Quote:
Originally Posted by lclund1946
You are right in that groups are a poor method to "begin" load development at any range as you will burn up a lot of components unless you get lucky. I believe that people confuse ladder testing and group testing, as you suggest, and overlook the usefulness of the ladder test as they dismiss it without fully understanding how to use it. I will attempt to better explain what I learned from the ladder test and how it led to the 4 groups that I shot and what I can read from them as far as how they will perform out to 500 yards which is what the load is designed for. I did not use a chronograph in this ladder but the Lab Radar
would have confirmed, as it did in Targets#2 , the moderate pressure increases from shot#1-#4 and the pressure spike (39fps) at shot #5 followed by a very moderate velocity increase with shot#6. This pressure spike indicated that the Rem brass was getting close to being fire-formed to my chamber and measurement of the Base datum showed only about 0.0002" spring-back from the chamber. This and primer flow of about 0.0025" indicated that I had reached my maximum for this load even though I had no sticky bolt lift or flattening of primers.
Looking at shots #1-6 there was only 0.1" vertical which told me that any of these shots would likely keep vertical POI to 1/2" at 500 yards. Shots #7,8 &9 (Full) showed that I had passed the potential with Varget but was still in the safe range with no pressure problems. Shots #4, 5 & 6 showed that these loads had the potential to shoot 0.3" groups at 500 yards. Target #3 confirms the potential 0.3" vertical to 500 yards but the ES may be a bit high to maintain that to 500 yards. This load will be on target with 3MOA to 300 and 8MOA to 500 and will surely take out a gopher or coyote. Hopefully Lee (triple duce) will get a chance to confirm this when he gets back from Kamloops. Good luck this weekend!
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Thank you for drawing attention to the key word “begin” in my post # 28, and support for my suspicion of common confusion regarding methods, procedures and terminology for load development. IMHO, there is a definite need for group testing during load development, I just do not start there.
I share your preference for initial testing using single shot / increment ladder procedure.
This does require consistent loading & shooting skills, (which are most often developed by shooting lots of groups).
I note that you report using ~.5% powder charge increments, but no reported target distance/range, (I suspect 100yds).
IMHE, I find Audette ladders shot @ >300yds to be easier to interpret, and certainly more illustrative of barrel harmonics.
I try to obtain the maximum usable information from each shot, and submit this provides the most cost&effort / benefit.
IMHE, 15 shot Audette ladder provides much more information than 3x5 or 5x3 groups, and a full 15 group series will require 45-75 shots.
I am curious how you measure your reported .0025” of primer flow?
and also of your use of PRE (pressure ring expansion) and CHE (case head expansion)?
I note that PRE & CHE are somewhat controversial
https://www.shootingsoftware.com/ftp...%2019%2004.pdf
and would appreciate your opinion and measured experience.
and also how you manage and store the large volume of measured data that you collect?
Good Luck, YMMV.