Ladder Test Results...need help analyzing.

[jtkratzer]

Shot my first two ladders today, nothing changed but the powder. Both shot at 300 yards, plotted each shot on a target at the bench indicating the impact with the powder charge for that shot. No signs of excessive pressure for either powder. Rounds were fired at the same aim point with two targets hung vertically to catch all the rounds. Aimed at the center of the top target.

260 Remington
140 gr Berger Hunting VLD
Nosler Brass
BR2 Primers

Powders:
H4350 - 41.5 - 44.5 grains
RL22 - 43.0 - 46.6 grains


Here's the result of the H4350. Rounds fell onto both targets. 44.2 grains is down toward the bottom.

And the RL22. They all fell on the second target.

I know 300 is usually the minimum for a ladder, and I'm wondering if there wasn't enough range to really spread them out. I'm surprised that none of the rounds of H4350 impacted higher than the lowest powder charge. My other 260 likes a max load of RL22. 45.7-46.6 of RL22 looks like it's work exploring. 42.4 - 43.6 in H4350 looks like something to try, just not sure I'm going to get the velocity I want from that charge. These were not shot over a chronograph.

 

[azsugarbear]

Shooting two or even three targets at the same time with the same loads is the best way confirm nodes. Without a second or third target to confirm results, an accidental grouping could be confused as a node. But if one target is all we have, I will be the first to stick my neck out.

With the first target, there appears to be a definite node with the H4350 between 41.5 and the 42.1 grains. Not sure what velocity was produced, but the grouping looks to be sound. There is a second potential node in the 42.7, 43.0 & 43.3 triangle. But experience tells me that having two nodes that close together doesn't make sense. One node is bogus, the other real.

The second target with the RL-22 is a tougher read. At best, I would it inconclusive. Wish I could be more help. Always shoot at least two targets. That way if a node is questionable on one, it can usually be confirmed or discredited with the result on the second target. Wish I could be more help.

 

[Mikecr]

I just don't see anything useful there.
Why are the increasing charge impacts falling lower & lower?

 

[jtkratzer]

Shooting two or even three targets at the same time with the same loads is the best way confirm nodes. Without a second or third target to confirm results, an accidental grouping could be confused as a node. But if one target is all we have, I will be the first to stick my neck out.

With the first target, there appears to be a definite node with the H4350 between 41.5 and the 42.1 grains. Not sure what velocity was produced, but the grouping looks to be sound. There is a second potential node in the 42.7, 43.0 & 43.3 triangle. But experience tells me that having two nodes that close together doesn't make sense. One node is bogus, the other real.

The second target with the RL-22 is a tougher read. At best, I would it inconclusive. Wish I could be more help. Always shoot at least two targets. That way if a node is questionable on one, it can usually be confirmed or discredited with the result on the second target. Wish I could be more help.

You mean shoot the same ladder rounds on two separate targets to ensure credibility of the results?

I'm not sure what you mean otherwise. I was trying to follow the first step of the ladder test here:
Long-Range Load Development

Just trying to find the accuracy window to start doing smaller powder increments around the nodes and shoot groups.

I just don't see anything useful there.
Why are the increasing charge impacts falling lower & lower?

No idea. That's why I'm here asking questions because I did not get results that are easy to see like on the link above.

 

[green 788]

You'll be much better off shooting an OCW test...

OCW Overview - Dan Newberry's OCW Load Development System

Shoot it according to instructions at 100 yards, and properly interpret your data... and you'll have the load you're looking for. I've been doing this over a dozen years, and never once has a properly conducted and interpreted 100 yard OCW test failed to produce a load that shoots tight at long range.

You can tighten ES by ancillary methods after you get the powder charge sorted out--which again, can be done easily with the Optimal Charge Weight load test.

Dan

 

[azsugarbear]

jtkratzer,

That's exactly what I meant. Load at least two rounds with same amount/grains of powder. Shoot the first round at target A and the second round at target B. Work up the ladder accordingly. Anyone can pull a shot - making a node appear where one does not exist, or destroying evidence of a potential node. But the chances of pulling the same shot twice in a row with the same powder charge are pretty remote. The second target allows the shooter to confirm or verify the results of the first target.

 

[Reynolds02]

41.5-42.1 looks good in the H4350, 2nd target would tell for sure

 

[justgoto]

I just don't see anything useful there.
Why are the increasing charge impacts falling lower & lower?

I'm thinking maybe the order of the cartridges were reversed?

 

[jtkratzer]

They weren't. I can see how that seems possible, but unless my wife or nefarious two year old "helped" me by resorting, I loaded them with increasing charges and they went into the ammo box as I loaded them.

I will probably try other powders and/or bullets before setting my load on the minimum charge of H4350. There's a lot of empty space in there and while accuracy is paramount, the velocity I'm expecting to see from that charge isn't going to give me the energy to make this a viable load for deer beyond 500 yards.

I'm optimistic about finding something that will get the Bergers into the 2850-2950 velocity. I'm getting 2900 out of a 20" tube with 129s, seems reasonless to get around that with 4 extra inches of barrel and being able to seat the bullets significantly farther out.

