What load development is best for factory rifles?

Discussion in 'Reloading' started by 243yote, Mar 9, 2010.

  1. 243yote

    243yote Well-Known Member

    Messages:
    77
    Joined:
    Apr 2, 2009
    The ladder test is a good article but it looks like from the pictures shown that the rifles used are customs jobs that the average guy could not afford with a mortgage, kids and understanding wife ,etc. So what would i look for in the average load development at 100yds? I have tried the ladder test and found my results to differ from the published data as i shoot a factory rifle out of the box. Plus the extra expense of firing so many rounds to develop a load? My loads were not as published because the loads were scattered. I shot from a solid shooting rest on all the load development. I changed nothing from OAl to powder or primers. They all grouped about 2 1/2 inches at 100yds. From the recommened start to max load. Most of the grouping was to the left and some were lined up dead center but high at 100yds. Some loads were touching which were about 1 gr apart and some would be about 1" apart or more that were 1/2 gr aprt? Loads were 1/2 gr apart on development. I did not change from my previous zero which was at 200yds. So what would i be looking for ? Am I missing some thing here?:rolleyes:
     
  2. Fitch

    Fitch Well-Known Member

    Messages:
    478
    Joined:
    Aug 5, 2009
    Forgive me if this is an incorrect assumption, but I'm assuming you are new to reloading.

    I've never used the ladder test myself. I've read about it but I haven't tried it. It is a good theoriticallly sound approach, I just don't use it.

    What I do first with a new rifle for which I'm going to do load development is go over it with a fine tooth comb to make sure it doesn't have any obvious problems. Load development is expensive in time, reloading components, and most importantly barrel life. If you do the math, it costs 25 to 50 cents a shot for barrel life on a .22-250 depending on the barrel and loads being fired. About half that on a .30-06, more on a Swift, even more (sometimes a lot more - like a buck a bang or more just for barrel wear) on some of the high powered rifles folks have built. So it is important to spend load development rounds wisely.

    That being the case, I do a lot of research into what I want to accomplish with the rifle. The hunting mission requirements are the key. They lead to choice of caliber, and bullet. Bullet choice is a major decision - load development is bullet specific - what works for one bullet seldom works for another. I use Mantuna's equations to pick bullet weight, manufacturers data and other shooters data to choose bullet type.

    Once the bullet is chosen, powder choice is next. I look at the impact of powder choice on barrel life, availability. My tools for powder choice are QuickLOAD, the bullet manufacturer's manual, and ballistic software.

    I don't shoot any magnum rifles so I use non-magnum primers.

    With the bullet and powder choices behind me, I put a high powered (8-32x40) scope on the rifle to use for load development only. It helps eliminate my old eyes as a load development issue. I hunt with different scopes but changing scopes hasn't ever cause a load to go bad, for me at least.

    At the range:

    I load 6 rounds at the starting load. 3 rounds for each group in 1/2 grain increments across the range I've choses from starting to max. I do my loading at home - if I start to see pressure signs, any pressure signs, I just pull the bullets on the remaining rounds.

    I do all my load development testing shooting through a chronograph. I make a written record of the velocity of every round.

    I shoot 3 of them as fouling shots and to make sure I'm on paper.

    Let the rifle cool. Then shoot carefully held and fired 3 shot groups letting the rifle cool to ambient temperature between groups. Each group is fired at it's own bullseye.

    By carefullly held and fired, I mean I have an inordinate fixation on the basics. Breathing, squeez, sight picture, being in a good comfortable position, the whole 9 yards. Pretend each shot is the only shot. If the groups aren't fires as carefully as possible, they are a total waste.

    I take the target home, take a digital picture of it and use the free OnTarget software to analyze the groups. I type the data into EXCEL and make plots of muzzle velocity, max width, max height, and average group radius as a function of powder charge. I just do it. I've found there is a lot more information in a target than most folks get out of it. I've invested in the test, the target and the chronograph readings are all I have to show for that investment. The data is paid for, the benefit comes from analyzing it and thinking about it.

    I'm looking for a lot of things when I analyze the target. How does the velocity vs powder charge look? Is it linear over the range or starting to round over? How do plots of dimensions look as a function of powder charge "and" as a function of muzzle velocity? In general, how does the powder/bullet combination shoot? What's the average of the group statistics over the whole range?

    The results of this analysis are the basis for continuing with this bullet and powder, changing powders, changing the bullet, etc.

