Ladder Test for finding powder charge

[Frequently Banned Troll]

Ever done that? Was it a good use of time?

I’m trying it for the first time this weekend. Two rifles, same caliber (6.5prx) 2 separate loads - every component is different. I’m hoping I can hone in on a good recipe in 2 times out shooting. Will see.

I’m going to shoot at 300m because parallax is that for the optics but will plot both impact and velocity.

 

[Nicoli7153]

I've done it for different bullets in my .308. Gave me a good understanding of pressure and velocity in that particular gun using different powders, primers and seating depth. Gave me a good idea what the gun likes/dislikes

 

[Wind Gypsy]

I've done ladder testing and used to do a lot of OCW testing, i dont believe i ever got to a position where either gave me particularly repeatable results of a charge weight being truly being the "best". I haven't messed with doing them beyond a 1 shot per charge weight ladder for velocity/pressure info in a while.

Load dev has went from OCW or Ladder testing to just picking a bullet/powder and finding an acceptable velocity a fair margin from pressure. If it doesn't shoot well, change bullet or powder. Occasionally i'll try 2 or 3 different seating depths with 10 rounds at each to see if there is an obvious difference. Usually there isnt.

 

[Sheltowee]

I ladder test nearly all of my handloads and have found it to be an effective way to find the most efficient load in a given cartridge/projectile combination. For most cartridges in the .308/.30-06 class, I will start at about 92% of recommended max charge and work up 2% with 10 rounds at each step. If I'm not satisfied with velocity, SD or ES, I'll slowly work up past 100% of max. Gives me a decent idea as to ES/SD but true statisticians will tell you that it is too small of a sample size. Then, I'll select a given load balancing raw velocity with SD and ES.

I've found pretty significant variances between steps using this method. For instance, variance of 42% in SD, 40% in ES with the 25-6.5 load charted below.

25-6.5 PRC, 127gr. HHT, H4831sc, ADG brass, 2.830" COAL, 2.283" CBOL

	Average Velocity(fps)	Extreme Spread(fps)	Standard Deviation(fps)	Best 5-shot/3-shot group
Load 1	2709	46	21	--
Load 2	2735	25	8.9	--
Load 3	Chrono Failed	--	--	--
Load 4	2792	51	14.9	.805/.159
Load 5	2825	60	15.6	.755/332

25-6.5 PRC, 127gr. HHT, H4831sc, ADG brass, 2.830" COAL, 2.283" CBOL

	Average Velocity(fps)	Extreme Spread(fps)	Standard Deviation(fps)	Best 5-shot/3-shot group
Load 6	2887	45	14.1	1.064"/.468"
Load 7	2937	62	20.6	.573"/.342"
Load 8	2977	28	9.2	.487"/.284"
Load 9	2993	36	11.9	.810"/.389"

The method promoted by Hammer Bullets is to load a round or two, increasing in constant steps, stopping when you start to see pressure signs (cratered primer, heavy bolt lift, etc.), then back down a half grain or so. That is certainly faster but I don't love it for identifying the most efficient load.

 

[Ben Lamb]

I have a small star wars notebook in my range bag that has a little girl giving darth vader flowers that I keep all my ladder testing notes in, not some spreadsheet like a dork.

It's a great way to help find that accuracy node. I've done it with every rifle I reload for, except one 30-06 that shot my standard reload to about 3/4 inch. About to jump back into testing on a 7PRC. Brass & dies will be here Monday!

 

[Carl]

I'll use a ladder occasionally to find pressure and velocity for a new combination (usually loading at the range instead of at home).

I don't use them anymore to find accuracy, personally.

 

[Mallardsx2]

 

[Sheltowee]

Yes Duckman, I've found ladder tests to be more effective than loading purely off of vibes. You do you, though.

 

[WapitiBob]

I do 1ea in 1gr increments at 100. If it isn't going to shoot, you'll see it.


I pick the best 2gr spread, then 3ea and look at vertical and group clocking


overlay of 70 and 70.5


Verify it groups at distance, done with less than 30 shots


this combination sucked

 

[Drake4]

Used to do them as well. I found way better and quicker results if you stretched out the distance to 500 yards or so though.

 

[Carbon]

I'll use a ladder occasionally to find pressure and velocity for a new combination (usually loading at the range instead of at home).

I don't use them anymore to find accuracy, personally.

Same. I found that once I started buying better barrels it didn't matter in accuracy.

 

[300stw]

i do 300 yards, 1 grain increments to find highest safe velocity,
then .2 grain increments starting at max going downwards, maybe 1.5 grains, 3 shots each, and watching how the horizontal string is,
if a gun with a clip i load to max oal for the clip, which may be way different then actual oal to find the lands in the barrel,

if a load shows great horizontal, i start changing seating depth .003 at a time,
i have 2 of the howa, randy edition 6.5 prc, 1 was easy to load for, solid .7 moa gun, the other, took about 100 rounds,
2 diff bullets, 2 diff powders, 2 diff primers, its real finicky on seating depth

 

[slatebuilder]

I use ladders to find pressure when loading something with minimal data available.

 

[Irrelevant]

I'll ask a dumb question, what else are you guys doing if not ladders?