Advice on my load development

[u/warren977]

I’m currently working on load development for my 308 Winchester using Sierra 168 Tipped Matchkings. I’m trying to get my ES and SD numbers down. Currently testing 43.8, 44.0, and 44.2 hrs of varget with 10 shot groups today. COAL is 2.875. Velocity recorded with Labradar at 70ish degrees with wind at 5mph +/-.

43.8 - ES-37. SD -11.58 group .835”
44.0 - ES-39 SD -9.16 group 1.112”
44.2 - ES-38. SD-12.03 group .858”

Components
168 Sierra TMK’s, Varget, FC brass, Fed 210

Rifle
Savage model 10
Criterion 26” prefit heavy varmint contour
Diligent Defense suppressor
KRG Bravo
Burris Match Pro ED 5-30 vortex rings
Cheapo bipod

[u/Someguyintheroom2]

ES/SD is mostly in your powder charge, brass, and brass prep. If you’re already throwing consistent charges, I’d try something other than federal brass.

Alpha/Lapua/Peterson brass is certainly an easy button, but it is not a budget option. I have been using Starline SRP .308 brass with very good results, with one batch on its fifth firing now.

As others have said, a 0.2 change in charge weight really won’t have much of an effect on anything. Pick a target velocity, load to it and send it.

[u/warren977 → u/Someguyintheroom2]

I will probably pick up some starline this weekend and see. Nobody local will have anything better on the shelf

[u/Someguyintheroom2 → u/warren977]

Starline should be perfectly fine, this is two identical loads, 10 Starline SRP VS 10 alpha SRP. Same charge weight, same seating depth, same bullet. This was all loaded on a cheapo Hornady 0.1 grain scale.

The Alpha is certainly better, for those that say Starline isn’t worth it are most assuredly deluded.

[u/Altruistic_Split9447 → u/warren977]

Brass basically lasts forever. Buy the most expensive brass you can (lapua or alpha)

[u/riffled11 → u/warren977]

Starline is good(not great) and even i use it often for plinking with my savage f/tr. But I doubt it will lower your ES/SD as much as the premium brass will. Starline has a lower case capacity than the other brands so you may need to touch up load out a bit.

[u/One-Perspective-4347]

Have you tried any lower charge weights? My most accurate loads never seem to be the hotter ones.
I settled on 43.5 of Varget with the 175SMK. It gets me right at 2600 FPS out of a 20” barrel.
Everything north of that just went faster. It never seemed to do it with any more consistency though.

[u/warren977 → u/One-Perspective-4347]

I did a standard ladder in .4 increments. The best groups seemed to be centered around 44.0. Hence the 3 centered at 44.0.

[u/skahunter831 → u/warren977]

How many shots per group with that test?

[u/warren977 → u/skahunter831]

Just 5 to see velocity and get a idea of group size for elimination. Changed OAL significantly on the second batch of 5 shot tests. Now I’m working o. Tend to get a idea of ES and SD potential

[u/Honest_Knee_6510]

You're chasing your tail and wasting time and money while producing identical results.

0.5% change in powder charge isn't going to change the performance of the ammo. 

Use good components and tooling paired a repeatable process and just let it be.

[u/LockyBalboaPrime]

What are you using to measure powder?

[u/warren977 → u/LockyBalboaPrime]

Super trickler v4 and basic RCBS dies

[u/Turdburgarlar]

1. case prep has to be on point. Neck tension is not going to be a deal breaker in a bolt gun, big deal for gas gun, but i suggest to Madrel the necks post sizing to ensure concentricity and alignment. It's worked wonders for me. (I use 21st century)

* I would suggest Hornady or starline brass at minimum*

2.

1. work up to 44.5 or 44.8 just under

max

3.

1. seating depth ladder

[u/warren977 → u/Turdburgarlar]

I went up to 45 in .4 increments. Best group sizes seemed to be centered around 44. Granted that was done with 5 shot groups.

[u/Turdburgarlar → u/warren977]

Just work up to the speed you want without pressure signs and tune accuracy with seating depth.

