”Ladder Load” - Finding Optimal Charge Weights”

 

This Week’s Tips or Tricks…

 

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Note: all below CBTO measurements noted were taken using a Hornady Bullet Comparator attached to a Hornady Dial Caliper as shown below.  Please also note that for all CBTO values documented below, I would also need to subtract 1.0035” from every CBTO measurement to get the corrected CBTO length.

 

Example: I measured CBTO with the Hornady Bullet Comparator attached to the Hornady Dial Caliper and noted the value as 2.8200”.  To find the length that you will need to subtract for your particular tool to get corrected CBTO, close the Dial Caliper jaws all the way down with the Bullet Comparator Tool and the correct size comparator inserted and document the value of the Dial Caliper when fully closed, in the case of my particular tool this value was 1.0035” when fully closed.  So to find corrected CBTO I would then calculate 2.8200” – 1.0035” = 1.8165” CBTO.  If you are using a digital caliper, simply close the jaws and press the ‘Zero’ button on your calipers to achieve your corrected CBTO.

 

 

                    

 

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TIP:  Before you just run out and start reloading as many “test loads” as your budget will afford you, understand your wallet doesn’t have to take more hits than a gym punching bag before you find a load that works…there is a scientific method to this madness!

This week we are going to take a detailed look at why many seasoned reloaders use a SWAG to find their initial optimal charge weights before conducting a traditional 3/5/10 shot group of any particular designated charge weight(s).  For those who don’t know, SWAG stands for Scientific Wild Ass Guess!  A “Ladder Load” test is named for its unique characteristic of incrementing stepped charge weights resulting typically in noticeably incremental velocity and Point of Impact (POI) grouping analysis on the target in a sequential manner, such as the rungs on a ladder.  Conducting a “Ladder Load” test early on in your load development process for a new rifle or handgun can teach you a ton of valuable information in regards to where your optimal charge weights may be, what your maximum charge weights might be, where you are likely to begin encountering high pressure, and where your reloads may begin to show extremely dangerous pressure signs that if not identified can lead to serious bodily harm or even death in worst case scenarios.

 

Note: All of the referenced values, data, and/or observations noted above and hereafter are strictly dependent to the rifle, bullet, powder, primer, brass, and conditions in which this test was conducted.  These results are all to be used as informational only purposes for you to see how the before and hereafter mentioned reloading methods can be applied to your particular reloading methods and practices and none of the following data should ever be used without proper understanding of metallic cartridge reloading and the exercise of safe and SAAMI compliant reloading practices and procedures.              

 

 

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First, let’s cover what some of the goals are and the types of data we are primarily targeting for by conducting an Optimal Charge Weight test or a “Ladder Load”:

 

·         Identifying where our optimal charge weight(s) starting point(s) may be…

·         Identifying where our MAXIMUM safe charge weights may end…

·         Identifying where charge weights may begin to produce HIGH PRESSURES

·         Identifying where charge weights may begin to produce EXTREMELY DANGEROUS PRESSURES

·         Identifying whether or not our firearm/brass/bullet/powder/primer combination was a good choice or if you may be “off in the weeds” with your components selections…

·         Finding our best performing handloads in the shortest amount of rounds...

·         Finding our best performing handloads with the least wasted development costs…

·         We must ensure accurate and consistent results in order to avoid any “false positives”, so you should conduct this test with your firearm secured firmly into/onto a sled, tripod, or with a bipod/monopod

·         For the best results when conducting this test, you should conduct it at 300 yards…however, for this test I was only able to gain access to the 200 yard range on ‘test day’…

 

 

 

Next, let’s identify our firearm testing platform and understand why we have selected the components which we have “married” together for this delicate dance with danger!!!

 

First, the firearm testing platform…we have a Colt Competition with 18” heavy Match Grade barrel with a Vortex Viper PST 6-24x50mm scope and Vortex ARD Mount, Vortex Bubble Level, BT Industries (Atlas) front bipod and rear monopod, Magpul PRS stock, and many other creature comfort components that are too many to list.  Note: picture of firearm platform displayed below was from last winter, but is still in its below displayed configuration.