    Once I think I have the load developed, I'll shoot five 3 shot groups of "the load" with cooling between groups, again chronographing each round to get a good SD number over 15 rounds. The first group is from a cold clean bore. The first group is very important - it is where the rifle will shoot if it hasn't had any fouling shots through it. I've been known to go back to the range and do a couple more cold clean bore groups at ranges out to and a 100 yards beyond where I expect to take my shots just to make sure I "know" where the rifle is going to shoot that first shot.

    I also invest more rounds of "the load" into shooting at expected ranges to develope my scope settings. I use external ballistic software to get a hypothetical drop card, then fine tune it at the range. Again, the SW is used to minimize the number of rounds it takes to get it "right".

    The trick is to get this all done right with out using up too much of the barrel life. Once the load is done, load up a hundred of them and spend them wisely.

    That's what I do. It works for me for developing hunting ammunition. Load development is to a large extent a personal process - different folks do it differently. If what one is doing works, go with it. If, as in your case, it doesn't seem to be working, perhaps some changes will give a better result. Hopefully you will get other input so you have some approaches to pick and choose from.

    Fitch
     
  3. J E Custom

    J E Custom Well-Known Member

    Messages:
    8,194
    Joined:
    Jul 29, 2004
    Good Advice !!!

    If you don't have a chronagraph I would Just try to match the bullet to the type of hunting
    and the rifle it's self (Light barrel,light bullets). Light weight factory barrels barrels on average
    shoot the lighter bullets better because of barrel torque and harmonics.

    What you want is the best 3 shot group (Size) and don't worry about where they hit because
    once you have found the most accurate load you can adjust the POI.

    The factory barrels will rarely shoot as well as the custom barrels and are much more finicky
    to the type of loads used.

    J E CUSTOM
     
  4. Moman

    Moman Well-Known Member

    Messages:
    827
    Joined:
    Feb 7, 2008
    Fitch, very impressive write up of load develpment. Would you mind elaborating just a little on how you analyze the target information? Never heard of OnTarget.
     
  5. Fitch

    Fitch Well-Known Member

    Messages:
    478
    Joined:
    Aug 5, 2009
    Thanks. I learned about the OnTarget SW here:

    OnTarget Software

    Data from a load development session will look like this after it's been analyzed in OnTarget:

    [​IMG]

    The data for each group includes CTC which is the max center to center distance in inches and MOA, ATC = Average distance from the bullet holes To the calculated Center of the group. The max width of the group, the max height of the group, and the vertical and horizonal distances from the point of aim to the calculated group center.

    Looking at this target it's pretty easy to see groups 3 and 4 are about as good as it gets for a first pass at load development - in fact they are "good enough". On other targets it's not so easy to see. I fired these groups on December 16th, it was cold, windy, and I didn't have my chronograph, but I know this rifle well so I went ahead with it anyway. That little CZ is a heck of a good rifle. I want the 55g load for coyotes. I use 40g NBT for groundhogs.

    I'm out of time at the moment - my bride of 41 years is dragging me off to buy fertilizer for the lawn - the sun is shining, she's thinking spring and it's going to rain so she wants the lawn fertilized. I scraped up a couple of tons of equine waste out of the barnyard this morning (I love skid-steer opportunitities) - but I think I just got her started ...

    Fitch
     
  6. 3degreesbelow0

    3degreesbelow0 Active Member

    Messages:
    37
    Joined:
    Oct 26, 2010
    .243yote, the purpose of the ladder test is to save components and money, you are trying to determine your barrels harmonic sweet spot or node, the barrel oscillates in a figure 8 the sweet spot would be the barrel being at the center of the 8.

    For the Load your developing you load one round for each powder charge from minimum to maximum, you fire them at 300 yards if you can or 200 if that is all that is available the farther away the better because it will amplify the barrels harmonics. You fire them one at a time at the same target, recording the location of each hit, this is important you need to know what powder charge is for each bullet hole.

    you should have a pattern not a group, in the pattern there should be a couple of rounds that are very close to each other clustered, You then take what those powder charges that are close to each other and load 3 rounds for those weights, shooting for groups at 100 yards like you would for common sight-in. Take the best group of those and adjust +/- 0.2gr in small cases or +/- 0.5grs in large capacity cases shooting 3 round groups for those. That should develope the best potential load for your gun in that bullet/powder combination.

    The advantage is you only shoot 3 shot groups on the powder charge that your rifle harmonics are most consistent with, instead of every powder charge as you are working up.
     
  7. boomtube

    boomtube Well-Known Member

    Messages:
    1,595
    Joined:
    Oct 8, 2007
    Ahhh...really don't think the Ladder test, or any other method, can tell the difference between custom and factory rifles. ??