How close to max powder do you typically find good loads?

[Don_Parsons]

308 winchester, 44.2gr of Varget with 168gr bullets Lapua brass seated 2.810,,, CCI 450 SM primers

It's one of my sweet hunting loads

 

[SGK]

So I spent about 3 hours at the range today. Conditions were great: next to no wind, 74F and low humidity. Unfortunately the sun was beating down on the firing line/barrel.

I took with me six, 5-shot loads.

1. 42.26 gr Varget (96.5% of listed max load) seated at 2.208" CBTO which I estimate to be 50 thou off the lands - this was the best performing load from my previous seating depth test (90, 50, 30 and 10 estimated jump) done at 96% of listed max load
2. 42.46 gr seated at 2.218" CBTO
3. 42.68 gr seated at 2.218" CBTO
4. 42.90 gr seated at 2.218" CBTO
5. 43.12 gr seated at 2.218" CBTO
6. 43.34 gr seated at 2.218" CBTO (98.5% of listed max load)

I was expecting 2 to do better than 3 on paper. It's closer to the CBTO of the HPS ammo (Sierra Matchking 168 gr with 44.5 gr of N540) I have been using until now. But it did not. Group wasn't as good and velocity SD larger as well. Seems like these ELD Match like a big jump in my rifle (if anything at all).

None of the above loads produced groups as good as the HPS 'factory' ammo.

Here's some velocity data: (figures more informative on relative basis than absolute basis)

Average then SD in fps

1. 2467.8 12.68
2. 2474.0 16.84
3. 2490.4 19.72
4. 2499.6 15.79
5. 2494.0 18.80
6. 2500.8 12.01

By way of comparison, 6 rounds of my HPS ammo produced

2571.5 16.53

Tighter groups but with a relatively large velocity SD.

I find it interesting that average velocities really flattened out (4-6) in my ELD-M ladder test.

I don't think I am getting any pressure signs (pic of primers attached; loads 1 left thru to 6 right). Please do let me know if you think otherwise. (Click thumbnail for larger image)



(Of course I was only doing 5 shot groups. Even with load 6 I can only be 95% confident that the population average is somewhere between 2485.9 and 2515.7 and the SD between 7.19 and 34.51.)

I think I need to keep progressing up the powder ladder and test a slightly shorter CBTO (longer jump).

 

[SGK]

So I have been staring at these fired cases and the particularly looking at the levelling off in velocity between loads 4, 5 and 6 and I'm a bit nervous. I understand velocity levelling off with increased powder charge to be a red warning flag. I'd appreciate some input. To my eye the primers are more flattened on my loaded ammo (PPU case, Hornady ELD-M 168gr, 43.34 gr Varget) than my fired HPS ammo (RWS case, Sierra MK HPBT 168 gr, 44.5gr N540). Velocities are lower but maybe that's just because the N540 is "high energy" although I am not sure how you get the higher velocity without greater pressure. I've tried to take a photo of the HPS fired case (left) vs my loaded fired case (right). Any thoughts?

(If you click on the thumbnail and then click on Show in Original you can see the image at full resolution.)

 

[DirtySteve]

I have never used N540. However I use 44.2 grains of Varget with a 175 VLD. The RWS case primers are more flattened but I think that load is safe. I see no brass flowing into the ejector cut nor is the primer cratered.. That is just my opinion more wiser men shall chime in soon.

 

[boltfluter]

So I have been staring at these fired cases and the particularly looking at the levelling off in velocity between loads 4, 5 and 6 and I'm a bit nervous. I understand velocity levelling off with increased powder charge to be a red warning flag. I'd appreciate some input. To my eye the primers are more flattened on my loaded ammo (PPU case, Hornady ELD-M 168gr, 43.34 gr Varget) than my fired HPS ammo (RWS case, Sierra MK HPBT 168 gr, 44.5gr N540). Velocities are lower but maybe that's just because the N540 is "high energy" although I am not sure how you get the higher velocity without greater pressure. I've tried to take a photo of the HPS fired case (left) vs my loaded fired case (right). Any thoughts?

(If you click on the thumbnail and then click on Show in Original you can see the image at full resolution.)

I see nothing alarming there. Carry on!

Paul

 

[SGK]

Ok thanks guys. I have just now loaded 5 rounds of each of:

43.34 gr @ CBTO 2.218” (last group fired from previous test - circa 40 thou jump)

43.34 gr @ CBTO 2.208” (50 thou jump, best performing jump from previous tests 90/50/40/30/10 jump)

43.34 gr @ CBTO 2.198” (60 thou jump)


43.56 gr @ CBTO 2.208” (99.0% of max)

43.78 gr @ CBTO 2.208” (99.5% of max)

44.00 gr @ CBTO 2.208” (100% of max)

Hopefully I will get to the range on Monday to see how things go.

 

[divingin]

So I have been staring at these fired cases and the particularly looking at the levelling off in velocity between loads 4, 5 and 6 and I'm a bit nervous. I understand velocity levelling off with increased powder charge to be a red warning flag.

I read conflicting information, but among those are this: A flat spot in a ladder of progressively loaded charges indicates the presence of a node. That's where you want to be.

Should you continue your ladder with more steps, you'll likely see another flat spot a couple/few grains higher.

To my eye the primers are more flattened on my loaded ammo (PPU case, Hornady ELD-M 168gr, 43.34 gr Varget) than my fired HPS ammo (RWS case, Sierra MK HPBT 168 gr, 44.5gr N540).

None of the pics show anything that would be of concern to me pressure-wise. Primer flattening is one of the least reliable signs anyways. Look for ejector swipe on the brass, or sticky bolt lift. Although these also mean (again, to me) you've gone a bit too far.

 

[Flouncer]

Can someone please post up a case showing ejector swipe or other sign of brass flowing ? - thanks.

 

[SGK]

If you Google "reloading pressure signs" you will find many examples of that (pics and vids). There are some examples here: https://www.primalrights.com/library/articles/understanding-pressure

 

[SGK]

It took stepping all the way to the max listed load (Hornady Manual) for me to get a 5 shot 100 yard group much closer to what I expect from this sporter rifle. I did a seating depth test at 43.34 gr of Varget (98.5% of listed max) - CBTOs of 2.218", 2.208", 2.198", estimated jumps of 40, 50 and 60 thou. 60 thou outperformed considerably. Unfortunately I had seated the next steps in powder load at 2.208". Nonetheless at 44 gr of Varget (100% of listed max) things tightened up considerably. The velocity SD of 14.95 fps was actually worse than the 11.79 achieved with 60 thou jump in the seating depth test (lower powder load; 11.79 fps SD) so there's more work to be done. But finally feeling like I am getting to the short strokes. Cartridge cases look ok to me. (Rings in target are spaced 1cm.)

 

[searcher]

As others said - it is common knowledge that the fuller a case is with the proper propellant, the more uniform each shot can be. This is why a lot of the loading manuals recommend accuracy loads that are close to 100% fill. Doesn't mean it will shoot in YOUR rifle - but that it should provide optimum velocity for that load.