7mm Rem mag ladder test.

[kilotanker22]

I have always used the OCW method of load development. In fact I had not even heard of the Satterlee load development until recently.

Today I decided to try it. I loaded a ladder test from 67.5 grains of RL 26 to 70 grains of RL 26. I was a little skeptical of what I would see as far as results. And didn't think that .2 grain incriments would make much of a difference. I used .25 grain incriments for the sake of getting me to the max charge evenly from where I wanted to start.

What I found was that .25 grains of reloder 26 made for a consistent change in velocity for every incriments tested. Except for a couple flat spots. It finally dawned on me the usefulness of the Satterlee ladder method. Finding flat spots across charge weights that will yield very low SD and ES. It has been my experience in the past that extremely accurate loads generally yield very consistent velocities.

I noticed a pattern today. Most incriments yielded about a 20fps gain in velocity. A few times in the test. A .25 grain incriment yielded 50 fps or so increased velocity. The next couple of increases in charge weight yielded velocities that were very very close together. Could this have to do with Barrel Harmonics and pressure wave timing? You could almost bet on where the next velocity node would be based on seeing a fairly large jump in velocity with a small change in charge weight. This fascinates me. Although I feel it is Unnecessary, I am gonna load up another 20 round Ladder test. Using smaller incriments. Trying to find exactly how wide each of these flat spots are. Then pick the flat spot that is close to the velocity that I am looking for and load up a ten round test right in the middle of the charge range. And see if it shoots well. Assuming that it does I will have completed load work up with less than 40 rounds fired. So I definitely see the value in the Satterlee method.

In all honesty, this 7mm Remington Magnum is yielding very respectable velocities for having a 24 inch ported barrel. One of my flat spots on the ladder yielded 3144fps and 3147 fps. The next highest flat spot yielded 3183 and 3179. The lower charge weight actually yielding the higher velocity there.

None of these loads showed any signs of pressure. Primers are still rounded and there is no cratering of the primer. No difficult extraction etc. Since I am already nearly 3200 fps. With a 150 grain .284 bullet. And have no pressure signs. And have a flat spot in velocity .5 grains wide. I feel very comfortable picking my charge. Weight. And verifying that it shoots well.

As it is I am about 100 fps faster than published data using the same components. And charge weights.

I know many of you probably have already solved this puzzle. But I feel that explaining my personal experience was worth the time it takes to write this and the ensuing discussion. Mostly for people who didn't understand or were skeptical of this type of load development. I wasn't able to find any posts across several forums sharing specific data and the results gained per each wrung on the ladder. Also, if my understanding of this method isn't correct I ask that y'all speak up.

I feel like 3180 fps average velocity for a 150 grain .284 bullet. Is a very reasonable velocity for a high BC hunting bullet.

P.S.
With Hornady Factory 139 grain Interlock ammunition. I got an average velocity of 3053 and an ES of 97 FPS.... With a group of around 2.5 inches.

I need some feed back here people's. What's your take on this method? And am I understanding it correctly?

[std7mag]

As we have discussed in PMs, i do a ladder test that i found from Sierra.
I do 10 rounds going up 0.3 gr increments.
I leave the chrono at home, as i'm not worried about velocity, just looking for accuracy nodes. Sometimes there will be 2 such nodes. The velocity will be, what it will be. Fast but not accurate doesn't help me. Don't get hung up on the chrono.
I shoot 3 rounds, and keep record of the shot number and where it landed.
I then number each hole on my target.
Closest 3 vertically is what i'm looking for. Middle shot number of those will be my powder charge.
Then you can test for seating depth. Which will help with group size.

When all that is done, i load 10 rounds and shoot 2 strings of 5 shots over chrono looking for ES/SD.
If the chrono likes my ES/SD i'll try it at 600 yards.
Certain powder/bullet combos don't combine well. While it may not show too much at closer range (200-300 yards) it will show at longer ranges.
Longer range is also where you true your ballistics, mostly by correcting the velocity.

[kilotanker22]

That makes sense to me. Its basically the same Idea. Just a different way of coming to the same conclusion. The difference being that I am trying to find flat spots in velocity and build my loads around those flat spots.

I have 2 good flat spots in the ladder from the other day. My plan is to load up 10 rounds of each. In the center of those flat spots. Shoot checking for SD and ES. As well as group size.

I am a little limited with seating depth. With this rifle and bullet. The closest I can get to the lands is .050. And still be able to feed through the magazine.

If the Satterlee method works. Then one of those 2 velocity nodes should shoot real well.

[Unclenick]

See what SDs you get for the 10 round sets. If you find they are big enough to erase the flat spot, you probably have to fire more 10-round strings to be sure the flats are real.

[std7mag]

Don't shoot for groups with the Magnetospeed strapped to the end of your barrel.

[kilotanker22]

Oh I dont. It changes my POI by about 4 inches vertically and opens groups to at least twice the size.

[kilotanker22]

Originally Posted by Unclenick

See what SDs you get for the 10 round sets. If you find they are big enough to erase the flat spot, you probably have to fire more 10-round strings to be sure the flats are real.

I was thinking about this earlier. I generally don't settle on a load without single digit SD numbers.