 

Besides just knowing both the basic physical and mechanical components that comprise this firearm platform we will be testing, we must also have a basic understanding of the accuracy of which this firearm platform is generally expected to operate at or is normally capable of.  For the case of this particular firearm platform, I already know that this rifle is routinely capable of ½ MOA average accuracy from using my tried and “trusty ole stead” recipe of Berger 77 gr. OTM bullets over the proper proportion of H4895 and CCI #BR4 primers.  If you are working up a new load for an old rifle, you will use your best recipe to date to “benchmark” anticipated accuracy against the new loads being developed.  If this is a brand new (or just simply new to you) firearm, you won’t have a benchmark accuracy to compare against…yet.  However, here is what you can expect as a general rule of thumb though.  Most typical mass production factory rifles are cable of 1.5 MOA or better straight out of the box these days with a few select types of quality ammunition.  Custom built firearm platforms will usually come with some sort of standard or guarantee of “1/x MOA” accuracy if they are a reputable builder.  Then there are those “other” guns…you know the ones that no matter how much load development you do, they just won’t ever get better than 2-3 MOA!  Whether it just be because you not so luckily got one of those “lemons” or you are reloading for a gun that just wasn’t ever designed for precision accuracy and was more of the suppressive or cover fire variants, you must establish and understand your reasonable expectation(s) for accuracy first.  If you don’t, you are just setting yourself up for a long, agonizing, and stressful process of failure in trying to achieve a set goal that just may not be possible for your particular platform.

 

 

 

 

 

Second, the equipment which we are using to make this “Ladder Load” test analysis possible so that you may see the results first-hand….

 

·         MagnetoSpeed V3 Chronograph

·         Kestrel 5700 Series Elite Weather Meter with Applied Ballistics

·         Bullseye Camera Systems, LLC. Bullseye AmmoCam Long Range Edition

·         Broken Box R LLC – “Ladder Load Test Target”

o   For access to our 8.5” x 14” printable “Ladder Load Test Target, simply sign-up for FREE to become one of our Reloader Rewards℠ Members at www.reloaderrewards.com and then accessing our online Reloader's Toolbox℠.

o   For complete details regarding our Reloader Rewards℠ Membership Benefits and our online Reloader's Toolbox℠ library, please click here now to explore our Membership Benefits.

 

 

 

Third, the components which we are attempting to “marry” together for this particular load development testing process…

 

·         Berger Bullets .224 77 gr. OTM…(bullets were all sorted by weight tolerance of +/-0.1 gr. to ensure maximum bullet weight consistency since our POI is VERY important during this test)

·         NEW Federal Lake City 5.56 Brass…(the only brass prep conducted on these cases was deburring the flash holes and uniformed the primer pockets for consistency)

·         Hodgdon Varget…(same Lot # was used for all test loads to ensure consistent burn rates)

·         CCI #BR4 Primers…(same Lot # was used for all test loads to ensure consistent burn rates)

 

 

 

Now, let’s get into the meat and potatoes of the “Ladder Load” test, what it looks like, and what sort of data analysis we were able to extract from this particular test…

 

First, we were able to successfully identify (2) potential Optimal Charge Weights from the following test…

 

·         Node #1 - ~20.2 gr. grouped around +/-0.50” vertical spread at 200 yds…Note: after shot #1 I had to readjust the Chronograph sensitivity back from pistol to rifle levels (why no MV was recorded) and I flat out just had a horribly bad trigger pull on this first shot.

 

·         Node #2 - ~21.6 gr. grouped around +/-0.75” vertical spread at 200 yds...Note: our Broken Box R LLC “Ladder Load Test Target” has markings vertically and horizontally at every ~0.50”

 

Now why did we select these (2) nodes???  When conducting a Ladder Load Test, we are looking for the closest cluster of impacts on the target within an adjacent sequence.  For example, in the below target we found shots 1-3 (20.0, 20.2, and 20.4 gr.) and shots 8-10 to be very closely clustered…we then find the median point of both of these (20.2 and 21.6) and we now have two presumed Optimal Charge Weight(s)!

 

·         Note: above we said a Ladder Load should demonstrate an incremental POI on the target such as climbing a ladder because we are increasing our powder charges incrementally thus increasing both the pressures and therefore muzzle velocities of each incremental charge weight tested also. 

 

o   PRO TIP #1: If you do NOT see any sort of noticeable vertical ladder rung stepping on your target, you may want to ensure your scale is properly calibrated and/or further examine all aspects of your reloading process to see where variations in your process may have been induced and therefore leading to the inconsistent and potentially erratic characteristics of the test results.  However, note that if your meticulous inspection conclusion finds that no particular aspect was at fault, re-run the same Ladder Load test to see if results are consistent.  If the results are consistently erratic, you have a rather definite conclusion that this particular “marriage” of components is NOT optimal and you should re-evaluate your choice(s) of components.  

 

 

 

Second, if we closely inspect our brass and primers now, we can also start to see the answers to many of our identified goals and objectives outlined above…

 

·         Identifying where our MAXIMUM safe charge weights may end and HIGH PRESSURES may begin…

 

o   In the case of this particular test, signs of our HIGH PRESSURES were already beginning to show in the primer/casing of the load marked (1) below as the primer is starting to flatten due to high pressures at the 21.2 grains of Varget in that particular load.  So, in this case our MAXIMUM safe charge weight is 21.0 grains for this particular load.

