my first ever ladder test, 6.5 CM - questions

[YZEATER]

i finally got to try out some ladder test loads that i made up a while ago.

6.5 CM on 7-22-18, 81 degree's
147gr eld-m , lapua brass (new) , cci small rifle primers, H4350 powder, 26" browning long range stalker.

i only shot for velocity, not for grouping on paper at distance.

started at:
36.0 gr - 2436 FPS
36.3 2427
36.6 2426
36.9 2445
37.2 2465
37.5 2498
37.8 2539
38.1 2569
38.4 2556
38.7 2554
39.0 2552
39.3 2587
39.6 2623
39.9 2640
40.2 2642 - max load in book


this is my first foray into doing a different type of load testing. i've always loaded up a bunch of different loads and shot for groups.

now for my questions. i loaded up 2 of each charge, i only shot 1 set. i loaded up a few more charges above max book, as it looks like i was coming into another node. i was not seeing signs of high pressure or sticky bolt lift. should i shoot them?

i also was going to shoot the 2nd batch and see if i get the same results on a different day. is this common practice, or just run with what the data already showed?

 

[Deviant]

I like to shoot the second batch in reverse order and compare the velocities as well as the impact on paper. I would shoot them the same day if it was me but that shouldn't really matter a lot. As far as going over the max recommended load you need to be careful and know what to look for in high pressure signs. Heavy bolt lift, flattened or cratered primers and ejector marks are all signs if high pressure but it looks like you are already educated in that area.

 

[Canhunter35]

I use 41.8(edit)gr of h4350 behind 147eldms in my 6.5cm for a velocity of 2739fps. 26" tube
My best advice is do your ladder test at 400yards plus and go with what you see on the paper.
On ur velocities 38.7 is ur flat spot but I would keep going on ur test

 

[Slick8]

I agree with canhunter, you need to shoot for groups at least 300 yards looking for minimum vertical spread where you see the flat spots in velocity.

I agree at 38.7 is a good node but it appears that 40.2 could be as well.

I'd run it again adding 40.5 on the top IF YOU SAW NO pressure signs while working up.

Do this with a target aT 3-400 yards and it will as Paul Harvey says give you the rest of the story.

Best of luck, I have one that I need to run a ladder test on as well.

 

[bob4]

If your comfortable I would continue up from 40.2 looking for the first sign of pressure. You may just find a good node in the 40.+ range. For myself, it's difficult to get to a range past 200 and that's an hour drive.

 

[FURMAN]

You can not find an accurate load based on velocities alone. You need to find the node when the bullets impact the target in a small node at the same time the velocity extreme spread is small. I can show you numerous loads with single digit es with crap accuracy. You are just wasting barrel life which luckily for you is quite high with a Creedmoor. The entire point of doing a ladder test on paper long range is so you can see the small vertical dispersion. This is always where the node is. You can not get small vertical at 600 plus yards without accuracy and low es.

 

[Mike 338]

IMO, that's not a ladder test. A ladder test in on paper, preferably at 500 to 600 yards with 3 shots of same charge weight in increasing increments.

What the OP is doing is looking for low extreme spread which often times, coincidentally, coincides with being the most accurate load. This may or may not be an effective way of finding a load but it needs further testing to be confirmed. Personally, I prefer the load increments to be .2 grains for this test so I'm more apt to identify 3 loads that are close together. The third, hopefully confirming the first two and possibly a forth confirming the first three.

I'd be more inclined to shoot the same day and in reverse.

 

[YZEATER]

thank you for the input. the reason i just used velocity was that i have seen guys getting results of doing it that way and didn't have the time to do that at the same time.

since i have another set of rounds already loaded up with a couple extra on top, i will do it on paper with those. i don't think i need to use anything below 38.0

 

[Remmy700]

I also use 147eldm with 41.8 gr of H4350 and have went up to 42.6 with same small primer Lapua brass. You are good man keep climbing just let the brass tell you when enough is enough, just pay attention and know how to read what its telling you.

 

[browning442]

I always try to shoot targets in conjunction with the ladder test, and make hand notes of impact locations while i do it. That way, i can find similar velocity nodes as well as nodes where the bullets are very close impact. Doing so with my 6mm-284, there were two nodes where velocity was within 3 fps and the bullets hit the same hole. I'll load up those two nodes now and back up to at least 300 yards, 3 rounds per node, and see which one is best.

 

[LeddSlinger]

Ladder are for group testing and verifying POI and vertical remains consistent through velocities. Most ladder tests don't span much more than a full grain, maybe 2 grains. Can't possibly know what a good "node" I'd if you're not shooting groups. Consistent speeds mean nothing if the accuracy is all over the place

 

[Deviant]

http://www.6mmbr.com/laddertest.html
It works for groups too when you combine it with a bullet seating test.

Al

 

[Gord0]

One thing that hasn't been mentioned yet is the fact that you are using virgin brass. Your load will likely change when using fireformed brass. And if you are running close to pressure with the new brass you will likely be over pressure with fireformed.

 

[LeddSlinger]

http://www.6mmbr.com/laddertest.html
It works for groups too when you combine it with a bullet seating test.

Al

Exactly. I like to find loads that shoot really well. Then I will run ladder tests with charge weights in .2gr increments above and below, then test seating depths in .005" increments. Usually .010" jam to .010" off the lands. The best accuracy in the middle of it all is where I settle for a load because that will be the most forgiving in temp swings and if a bullet seating depth is a little off