Load Development Ladder Increments -.308

[SGT G]

Going to do some load development for my .308 win

Components:
Federal FC Brass
Federal Large Rifle Primers
Reloader 15
Nosler Custom Competition 168s

What increments of powder charge are you guys jumping for ladder charges?

.5 grains?

At 42.5 a .5 grain increase is a 1.17% change in powder charge, which I feel is quite minimal, maybe negligible.

Thoughts?

 

[ASD9055]

What is your maximum going to be? Some peole say 10 steps from starting to max. There are many "opinions" on step size

 

[kiwijohn]

I go 0.3 intervals in conjunction with simulation using GRT.
So to be clear I am wanting velocity to remain supersonic (hence GRT modeling) and the 0.3 increments show me where the accuracy node is, I don't use 10 steps more like 5, if I am more than 1.5 grains away from a node and staying supersonic I am using the wrong combination of components.
My approach works for me, your purposes may differ.

 

[Eagle Six]

I usually do .3 grain as a start and narrow it down from there according to results.

 

[RegionRat]

Depends on what your definition of "load development" and "ladder" means.

Like kiwijohn said, 308 Win is not unknown territory unless you are using unknown bullets in a sporting factory gun.

If this rifle has a good competition barrel profile and known good chamber, you can cut to the chase and just test the typical competition load recipes, in so many words skip straight to fine group tuning.

If this is some unknown factory chamber with a sporting barrel, and you are testing unknown bullets and recipes, then your powder step interval needs to be as they suggested... smaller.

With a classical Audette Ladder Test, you would want to run in 0.2 - 0.3 grain steps to be able to read the vertical wave data with clarity. If those vertical waves are not very wide a coarse step size just makes the whole test difficult to read and you may as well then use a different method which we would not call a "ladder".

You mentioned Nosler 168 Custom Comp, which implies match shooting.

If this is a match rig, then I would skip to testing the Pet Loads and save yourself the effort and resources of shooting a typical full "ladder test".

You can get better advice if you also describe the rig and the type of shooting you are pursuing, for example hunting, Highpower Sling, F-T/R etc. (I didn't list BR on purpose since you won't be competitive with those bullets anyway.)

Match guns tend not to show very strong vertical waves in ladder tests because the barrels and stocks do a much better job, hence they are intentionally designed to avoid those harmonic problems. Nothing wrong with testing for your own background if you are just starting out, just be prepared for the results.

If this is a factory sporting carry rig, then use fine steps (at distance) in your ladder so that the vertical waves are obvious.

Good Luck and in for the range report.

 

[Straightshooter1]

Going to do some load development for my .308 win

Components:
Federal FC Brass
Federal Large Rifle Primers
Reloader 15
Nosler Custom Competition 168s

What increments of powder charge are you guys jumping for ladder charges?

.5 grains?

At 42.5 a .5 grain increase is a 1.17% change in powder charge, which I feel is quite minimal, maybe negligible.

Thoughts?

I've found that .5 is just too large of an increment for this size of cartridge. Either .2 or .3 better helps identify a "node" and how large is might be and where you might be within it. With RL-15, I think you might find something around 43.0 grs that'll work.

FYI: A few year back I tried the Nosler 168 CC's and they did ok. But I went back to the 168 SMK's as they did better. You're experience may be different . . . ???

 

[762plinker]

tell us about the rifle and the type of shooting and we will tell you about load development.
i have several 308's with twist from 15 to 10, bbl length from 20 to 24.
based on your components i am guessing you are not expecting much

 

[SGT G]

So the rifle is a trued 700 action, 1:11.5 twist 22” barrel, sico Harvester suppressor, set in a hs precision stock.

Just want to ring steel out to 800yards or so.

Looking for 1 minute, maybe better accuracy.

 

[RegionRat]

Then pick a decent day and run your fine step ladder out to at least 600 yards or more.

Before this, make sure the barrel has enough rounds to be done speeding up to make the effort worth the trouble.

Make sure your suppressor is clean and ready, but then make sure as time passes that it doesn't load up. If they gain weight, they change your tune.

If I may suggest something... try some factory match ammo to see how the rig shoots while you break in and sight in. If you like the results, you can cut to chase by just roughly cloning match ammo to get yourself rolling. Then by all means run any tests you like for background and to see if you can do any better.

I didn't look hard for 168, 169 loads, but these two below are examples. Decent for a baseline, but these are 175 grain not 168.
https://www.targetsportsusa.com/imi...ain-m118lr-match-jhp-imi7-62-51-p-112293.aspx
https://www.targetsportsusa.com/fed...ra-matchking-hollow-point-gm762m2-p-3017.aspx

Depending on the specifics of the chamber reamer, you could just make a clone of the 168 match ammo for sight in purposes and you may find it fits the bill. Anything close to 41.5 grains of H4895 in mil spec brass used to do a decent job at magazine length. The only issue I can see is the 168 SMK wasn't good at transonic speeds which are right near your limit distance. I am not familiar with the detail difference of the Nosler version, but will vouch for the 169 and 175 SMK and their clones. They do fine out past where the 168 SMK used to fall apart. Nothing wrong with sticking with 168 if you will be 800 max.

Good Luck and have fun!

 

[Doom]

The 308 is such a well known caliber and there are known loads that work well in just aboutt any rifle. with RL-15 and a 168 target bullet you should find a load in the 43-43.3 grain range (depending on case) that shoots well. Work up but you should be good in that range.

 

[mac86951]

I want to ask first; are you testing for accuracy first, are you loading for check of pressure signs, or going for all-in one batch?

I think you'll find that some of us load up pressure signs first and load up 0.5gr or ~1% increments to check for signs of pressure limits (pierced primers, cratering, case head size, ejector swipe, etc.).

For accuracy loads, generally the above test narrows the 'feasible' load range in your rifle and then I'd recommend from there re-sent the experiment to increments of 2x the capability of your powder measuring system. IE do you want to throw your charges, or are you like us suckers who now count the kernels of Varget for our 223?

Depending on your goals, 308 starts to shine with loads that are +/- 0.1gr; and I'd recommend fine tuning with +/- 0.4gr to find something accurate and working in from there until you're happy, or until.yoy see the prices of improved powder measuring devices.

Take into account that your shooting weather/temperature matters, so add that to your notes.

-Mac