I have not decided for sure if I want to load another ladder test using .1 grain increments. Or load up 20 rounds at the load I think I will end up with. Chronograph a ten round string and shoot a few groups at 100, and 200 yards to see how it looks.

[hounddawg]

Lots of the long range benchrest guys use the Satterly method so it does work

I pretty much use Erik Cortina's 100 yard test method slightly modified. Takes a lot of the environmental conditions and shooter errors from the equation.

one of my tests https://thefiringline.com/forums/sho...d.php?t=599693

results at 300 https://thefiringline.com/forums/att...0&d=1548737198

[kilotanker22]

I saw your threads, but wasn't really sure I followed the information you were putting down.

[std7mag]

Hopefully i can shoot as well this spring with my 600 yard match.
Last year using Stevens 200 with factory 7mm-08 barrel, reamed to AI. Bipod, rear bag.
Was literally 3rd time i've shot laying prone, first time out to 600 yards.
Nervous as heck!
Did 173, 173/1X, 173/2X.
Guy running match said i was consistant, that's for sure. Lol
Still haven't decided wether i want to shoot my 284 Win Mauser, or wifes Savage110FP in 223 Rem.

[std7mag]

I did take my Savage 111 in 7mm Rem Mag out one day this winter to see how she does at 600 yards.
Shooting off the bench, 150gr ABLR over RL26.
Hits were no where near the BDC reticle, no surprise. But were exactly where Strelok Pro said they would be.
Somehow got lucky as all get.
1.5" three shot group at 600 yards.
The ABLR is accurate!
Just hearing very mixed results on game, but so too the ELDX.

[kilotanker22]

A lot of people blame the bullet or gun. All the time I hear people say their bullet did this or did that. I hear people talk about their bullet blowing up and not penetrating. Yet they never find the animal. When in all reality when these bullets fail. It is likely due to user error.

Either poor shot placement or impact velocities being too low. Or some people just can't shoot.

[old roper]

http://www.65guys.com/10-round-load-...t-ladder-test/

Suppose to be done 10rd

[hounddawg]

I saw your threads, but wasn't really sure I followed the information you were putting down.

the original 100 yard load development thread by Cortina

http://forum.accurateshooter.com/thr...yards.3814361/

don't underestimate Savage actions, one of my rifles was built on a action rescued off a Stevens 200 that had been ran over by a forklift ..long story but I bought it for $25 a few years back

[kilotanker22]

Yep. That's the article I read before trying this. Instead of starting 1.5 grains below what I set as max I started 2.5 grains believe max.

I ended up just loading 15 rounds each of the loads in the middle of the two that spots I decided to roll with. I will Chronograph a ten round string of each. And shoot a group with each load.

[Unclenick]

The issue with 10 round incremental tests is that 95% confidence still allows ±30% or so of variation off the linear trendline at that sample size. So it's one of those things that might work most of the time, but then sometimes will be off.

The velocity flat spots themselves have been known about for a long time. In the 1995 Precision Shooting Reloading Guide, Dave Milosevich has a plot of charge vs. velocity on page 91 for a 20 shot string in 0.2-grain increments fired in a .308 Match rifle using 190-grain SMK's, in the range of 2450 fps to 2700 fps. It has two distinct flat spots, both 4 load increments long. One at about 2540 fps and one at about 2630 fps. He says:

"For years Mid Tompkins and others have said that the 190 grain Sierra Matchking shot best out of the typical .308 Winchester NRA Match Rifle when loaded to around 2,525 fps. Can it be made to go faster? Sure. There are a number of loads that will drive the 190 grain Sierra at 2,600 fps without overtaxing the system. Do I load to 2,600 fps? No. The loads that seem to be the most accurate (group best day in and day out) hover around 2,500 to 2,525. There is a "sweet spot" for lack of a better term, when all of the component parts (including the rifle) seem to work best together."

Well, first you note those recommended best velocities don't exactly match either flat spot in his curve. But let's assume that for his particular powder choice in his particular rifle the 2,540 fps flat spot has good enough correspondence to call it a match to his average best historical velocity of 2,512.5 fps for most match rifles. Just take of 27.5 fps to see adjust that rifle and load to agree. But then we have the problem that the second flat spot, also less 27.5 fps to reflect the typical rifle, is at 2602.5 fps equivalent to historical behavior, which is right where he says grouping is poorer. And it was the flatter of the two spots.

What Milosevich says, referring to flat spot plots is:

"This is not a sure-fire way to find the best load, but it does offer a place to start looking. If one were to take the time to combine shooting a similar series for "group" while chornographing at the same time, the results might be even more enlightening; especially if there were "flat" sections of the velocity curve that matched identifiable clusters of impacts on the target."

What I think explains this is there are other factors involved in a truly golden sweet spot load. Ask yourself why do barrel tuners work without changing velocity? Also ask yourself if you had a set of velocity flat spots and you had a barrel tuner to bring the barrel movement into coordination with the velocity flat spots, how much tighter would the groups be? Even absent the tuner, I've thought for some time the fact seating depth tuning narrows groups means a really fully tuned load was going to coordinate several influences; barrel time coordination with pressure wave distortion and muzzle deflection and with a velocity consistency flat spot, and that getting all these ducks in a row is where one-holer loads come from.

