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 308 Win load work up. 
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Location: Everett
Joined: Thu Aug 13, 2020
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Real Name: Nathan
I thought I'd do a write up of some load development I was doing this weekend.

All testing is done at 100 yards, with different weather conditions(68degrees one day, 55 the next humidity also changed). The overall purpose of the following tests was, and is, to take this load to 1000 yards or more.

First, the brass, primers, powder, and projectiles used are as followed.

Brass: LP(Large primer) Lapua Brass
Primer: Fed 210
Projectile: Sierra 175gr SMK
Powder: IMR 4064

Rifle Specs:

1:10 twist 20" barrel UPR10 Upper.

I do have a load work up for AR Comp, but I need to do more tests on that. So I'll do a write up on that later if this gains some interest with inquiring minds. Most of you should know not to copy these loads. This is strictly for informational uses only. Work up your own load for your chamber.

This first part is all 1 round with each charge weight. Looking for data points to explore ladder tests for velocity nodes.

Charge weights Velocity
41.0 2431
41.2 2476
41.4 2480
41.6 2497*
41.8 2495*
42.0 2500*
42.2 2509
42.4 2531
42.6 2532
42.8 2553
43.0 2575 *
43.2 2573*
43.4 2574 *
43.6 2598
43.8 2598
44.0 2632


As you can see, with my tests, 4064 produced 2 good nodes for me(marked with *). One between 41.6 to 42.0grs. The second, between 43grs and 43.4grs. Both within 1 grain of one another. This test was done in 68 degree weather. So I'd bet that colder weather and warmer weather will effect the over all velocity that we see above. But, not the node.

With that said, the next day I tested the highest node in the 43gr area. and the lowest in the 41.8 area. 3 shot strings to look for velocity consistency. I will do a larger string(10) to find the SD and ES. I also was not looking at group size either. That will be later with more development with seating and tuning the brake.


First node:
Charge Velocity
41.8 2477
41.9 2485
42.0 2480
AVG 2480

Second Node:

Charge Velocity
43.1 2554
43.2 2550
43.3 2550
AVG 2551

I did a rough estimate of the average between the 3 sets.

Unfortunately, I ran out of time this weekend to set my sights on getting the SD ES, and starting the seating depth test. With MC excel I was able to put together a graph with some numbers with neck tensions as well. I can include those later when further testing is done.

I do like the 43.2 grain area. As it produced 50FPS above what the GMM produced in my rifle. I did not experience, or see any signs of pressure. Such as heavy bolt lift, swipes etc. This rifle does cause primer cratering WITH factory loads. So I do not look for that as much with tests. I rely on the chrono and bolt lift. Even with the highest charge of 44.0grains. I did not have heavy bolt lift.


Sun Oct 10, 2021 11:40 pm
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Great input!
Thanks!
:wagwoot:

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Mon Oct 11, 2021 5:39 am
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Yesss, very interesting to follow along. thumbsup

Curiosity question: What is it about the potential nodes at 42.4-42.6 and 43.6-43.8 that made you discard them from further testing?

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Mon Oct 11, 2021 6:27 am
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MadPick wrote:
Yesss, very interesting to follow along. thumbsup

Curiosity question: What is it about the potential nodes at 42.4-42.6 and 43.6-43.8 that made you discard them from further testing?


At the time, just by going off face value of the data I had. I was looking for a flat spot across 3 or more charge weights. Much like seating depth testing, I wanted to see a consistent flat line with 3 charge weights. Those two areas gave me a small window to work with. Say if I was at a match with that load, there isn't much wiggle room for adjustment as the day goes on. That half a grain leaves me plenty of room to dial up or down from 43.2 for load adjustment depending on day.


Mon Oct 11, 2021 10:02 am
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Thanks!

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Mon Oct 11, 2021 10:21 am
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I don't have the data readily available but my ladder test showed that my Seekins Precision 308 has its best groups with a 165 gr Hornady in front of 43 grains of 4064 with a CCI LRP. That's all I load now for it.

My Savage 99C 308 likes 42 grains 4064 with a 165 gr bullet.

4064 is outstanding 308 powder, I've tried W748, W760, H335....but 4064 was the best.

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Mon Oct 11, 2021 2:02 pm
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The ol Scott Saterlee method. So much more efficient it nearly takes the fun out of it


Mon Feb 28, 2022 4:00 pm
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Never could get 175gr smk to shoot consistently in my 5r which, ironically, was designed for that projectile.

My rifle had a different twist rate than yours but it loved the berger vld 175 over 44 grains of varget at 2.920 coal. Had to sacrifice a little consistency and seat them at 2.850 to mag feed though.

I’ll be interested to see how your rifle performs with different seating depths.

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Mon Feb 28, 2022 6:25 pm
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Location: Everett
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Real Name: Nathan
Sinus211 wrote:
Never could get 175gr smk to shoot consistently in my 5r which, ironically, was designed for that projectile.

My rifle had a different twist rate than yours but it loved the berger vld 175 over 44 grains of varget at 2.920 coal. Had to sacrifice a little consistency and seat them at 2.850 to mag feed though.

I’ll be interested to see how your rifle performs with different seating depths.


With 4064 on the SMKs I ended up with a CBTO around 2.235. Which isn't too far from the factory, but it shot better. Average group was between the .5s to low .7s.

Right now, I am running the 175gr OTM Berger bullets with Varget. Tests between primers, large and small. Palma brass, and regular brass. So far, the results are interesting. Palma is leading it with better numbers for SD and ES goes. But velocity lacks from 25 to 40 fps slower, and about a half grain behind the larger primers(205/205M and 210/210M).


Fri Mar 18, 2022 5:39 pm
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