308 100 yard ladder test

[CaptJim]

I know 300yds would be better and show more of a spread but only the 100 yd range was accessible and I had read Eric Cortina's article about this so I thought I would try it at 100.

Would like to receive guidance on this first attempt at a ladder test with my .308
I shot 10 rounds, one round at each charge wt. starting at 40.8 gr and ending at 44.4 gr. in .4 gr steps. The aiming point was on the horizontal line in each case. This was with 155gr Scenars in new Lapua Palma brass, Win small rifle primers and Shooter's World Precision Rifle as a Varget clone.
The vertical spread is small, but looks like 40.8 to 42.0 gr may be a node; as well as 42.8 to 43.2 for lower nodes. I didn't load any higher than 44.4, but I feel sure there may be another higher one.
Thanks for any info,
CJ

 

[acloco]

Less than 1/2" dispersion from 40.8 to 44.0 gr?

 

[Jet]

One shot ladders can be hard to interpret. Recommend 2-3 shots per pkwder charge and retest. Since it appears you didn't have pressure signs recommend you start a little higher than 40.8.

Tell us a little about your setup. Bipod, rear bag squeeze, etc

Good Shooting
Rich

 

[762plinker]

One shot ladders can be hard to interpret. Recommend 2-3 shots per pkwder charge and retest. Since it appears you didn't have pressure signs recommend you start a little higher than 40.8.

Tell us a little about your setup. Bipod, rear bag squeeze, etc

Good Shooting
Rich

bah humbug..a simple ladder is a STARTING POINT not an endpoint..where is the velocity DATA for that string, no velocity, wasted time

 

[Beiruty]

Node === MV increases point of impact decrease
Charge increase -> MV increase

 

[Straightshooter1]

I know 300yds would be better and show more of a spread but only the 100 yd range was accessible and I had read Eric Cortina's article about this so I thought I would try it at 100.

Would like to receive guidance on this first attempt at a ladder test with my .308
I shot 10 rounds, one round at each charge wt. starting at 40.8 gr and ending at 44.4 gr. in .4 gr steps. The aiming point was on the horizontal line in each case. This was with 155gr Scenars in new Lapua Palma brass, Win small rifle primers and Shooter's World Precision Rifle as a Varget clone.
The vertical spread is small, but looks like 40.8 to 42.0 gr may be a node; as well as 42.8 to 43.2 for lower nodes. I didn't load any higher than 44.4, but I feel sure there may be another higher one.
Thanks for any info,
CJ
View attachment 1404307View attachment 1404308View attachment 1404309

Sorry to say that one shot ladder test like this is a waist of your time as there's just too much variability from one shot to another with an identical load. You're better off shooting 3 or 5 shots groups and looking at the Mean (not the ES) of each group to better interpret a ladder test.

 

[kiwijohn]

I think you are under utilising the advantages of Small Primer Brass. Most folk use it for its ability to handle hotter loads. Look for a higher node, as you have suggested yourself.
What is the end result you want with this combination? Is it small groups at mid ranges or stability at 1000yds?

 

[CaptJim]

One shot ladders can be hard to interpret. Recommend 2-3 shots per pkwder charge and retest. Since it appears you didn't have pressure signs recommend you start a little higher than 40.8.

Tell us a little about your setup. Bipod, rear bag squeeze, etc

Good Shooting
Rich

Small Caldwell Rock Jr. front rest, old Protektor rear bag. First time using this combo, in fact, I am new to to this type of shooting.
The gun is a trued Rem 700 with a 24" Rock Creek 308 1:11.25 barrel.

 

[CaptJim]

I think you are under utilising the advantages of Small Primer Brass. Most folk use it for its ability to handle hotter loads. Look for a higher node, as you have suggested yourself.
What is the end result you want with this combination? Is it small groups at mid ranges or stability at 1000yds?

Yes, I understand. I have other large primer brass but bought this because of its quality and consistency, and the fact I have more small rifle primers than large.
The longest range available to me now is 300 yards. Once I feel comfortable with that I would like to shoot farther.
CJ

 

[CaptJim]

Back to the drawing board...
Thanks to all for your input.
CJ

 

[Ned Ludd]

If 100 yds is all you have, use an optimal charge weight (OCW) approach. This is done by shooting 3-shot groups at each increasing charge weight. A "node" would be characterized as two or more adjacent groups (i.e. charge weights) where the center-point of each group remains constant with respect to the point of aim. It is not about the size of each group, only their location with respect to the POA. Load to the center of the "node" in terms of charge weight.

