Audette Ladder Test - Help!

[rsplante]

I plan on running my first Audette Ladder Test this weekend and I have some questions. So far, in preparation I have dragged out my brand spanking new Match Lapua .223 brass (they don't make 5.56, but considering that it is 8-10 gr heavier than my LC brass... My understanding has been that the NATO stuff had heavier walls, and since the Lapua is heavier than my 5.56 LC brass...) I have reamed the flash hole (hey, even Lapua is not perfect), normalized the primer pocket, and run all of it through my full length sizer/Dillon RT1200 trimmer (the trimmer did not touch any of them). I picked out 25 cases that were identical weight to 0.1gr (all 97.1 gr), Weighed all the bullets and picked 25 - 77gr SMK (76.9gr), I even weighed a primer to see what the total weight should be. I used an RCBS 1500 Chargemaster to weight each charge. 23.5, 24.0, 24.5, 25.0, 25.5gr. of VARGET. I planned to go to 26 gr; however, in the Lapua, 25.5 gr comes up to the neck. I weighed every completed round and they are all within 0.2gr of my calculated weights. I ran them through my Hornady Concentricity gage upgraded with a Starrett .0001" dial indicator. All were within .002" runout. I will be using a Chronometer, and shooting at 300 yd. Even though I will be shooting single shot, I loaded them to magazine length since that is what I am trying to optimize for. I will be using an Original Bob Sled to help facilitate the single shots. I also plan on using five identical targets to address the problem of marking my shots at 300yd without a pit. (Each load will get it's own target).
Oh, almost forgot, the rifle... It is a LaRue Tactical 5.56 OBR with a 20" barrel, SJC Titan Compensator, Magpul PRS stock, Harris bipod, and a NightForce NXS ZS 8-32x56 scope (mil/mil.)

Now for my questions. I read on one site about Audette Ladders that the guy was shooting each round from a cold barrel (he said the test took all day). How important is that? I can work around that if necessary, as I have seen another engineer at the range rig up an electric air pump to flow through the barrel to cool it. Second question, if I do not cool the barrel, should it be shot round robin, or straight through each load. (i.e. one shot from each charge group and repeat five times, or shoot all of each charge group before moving on to the next group.) Third question is unrelated to the ladder test, but since my 25.5 gr load came up to the neck, I stopped there. What could I expect to happen if I went to 26 gr. and crushed the VARGET setting the bullet? I am assuming that would be entering into unnecessarily dangerous territory, both because of the density of the charge, and because it would knock off the retardant on each grain of powder increasing the speed of the powder burn.

 

[MitchAlsup]

Re: Audette Ladder Test - Help!

Varget and compressed loads pretty much simply go together.

However, you step size of 0.5 gr (2%) is way too big for a charge weight in the 24.x gr range. Half of this step size is prefered.

 

[Mutt]

Re: Audette Ladder Test - Help!

I follow THIS procedure more or less, with good results. It's a good read.
I shoot a string of foulers but that's me. To each his own.
I do one shot per charge up the ladder allowing a couple minutes to cool adequately in between shots. Then I reverse it, and then go up again til I'm done.
Careful with the air down the tube thing...you might be introducing moisture inside your bbl. Maybe better blowing air over the exterior surface to facilitate cooling around the outside of the barrel?...just a thought, I could be wrong.

~Mutt

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mutt</div><div class="ubbcode-body">I follow THIS Careful with the air down the tube thing...you might be introducing moisture inside your bbl. Maybe better blowing air over the exterior surface to facilitate cooling around the outside of the barrel?...just a thought, I could be wrong.

~Mutt </div></div>
I hadn't thought about that. Good point. I have a Stainless Steel barrel though. Do I still need to be concerned about moisture? And as for fowlers, No problem, this will be my first time at 300yd, so I will need to make sure I've made the right scope adjustments before I start the ladder test.

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">Varget and compressed loads pretty much simply go together.

However, you step size of 0.5 gr (2%) is way too big for a charge weight in the 24.x gr range. Half of this step size is prefered. </div></div>
It sounds like you have done it before. No obvious signs of pressure? I had read somewhere that crushing VARGET caused it to increase the burn rate. I guess I can carefully venture into that area. I've run 26gr of VARGET before with Lake City brass, but don't remember it being all that high in the case. (77gr SMK @ 2850 fps.) This is my first ladder test and I was going to reduce the step size once I get a rough idea where the nodes are. Do you think I should start out with smaller steps?