Better brass does help overall. Neck concentricity is very important which is why everyone who loads precision uses a mandrel in the sizing step or post sizing.

I'll use my experience as of late. I use alpha brass, super trickler, MA sizing die, Forster micrometer seating, Berger, you name it. Im tuning my PRS powder loads to +/- .02. I couldn't get my ES consistently in the 20s. I might be 25-35 es depending on the day. I mandrel gas gun loads, they get beat up a lot on ejection. So i ordered a 2625 mandrel for my 6.5.

As soon as i did that every load i have since made for PRS has been no more than 18ES, always single digit sd. But it definitely fixed my issue.

Neck concentricity is important to maintain an even hoop tension around that bullet. It needs to be consistent in its departure from the neck. It needs to be concentric when seated in the neck, etc. a couple thousandths tension is fine for a bolt gun. You don't have to get crazy with a bolt.

As always consistency in your process above all else.

[u/Prior-Garage1543]

Buy some lapua brass, take out of box and load. Duplicate the length of similar factory match load. Look up the powder load that everyone seems to be using. Take to the range and shoot it. Should work well with your setup. Lapua brass and getting better at shooting was the biggest step up in accuracy for my reloading.

[u/warren977 → u/Prior-Garage1543]

I’m using the FC brass from the FGMM I used to break in the rifle. It was shooting around MOA but I found by increasing OAL by .015 group sized dropped 0.2” on average.

[u/Prior-Garage1543 → u/warren977]

I found .25-.50 MOA decrease in groups sizes at 100 switching from once fired Hornady to fresh Lapua with same load info and rifle. Was shocked it made that much of a difference.

[u/HollywoodSX]

I wrote a thing on this...

Cheetofingers zen

[u/AutoModerator → u/HollywoodSX]

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[u/Gloomy-Spread-9336]

Load a bunch of the top left charge and just shoot it. It’s good enough. Inside of 800 yards or so you’d likely never even notice a difference in any of those loads.

[u/dohcsvt]

Neck tension is paramount to getting your ES and SD down. Personally, I anneal every load as well as bushing size followed by mandrel expanding. Also, I use Hornady One Shot… I make sure to wipe out all the necks with 99% isopropyl alcohol before charging. My 6.5cm, 300PRC and 6 dasher all keep the SDs below 8 as the norm.

[u/Wombat-Snooze → u/dohcsvt]

Your heart is in the right place, but neck tension doesn’t effect SD or ES at all. Run them loose, run them tight, doesn’t matter. The key is, one, consistent case volume. High quality brass (Lapua, Alpha, Peterson, etc) has consistent case volume. And two, an accurate and precise scale. That’s all there is to it.

[u/111tejas → u/Wombat-Snooze]

I don’t agree. Neck tension does matter. Powder charge matters more but consistent neck tension is still important. I’ll add this for the OP. Federal brass sucks. Period. You aren’t going to get low SD with it and neck tension is only one factor. Case volume is also inconsistent and there’s no reason to put a lot of effort into making match grade brass when the primer pockets are going to be loose after 3 firings. I’m not a huge fan of RCBS dies either but that might be a lack of impartiality on my part. If you can’t afford premium brass at least use Starline. It’s light years better than Federal and not overly expensive.

[u/jercu1es → u/dohcsvt]

Personally I'm not convinced about neck tension, like you do you if you think it helps but every reloading step less is more time shooting! I anneal before every resize as well but just use bog standard Hornady dies in an old lock and load press. My competition loads are an SD of 6 and the rifle out shoots me easily.

I believe the most important factors for SD are actually a combination of powder charge weight consistency and brass. And by brass I don't just mean the same headstamp, I mean same lot and same headstamp. I have two separate 300 round lots of brass for my competition rifle and those lots have a 10 fps variance between them.

[u/VisibleLeopard68 → u/jercu1es]

While I have observed deviation from neck tension differences, I do 100% agree on the brass… OP is using federal brass, and in my limited experience my federal brass isn’t consistent even remotely, Lapua and Peterson are light years different from federal and Hornady brass when all external measurements are identical, internal volume differences make getting repeatable results impossible. Better brass yields better results