If you're comfortable shooting at 300 yd, you could try the ladder approach again. However, even 300 yd is a pretty short distance for an optimal ladder test. As you have already observed, the shorter the distance, the less vertical, meaning the "Y"-axis, or vertical output, has been substantially compressed. Thus, interpretation may be much more difficult than it would be at a range of 500-600 yd. Nonetheless, you may be able to see what you need. Because only a single shot is required at each charge weight, you might consider doubling up and carrying out two identical tests, one after the other. This can sometimes help with interpretation.

As a final note, any load you develop in virgin brass will likely require tweaking once the brass has been fire-formed. There is certainly nothing wrong with working up a fire-forming load in virgin brass. However, fire-forming brass doesn't require that the load be in the mid to upper range of safe operating pressure, so you may not need or want to go any higher in terms of charge weight than you already have. Once you are comfortable with the results and have selected a charge weight, tune the load with seating depth, then have some fun with it. My point is that it may not be necessary to develop a load in virgin brass to the "Nth degree". You can work a load up that shoots reasonably well while learning about the reloading process and fire-forming the brass, without going to extremes to wrest the utmost precision from it.

 

[Owens85]

Small Caldwell Rock Jr. front rest, old Protektor rear bag. First time using this combo, in fact, I am new to to this type of shooting.
The gun is a trued Rem 700 with a 24" Rock Creek 308 1:11.25 barrel.
View attachment 1404353

Use three shot groups for each powder load to help distinguish a good starting load. Stay on those 2 concrete benches those wood ones at riviana are pretty wobbly.

 

[mjl650]

Use three shot groups for each powder load to help distinguish a good starting load. Stay on those 2 concrete benches those wood ones at riviana are pretty wobbly.

And the wooden ones on the 300 are even worse.

 

[Owens85]

And the wooden ones on the 300 are even worse.

Yeah you ain't wrong. Can't rest your arm or it will move a mile.

 

[Ccrider]

Yeah you ain't wrong. Can't rest your arm or it will move a mile.

Learn how to shoot/ handle Gunn off the wood and you can shoot off of anything. Of course, easier said than done.

 

[Dusty Stevens]

Looks as if you werent using wind flags?
Also if you were actually shooting in that position that rear bag hitting the grip is going to cause issues as will the position of that front rest on the forend.

 

[Owens85]

Learn how to shoot/ handle Gunn off the wood and you can shoot off of anything. Of course, easier said than done.

I don't do to bad at the wobbly benches have gotten some what use to it. Just have to learn what you can do and you can't on those type benches but I'll take a concrete bench first.This was 200 yards on that wobbly bench. First time out with that barrel.

 

[CaptJim]

If 100 yds is all you have, use an optimal charge weight (OCW) approach. This is done by shooting 3-shot groups at each increasing charge weight. A "node" would be characterized as two or more adjacent groups (i.e. charge weights) where the center-point of each group remains constant with respect to the point of aim. It is not about the size of each group, only their location with respect to the POA. Load to the center of the "node" in terms of charge weight.

If you're comfortable shooting at 300 yd, you could try the ladder approach again. However, even 300 yd is a pretty short distance for an optimal ladder test. As you have already observed, the shorter the distance, the less vertical, meaning the "Y"-axis, or vertical output, has been substantially compressed. Thus, interpretation may be much more difficult than it would be at a range of 500-600 yd. Nonetheless, you may be able to see what you need. Because only a single shot is required at each charge weight, you might consider doubling up and carrying out two identical tests, one after the other. This can sometimes help with interpretation.

As a final note, any load you develop in virgin brass will likely require tweaking once the brass has been fire-formed. There is certainly nothing wrong with working up a fire-forming load in virgin brass. However, fire-forming brass doesn't require that the load be in the mid to upper range of safe operating pressure, so you may not need or want to go any higher in terms of charge weight than you already have. Once you are comfortable with the results and have selected a charge weight, tune the load with seating depth, then have some fun with it. My point is that it may not be necessary to develop a load in virgin brass to the "Nth degree". You can work a load up that shoots reasonably well while learning about the reloading process and fire-forming the brass, without going to extremes to wrest the utmost precision from it.

Thank You sir.
CJ

 

[CaptJim]

Looks as if you werent using wind flags?
Also if you were actually shooting in that position that rear bag hitting the grip is going to cause issues as will the position of that front rest on the forend.

No, no wind flags. This pic taken after a shot. the recoil slid the rifle back. I know the setup is wonky. I have another rest I used to use, I may try it next time, it is a one-piece rig.

 

[Ccrider]

No, no wind flags. This pic taken after a shot. the recoil slid the rifle back. I know the setup is wonky. I have another rest I used to use, I may try it next time, it is a one-piece rig.
View attachment 1404463

Got one of these. Don’t worry with trying to use it. It moves in too many different places for consistent accurate shooting. It makes a decent gun cradle though.