Help reading a ladder test please

[lancetkenyon]

OK, so I have been reloading for years, and have worked up some amazing hand loads over the years for various rounds with great results. It has always been: work up a 100 yard load using 5 round groups and then verify it holds out to 600-800 yds. About 140-200 rounds per load.

I have been reading about the "ladder test" method, and tried it for the first time this weekend. Shooting was performed at 606 yds. (couldn't find a perfect 600 shot with no obstructions) verified with a Leica 1600B from prone with bi-pod, and rear bag. Come up of 7.25 MOA (+43.5") and 1.5 MOA (9") right, and not touched throughout shooting even when the wind slowed or shifted. This was calculated hoping for 3450 FPS.

A little information about the gun, caliber and round in case it is needed.

Rifle:
Trued Rem 700 LA and bolt
28" Shilen #4 Heavy Sporter 1 in 10" twist
.25-06 Ackley Improved
H&S Precision stock w/ full length bedding block
Shilen trigger @ 2#
Leupold 6.5-20x50 LR VX-III
Rifle has approximately 320 rounds down the barrel.
Rifle shoots 100 gr. Barnes TTSX @ 3598 FPS over 60.3 grains of RL22 @ .504" 5 shot group @ 100 and 2.25" @ 400 yds.
Other load is 100 gr. SMK @ 3658 FPS over 60.2 grains of RL22 @ .331" 5 shot group @ 100 and 3.04" group @ 600 yds.

Remington Brass fire formed, sized, primer pockets uniformed, flash holes de-burred, necks turned, trimmed and chamfered for VLDs.
CCI LR 250 Mag primers
Alliant RL22
.257 Berger 115gr. VLD Hunting B.C .466 jammed .0010 into lands
Charges were each hand weighed with an RCBS 505 to within a single granule of powder. Charge weights were at .5 grains difference (approximately .9%).

Shooting conditions:
1285' AMSL elevation
59-68*F
11:45AM-2:00PM
Fluctuating wind between 0-8MPH as recorded with Kestral from 120* and flags set at 100 yd. intervals
Rifle was cleaned recently, so I shot 10 rounds of the 100 SMKs at my steel @ 600 yds. with an approximate 4" group to warm up and foul the barrel. Cold/clean bore shot was within 2" of anticipated POI with my recorded dope.
Method was: fire a round, check and mark impact, repeat.

Loads and corresponding velocities of the new rounds:
1. 55.0 @ 3304 fps (max load for standard .25-06 Remington)
2. 55.5 @ 3329 fps
3. 56.0 @ 3362 fps
4. 56.5 @ 3395 fps
5. 57.0 @ 3426 fps
6. 57.5 @ 3447 fps
7. 58.0 @ 3486 fps
8. 58.5 @ 3527 fps
9. 59.0 @ 3554 fps
10. 59.5 @ 3580 fps
11. 60.0 @ 3614 fps (had slightly flattened primer and sticky bolt lift)
60.5 to 64.0 were not shot.

My questions:
1. Should the group you choose be at the top of the spread, or does that matter? It looks like #6, 7, 8 are all in the same plane barring wind drift (or lack thereof) with the shifting or dying winds.
2. Is that #6, 7, 8 my "accuracy node" where I should stat fine tuning loads by .2 grains and seating depth?

Thanks in advance. Any other advice or observations would be very welcome. Sure is nice shooting 11 rounds instead of 55 rounds to start working on a load development.

 

[redbullitt]

3 4 5 look to be your low node, but I would check out around 6 7 and 8. I bet you would find a good load there with acceptable velocity.

You want minimal vertical dispersion, and THAT is it right there at 6 7 8 lol. I would start fine tuning from a little bit (.2 or so) under 6 up to a little over shot 8. Find a good powder charge first, then see what you can get with seating depth after that.

I really like doing the ladder first. It leaves very little doubt for what your barrel wants.

 

[gewehr]

Good work, like redbullit said somewhere between 6-8 will probably yield you speed node

 

[mdmp5]

6,7,8 gets my vote as well. I called it before I read the other responses, so that should count as 3 separate unbiased opinions. Good luck with the further load development.

 

[mdmp5]

I know nothing about that caliber, but I am surprised to see that you are shooting a 100 gr bullet with RL22. I would figure you would go with a faster powder.

 

[lancetkenyon]

The .25-06 Ackley Improved is very similar to a .257 Weatherby Mag. Think .270Win with a reduced taper body and 40* shoulder pushed forward and necked to .257 caliber. Sexy looking with long bullets for sure!

I tried all kinds of powder for my 100 grain loads, but with the case capacity and barrel length, I guess my rifle really likes RL22. The speeds are really impressive, and accuracy was second to none with all of the powders I tried.

I tried: IMR4350, IMR4831, IMR7828, RL19, RL22, H414, H4350, H4831 during load development for the 100gr loads. Best groups by far were with RL22. I had a few slightly faster loads with H4831, but not anywhere near in accuracy.

I also run RL22 in my .300RUM for Barnes 175gr. LRX, 175gr. SMKs, and 210gr. SMKs with amazing results, and in my 7mm shooting 150 and 168 gr pills. I figure if one powder does 8+ loads well, why switch? So I went with RL22 for the 115gr Bergers too. Velocities met what I was hoping for (3400fps), and the accuracy node is right above that range plus a little!

So thanks for the help and keep the information coming. I will be trying .2 grain increments from just below #6 to just above #8 now. Should I perform another ladder test at 600 yds. with that criteria? Then see if there is another smaller accuracy node and then try 5 round groups and seating depth for fine tuning?

 

[steve123]

I wouldn't try to go above 8 because 9 is out of the node. Plus R22 is temp sensitive and come summer 8 could be closer to 9 in velocity.

7 would be a good place to experiment with a few 10th's up and down.

By the looks of the accuracy you're getting the seating depth might not need to be adjusted. I lucked out and got such good accuracy with last two ladders and new barrels I left seating depth alone.

Come on up to Ashfork this Sunday and shoot the AZPRC with us! There's a thread about it in the tactical competitions forum.

 

[mdmp5]

I don't think I would repeat the ladder. You did it once and got readable results. If for some reason the shots didn't line up as nicely, it is gonna confuse the hell out of you. Take your 6,7,8 loads and try to find the best group now. You don't need to shoot 600 yds to do it. I would take it in to 300 max, preferably 200. Get the tightest and then play with the seating depth.

 

[sharpshooterbr]

Nice shooting for starters! 6,7, and 8 is showing about .25" of vertical, which is awesome. Like the others have stated, now you need to fine tune the load with that range. I also agree with sticking towards 6 and 7 more, as my experience with RE22 has shown to be VERY temp sensitive, and you don't want to lose the node when the weather warms up.