Incremental Load Development Details

[Stugotz]

When shooting a "ladder Test", How long do you wait between shots? I'm thinking that it's gonna take about 3 shots to get on paper at 300 Yds and to foul the barrel. I'm planning to load 15 rounds for the test, but I don't know how High I'll get before I start to see pressure. If I'm able to go the full 15 with no pressure signs, 18 consecutive rounds without letting the barrel cool will probably get it mighty hot. On the other hand, I've been reading that waiting more than a minute between shots often causes the following found to fly out of the group. The barrel is 30", 1.250 dia for 6" then tapered to 1.139 at the brake. Your thoughts???

 

[mike in co]

depends on how your load heats the bbl.

some of my loads i do 1 min, some only 30 secs.....my latest was 2 min !
it was a 7rem mag in a factory hunting bbl with 4831 and heading for 3000 fps with sierra 168 match moly. how did the long time affect this ladder ?

shots 3,4,5 and 6 ( 0.7 gr steps) formed a 0.204" group at 100 yds.....

mike in co

 

[Stugotz]

Lynn,
I saw that you did Calfee's "cooked round" test. Will this have any influence on how you shoot your next ladder test time wise?

 

[Stugotz]

Lazzeroni Patriot. 240 Gr. Sierra. Planning on starting at 60gr. RL22 and working up in .5 gr increments.

 

[mike in co]

depending on the scope/power and distance, you may benefit from a "cross" instead of a dot. i find the long cross allows me to ensure i have not tilted the rifle.
i simply log each shot on a target at the bench....the cluster gets very obvious...sometimes more than one.

1% of case volume for the ladder, can then be fine tuned once you find the cluster/s.

mike in co

 

[Stugotz]

I agree Mike, a "cross" works better for me as well. I'm sure it's largely mental, but I shoot better when there are straight lines to reference as opposed to just a single dot. I also received last night some of the Caldwell "orange peel" targets that are 12" X 18". My plan is to draw a "cross" in silver sharpie near the bottom. I'm hoping that the orange peel's will make it easier to determine point of impact at distance.

 

[runningbear]

I am fairly new to this forum and while browsing I never heard of a ladder test before. Could someone explain it further for me? Do you actually shoot just one round at each increment? Thanks for your explanation.

 

[Stugotz]

Here's a link to an article by Randolph Constantine from the 1997 Precision Shooting Annual. I've read it about 10 times now. Each time it seems to make a bit more sense.......

http://www.washtenawsportsmansclub.org/groups/cba/downloads/incredload.pdf

Yea Runningbear, you only need one round at each charge weight. Take a look at the link above, it should get you started.

 

[mike in co]

I am fairly new to this forum and while browsing I never heard of a ladder test before. Could someone explain it further for me? Do you actually shoot just one round at each increment? Thanks for your explanation.

yes

typically 1% case vol increments from low to max listed.

you maybe able to go higher..all rifles are different.

the shooter is responsible for his safety,
the object is to fine a node or two( where group/clusters form) and then fine tune from there.
200 yds is better than 100...eaisier to see clusters.....
part of the process is to foul the bbl, and then shoot the increments in the same time interval( same bbl condition/heat)

mike in co

 

[Stugotz]

Mike and Lynn, Need Some Help...

I guess I should have listened to Lynn and loaded 20 rounds to bring with me. I only loaded 10 and ran out before I showed any pressure. The chrono #'s are below. RL22; 240 Sierra MK; Lazzeroni Patriot; Range is 300 Yds. The silver lines are 1 inch apart........

59.5 2458
60.0 ERROR
60.5 2516
61.0 2538
61.5 2560
62.0 2571
62.5 2607
63.0 2621
63.5 2638
64.0 2653

These are the first round of shots after fireforming. Fireforming loads were avg. 2630 FPS with 61.0 Gr. Is it common for velocity to go down this much after the cases are fireformed?

I'm going to load a little higher to figure out where max load is and hopefully find a spot where 4 or 5 group together, but assuming that does not happen, I'm guessing that the load to go with would be 61.5 Gr? (shot #5).

Thanks for your help!

 

[Stugotz]

Thanks for the advice Lynn. I'm going to try to make it back to the range tomorrow.

I was fireforming with the same bullets (different lot, and the bearing surface on these are a bit longer) and the temp was about the same on the day i shot the fireforming loads over the chronograph. This is a different lot of powder as well, but I didn't think that would account for 100fps diff in velocity.

Will see what happens when when I get back to the range.

