.308 Win load development questions

[186thFCo]

So I'm trying a different way in load development for my .308 win. I took my Magnetospeed to the range use that to look for velocity nodes. I started by firing 15 rounds starting at 42 grains and ending at 46.2 grains going up by .3 grains. Here is what I got.

Charge weight (grains) MV (fps)

1) 42 @ 2545

2) 42.3 @ 2548

3) 42.6 @ 2588

4) 42.9 @ 2624

5) 43.2 @ 2634

6) 43.5 @ 2647

7) 43.8 @ 2641

8) 44.1 @ 2677

9) 44.4 @ 2680

10) 44.7 @ 2680

11) 45 @ 2746 (Book Max Hodgdon web site)

12) 45.3 @ 2714....?

13) 45.6 @ 2736

14) 45.9 @ 2760

15) 46.2 @ 2777

​​​​​​As you can see I have a very clear node with loads 8, 9, 10 and have another at loads 1 and 2. Obviously I would like to explore 8, 9, 10. So my question is where do I go from here? Do I start shooting for five shot groups or do I break down the loads further and get MV readings again? I have never done load development this way before I have always use the 300 yard ladder test method and than a 2nd test at 400 yards. I can't do this right now cause the farm I shoot at has their corn up.
Also none of the loads showed any pressure signs and all loads where jammed .010 into the grooves but I'm not sure if I should push it any further should I though?

 

[MtnCreek]

I'd shoot 44.3, 44.5 & 44.7 for groups and assuming you find acceptable accuracy, pick one.

 

[pmclaine]

Am I missing it? What powder are you using?

Sorry for asking if I missed it.

 

[186thFCo]

I'm using Varget, 175gr SMK, CCI BR primers. and federal brass

 

[ubet]

44.1-45 and did an optima charge weight test. My rifle with Lapua brass br2, 175 smk, varget likes 44.7. And according to my dope I'm at 2758fps.

Sent from my SM-N920V using Tapatalk

 

[pmclaine]

I'm using Varget, 175gr SMK, CCI BR primers. and federal brass

Received, Thank you.

Sorry but I am the odd duck that doesn't find love with Varget.

IMR 4895 and 4064 are working well for me and I can find them more readily than Varget.so Ive stuck with the dinosaur propellants.

 

[demolitionman]

I hope you have better luck with 308 Federal brass than me! Split necks after 3 firings with a 41 gr charge of 4064.

 

[918v]

R u using brass polish containing ammonia in your media?

 

[skulldragr17]

I'd shoot 44.3, 44.5 & 44.7 for groups and assuming you find acceptable accuracy, pick one.

I would do this, but load up about 3 of each charge instead of only 1. This will get you a more accurate reading of the velocity node. The result of this test will dictate what charge weight to go with. The only other three things to test (unless you want to get super picky with hand loading) would be neck tension, jump and primers.

 

[Eznutz]

Start at 44.5 since it right in the middle of the node and do load development for jump. Start at 0 and move out to 30 or 40 thousandths. Identify which group "settles" and confirm it. Then you have your load. I'd check my lands every couple hundred shots to see if the lands have receded any and try to keep them the optimal distance. For what its worth I had great results with varget and 175 gr bullets in my 308.

 

[186thFCo]

Ok so i went to the range with 15 rounds, 5 rounds loaded with 44.3gr, 5 of 44.5gr, and 5 with 44.7gr. 44.5 gr was the best giving me an SD of 7.8 with an average velocity of 2676fps. Should i go with this and start playing with seating depth or should i tweak the charge weight some more to try and get the SD lower?

 

[mikehotel]

you are on the right track, my r700 likes 44.5g, try varing your seating depth. BTW, SD of 7.8 is pretty nice

 

[186thFCo]

Ok so I'm now loading rounds to shoot for groups with different seating depth. I'm starting with .030 jumping and getting closer to the grooves by .005 for each string. Should I shoot 5 shots or three for this test?

 

[flyright]

Berger suggests .04 jumps to find OSD. I used this method and definitely found a preferred seating depth with 3 different bullets after my OCW tests. I then went to .02 each side and found very little difference on either of those sides - in other words, with one of the 175 loads - 2.82 beat out 2.78 and 2.86 by quite a bit. 2.84 was about equal to 2.86 but 2.82 down to 2.80 gave identical results. That was a (basically) one hole group - .08 and I stopped load development there. I was very tired of doing it at about 190 rounds into a very finicky .308 custom barrel but the results paid off. I figured this would give me a bit of wiggle room for inconsistent ogives and I bought up a bunch of the components. I have been able to repeat that one hole performance in winter and summer on good days. That load will consistently produce 3/4 moa at 100 yds (at worst) and stays about 1/2 to 3/4 moa out to 800 yds so I've stopped the tweaking and just loaded a bunch of them. My shooting buddies are chasing that better/perfect load every day and try to tell me that the barrel was just getting "broken in" and I should try experimenting with their latest and greatest bullets, powders etc. I just keep that "go to" load for that rifle. I guess I've given up. Hey! I just got a new rifle to play with last week - so, here I go again...

 

[flyright]

And 3 shot groups should give you a good idea of what is working...

 

[186thFCo]

how far away from the grooves should I start? .030, .040, .050.....etc?

 

[NukeMMC]

how far away from the grooves should I start? .030, .040, .050.....etc?

Some of that depends on your magazine's max OAL. If you have a recent Remington with one of their extremely long throats, you may be limited by magazine length long before being .020" from the lands.
The SMK is pretty jump tolerant, so starting at .030" is not bad by any means. It's pretty rare to find someone jamming SMKs.

 

[flims]

You may be interested in this article i wrote about load development in <50 rounds https://www.rifletalks.com/equipment-reviews/rifles/load-development-for-308win-in-under-50-rounds/

 

[Deleted member 113831]

So I'm trying a different way in load development for my .308 win. I took my Magnetospeed to the range use that to look for velocity nodes. I started by firing 15 rounds starting at 42 grains and ending at 46.2 grains going up by .3 grains. Here is what I got.

Charge weight (grains) MV (fps)

1) 42 @ 2545

2) 42.3 @ 2548

3) 42.6 @ 2588

4) 42.9 @ 2624

5) 43.2 @ 2634

6) 43.5 @ 2647

7) 43.8 @ 2641

8) 44.1 @ 2677

9) 44.4 @ 2680

10) 44.7 @ 2680

11) 45 @ 2746 (Book Max Hodgdon web site)

12) 45.3 @ 2714....?

13) 45.6 @ 2736

14) 45.9 @ 2760

15) 46.2 @ 2777

As you can see I have a very clear node with loads 8, 9, 10 and have another at loads 1 and 2. Obviously I would like to explore 8, 9, 10. So my question is where do I go from here? Do I start shooting for five shot groups or do I break down the loads further and get MV readings again? I have never done load development this way before I have always use the 300 yard ladder test method and than a 2nd test at 400 yards. I can't do this right now cause the farm I shoot at has their corn up.
Also none of the loads showed any pressure signs and all loads where jammed .010 into the grooves but I'm not sure if I should push it any further should I though?

All those loads in blue are too hot for Federal brass. You will be lucky to get 3 firings at that pressure.

Your node is going to be 43.5 - 43.8.

 

[LANCER]

I hope you have better luck with 308 Federal brass than me! Split necks after 3 firings with a 41 gr charge of 4064.

You should anneal. If you don't have an annealer, I could anneal them for you on an AMP, or there are others here that will do it for you also.

 

[LANCER]

Those loads seem way hot for Varget and 175 SMK. Any pressure signs?

 

[fx77]

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