Need Help Interpreting Load Data

[powerspc]

Hi,
Now that I have some data the next step is what the heck do I do with it? I’ll say up front that I am not the world’s greatest shooter so I toyed with the idea of throwing out 1 flyer in each group? I’m here to learn and don’t take things too personally so any help appreciated. Where would you go from here?

P.s. Apologies upfront if this is in the wrong thread.

Brass: Hornady
Bullet: Hornady 178 BTHP Match
Primer: Federal 210
Powder: Hodgdon VARGET
Distance: 100 Yards
Chronograph: LabRadar
C.O.L. 2.9390”
Bullet Seating Depth: 2.2760”
Rifle: Cadex Kraken
Caliber: .308 Winchester
Case Length: 2.0045”
Headspace: 1.6250”
Barrel Length: 24”
Twist: 1-11.25”

Temperature: 64F
Humidity: 91%
Wind: 10 mph SSW
Elevation: 307’
DNR=Did Not Record (chronograph did not pick up)

String #1 35.0 gr.
Shot 1: 2087
Shot 2: 2185
Shot 3: DNR
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2087
Max. Velocity: 2185
Avg. Velocity: 2136
S.D.: 69.1
E.S.: 98

String #2 37.1 gr.
Shot 1: 2282
Shot 2: 2268
Shot 3: 2280
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2268
Max. Velocity: 2282
Avg. Velocity: 2277
S.D.: 7.7
E.S.: 14

String #3 39.2 gr.
Shot 1: 2397
Shot 2: 2381
Shot 3: 2369
Shot 4: 2314
Shot 5: 2382
Min Velocity.: 2314
Max. Velocity: 2397
Avg. Velocity: 2369
S.D.: 32.2
E.S.: 83

String #4 41.3 gr.
Shot 1: 2514
Shot 2: 2495
Shot 3: 2526
Shot 4: 2500
Shot 5: DNR
Min Velocity.: 2495
Max. Velocity: 2526
Avg. Velocity: 2509
S.D.: 14
E.S.: 31

String #5 42.4 gr.
Shot 1: 2564
Shot 2: 2555
Shot 3: 2572
Shot 4: 2568
Shot 5: 2567
Min Velocity.: 2555
Max. Velocity: 2572
Avg. Velocity: 2565
S.D.: 6.5
E.S.: 17

 

[Subwrx300]

Well the difficult part of this test and data is that the charge increments are very large. If you didn't see signs of pressure at the max charge you shot (42.4 if I'm not mistaken), you should reshoot 41gr -42.4 at an interval of .3gr (41, 41.3, 41.6, 41.9 and 42.2; maybe add 42.4 as control). Shoot them with chrono just like you did above but on a wider flat Target with all aim points on same horizontal line like this:

That will show you the relative impact point as charge increases. Your looking for a flat spot in terms of elevation and windage point of impact (like 41.8-42 above).

You should have better data after doing above. Repost the new test and we can help further if needed.

 

[powerspc]

Hi Sub, Thanks for taking a look. I had already shot another series before I saw your post and think I may have at least come close to what you had suggested. I think this is starting to make some sense to me, if you look below I'm guessing 42.2 may be the ticket? Or is it 41.7 because of the low ES?

P.s. I was having a few chrono issues that day .

Brass: Hornady
Bullet: Hornady 178 BTHP Match
Primer: Federal 210
Powder: Hodgdon VARGET
Distance: 100 Yards
Chronograph: LabRadar
C.O.L. 2.9390”
Bullet Seating Depth: 2.2760”
Rifle: Cadex Kraken
Caliber: .308 Winchester
Case Length: 2.0045”
Headspace: 1.6250”
Barrel Length: 24”
Twist: 1-11.25”

Temperature: 57F
Humidity: 63%
Wind: 10 mph NE
Elevation: 307’
DNR=Did Not Record (chronograph did not pick up)

