Help interpret this load data...

[canny]

I began the load work up for my custom 7mm rem mag. I started with the ladder test. I loaded 10 rounds at the same seating depth, varying the charges .3 grains each. The initial load was 67.5 grains with the final load 70.2 grains. From what it appears to me I have 3 separate accuracy nodes:

Shots 1&2 (67.5-67.8)
Shots 5&6 (68.7-69.0)
Shots 9&10 (69.9-70.2)

What says the GS?

[JakeGraves]

At what distance was this shot? Mine offered a lot more consistent data shot at 600 but still had unexplained overlaps. I would shoot it again with same loaded rounds at same range and compare to rule out a bad shot. It appears that loads 1-7 have potential.

[SmTx]

IDK if you've seen this but this is how I start all of my loads after learning this method.

http://forum.accurateshooter.com/index.php?topic=3814361.0

[yanta61]

At what distance was this shot? Mine offered a lot more consistent data shot at 600 but still had unexplained overlaps. I would shoot it again with same loaded rounds at same range and compare to rule out a bad shot. It appears that loads 1-7 have potential.

X2. each load should be a little higher that the previous.

[canny]

These shots were taken at 150 yds because thats how far my range is at the moment. I was also confused as to why the spread did not gradually get higher as the charges increased. These loads were very carefully put together to ensure that the powder charges were correct, the seating depths were constant, and each case shoulder was bumped back the same .002". I will rework these loads and see if I can duplicate these results.

[JakeGraves]

These shots were taken at 150 yds because thats how far my range is at the moment. I was also confused as to why the spread did not gradually get higher as the charges increased. These loads were very carefully put together to ensure that the powder charges were correct, the seating depths were constant, and each case shoulder was bumped back the same .002". I will rework these loads and see if I can duplicate these results.

At only 150 yards, I don't think you will see measurable results from shooting a ladder test. I would focus on 3 shot groups and then fine tune by changing OAL.

[JakeGraves]

http://www.6mmbr.com/laddertest.html

Very good article by Jason Baney if you haven't seen it.

[Zen Archery]

you need to load 3 bullets same load shoot group to get more accurate representation.
if you have a data book you'd mark each shot where you broke the trigger and then mark where it actually hit. (you'd also load all other data, shooting position, bag, tripod, wind, temperature, parameter, shadows, wind direction, if you passed gas when shooting hahaha, etc)
it takes time and effort but if you are wanting a real accurate load that would be my suggestion.

[yanta61]

Yeah you need to try and find a place to shoot further if your going to do the ladder test. If you cant find anymore room, Then i would try the 3 shot groups.

[bboswell]

At only 150 yards, I don't think you will see measurable results from shooting a ladder test. I would focus on 3 shot groups and then fine tune by changing OAL.

Yeah you need to try and find a place to shoot further if your going to do the ladder test. If you cant find anymore room, Then i would try the 3 shot groups.

This is what I found when trying ladders at 200.

I went back to 3 shot groups and watching for consistent velocity

[BrianL]

I don't think that grouping helps figure much out. Best I could guess is start at 67.8 and load 3 the same, and go up at .1 grain at a time to see what happens

[treestand]

This is what I found when trying ladders at 200.

I went back to 3 shot groups and watching for consistent velocity

I agree with the importance of watching velocity. It is easy to be off a 0.5 MOA due to shooter error but the most accurate rounds at a given load will chronograph very close to one another.

[Creedmore]

To do a successful ladder, you need to be at least 500yds, and over a chronograph.

[dustoffer]

I've not been a fan of the ladder technique--I start with a fixed charge and vary the seating depth, starting .005" off jam, then .015" then .025", then .035". 3 rounds of each plus a round for barrel fouling. Shoot the groups at 100 off a proper front rest and good san**** rear rest, allowing barrel to cool a minute between shots, 5 or 10 minutes between groups (depending on air temp). Pick the best group, go back to the reloading bench and load 3 of the best grouping length, then 3 .005" shorter and 3 .005" longer. Go back to the range and shoot again. Should have it pretty well nailed down by now. Once you've found the rifle's "sweet spot" in terms of bullet jump as measured by distance off jam, you can tinker with propellant charge. Biggest problem I've encountered is most rifles' throat is so long that when you find the sweet spot, the cartridge is too long to work thru the magazine.

[tgridley]

I shoot gunwerks LR 1000 in 7 mag and load 72.5 grains of Retumbo with 168 grn burger.
C.O.A.L is 3.42
Velocity is 3045fps
Shoots lights out.
Another load to try is 70.7 grains of H 1000 This will get you 3025fps.