First ladder test results

Tater1985

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Joined
Oct 17, 2011
Messages
50
Location
Indiana
I tried my first ladder test over the weekend. It is easy for me to see that there is a definite node, but towards the lower end. It seems like sometimes there is another node towards the upper end, or even just before pressure signs begin to show. I would like to share my results and get some opinions on whether or not I should load the last 2 charges from my first test, along with 2 or 3 more increasing charges to see if there is another node at the top end.

Data:
New Lapua Brass
CCI 250 primers
H4350
143gr ELD-X
22” barrel

Hornady lists 41.5gr as MAX
Hodgdon lists 41.8gr as MAX

I figured I would load one step above the higher listed max, so I loaded 42.1gr as my 10th charge (39.4 – 42.1 in 0.3gr steps). I never encountered any obvious pressure signs on brass or primers, no sticky bolt lift.

There was some light variable wind from left to right. I would have liked to do this at 4-500 yards, but 330 yards is what I had access to. Point of aim was ¼ of a 2in orange dot, so it is 1in point to edge. The second ladder as a whole, shot much closer together than the first (just under 1 MOA for all 10 charges), which may have just been for the barrel getting some good fouling. I shot two sighters from a clean bore prior to starting the first ladder.

To me there appears to be an obvious node around 3,4, and 5 (40.0 – 40.6). It was pretty erratic above this but I started to wonder if it was settling back down around 9 and 10. So I was wondering if I should try something like 9, 10, 11, and 12 (41.8, 42.1, 42.4, and 42.7) to see if there is another node on the higher end. Thoughts?
 

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QuietTexan

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Nov 16, 2020
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Texas
6.5mm based on the bullet, is it a Creedmoor? Numbers look that way. If it is it's running on the slow side, how many rounds down the barrel?

Edit: found your other thread. Sounds like a new rifle with not a lot shot through it yet. My 6.5 speed up measurably over the first 100 rounds, almost 100FPS. I'd shoot the rest of the brass through with a nice mild load (like the #4) and see what it does over as many identical rounds as you can load. You'll probably net 50fps more from it. Once it settles down, then shoot the ladder. It's going to be a tail chase if your velocity is moving upwards in a new barrel and you're trying to find a node.

I would not go 1.4gr over max with a known sensitive powder like Win 760 going into summertime temps. It's already hit 90* here. Max it out at 30* then shoot it at 80* and you might not like what happens.
 
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Bob Wright

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Jan 23, 2018
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Location
Litchfield Park, Az.
So your brass is new and your barrel is as well?
All your brass needs fireforming as mentioned by QuietTexan. That will lower your pressure on the second firing.

Yes, you need to carefully find upper pressure signs and call that your max. In the meantime, you could fireform all your brass by doing seating depth tests in the upper portion of your powder weights. Pick one and experiment with seating depth.
Then, re-shoot that ladder starting in the middle, going up towards your new found max.
You should clearly see a higher node.
 

Tiny Tim

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Jan 26, 2015
Messages
892
If all is new, shoot it and work on your shooting skills and wait till your brass is FF and your barrel "settled" before doing load development. Then try again. And as Bob stated, Be careful of temps.
 

Tater1985

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Joined
Oct 17, 2011
Messages
50
Location
Indiana
6.5mm based on the bullet, is it a Creedmoor? Numbers look that way. If it is it's running on the slow side, how many rounds down the barrel?

Edit: found your other thread. Sounds like a new rifle with not a lot shot through it yet. My 6.5 speed up measurably over the first 100 rounds, almost 100FPS. I'd shoot the rest of the brass through with a nice mild load (like the #4) and see what it does over as many identical rounds as you can load. You'll probably net 50fps more from it. Once it settles down, then shoot the ladder. It's going to be a tail chase if your velocity is moving upwards in a new barrel and you're trying to find a node.

I would not go 1.4gr over max with a known sensitive powder like Win 760 going into summertime temps. It's already hit 90* here. Max it out at 30* then shoot it at 80* and you might not like what happens.
Thanks for the reply. I now realized i left out my powder, which is H4350. I have found a load with w760 and the 140gr BTHP, which ended up being about a grain under book max and i tried charges all the way up to a grain over max for pressure test. And the final charge of 40.4 was tested at 60*.

As far as round count, before i started this ladder test, i had right at about 100 rounds through the barrel.
 