String #1 41.5 gr.
Shot 1: 2533
Shot 2: DNR
Shot 3: DNR
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2533
Max. Velocity: 2533
Avg. Velocity: 2533
S.D.: -
E.S.: -

String #2 41.7 gr.
Shot 1: 2524
Shot 2: 2527
Shot 3: 22526
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2524
Max. Velocity: 2527
Avg. Velocity: 2526
S.D.: 2
E.S.: 2.1

String #3 42.0 gr.
Shot 1: 2529
Shot 2: 2519
Shot 3: 2547
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2519
Max. Velocity: 2547
Avg. Velocity: 2532
S.D.: 28
E.S.: 14.3

String #4 42.2 gr.
Shot 1: 2588
Shot 2: 2549
Shot 3: 2558
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2549
Max. Velocity: 2588
Avg. Velocity: 2565
S.D.: 38
E.S.: 20

String #5 42.4 gr.
Shot 1: 2568
Shot 2: 2588
Shot 3: 2566
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2566
Max. Velocity: 2588
Avg. Velocity: 2574
S.D.: 22
E.S.: 12.2

 

[Subwrx300]

Hi Sub, Thanks for taking a look. I had already shot another series before I saw your post and think I may have at least come close to what you had suggested. I think this is starting to make some sense to me, if you look below I'm guessing 42.2 may be the ticket? Or is it 41.7 because of the low ES?

P.s. I was having a few chrono issues that day .

Brass: Hornady
Bullet: Hornady 178 BTHP Match
Primer: Federal 210
Powder: Hodgdon VARGET
Distance: 100 Yards
Chronograph: LabRadar
C.O.L. 2.9390”
Bullet Seating Depth: 2.2760”
Rifle: Cadex Kraken
Caliber: .308 Winchester
Case Length: 2.0045”
Headspace: 1.6250”
Barrel Length: 24”
Twist: 1-11.25”

Temperature: 57F
Humidity: 63%
Wind: 10 mph NE
Elevation: 307’
DNR=Did Not Record (chronograph did not pick up)

String #1 41.5 gr.
Shot 1: 2533
Shot 2: DNR
Shot 3: DNR
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2533
Max. Velocity: 2533
Avg. Velocity: 2533
S.D.: -
E.S.: -

String #2 41.7 gr.
Shot 1: 2524
Shot 2: 2527
Shot 3: 22526
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2524
Max. Velocity: 2527
Avg. Velocity: 2526
S.D.: 2
E.S.: 2.1

String #3 42.0 gr.
Shot 1: 2529
Shot 2: 2519
Shot 3: 2547
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2519
Max. Velocity: 2547
Avg. Velocity: 2532
S.D.: 28
E.S.: 14.3

String #4 42.2 gr.
Shot 1: 2588
Shot 2: 2549
Shot 3: 2558
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2549
Max. Velocity: 2588
Avg. Velocity: 2565
S.D.: 38
E.S.: 20

String #5 42.4 gr.
Shot 1: 2568
Shot 2: 2588
Shot 3: 2566
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2566
Max. Velocity: 2588
Avg. Velocity: 2574
S.D.: 22
E.S.: 12.2

View attachment 6954730

I would suggest trying .1 intervals on between 41.7 and 42.1. The impact points on target are virtually identical and speed is nearly same avg between the groups.

Find the best from that series and run seating depth test at .10-15 intervals from where you are now. I think you will find one that shoots lights out.

It looks like somewhere around 41.8/9 will be good and then adjust seating depth to bring it tighter.

 

[Deleted member 113831]

Hi Sub, Thanks for taking a look. I had already shot another series before I saw your post and think I may have at least come close to what you had suggested. I think this is starting to make some sense to me, if you look below I'm guessing 42.2 may be the ticket? Or is it 41.7 because of the low ES?

P.s. I was having a few chrono issues that day .

