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Load Data

03 Oct 2018
@ 10:37 pm (GMT)

Andrew Murray

Hello! Here is a whole pile of load data from today. I thought I might share it. I will post photos of the groups afterwards. All loads had 6 shots (2x3 - 1 for accuracy and 1 for speed, using magneto speed chronny) except 1 (listed below). I also had some issues with the chronny on some groups as you will see. The issue seemed that the sensor was to far below the bullet path.

Projectiles: 168 grain Hornady Z-Max (A-Max with green tip)
Primers: Magtech Large Rifle (No 9)
Brass: Winchester Factory brass.
Powder tests was both AR2206H and AR2208

AR2208 (COAL 71MM) Group Size Velocity (fps) ES
46gr 22.6mm (0.85MOA) 2748, 2711 (did not chamber) 37
46.5gr 15.6mm (0.58MOA) 2733, 2791, 2782 62
47gr 32mm (1.2MOA) 3396, 4509 1335 <---- o.O 3396 from a .308!!
47.5gr 16.5mm (0.62MOA) 3146, 4731, 3241 Who said AR2208/Varget was overrated???
48gr 16.4mm (0.61MOA) Error, 3233, 3158 75 <---- This data may also be wrong


AR2206H (COAL 71MM) Group Size Velocity (fps) ES
41.5gr Crimped 40mm/6.4mm (0.25/1.5) 2619, 2602, 2632 30 <---- shot pulled, more testing
41.5gr (no crimp) 31.1mm (1.17MOA) 2652, 2641 11 <---- Only 2 shots per group
43.5gr Crimped 48mm (1.8MOA) 2727, 2757, 2744 30



AR2206H (COAL 70MM) Group Size Velocity (fps) ES
43gr 31.8mm (1.20MOA) 2728, 2705, 2691 37
43.5gr 25.1mm (0.94MOA) 2722, 2723, 2729 7
44gr 34.7mm (1.30MOA) 2744, 2758, 2774 30
44.5gr 15.1 (0.56MOA) 2791,2797, 2826 35

So, I hope you find this info as valuable as I do, particularly the velocities. The bottom load is screaming along.
The reason I started along this is because when my usual load (43.5gr AR2206H 71mm) was chronographed the ES was 75fps. However I am beginning to think that the chronograph was not correctly installed (installed the same way as the crazy loads above),so I will revisit this load again.

That said it has been very valuable and if indeed the 308 is getting over 3000fps on AR2208 I'll be looking for a barrel soon.

Photos next.

Replies

03 Oct 2018
@ 10:47 pm (GMT)

Andrew Murray

Re: Load Data
Sorry the tables are squished above, I had them all nice and formatted :(

So loads I will be following up for further testing are:
AR2208 at 47.5 & 48 grains
AR2206H at 71mm 41.5 crimp, and 70mm 44.5 gr (possibly 43.5 too)
Plus my original load with the chronograph mounted better.

AR2208 71mm
46gr

46.5

47

47.5

48


AR2206H 71mm Crimp
41.5 crimp

41.5 No crimp

43.5 Crimp


AR2206H 70mm
43gr

43.5

44

44.5
04 Oct 2018
@ 03:48 am (GMT)

Paul Leverman

Re: Load Data
Nice testing, Andrew. It looks like there may be a couple of sweet spots to revisit. Your groups share an uncanny resemblance to some of mine that I was working on. It would be nice if there was an interpretation paper/guide for group shape, it would definitely speed things up. But with experience, I'll probably figure it out. Keep us posted, looking really good.
04 Oct 2018
@ 10:03 am (GMT)

Bob Mavin

Re: Load Data
Hi Andrew.

I'm using Lapua palmer cases, no way I could get 48 gns of 2208 in my cases. I'm using 46gns for 2850fps 25" barrel, 1/2 MOA groups at 500yds
04 Oct 2018
@ 10:23 am (GMT)

Bob Mavin

Re: Load Data
Same pill 168 Z-Max[b]
04 Oct 2018
@ 10:36 am (GMT)

Andrew Murray

Re: Load Data
Cheers Paul and Bob,

Those are impressive figures Bob, I was suspicious that the load was going faster than 3000fps. Perhaps it is possible though?