 

[chino69]

Ladder test question

On your ladder test it seems to have come out pretty well.Shots 1,2 and 3 are the only shots that are really clustering.From your chrono numbers it looks like you stopped right before the next cluster.It looks like 0.5 gr of powder was giving you roughly 30 fps of change and your last shot was only an increase of 15 fps.I would load up 20 rounds starting at 59.0 grains and go up until you reach pressure.I suspect one point at the beginning of your test and the next one right above were you quit.
As an observation if you look at your first 3 shots
you will see very little vertical for 300 yards especially when you consider you had 1.5 grains worth of variance in the powder charge.I would load 10 rounds at load #2 and make some 3 shot groups.
Lynn

Lynn,
Why would you choose the first cluster (1,2, & 3) instead of the second cluster (4, 5 & 6). It seems to me that the load for round #5 would be the one tp try. Am I missing something?
Chino69

 

[mike in co]

Lynn,
Why would you choose the first cluster (1,2, & 3) instead of the second cluster (4, 5 & 6). It seems to me that the load for round #5 would be the one tp try. Am I missing something?
Chino69

cause...4,5,6 are all vertical changes...further out more change.

1,2,3 are more of a cluster than a vetical line.

nothing wrong with 456 for short range, but not for long range

mike in co

 

[chino69]

Ladder test answer

In a ladder test you are only interested in the vertical.Shots 1 2 and 3 show about 0.250 of vertical for a 1.5 grain change in powder charge.Shots 5,6 and 7 show about 3/4 inch for the same amount of powder.
If you doubled the distance to 600 yards alot of shooters would die for 1/2 inch of vertical.You won't find anubody getting excited about 1.5 inches.
Lynn

Lynn and Mike,
Thank you as I misunderstood the idea of a ladder test. The key here is the vertical distance and I will be using this method shortly. A little explanation goes a long way. I understood the basic concept but missed the part about the vertical.
Chino69

 

[taxman]

Thank you

Guys,

This is the easiest explanation I have read for understanding the ladder test!!

Thank you!

Tony

 

[Stugotz]

.......I have run ladder tests all the way to 1,000 yards and they are still the way I determine my powder charge,BUT you will still have to play with the seating depth to get the groups in nice little clusters.......


Lynn

Lynn,

I didn't get to post a photo of the 2nd ladder test that I did, but I found another group of three shots that clustered nicely at 64, 64.5 and 65 grs and have been shooting that for the last couple of weeks. Will you elaborate a bit on how you "play with seating depth"? So far, all testing has been just touching the lands and I want to see what happens with changing that up a bit. Do you load up 3-5 round groups at various depths and just start shooting groups. Seems like this could take much more rounds than the ladder test.

 

[Stugotz]

Thank You

 

[dan newberry]

OCW is superior to ladder tests...

OCW or Optimal Charge Weight (admittedly my own system) is a more reliable way to arrive at the best powder charge for the bullet and powder combo you're using.

www.clik.to/optimalchargeweight

...on the left of the main page, click on OCW versus ladder test... there you'll find some information helping you understand why ladder tests often fail to yield any usable results, or worse yet lead you to the wrong conclusion.

It is entirely possible to use a non-optimal load and get good accuracy, and you may even win a match or two with it.

But an optimized load will be more resistant to slight pressure changes brought on my temperature swings, slight powder lot variations, odd brass cases, etc.

Dan

 

[dan newberry]

Mike,

You're not understanding OCW. If you believe the ladder test can work (and it of course can), then you're looking for the same three charge increments with OCW--you're just more likely to find the true sweet spot with OCW than with ladder.

The round robin firing sequence of OCW factors out the effects of a fouling and heating barrel, whereas the ladder test disadvantages (or sometimes advantages) the same charge weight range because that particular range is always being fired through a barrel in the same condition of foul and temperature. OCW negates this by plotting shots on the target from the same charge weight but in varied bore conditions. This is of vital importance to the resilience of any load recipe--it must perform the same from a perfectly clean, cool barrel as it does from a fouled and/or warm barrel. .

A perfectly executed ladder test where no false leads enter the string will lead you to the same charge weight OCW will lead you to.

It's just that with OCW, you're factoring out the error potential to a much greater degree than you have with a standard ladder--and you're more likely to arrive at the optimal charge weight.

There is absolutely no difference in the seeking of the best hunting load as opposed to the best BR load--we're always after the highest accuracy potential available.

I'm not sure what you think OCW is, but you're obviously mistaken as to its method and goal.

Edit to add: You mention that my OCW method starts with 36 rounds and 7 targets. It doesn't. Generally, it's only 5 targets and less than 20 rounds. I think someone has given you bad information about OCW...

Dan

 

[dan newberry]

again you can beat your drum all you want, but it is not an apropriate method for most benchrest shooting.

Mike, respectfully, that is the kind of arrogance that is found too often in BR circles.

For any others who want to understand what OCW accomplishes, let me put it in this nutshell:

OCW is essentially a multiple ladder test, with the emphasis on round robin firing which spreads the error factor introduced by a heating and fouling barrel across the entire spectrum of tested charges. (Now why wouldn't you want that?)!!

With the ladder, your higher charges are always going to be being fired through a fouled and/or very warm barrel. With OCW's round robin sequence, the effects of barrel heating and fouling are factored nearly completely out.

It's an easy process to understand, and it will work just as well with high dollar rifles shooting 1/4 MOA or smaller groups as it will with factory grade stuff.

Over and out for now...

Dan