Brass: Hornady
Bullet: Hornady 178 BTHP Match
Primer: Federal 210
Powder: Hodgdon VARGET
Distance: 100 Yards
Chronograph: LabRadar
C.O.L. 2.9390”
Bullet Seating Depth: 2.2760”
Rifle: Cadex Kraken
Caliber: .308 Winchester
Case Length: 2.0045”
Headspace: 1.6250”
Barrel Length: 24”
Twist: 1-11.25”

Temperature: 57F
Humidity: 63%
Wind: 10 mph NE
Elevation: 307’
DNR=Did Not Record (chronograph did not pick up)

String #1 41.5 gr.
Shot 1: 2533
Shot 2: DNR
Shot 3: DNR
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2533
Max. Velocity: 2533
Avg. Velocity: 2533
S.D.: -
E.S.: -

String #2 41.7 gr.
Shot 1: 2524
Shot 2: 2527
Shot 3: 22526
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2524
Max. Velocity: 2527
Avg. Velocity: 2526
S.D.: 2
E.S.: 2.1

String #3 42.0 gr.
Shot 1: 2529
Shot 2: 2519
Shot 3: 2547
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2519
Max. Velocity: 2547
Avg. Velocity: 2532
S.D.: 28
E.S.: 14.3

String #4 42.2 gr.
Shot 1: 2588
Shot 2: 2549
Shot 3: 2558
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2549
Max. Velocity: 2588
Avg. Velocity: 2565
S.D.: 38
E.S.: 20

String #5 42.4 gr.
Shot 1: 2568
Shot 2: 2588
Shot 3: 2566
Shot 4: DNR
Shot 5: DNR
Min Velocity.: 2566
Max. Velocity: 2588
Avg. Velocity: 2574
S.D.: 22
E.S.: 12.2

View attachment 6954730

Is there a particular reason you are running these so slow?

 

[powerspc]

I would suggest trying .1 intervals on between 41.7 and 42.1. The impact points on target are virtually identical and speed is nearly same avg between the groups.

Find the best from that series and run seating depth test at .10-15 intervals from where you are now. I think you will find one that shoots lights out.

It looks like somewhere around 41.8/9 will be good and then adjust seating depth to bring it tighter.

Excellent; I may not get out for a few days (crappy weather) but I will run it exactly as you described using, 41.7, 41.8, 41.9, 42.0 and 42.1. Once I have that quick question on seating depth, when you say adjust at .10-.15 increments is that out (closer to lands) or in (farther from lands)?

 

[powerspc]

Is there a particular reason you are running these so slow?

Hi Skook,

No, other than I am new to reloading and using the Hornady 10th edition as guide. They listed 42.4 as Max Load, so although I went to 42.4 I wasn't sure I needed to try and go beyond as I think I was seeing what I wanted at less than the Max Load. My goal was to shoot .5 MOA or better with as low an ES as possible. I'm going to run another 5 strings using the suggestion above and see how that looks.

 

[Deleted member 113831]

Hi Skook,

No, other than I am new to reloading and using the Hornady 10th edition as guide. They listed 42.4 as Max Load, so although I went to 42.4 I wasn't sure I needed to try and go beyond as I think I was seeing what I wanted at less than the Max Load. My goal was to shoot .5 MOA or better with as low an ES as possible. I'm going to run another 5 strings using the suggestion above and see how that looks.

The books are a guide to be heeded to be sure, but your chrono will give you the most relevent feed back for your particular rifle and load combo.

To get low SD's, the powder typically needs to reach the optimal pressure range. Out of your 24" barrel, these should be safely and sanely running 2650fps or so in the optimal pressure range. It is true that there is usually a low node at the bottom, or just off the bottom of the optimal pressure. Federal Gold Medal Match is an example of a factory load that does this. It makes it very forgiving for many different rifles but it also makes it slow.

If you continued your testing up to at least say, 43.5 or 43.7 grains, It's my guess you would find a good spot. Then fine tune seating depth from there.