2500 fps with the Berger 140s limits me to 550 yards to stay about 1800 fps and 1000 ft lbs.

 

[Mikecr]

Never seen it upside-down. Did you keep barrel temps stable?

 

[Robinhood493]

Never seen it upside-down. Did you keep barrel temps stable?

I would like to see the answer to this. I also often see increasing charges go down on paper instead of up. Doesn't make sense to me.

 

[Mikecr]

It's common in ladder testing for SOME higher charge shots to impact lower by region.
Same with varying horizontal.
But not all & with such a strong trend right down the targets..

So I don't believe much of the results shown so far.
IMO, there are other factors invalidating this test.
Maybe bad primer striking, bad seating choice, varying barrel or powder temps, bad scope, bad rest/hold, big headspace variance, big neck tension variance, questionable organization.

Some things just need to be taken care of before benefiting from ladder testing.

 

[azsugarbear]

I use a modified ladder test in developing my loads. Testing via the ladder approach can use up a lot of bullets and barrel life. So I use Kirby Allen's method, then follow up with short ladder to confirm results.

Kirby Allen, a well-respected gunsmith on this site, develops his loads by finding the max powder charge where max velocity/pressure is achieved - usually exhibited by a slightly sticky bolt lift. He then back off two grains - and that is his load. This method has its share of critics, but I have found that in shooting a ladder test there is a node near the top or peak of the pressure curve.

So that is what I do. I load up a single round with a specific charge and then load subsequent rounds with a 1 grain incremental increase. When the bolt lift gets sticky, I stop. I then back off two grains and the load up enough rounds for a short ladder test. For example, if max load is 65 grains, then I back off to 63 grains. I then load a ladder test in .3 grain increments starting at 61.5 on up to 64.5. I almost always find a node somewhere within this spread.

I have found this method saves both time and money. To each his own.

 

[jtkratzer]

Never seen it upside-down. Did you keep barrel temps stable?

Yup, and the bore wasn't shinny clean when the ladder was started. And I gave 2-4 minutes between shots so the barrel wasn't anything more than barely warm to the touch.

IMO, there are other factors invalidating this test.
Maybe bad primer striking, bad seating choice, varying barrel or powder temps, bad scope, bad rest/hold, big headspace variance, big neck tension variance, questionable organization.

Some things just need to be taken care of before benefiting from ladder testing.

Let's discuss those things that need to be taken care of:

Savage Model 10 Predator Hunter with the action properly torqued using a FAT wrench into an aluminum bedding block. Barrel is a 24", probably varmint weight, fluted, 1:8 twist.

EGW base was torqued to 15 in lbs.

IOR V-TAC steel rings torqued to 65 in lbs to the base.

Rings were torqued to hold the scope at 12 in lbs and done in a rotating order from completely loose to tension, to torque spec.

Action was leveled from the Picatinny rail. Scope is a Vortex Viper PST FFP 6-24x50 EBR-1 MRAD and was leveled using a plumb line.

Front and rear rest were used.

I don't think there's anything missing on the rifle.

As far as the loads...all trimmed to the same length. All charges weighed on a digital scale to the 1/10th of a grain and measured twice if the pan didn't return to 0.0 on the scale after charging the case.

Bullets are Berger Hunting VLDs, loaded to 0.001 off the lands after measuring with a bullet comparator.

Bullets were seated using a Forster Ultra Micrometer seating die and were measured after seating to confirm seating depth of 0.001 off the lands.

Not a single issue from the primers, CCI BR2s, and the pockets were cleaned and flash holes inspected before loading.

Rifle was purchased used with less than 300 rounds through the tube and I have pictures of groups the rifle shot with other bullets (AMAX, which I don't want to use for deer) and it was used to ring steel plates out to 700 yards.

The rifle isn't the issue. I know it's just a Marine Corps rifle range, but I've shot expert 4 years in a row and never shot anything else.

I have another 260 that I put a 0.174" group together with, a factory Model Seven that only had a trigger job done.

No, I'm not a competitor or professional, but I know I can shoot, especially off a rest, at 300 yards.

I use a modified ladder test in developing my loads. Testing via the ladder approach can use up a lot of bullets and barrel life. So I use Kirby Allen's method, then follow up with short ladder to confirm results.

Kirby Allen, a well-respected gunsmith on this site, develops his loads by finding the max powder charge where max velocity/pressure is achieved - usually exhibited by a slightly sticky bolt lift. He then back off two grains - and that is his load. This method has its share of critics, but I have found that in shooting a ladder test there is a node near the top or peak of the pressure curve.

So that is what I do. I load up a single round with a specific charge and then load subsequent rounds with a 1 grain incremental increase. When the bolt lift gets sticky, I stop. I then back off two grains and the load up enough rounds for a short ladder test. For example, if max load is 65 grains, then I back off to 63 grains. I then load a ladder test in .3 grain increments starting at 61.5 on up to 64.5. I almost always find a node somewhere within this spread.

I have found this method saves both time and money. To each his own.

That's where I'd like to find a node for accuracy and the most velocity...I supposed everyone wants that.