That's impressive if it's true for a 308, especially with that weight projectile. Mine is the factory 24" on the Howas.

As for the capacity, it was fairly full... the loads for 06H @ 44.5 70mm and the 43.5 crimped load began to show some minor cratering on the primers for roughly half of those cases. Most did not show any adverse pressure signs.

I was also skeptical given the volume and possible carbon caking jacking pressures. Gave the rifle a full copper strip and a heavy scrub on the throat/chamber area. It was pretty filthy.

Exciting stuff.
08 Oct 2018
@ 10:17 am (GMT)

Andrew Murray

Re: Load Data
I'll be doing up a run if loads again and taking them out for testing this Wednesday. 41.5gr with the crimp to test.

47.7 and 48 of AR2208

44.5gr 06H @70mm COAL

And 43.5gr at 71mm

Some definitive results hopefully.

Stay tuned. Photos and hopefully videos to come.
10 Oct 2018
@ 02:39 pm (GMT)

Andrew Murray

Re: Load Data
Ok so here is the data!

The AR2008 loads proved to be most accurate. My original load of 43.5gr AR2206H @ 71mm COAL was not as accurate in terms of velocity or group as I had hoped :(

Velocities (6 shots each)
AR2206H: 2724, 2718, 2748, 2723, 2704, 2728 ES:44 Avg: 2724
'08 @47.5gr: 2796, 2809, 2799, 2789, 2807, 2808 ES: 20 Avg: 2801
'08 @48gr: 2824, 2813, 2814, 2821, 2821, 2812 ES: 12 Avg: 2817

Quite pleased with the ES with the AR2208 loads.

The groups however are interesting. I'd like some advice if you can offer:

In both groups (of the 2208 loads) you can see that 1 shot breaks away from the main group. Down and to the left, in both groups it was the 3rd shot. There is a similar pattern above to with these loads, not really noticeable on the others. Both groups are 4 shots

I am wondering if perhaps it is a psychological thing? The pressure on for the 3rd shot to not ruin the group??

Either way the photos are below. You can see the 47.5gr load is a one hole group (if you discount the low and left shot). The 48gr is not much bigger.

47.5


48
11 Oct 2018
@ 12:20 am (GMT)

Paul Leverman

Re: Load Data
Nice shooting, Andrew. Wish I could offer some sort of solution. You may be onto something about the psychological aspect, but then, the similarity between the groups might say otherwise. It may be an operator error, something along the lines of a tighter grip, or a slightly different hold on the shoulder, or eye position. Now that you have the load dialed in, on your next outing, try three shots and see if the pattern remains the same. If it is psychological, you will have the knowledge that it is possible to do a one hole group, you've proven you can do it, and this may help overcoming that aspect. (But then, all of the above may just be a big pile, reference the second sentence.) Your .308 certainly isn't picky about the load. I would have expected a larger difference with a .5gr variance, but that just shows the vagaries of barrels. Certainly makes it easier for you. In any case, it is still good shooting, and maybe after another couple thousand rounds, mine will look that good.
11 Oct 2018
@ 08:16 am (GMT)

Andrew Murray

Re: Load Data
Cheers Paul,

That's very kind of you. It is interesting to be sure! I only made 10 rounds of each but after these results I will do up another 10 of each. No chronny this time. I also need to test some other loads but I got rained out yesterday. The range is not covered...

But very excited to shot that way and like you said. Knowing that such accuracy is possible is great and I am sure will help overcome any psychological factors. It is interesting to see these groups compared with the earlier tests loads of the same powder. Those groups have he fire at the top, the second lot at the bottom...

There is of course the rifle factor and perhaps a rebedding would correct it...
11 Oct 2018
@ 03:05 pm (GMT)

Andrew Murray

Re: Load Data
Out of ammo Waz! 6 for the chronny and for for the group. Believe it or not most of the ones with the chronny were in the black circle. You can see the that weren't in the 48gr photo.