 

[powerspc]

The books are a guide to be heeded to be sure, but your chrono will give you the most relevent feed back for your particular rifle and load combo.

To get low SD's, the powder typically needs to reach the optimal pressure range. Out of your 24" barrel, these should be safely and sanely running 2650fps or so in the optimal pressure range. It is true that there is usually a low node at the bottom, or just off the bottom of the optimal pressure. Federal Gold Medal Match is an example of a factory load that does this. It makes it very forgiving for many different rifles but it also makes it slow.

If you continued your testing up to at least say, 43.5 or 43.7 grains, It's my guess you would find a good spot. Then fine tune seating depth from there.

1. I am having fun (Important)
2. I enjoy Shooting (Very Important)
3. I love to learn (Most Important)

I will run both scenarios, the one suggested by Subwrx300 and the one you are suggesting, I think it will prove interesting. So, for this I will run 5 strings at:

42.9 (starting a 1/2 grain up from where I ended which showed no signs at all of over pressure), 43.1, 43.3, 43.5 and 43.7 to see what that looks like as well (checking carefully for signs of over pressure as I go)

I probably won't get back out until next week but will post results from both test as soon as I have them.

 

[Deleted member 113831]

There is no down side to going slow. I think that shows good judgement. Too many others jump right in over their heads and do stupid dangerous stuff. You're doing just fine.

 

[Strykervet]

In addition to shooting groups in the string like Subwrx300 says, I'd also do it two more times at least, ideally on a couple different days. And make sure the weapon is secured well using whatever you have available. Sandbags are great. The less it moves the more accurate your data will be. If you have real rest to lock it in, use that. The more consistent and stable the better the data. This way you'll know you're groups are as tight as can be, and you'll have repeated it a couple times to ensure any one group isn't an anomaly.

I use a similar load, new Lapua brass, CCI34's, 175SMK's, 41.8gr. RE15 in an SR25. It'll be the once fired brass that'll get reworked to find the best possible load.

 

[powerspc]

I got a chance to test another set today (41.7, 41.8, 41.9, 42.0 and 42.1). I think for sure that as the charge goes up my groups start to tighten (at least that’s what I think I see). All of the targets were at the same elevation and I was shooting from a bipod with a rear bag for support. I’ll keep this a little simpler unless I’m leaving out the most important parts:
41.7
Min Velocity.: 2497
Max. Velocity: 2515
Avg. Velocity: 2505
S.D.: 8.98
E.S.: 18

41.8

Min Velocity.: 2497
Max. Velocity: 2537
Avg. Velocity: 2522
S.D.: 16.34
E.S.: 40

41.9

Min Velocity.: 2500
Max. Velocity: 2535
Avg. Velocity: 2524
S.D.: 13.94
E.S.: 35

42.0

Min Velocity.: 2516
Max. Velocity: 2540
Avg. Velocity: 2525
S.D.: 10.41
E.S.: 24

42.1

Min Velocity.: 2525
Max. Velocity: 2545
Avg. Velocity: 2536
S.D.: 8.7
E.S.: 20

Unfortunately my time this week is a little limited but I think Thursday or Friday this week I will be able to run: 42.9, 43.1, 43.3, 43.5 and 43.7. Then I think (hope) it will all start falling into place for me. Thanks!

P.s. Sorry about the zero but I didn’t want to start fiddling with the scope after I started.

 

[Subwrx300]

Well from current targets, I think 42 or 42.1 is your load. You could always continue to test for higher node and see when you get pressure signs. I wouldn't worry about the flyer. It looks a bit like something is happening with your form or consistency during each group as most of the other groups have a high right/low left appearance also. Maybe not but overall looks pretty good.

From here a seating depth test could certainly tighten things up considerably.

But the nice aspect about 42.1 is the group is starting to drop a bit lower than 42.0. This means that if a charge is a tiny bit light (say .1 grain) it will launch slightly higher than normal to make up for the lower velocity and at some point downrange will still hit the same point of impact as 42.1.