 

[seanhagerty]

Re: Audette Ladder Test - Help!

You didnt say what primer you are using, but with CCI SR primers I have had flattening of the primer at 24.5gr with 77gr SMK's.

I have shot several of these ladder tests and I only used one target. So, I had to go down range, mark the target, then return and shoot the next shot. That was my cooling time.

I used 0.3 gr increments on my ladder test with varget for the 223. The picture below was shot at 400 yards, and I got great vertical seperation with that process.

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Mutt</div><div class="ubbcode-body">I follow THIS procedure more or less, with good results. It's a good read.
I shoot a string of foulers but that's me. To each his own.
I do one shot per charge up the ladder allowing a couple minutes to cool adequately in between shots. Then I reverse it, and then go up again til I'm done.
Careful with the air down the tube thing...you might be introducing moisture inside your bbl. Maybe better blowing air over the exterior surface to facilitate cooling around the outside of the barrel?...just a thought, I could be wrong.

~Mutt </div></div>

Thanks for the reference. I read it, and it looks like I should only have to wait for 1 or two cooling periods. He says that after a few fowlers, he shoots around 15 rounds and lets it cool off. He also says that he runs his ladder the way he will be shooting. Since I am shooting a gas gun, and will tend to be shooting through a hot barrel, I guess that minimizes the need for cooling during the test. My favorite bit of advice is the bullet coloring. Since I am not shooting benchrest, his advice to use a single target is not as applicable (he seems to base his advice to use a single target on not having to reset the gun setup. Shooting from a bipod, I would guess that using multiple targets whould be less important of a concern.) I will try the bullet coloring though. He uses permanent color markers like sharpies at the front of the ogive. On those that are hard to discipher, he uses a Q-tip and isopropyl alcohol to transfer the color from the target to the Q-tip. Thanks again.

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Sean Hagerty</div><div class="ubbcode-body">You didnt say what primer you are using, but with CCI SR primers I have had flattening of the primer at 24.5gr with 77gr SMK's.

</div></div>

I'm using Federal 205M primers. I know, pretty light, but I still have 1200 left to go through. I have not had any obvious problems with them. i.e. no burn-thru, no cratering, no obvious gas leakage. My vision is not good enough to detect if the edges are getting squared off any. I know that they are not flowing to fill the primer pocket like some examples I have seen pictures of. I need to find another one of those pocket microscopes I used to have but misplaced (about 60x).

 

[Mutt]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fully Involved</div><div class="ubbcode-body">...Since I am not shooting benchrest, his advice to use a single target is not as applicable (he seems to base his advice to use a single target on not having to reset the gun setup. Shooting from a bipod, I would guess that using multiple targets whould be less important of a concern.) I will try the bullet coloring though...Thanks again. </div></div>

Yes and no. I don't shoot BR either but I found using one target and aimpoint highly convenient for examining the results and minimizing any confusion or [for me] mental errors. That's also where all those purty colored holes pay their dividends...
Now I'm not saying 'don't shoot multiple targets' I'm just conveying a bit of reason for one.
It sounds like you're on your way to settling on a routine that works for YOU, though. Good luck. Post some results so we can peak at the purty holes

~Mutt

 

[rsplante]

Re: Audette Ladder Test - Help!

Will do. Of course, apparently I have to subscribe to some sort of website that will host my pictures in order to post. Any suggestions?

 

[Boomholzer]

Re: Audette Ladder Test - Help!

You should allow one shot per week on a 30rnd mag, for proper cooling.

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Boomholzer</div><div class="ubbcode-body">You should allow one shot per week on a 30rnd mag, for proper cooling. </div></div>
That sounds like a government job. lol

 

[TexIndian]

Re: Audette Ladder Test - Help!

Photobucket.com is a free photo hosting site that lots of folks use. You just upload your pics to that site and then use that URL to link it to forums like this one. They automatically resize your photos (both in pixels and file size) to make it much easier for those not familiar with all that technical stuff. It may offer other features, but I don't use it myself so I'm not up on all the details.