Next time I go out I'll sight it in. 3" high at 100yds should give me 3" below at roughly 300 at those velocities. Not a bad trajectory from a 308.

It us interesting the things we pick up from our dads though. I got my work ethic from mine. He never brought work home but he worked bloody hard when he was at work. Would never take a sick day, but happily take extended holidays. I used to work for him, I could be bleeding out of the eyes and he'd make me get to work but if I wanted a long weekend he would be okay as long as I had the leave accrued for it.
11 Oct 2018
@ 05:34 pm (GMT)

Warwick Marflitt

Re: Load Data
How lucky we were to have such great role models for dads. Once you get your loads sorted out around 47.5 looks good. Load up and do your drop charts in 20 meter steps or 10 if you want to out to the distance your competent to shoot too and then you can dial up to be on target every time 😊 the wind will be your nemesis until you get to know it's idiosyncrasies. Keep at it mate. Nothing succeeded's like success !
12 Oct 2018
@ 05:02 pm (GMT)

Paul Leverman

Re: Load Data
Not to hijack your thread, Andrew. Just to show you that I feel your pain. It gets kind of confusing, so bear with me.

First photo, first group, shots 7,8,9; two shots far right, one shot topmost



Third group, (13,14,15) second photo. Same shape, just smaller. This group had an ES of 7 (2856,2849,2853)

I'm thinking that maybe I push into the rifle anticipating the trigger release, but that's a guess, and I will have to wait until the next range day to test.
12 Oct 2018
@ 05:04 pm (GMT)

Paul Leverman

Re: Load Data
I'll try again for the other photo.

[img][img]https://i.imgur.com/44SdUVf.jpg[/img]
12 Oct 2018
@ 05:05 pm (GMT)

Paul Leverman

Re: Load Data
One more then I quit.

[img][img]https://i.imgur.com/44SdUVf.jpg[/img][img]https://i.imgur.com/44SdUVf.jpg[/img]
12 Oct 2018
@ 05:07 pm (GMT)

Paul Leverman

Re: Load Data
I give up.
12 Oct 2018
@ 07:01 pm (GMT)

Andrew Murray

Re: Load Data
Quote:
One more then I quit.


[b]
12 Oct 2018
@ 07:05 pm (GMT)

Andrew Murray

Re: Load Data
[quote]One more then I quit.

[b][img][/b][img]https://i.imgur.com/44SdUVf.jpg[/img][img]https://i.imgur.com/44SdUVf.jpg[/img][/quote]

to get youy photos working I just deleted the first (img) in the code. You had it doubled up. Probably confused the forum and it went blah
13 Oct 2018
@ 12:22 am (GMT)

Paul Leverman

Re: Load Data
Thanks, Andrew. You can see what I'm getting at, though. My thoughts were that if it was a bedding or a load problem, it would be more erratic instead of repeatable. In my case, I'm pretty sure it is operator error, as indicated by the general shape from load to load, which wouldn't be bad if all my groups were less than .2moa (yeah, right).

These were like yours, .5 grain increments. Way different results than yours, but it is a stock Savage barrel, so it whips around pretty good.
13 Oct 2018
@ 07:35 am (GMT)

Andrew Murray

Re: Load Data
Yeah that's true. The rifle does actually fail the 1 o'clock test. But to put 3 in one hole makes me think it is not so much of an issue.

I guess the disappointing thing is that if the 47.5gr (AR2208/Varget) load is what it like then I need to be vigilant watching case issues (pressure signs) also barrel life may be not quite as long as it could be with a lower load.

I still need to check the 41.5 gr load crimped and the 44.5 load @ 70mm COAL (both AR2206H). These might prove equally accurate and therefore suitable, just not quite as fast.