This "convergence" is something I try to tune into my loads if I can't find a node that is flat POI on both sides +-.1gr of best load.

 

[powerspc]

Well from current targets, I think 42 or 42.1 is your load. You could always continue to test for higher node and see when you get pressure signs. I wouldn't worry about the flyer. It looks a bit like something is happening with your form or consistency during each group as most of the other groups have a high right/low left appearance also. Maybe not but overall looks pretty good.

From here a seating depth test could certainly tighten things up considerably.

But the nice aspect about 42.1 is the group is starting to drop a bit lower than 42.0. This means that if a charge is a tiny bit light (say .1 grain) it will launch slightly higher than normal to make up for the lower velocity and at some point downrange will still hit the same point of impact as 42.1.

This "convergence" is something I try to tune into my loads if I can't find a node that is flat POI on both sides +-.1gr of best load.

First, I greatly appreciate the help and analysis; 42.1 would have been my guess as well. No doubt there are some form issues which I am working through at the same time as I am forced to shoot weak hand, non-dominant eye due to some issues with my dominant eye. I'm definitely getting more comfortable doing so.

I think I will try to test for a higher node since I'm still in the learning phase (and will always be I guess) to see what that tells us, I will post that later this week hopefully. Once I have that I can start playing with the seating depth and then have a least a rudimentary understanding of how to do load development from initial selection of brass, primer, powder and bullet to selecting a final charge weight and seating depth. Thanks again.

 

[powerspc]

So, I shot today 42.9, 43.1 43.3, 43.5 and 43.7 off a bench with a bipod and rear bag. No signs at all of overpressure but there was some wind blowing right to left at 16 mph. The data looked like this:
42.9
Min Velocity.: 2584
Max. Velocity: 2596
Avg. Velocity: 2590
S.D.: 8.88
E.S.: 13

43.1
Min Velocity.: 2586
Max. Velocity: 2604
Avg. Velocity: 2592
S.D.: 6.77
E.S.: 18

43.3
Min Velocity.: 2600
Max. Velocity: 2617
Avg. Velocity: 2611
S.D.: 6.95
E.S.: 18

43.5
Min Velocity.: 2605
Max. Velocity: 2637
Avg. Velocity: 2626
S.D.: 13.2
E.S.: 31

43.7
Min Velocity.: 2635
Max. Velocity: 2648
Avg. Velocity: 2642
S.D.: 6.52
E.S.: 14

The most interesting group I think was 43.5 which looked like this shot for shot:
Shot 1: 2632
Shot 2: 2622
Shot 3: 2636
Shot 4: 2605
Shot 5: 2637

I typically throw out the flyer when calculating MOA but wasn’t sure if that was an accepted practice when looking at groups (ES)? Something looks off on shot 4 which seems to be an anomaly in that string. If I throw that one out then the average velocity was 2632 and the ES would be 15. I’m thinking it may have been a .1-.2 grain light? I’d also like to think (although I can’t prove it, it sort of makes sense in my head) that that may have been the flyer which was low. Otherwise that was, I think, my best group of the day and honestly about as good as I can probably shoot (at least right now).

Would you just run with 43.5 and maybe tinker with the seating depth? Or does it become “good enough” at some point and just leave it alone?

 

[Deleted member 113831]

So, I shot today 42.9, 43.1 43.3, 43.5 and 43.7 off a bench with a bipod and rear bag. No signs at all of overpressure but there was some wind blowing right to left at 16 mph. The data looked like this:
42.9
Min Velocity.: 2584
Max. Velocity: 2596
Avg. Velocity: 2590
S.D.: 8.88
E.S.: 13