 

 

 

 

·         Identifying where charge weights may begin to produce EXTREMELY DANGEROUS PRESSURES

 

§  IF YOU SEE ANY OF THESE BELOW NOTED OR OTHER NOT HEREIN MENTIONED CHARACTERISTICS HAPPENING, IMMEDIATELY STOP LOAD DEVELOPMENT AND INSPECT AND DETERMINE WHAT IS GOING ON BEFORE SERIOUS INJURY OR EVEN DEATH MAY OCCUR!!!

 

o   In the examples of the two casings below, we see one casing that has yet to be fired and in its original condition and the other which shows multiple signs of dangerously high pressures:

 

§  Note when comparing the primer and primer pockets of the casing on the left to the casing on the right (Figures 1 & 2), the primer cup on the left is unfired and still in its original rounded form with a smaller diameter base to the cup.  The primer on the right that was excessively over-pressured has been flattened to the point where the primer cup is beginning to expand and flow outward filling into the primer pocket noted by the now much larger diameter of the primer cup base.

 

§  Note the half-moon marks on the head of the casing on the right (Figures 3 & 4).  This is where the brass casing was pushed back against the bolt face and extractor by way of the excessively high pressures resulting in a very well distinguished extractor mark at this dangerously high 22.5 gr. powder charge. 

 

§  Note the extreme flattening of the primer on the right (Figure 5.) when excessively loaded at the 22.5 gr. as opposed to the unfired primer on the left which is loaded below our MAXIMUM safe charge weight!  NOTE: THIS CHARGE WEIGHT WAS ONLY CONDUCTED BY A PROFESSIONAL IN ORDER TO DEMONSTRATE HOW RAPIDLY PRESSURES MAY SPIKE WITH JUST A +1-2 GRAIN CHARGE WEIGHT VARIANCE…NEVER ATTEMPT SUCH TESTS AS THIS BEYOND THE FIRST SIGNS OF HIGH PRESSURES DURING YOUR LOAD DEVELOPMENT PROCESS!!!

 

 

 

 

 

Next, let’s go back and take a little closer look at the (2) potential Optimal Charge Weights we identified above…

 

·         Node #1 - ~20.2 gr. grouped around +/-0.50” vertical spread at 200 yds

·         Node #2 - ~21.6 gr. grouped around +/-0.75” vertical spread at 200 yds...

 

Now, let’s clearly outline and analyze ALL the data we have from this test and see what our results are…

 

·         MAXIMUM safe charge weight…21.0 gr…

·         HIGH PRESSURES began to exhibit…21.2 gr…

·         Node #2 at ~21.6 gr. grouped well at +/-0.75” vertical spread at 200 yds; however, this powder charge exceeds our MAXIMUM safe charge weight determined to be at 21.0 gr…therefore…

·         OPTIMAL CHARGE WEIGHT...must be ~20.2 gr which is well under our Maximum safe charge weight and incidentally also provided the least vertical spread of 0.50” at 200 yds. 

 

 

 

What do we do now that we have established our initial Optimal Charge Weight from our “Ladder Load” test???  Now you have a bit more load development ahead of you to begin optimizing seating depths, tweaking your case prep practices, crimp, neck tension, and so on and so forth in order to find that very best 3/5/10 shot grouping that this particular load is capable of producing at a given distance.

 

So what is the moral of this story folks...ALWAYS access ALL relevant data and conduct a thorough analysis BEFORE establishing a basis for your conclusions.  Doing so will keep you on target and SAFE to shoot and reload yet another day!!!  

 

If you are interested in reading more in-depth about the Audette “Ladder Load” test method and other methods such as that by Dan Newberry called the Optimal Charge Weight or OCW test, please click on the following link:

           

Audette ‘Ladder Load’ vs. Newberry ‘OCW’ Test Methods…

 

 

         

 

 

For any additional questions regarding information or to purchase your Kestrel 5700 Series Weather Meter, MagnetoSpeed Chronograph, or a Bullseye Camera Systems please click on the following link for Broken Box R LLC’s website as we are an Authorized Dealer for both the Kestrel and MagnetoSpeed product lines or give us a call at 888-869-3150 Ext. 1 today!

https://www.brokenboxr.com

 

 

 

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Do you have a Tip or Trick regarding reloading that you would like to see posted?  Please send us your Tip(s) or Trick(s) and we will see about getting them posted!

 

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Written By:  Kyle R. CEO of Broken Box R LLC

 

Copyright © 2016 Broken Box R LLC – All Rights Reserved

This article was first published on November 17th, 2016.