Have you bed your rifle yet? I wonder how far into the barrel channel you went? Does going further into it drop the whip? But like you said it is a stock barrel.
13 Oct 2018
@ 08:28 am (GMT)

Paul Leverman

Re: Load Data
I did bed the rifle and because it is a Savage, I bedded out past the barrel nut. Without taking it apart and measuring, I would guess about an inch past the nut. I can only assume the whip is lessened by the distance, as the bedding material would support and dampen that portion it is in contact with. On two of my other rifles, I went as far as five inches past the action, but these are long and very heavy barrels and it was more for support to take some of the strain off the action. Yours is a heavy barreled 308, is it not? I don't think going further out will hurt anything, and it would certainly take some strain (if there is any) away from the action.

Also, is your rifle suppressed?
13 Oct 2018
@ 10:32 am (GMT)

Ben Law

Re: Load Data
Hey Andrew, try removing the trigger and do the 1oclock test without it.

With my howa, it was failing the test, i thought the bedding job was close to perfect and couldnt work out why.
Anyway without the trigger fitted, passed no probs.
So refit the trigger but only tighten the screw up very lightly, and still all good. Start to tighten up the trigger up and it starts to fail again.

So i figure with any torque on the trigger screw it starts to flex the action around the tang.
I put some loctite on the screw and it shoots .3-.4moa all the time with almost any load ive tried in it. Its a 223 24" heavy fluted barrel by the way.
13 Oct 2018
@ 10:53 am (GMT)

Warwick Marflitt

Re: Load Data
Just a thought. If the action is moving in its bedding it might be catching up in one of two positions and it takes 3 shots worth of recoil to pop it there and the next shot pops it back and the 3 shot dual battery position cycle starts again? The problem is how do you prove that this is the case? I'm only fabricating a possibility that could be completely wrong. Would a gun vice or shooting sled be useful to diagnose these befuddling annoyances. Maybe pulling the action and very scrupulous inspection of the bedding with a big strong magnifying glass and looking for any movement marks will provide answers. It will be a minute amount of movement less than half a degree?

A Mere One-Degree Difference

by Antone Roundy | 

I've been thinking lately about the big differences little things make.

Consider this. If you're going somewhere and you're off course by just one degree, after one foot, you'll miss your target by 0.2 inches. Trivial, right? But what about as you get farther out?

After 100 yards, you'll be off by 5.2 feet. Not huge, but noticeable.After a mile, you'll be off by 92.2 feet. One degree is starting to make a difference.After traveling from San Francisco to L.A., you'll be off by 6 miles.If you were trying to get from San Francisco to Washington, D.C., you'd end up on the other side of Baltimore, 42.6 miles away. Traveling around the globe from Washington, DC, you'd miss by 435 miles and end up in Boston.In a rocket going to the moon, you'd be 4,169 miles off (nearly twice the diameter of the moon).Going to the sun, you'd miss by over 1.6 million miles (nearly twice the diameter of the sun).Traveling to the nearest star, you'd be off course by over 441 billion miles (120 times the distance from the earth to Pluto, or 4,745 times the distance from Earth to the sun).

Over time, a mere one-degree error in course makes a huge difference!

13 Oct 2018
@ 11:28 am (GMT)

Andrew Murray

Re: Load Data
Cheers guys. That's all really great advice. The other thing I need to eliminate which I will do on the next shoot is form factor. I'll really focus on it to make sure I am not a variable in the equation but checking the trigger fit and if needed making some room in the stock sounds good, plus also looking for those jump marks Warwick.

And Paul, rifle is not suppressed or braked. I am already about 50mm into the channel which is enough I think. I was thinking maybe for you but you're best to ask someone with more knowledge as I don't know enough to say so.
14 Oct 2018
@ 02:14 pm (GMT)

Paul Leverman

Re: Load Data
Andrew - I went to the range today to test loads and form. Two of the rifles I shot (Parker-Hale 30-'06, Norma), all groups were similar in shape. From this I think it is safe to conclude it is me, after all, it is highly unlikely that two would shoot identically. Just passing along info.
14 Oct 2018
@ 06:16 pm (GMT)

Andrew Murray

Re: Load Data
Well that's a positive as you can look at your form and work on that. It's by no means encouraging but one less piece of the puzzle to figure out.
 

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