43.1
Min Velocity.: 2586
Max. Velocity: 2604
Avg. Velocity: 2592
S.D.: 6.77
E.S.: 18

43.3
Min Velocity.: 2600
Max. Velocity: 2617
Avg. Velocity: 2611
S.D.: 6.95
E.S.: 18

43.5
Min Velocity.: 2605
Max. Velocity: 2637
Avg. Velocity: 2626
S.D.: 13.2
E.S.: 31

43.7
Min Velocity.: 2635
Max. Velocity: 2648
Avg. Velocity: 2642
S.D.: 6.52
E.S.: 14

The most interesting group I think was 43.5 which looked like this shot for shot:
Shot 1: 2632
Shot 2: 2622
Shot 3: 2636
Shot 4: 2605
Shot 5: 2637

I typically throw out the flyer when calculating MOA but wasn’t sure if that was an accepted practice when looking at groups (ES)? Something looks off on shot 4 which seems to be an anomaly in that string. If I throw that one out then the average velocity was 2632 and the ES would be 15. I’m thinking it may have been a .1-.2 grain light? I’d also like to think (although I can’t prove it, it sort of makes sense in my head) that that may have been the flyer which was low. Otherwise that was, I think, my best group of the day and honestly about as good as I can probably shoot (at least right now).

Would you just run with 43.5 and maybe tinker with the seating depth? Or does it become “good enough” at some point and just leave it alone?

View attachment 6957942View attachment 6957941

I would do 43.7 or even 43.9 because you are right in that velocity window I mentioned before. At 43.7 you have good velocity and SD, so the powder is burning well and there is plenty of head room for summer heat. That load has really small vertical dispersion on the target which indicates good barrel timing, and is only 0.5 moa wide. I think you could be done right there if you want to be.

 

[powerspc]

Thanks Skook, I haven't shot 43.9 but I like the idea since I'm not seeing any signs of over pressure. I think I might shoot some larger groups at 43.7 and 43.9 and see what that looks like. Your feedback is very much appreciated. Once I settle on a load here I'll be going through the same process with the .338LM and .300WM barrels but I am now a lot more confident I can do so safely (most importantly) and make some sense out of what I'm seeing in the results.

 

[EchoDeltaSierra]

I've done load developments for 3 rifles and have worked with two other friends who've used the same process with success. One can find optimal charge weight with merely data from the chronograph. This is a tremendous time saver as it eliminates a lot of variables.

Load 10 rounds in .2 grain intervals. I last ran this with Lapua brass, 140gr ELD pills, and H4350 and selected 41.6 through 43.4 grains.

It is EXTREMELY important to make sure the charges are dropped accurately and when shooting every shot's speed needs to be measured accurately (no chronograph errors).

There should 2-3 steps in this 10-shot ladder that are very similar velocities. Pick what appears to be the middle of the low point and load a second ladder with 5 rounds at that mid point, and 5 rounds at -.2, -.1, +.1, and +.2 (25 rounds total). Shoot these 5-round groups over the chronograph. Marking paper isn't necessary; the last one of these I ran was shot at steel hangers at 200m.

Look at the data for each of the five groups and it should be apparent where the standard deviation drops, and then starts to rise again. The mid-point of the low will be the OCW (optimal charge weight).

With the OCW established, fine tuning can be done with things like bullet jump, neck tension, etc. Marking paper (I like to shoot this stuff at 200-300) is necessary at these stages to determine what improves groups.

Also, this is merely "a way", not necessary "the way", though it seems like a very effective way to find OCW and remove anything like shooter and environmental changes or error. Feedback or question are always appreciated.

 

[Deleted member 113831]

Here is a faster way.

Load 2 rounds each at your maximum acceptable over all length in .2 grain intervals starting 2 grains below max....record velocities for each pair. Use the recorded velocity along with other traditional pressure signs to determine max charge for your rifle.

Once max charge is determined, back off 2% and adjust seating depth deeper in .005" increments to adjust barrel timing until groups tighten up.

You are done.

 

[powerspc]

Here is a faster way.

Load 2 rounds each at your maximum acceptable over all length in .2 grain intervals starting 2 grains below max....record velocities for each pair. Use the recorded velocity along with other traditional pressure signs to determine max charge for your rifle.