QuietTexan

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Nov 16, 2020
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252
Location
Texas
I think your options are:
  1. Accept the slower speed and try to tighten the group around #4 with seating depth
  2. Push the pressure and find out where the real max is - you're using good brass so you risk wasting case life in shooting out the primer pockets, not sure if you care about that
  3. Reshoot a seating depth first before the ladder - this is going to change where you see pressure signs depending on how close to the lands you put the bullet versus how much case capacity you gain seating further out.
  4. Change to a different powder if you really need more speed. I can get 2780 out of Superperformance in a 22" barrel, and found a nice 'no pressure signs/hot weather' node at just over 2700.
You had said you didn't have your measuring tools yet back when you were working up the Win 760/140 BTHP load - do you have them now? I'm seeing a need for seating depth adjustments, with makes me lean towards saying shoot seating depths tests to use up the rest of the new brass, then reshoot the ladder. The difference between your velocity and vertical grouping charts would probably push me to moving to another powder to see if I could square up the best vertical group with a flater spot on the velocity chart, but I get that you can't just run buy a pound of a half dozen powders and 500 same-lot bullets currently.
 

Tater1985

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Joined
Oct 17, 2011
Messages
50
Location
Indiana
I think your options are:
  1. Accept the slower speed and try to tighten the group around #4 with seating depth
  2. Push the pressure and find out where the real max is - you're using good brass so you risk wasting case life in shooting out the primer pockets, not sure if you care about that
  3. Reshoot a seating depth first before the ladder - this is going to change where you see pressure signs depending on how close to the lands you put the bullet versus how much case capacity you gain seating further out.
  4. Change to a different powder if you really need more speed. I can get 2780 out of Superperformance in a 22" barrel, and found a nice 'no pressure signs/hot weather' node at just over 2700.
You had said you didn't have your measuring tools yet back when you were working up the Win 760/140 BTHP load - do you have them now? I'm seeing a need for seating depth adjustments, with makes me lean towards saying shoot seating depths tests to use up the rest of the new brass, then reshoot the ladder. The difference between your velocity and vertical grouping charts would probably push me to moving to another powder to see if I could square up the best vertical group with a flater spot on the velocity chart, but I get that you can't just run buy a pound of a half dozen powders and 500 same-lot bullets currently.
Great reply, and one that made me realize something i hadnt thought of.

I had used the 0000 steel wool and closing the bolt on a bullet seated long method of finding where the lands were. Just kept polishing the marks off and seating it about .005" more each time until i had no more marks when closing the bolt. I also made a dummy case from a fire formed piece of brass to fit my Hornady tool the morning i did the test above. Both yielded a CBTO of approximately 2.200" at the lands. I loaded for the test at CBTO 2.190" (.010" off the lands). I have no plans to seat any closer, only to back off. So i should be good pressure wise.

However, i noticedbwhen loading that ladder that i notices very slight crunching of kernels at 41.8, and definite crunching at 42.1, so while i may be able to test a little bit higher in charge weight, i will be running out of room on seating depth if i would happen to find a node up there. (Right?)

Ultimately i dont NEED the speed. The gun is for fun, maybe use it for deer from time to time, good chance i would poke a few yotes with it. But mostly just to play at longer distance as i have never had a rifle to do that sort of thing with. I just figured a little extra velocity could only help a little with a less than perfect distance or wind call.
 

deweyduck

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Joined
Jun 27, 2013
Messages
42
Location
Atlanta, GA
6.5mm based on the bullet, is it a Creedmoor?over as many identical rounds as you can load. You'll probably net 50fps more from it. Once it settles down, then shoot the ladder. It's going to be a tail chase if your velocity is moving upwards in a new barrel and you're trying to find a node.

I would not go 1.4gr over max with a known sensitive powder like Win 760 going into summertime temps. It's already hit 90* here. Max it out at 30* then shoot it at 80* and you might not like what happens.
max at 90* equals 90°. Just type in 90 in the normal way, then using the number keypad on the right side turn on the num lock, then press and hold the alt key while typing 0176 on the right side number keys, release the alt key, and there it will be. You can thank me later. I've been fighting this problem way too long and when I saw this post I just had to figure it out.
 
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Tater1985

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Joined
Oct 17, 2011
Messages
50
Location
Indiana
I tried shooting a pressure test at 100 yds today to see how data would compare to the attempted ladder test at 330 yds last weekend.

I elected to skip 1 and 2 and load an 11th and 12th charge since i didnt see pressure in 1-10. So charges are numbered in first pic, results in second pic.

Is there any better data here? I believe i am starting to see some mild pressure in 11 and 12, but bolt lift was still not much heavier than normal, maybe just a little.

I was wondering if 9 or 10 (maybe between the two) would be a good place to test seating depth. And then do OCW following that?
 

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