator.
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#6821414 - 07/13/17 09:06 AM Re: Fast and efficient ladder test. [Re: FiremanJG]
patriot07 Online   content
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Registered: 11/06/11
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Makes sense. Thanks for the helpful posts.

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#6821683 - 07/13/17 01:51 PM Re: Fast and efficient ladder test. [Re: FiremanJG]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 21142
Loc: Wolfe City, TX
yingyang
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#6821718 - 07/13/17 02:32 PM Re: Fast and efficient ladder test. [Re: FiremanJG]
Buzzsaw Online   content
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Registered: 06/29/11
Posts: 9428
Loc: Frisco, Texas
greatness JG !!
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#6822094 - 07/13/17 08:40 PM Re: Fast and efficient ladder test. [Re: FiremanJG]
Big Fitz Offline
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Registered: 12/06/09
Posts: 2191
Loc: McKinney, TX
Very nice! I think your mapping needs improvement though... peep
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#6822134 - 07/13/17 09:39 PM Re: Fast and efficient ladder test. [Re: FiremanJG]
Smokey Bear Online   content
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Registered: 05/11/17
Posts: 165
Loc: Texas
Good work! It's always nice when things come together on the first go. I have only been loading 8208 a short while but it is rapidly becoming one of my favorite powders.
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#6822153 - 07/13/17 10:10 PM Re: Fast and efficient ladder test. [Re: Big Fitz]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 21142
Loc: Wolfe City, TX
Originally Posted By: Big Fitz
Very nice! I think your mapping needs improvement though... peep


Next time I'll call you, and you can do it, then.

Actually, the next time will be Tuesday or Wednesday. Wait by the phone.
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#6822371 - 07/14/17 08:39 AM Re: Fast and efficient ladder test. [Re: FiremanJG]
redchevy Offline
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Registered: 10/25/04
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Maybe I'm understanding a ladder test wrong, but some of the results look odd to me. Were all rounds fire with the same point of aim?
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#6822402 - 07/14/17 08:59 AM Re: Fast and efficient ladder test. [Re: redchevy]
OkieDokie Online   happy
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Registered: 01/28/08
Posts: 956
Loc: southern OK
Originally Posted By: redchevy
Maybe I'm understanding a ladder test wrong, but some of the results look odd to me. Were all rounds fire with the same point of aim?


Yes.
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#6822421 - 07/14/17 09:15 AM Re: Fast and efficient ladder test. [Re: OkieDokie]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 21142
Loc: Wolfe City, TX
Originally Posted By: OkieDokie
Originally Posted By: redchevy
Maybe I'm understanding a ladder test wrong, but some of the results look odd to me. Were all rounds fire with the same point of aim?


Yes.


Yes.

Hard to read this one since powder charges next to bullet holes are in pencil.

In there, 3 loads grouped 2" at 300 yards. That's telling us between 40.0 gr and 40.9 gr is the node. Focus on that area and group shoot each charge.
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#6822437 - 07/14/17 09:24 AM Re: Fast and efficient ladder test. [Re: FiremanJG]
redchevy Offline
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Registered: 10/25/04
Posts: 25753
Loc: Texas
It appears most of your 38 and 39 grain charge weights impacted higher than the 40-41 grain charges, or am I seeing something wrong? I would have expected the opposite.
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