[hounddawg]

From what I have found flat velocity nodes can be radically altered by changing any of the following. Powder charge, powder type ( Varget, RL 15 etc), primer selection, seating depth and is only valid for the particular barrel it is being shot from. It can also change over time as the throat wears or temperature varies, I am going to head to the range in a few to "chase the throat" on my tactical build .260, it is about time to rebarrel that rifle but I am going to try and make it through this summer with it. Saying a bullet shoots best at a certain speed is simplifying the matter. It is a combination of a lot of variables

[kilotanker22]

Originally Posted by Unclenick

The issue with 10 round incremental tests is that 95% confidence still allows ±30% or so of variation off the linear trendline at that sample size. So it's one of those things that might work most of the time, but then sometimes will be off.

The velocity flat spots themselves have been known about for a long time. In the 1995 Precision Shooting Reloading Guide, Dave Milosevich has a plot of charge vs. velocity on page 91 for a 20 shot string in 0.2-grain increments fired in a .308 Match rifle using 190-grain SMK's, in the range of 2450 fps to 2700 fps. It has two distinct flat spots, both 4 load increments long. One at about 2540 fps and one at about 2630 fps. He says:

"For years Mid Tompkins and others have said that the 190 grain Sierra Matchking shot best out of the typical .308 Winchester NRA Match Rifle when loaded to around 2,525 fps. Can it be made to go faster? Sure. There are a number of loads that will drive the 190 grain Sierra at 2,600 fps without overtaxing the system. Do I load to 2,600 fps? No. The loads that seem to be the most accurate (group best day in and day out) hover around 2,500 to 2,525. There is a "sweet spot" for lack of a better term, when all of the component parts (including the rifle) seem to work best together."

Well, first you note those recommended best velocities don't exactly match either flat spot in his curve. But let's assume that for his particular powder choice in his particular rifle the 2,540 fps flat spot has good enough correspondence to call it a match to his average best historical velocity of 2,512.5 fps for most match rifles. Just take of 27.5 fps to see adjust that rifle and load to agree. But then we have the problem that the second flat spot, also less 27.5 fps to reflect the typical rifle, is at 2602.5 fps equivalent to historical behavior, which is right where he says grouping is poorer. And it was the flatter of the two spots.

What Milosevich says, referring to flat spot plots is:

"This is not a sure-fire way to find the best load, but it does offer a place to start looking. If one were to take the time to combine shooting a similar series for "group" while chornographing at the same time, the results might be even more enlightening; especially if there were "flat" sections of the velocity curve that matched identifiable clusters of impacts on the target."

What I think explains this is there are other factors involved in a truly golden sweet spot load. Ask yourself why do barrel tuners work without changing velocity? Also ask yourself if you had a set of velocity flat spots and you had a barrel tuner to bring the barrel movement into coordination with the velocity flat spots, how much tighter would the groups be? Even absent the tuner, I've thought for some time the fact seating depth tuning narrows groups means a really fully tuned load was going to coordinate several influences; barrel time coordination with pressure wave distortion and muzzle deflection, and with a velocity consistency flat spot, and that getting all these ducks in a row is where one-holer loads come from.

I haven't quite thought about it in that way. I find this all very fascinating. I will continue to test this method and acquire information pertaining to each of my rifles. I record all of my data so I will be able to compare it to future rifles and loads.

[std7mag]

Ahhhh the notes in the handloaders logbook...

Sometimes i think i should hire a secretary...

[kilotanker22]

std7mag, maybe you should.....

I will shoot these groups, and fore the strings for velocity tomorrow. If I can shoot sub 1 inch, and have single digits SD I will be happy for this rifle.

[std7mag]

Ya think???

[kilotanker22]

Haha yeah.

In the last couple years I haven't found a gun that I couldn't shoot well. Maybe I am getting better, or lucky..... I don't know. I am generally not satisfied without excellent results.

[kilotanker22]

Originally Posted by Unclenick

See what SDs you get for the 10 round sets. If you find they are big enough to erase the flat spot, you probably have to fire more 10-round strings to be sure the flats are real.

Worked out pretty well. I loaded several of the flat spots in velocity. One stood out from the rest....

150 grain ELD-X
69.62 grains. rl26
Avg 3207
SD 2
ES 5

I picked up a little bit of speed over the ladder test, but this was a ten round string for velocity. Giving a couple minutes for cooling between shots. It was also 20 degrees warmer today. Than the day I tested the ladder.

I also loaded an extra 3 rounds of each load to see how it grouped without the Magnetospeed. (This rifle is pretty hot after 5 rounds) and 3 round groups are good enough for me with a pencil barrel hunting gun.

Group with this load was just over 1 inch. Worked out to .987 MOA. I am happy with it. I think that's where I will stop load development for this rifle.

[Unclenick]

You're going to stop? But you haven't shot the barrel out yet!

[kilotanker22]

The rifle is 30 some years old. I am sure it's already halfway there. Plus I only plan to hunt with it for the time being. Probably use the action at some point for a new build.