Once max charge is determined, back off 2% and adjust seating depth deeper in .005" increments to adjust barrel timing until groups tighten up.

You are done.

I get the first part; so if my max load is 43.9 I would:

• Shoot 2 shot groups at: 41.9, 42.1, 42.3, 42.5, 42.7, 42.9, 43.1, 43.3, 43.5, 43.7 and 43.9.
• Determine Max load, for sake of argument say it is 43.9
• Back off 2% which would put me at 43.0

I am currently seating at 2.2580 which is 20/1000 off the lands (2.2780), so next I would:

• Shoot all of my rounds using a 43.0 grain charge

How am I adjusting the depth from here? Should I be moving closer or further away from the lands?

 

[Subwrx300]

@Skookum 's method is good way to go moving forward. But you don't need to reshoot the charges you've already shot. You have data for those. Maybe pick up where you stopped and go up from there. Then plug all charges and velocities into excel and see what you get from a graph.

Personally though, I have a hard time starting with a low SD. Good SD doesn't matter if it won't group decently. I usually find that with a decent grouping load, SD around 10 is plenty to keep you consistent to 600-700. With a 308, things start to get tricky at 800-1000 but that's more to do with wind.

I'd recommend finding a load that's .5-.75 and just start shooting it more to distance. Then after a few hundred rounds, you can keep tinkering and try to perfect it while you have a decent load to practice with.

 

[powerspc]

@Skookum 's method is good way to go moving forward. But you don't need to reshoot the charges you've already shot. You have data for those. Maybe pick up where you stopped and go up from there. Then plug all charges and velocities into excel and see what you get from a graph.

Personally though, I have a hard time starting with a low SD. Good SD doesn't matter if it won't group decently. I usually find that with a decent grouping load, SD around 10 is plenty to keep you consistent to 600-700. With a 308, things start to get tricky at 800-1000 but that's more to do with wind.

I'd recommend finding a load that's .5-.75 and just start shooting it more to distance. Then after a few hundred rounds, you can keep tinkering and try to perfect it while you have a decent load to practice with.

Am I trying to find the absolute max load? In other words would you keep increasing the load in small increments until you start to see signs of overpressure? I stopped at 43.7 but could have kept creeping up since I wasn’t seeing anything concerning. I was hitting good velocities at 43.7 but maybe 43.9 or 44.1 or 44.3 would have been better? Hodgdon shows the max load at 45.0 for both 175 and 180 grain bullets (they didn’t show a 178 gr). I feel like I can safely shoot faster loads, is that at least part of what I should be working towards?

 

[Subwrx300]

Well in general, most guys here shoot the fastest load that has acceptable precision and good SD. While the most precise load is not always at the top end of speed, in some rifles they are above max book load (while also not showing pressure signs).

The three major signs are flat/cratered primers, ejection port flow and sticky bolt handle on primary extraction. If you get more than one of those, you are usually at or slightly past acceptable pressure limit. If you get all three at once, you are significantly past limit.

Reloading books tend to be a bit conservative but each rifle is different, so we test in our own rifles to be safe.

I'd say being over a grain under book max, you can safely test up to and maybe slightly past to test upper limit. You may find groups get much tighter in node towards the top end (but you might not too).
Once you find the limit, test from .2-3 less than max down to 1.5 less than max in .2 or .3 grain intervals. Pick the one that shoots best.

 

[Deleted member 113831]

Am I trying to find the absolute max load? In other words would you keep increasing the load in small increments until you start to see signs of overpressure? I stopped at 43.7 but could have kept creeping up since I wasn’t seeing anything concerning. I was hitting good velocities at 43.7 but maybe 43.9 or 44.1 or 44.3 would have been better? Hodgdon shows the max load at 45.0 for both 175 and 180 grain bullets (they didn’t show a 178 gr). I feel like I can safely shoot faster loads, is that at least part of what I should be working towards?