Have you tried using a drop tube to dump your powder into your cases? It makes the powder settle much better without the need to vibrate the case to avoid crushing so much. If you're weighing each charge, you can use a funnel with built-in drop tube ( Forster makes one). If you're using a powder measure, Sinclair makes tubes that will fit on most brands of powder measures. Before I discovered drop tubes, I either tapped the sides of the case (tedious) or held the case against a source of vibration (like a power drill) to make the powder settle down into the case.

I'm getting ready to do some load development myself for a couple new guns, incl a new OBR. Mine is almost exactly like yours except for the caliber and scope. I've got an OBR Lite on order, too, so I'm interested in your results.

 

[Voyagertwelve]

Re: Audette Ladder Test - Help!

I agree with the one shot per week method, but would add that you need to keep temperature comsistant and may need to skip some weeks.

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: OldTex</div><div class="ubbcode-body">
Have you tried using a drop tube to dump your powder into your cases? It makes the powder settle much better without the need to vibrate the case to avoid crushing so much. If you're weighing each charge, you can use a funnel with built-in drop tube </div></div>
Yes, I'm using an RCBS funnel with a 4.5" drop tube.

I'll give photobucket a try, and I'll post the results of my testing here.

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: OldTex</div><div class="ubbcode-body">
I'm getting ready to do some load development myself for a couple new guns, incl a new OBR. Mine is almost exactly like yours except for the caliber and scope. I've got an OBR Lite on order, too, so I'm interested in your results. </div></div>

I had planned to get an OBR in 7.62 someday; however, now I am torn whether to get another gas gun or get a Winchester 700 bolt gun. What do you think. Any reason to go with two gas guns?

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Voyagertwelve</div><div class="ubbcode-body">I agree with the one shot per week method, but would add that you need to keep temperature comsistant and may need to skip some weeks. </div></div>
Ahh, I wouldn't need to worry about that. It has been consistently over 100 degF the past month or so until this week. We had a cold spell this week, it's been in the low 90's.

 

[TexIndian]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fully Involved</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: OldTex</div><div class="ubbcode-body">
I'm getting ready to do some load development myself for a couple new guns, incl a new OBR. Mine is almost exactly like yours except for the caliber and scope. I've got an OBR Lite on order, too, so I'm interested in your results. </div></div>

I had planned to get an OBR in 7.62 someday; however, now I am torn whether to get another gas gun or get a Winchester 700 bolt gun. What do you think. Any reason to go with two gas guns? </div></div>

That's a personal choice depending on what kind of shooting you do or want to do, and where your collection stands at the moment. Because I was mainly into hunting when I was younger, I have tended toward bolt or single-shot rifles over the years. My semi-auto collection was pretty thin in comparison so now I'm playing catch-up in that department. When I was just getting started, I got an M1A and a good bolt gun, then a couple pistols and an O/U shotgun. Once I had the basics covered, I could just go where my interests led me.

 

[rsplante]

Re: Audette Ladder Test - Help!

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: OldTex</div><div class="ubbcode-body">That's a personal choice depending on what kind of shooting you do or want to do, and where your collection stands at the moment. Because I was mainly into hunting when I was younger, I have tended toward bolt or single-shot rifles over the years. My semi-auto collection was pretty thin in comparison so now I'm playing catch-up in that department. When I was just getting started, I got an M1A and a good bolt gun, then a couple pistols and an O/U shotgun. Once I had the basics covered, I could just go where my interests led me. </div></div>

I hear you. I was afraid you would say something like that. Right now my collection consists of the 5.56 OBR, an SKS, a .22LR, an O/U shotgun, a gas operated shotgun, a G22 and a G27. I'm trying to decide between a 1911, a 10mm and a .45 Super for my next handgun. After that I've been tossing around the idea of an M1A, a Remington 700, or an OBR in 7.62. So the next rifle is very much in the speculative/virtual stage. I wish I could tell you what I plan to do with it. That is in the same category as what I want to do when I grow up (and I'm 56y.o.) Right now, I am just having a good time reloading and shooting paper, steel plates, and clay pigeons. I have a deal in the works to make a friend of a friend some ammo in exchange for a hog hunt, but other than some ducks and squirrels, no hunting experience so far.