Sorry, I didn't mean to confuse you. The load you are working on now is good to go if you want it to be, as I mentioned in post #16.

If you started from scratch, and worked this load up again using the method I talked about, you would most likely end up exactly where you already are. You just got there a different way this time.

Some day, when working up another load, the max load I referred to would be a maximum pressure load. Then proceed as in post #19. I tend to load for the middle node rather than the top one. The upper nodes tend to be considerably smaller, and a small change in weather can throw you out of the node as well as cause serious over pressure in the heat of the summer. My method may not produce the absolute best groups all the time. What they will do, is produce more forgiving, safe and workable loads that don't have to be agonized over.

Also, I'm guessing you aren't actually loading a 308 to 2.258" OAL. I'm hoping you meant 2.850" OAL.

 

[powerspc]

Hey Skook,

Okay thanks; I'm caught up now. I think I will shoot some larger groups at 43.5, 43.7 and try 43.9, the velocity there seems right where it should be, I'm seeing no signs of over pressure (haven't shot 43.9 yet, but will proceed with caution as always) and I shot decent groups. I may or may not play with the seating depth afterwards but if I do it will be primarily to understand how that does or does not effect the results. 2.2580" is the head to ogive measurement, the C.O.L. is 2.920". 2.2580" puts me 20/1000 off the lands which I think is good(?)

When I move off this caliber to .338LM and .300WM I will try the method you described above.

 

[Deleted member 113831]

I may or may not play with the seating depth afterwards but if I do it will be primarily to understand how that does or does not effect the results.

I think you will be very surprised how much seating depth affects group size and shape. Over the years, I've come to the practice of using seating depth to tune a load more than anything else.

Doing a seating depth test of a single identical load with say, a .050" total range of adjustment, you will see groups that look like absolute ass. Then you will also see some groups that really tighten up as the barrel timing is altered and the bullets are exiting the barrel at the optimal moment. Barrel timing is the thing. Traditionally reloaders have altered the load in small powder increments, but the problem with that is that you are altering your pressure curve MORE and altering barrel timing to a smaller extent.

Once you get your powder charge burning optimally, you want to change that as little as possible. That is why I find the max charge and back off 2%. That is very often the spot where the powder is burning well, but isn't getting spikey. So, you use a charge in that area and fine tune seating depth. Once you find the seating depth that seems best, then you can go a little further and refine your powder charge within a very small range, say .2 grains up or down just to see what that does.

On the other hand, if you are using this method, and NO decent groups show up, you can be assured fairly quickly that this bullet / powder combination isn't going to work and you can put your efforts toward another combination.

 

[powerspc]

I think you will be very surprised how much seating depth affects group size and shape. Over the years, I've come to the practice of using seating depth to tune a load more than anything else.

Doing a seating depth test of a single identical load with say, a .050" total range of adjustment, you will see groups that look like absolute ass. Then you will also see some groups that really tighten up as the barrel timing is altered and the bullets are exiting the barrel at the optimal moment. Barrel timing is the thing. Traditionally reloaders have altered the load in small powder increments, but the problem with that is that you are altering your pressure curve MORE and altering barrel timing to a smaller extent.

Once you get your powder charge burning optimally, you want to change that as little as possible. That is why I find the max charge and back off 2%. That is very often the spot where the powder is burning well, but isn't getting spikey. So, you use a charge in that area and fine tune seating depth. Once you find the seating depth that seems best, then you can go a little further and refine your powder charge within a very small range, say .2 grains up or down just to see what that does.

On the other hand, if you are using this method, and NO decent groups show up, you can be assured fairly quickly that this bullet / powder combination isn't going to work and you can put your efforts toward another combination.

Excellent, putting holes in paper is one thing but doing it with a plan and a purpose in an entirely different thing. Can't wait to get back out!

 

[CJS-6.5]

L.O.A.D.D.AT.A.

Lots of anthropiods drawing dumb ass theories again.