Loading development - find powder charge with low SD node

[longrangeprecisionshooter]

I am new to reloading and have done some research on the load developments methodologies out there. But have a question regarding find the low SD node for powder charge.

I saw people are saying finding the powder charge with low/lowest SD node, does that mean:
1.Load 3-5 rounds for each powder charge in 0.2-0.5gr increment with a default seating depths
2.Shot these rounds, say 5 rounds each for 10 different charges
3.Find the speed you want and see which powder charge gives the lowest SD around that speed
4.Then play with seating depths for group size from there?

Thank you.

 

[B Nettesheim]

Yes

 

[Jager]

Well, although most of us are delighted when the chrono stats are quiet... most of us are far more tickled to see tiny little groups on target. And while great SD/ES numbers sometimes line up with great accuracy, that's often a hit or miss proposition.

Cart before the horse, in other words.

But, yes. I'd recommend running a ladder of different charge weights, using a single bullet seating depth. Rather than focusing on low SD numbers... concentrate on finding which charge weight(s) give you the best group(s). You're looking for patterns - groups tightening up and then opening back up - not a one-off nice group.

Once you've narrowed down to a charge weight that you like, run a seating depth ladder to refine it further. Again, looking for a pattern, not a one-off.

The target rules.

 

[Straightshooter1]

Well, although most of us are delighted when the chrono stats are quiet... most of us are far more tickled to see tiny little groups on target. And while great SD/ES numbers sometimes line up with great accuracy, that's often a hit or miss proposition.

Cart before the horse, in other words.

But, yes. I'd recommend running a ladder of different charge weights, using a single bullet seating depth. Rather than focusing on low SD numbers... concentrate on finding which charge weight(s) give you the best group(s). You're looking for patterns - groups tightening up and then opening back up - not a one-off nice group.

Once you've narrowed down to a charge weight that you like, run a seating depth ladder to refine it further. Again, looking for a pattern, not a one-off.

The target rules.

Ditto this ^^^^^^

My only other comment would include that I only use SD and ES chrono numbers to tell me how consistent I'm preping and loading my cartridges; that's it. Otherwise, load development results are only about what I see on paper. When I'm getting good groups on paper for a particular load (like less than .5 MOA), the SD's and ES's will invariably be good, but not necessarily the lowest.

 

[Homerange]

Another data point is high case fill percentages often return the lowest ES however as others have mentioned what get printed on paper really matters unless you need consistent results at extreme ranges

 

[David Christian]

I am new to reloading and have done some research on the load developments methodologies out there. But have a question regarding find the low SD node for powder charge.

I saw people are saying finding the powder charge with low/lowest SD node, does that mean:
1.Load 3-5 rounds for each powder charge in 0.2-0.5gr increment with a default seating depths
2.Shot these rounds, say 5 rounds each for 10 different charges
3.Find the speed you want and see which powder charge gives the lowest SD around that speed
4.Then play with seating depths for group size from there?

Thank you.

@longrangeprecisionshooter, in my opinion you have the basic framework to start with. The idea with this framework is to find a WIDE and stable powder node in which the entire rifle system is happy. This place will show multiple and consecutive lode increments with similar vertical POI’s on target, AND consistent speeds and low ES/SD numbers. Don’t get fooled by the one off, 1 hole print, super low numbers, surrounded by crap groups or crap numbers. Regardless of the group shapes, I am initially looking for stability in the charge.

Once I have settled on the powder charge, I then move to tightening the groups by adjusting the seating depth. In essence, changing the seating depth is simply a fine tuning of the bullet exit time from the barrel. Small increments can show big differences in the tighness and shape of my groups. Again, I ignore the one off holy grail group that is surrounded by crap. I am looking for a wide seating depth.

Good luck in your pursuit of accuracy and precision!

 

[ChrisNZ]

Small groups and low velocity spread are often related but not one and the same. If you want to chase the latter after you've identified a reasonable node, focussing on consistent brass prep techniques will yield the best outcomes.

 

[6bra1k]

chase TARGET data, not sd/es. both are nice but are based on large data set, as in 1000 shots, not 3-5 shots.
simple ladder powder increment is 1/100 of case volume. 0.5 for mag cases.
10-12 shots in single increment at some chosen seating depth. ( i start TOUCHING the lands). use flags 200/300 yards log speed and position of each shot on a target on the bench. while you may have a speed in mind do not ignore a lower speed that shoots well. with this first target circle shots
1 2
123
234
345
456 and on
you are looking for a small group with little to no vertical.
you may find 2 or 3 that look good.
load three of the middle of each group, and go back and shoot them.
pick the best and go shoot two 5 shot groups.
you can now play with seating depth and neck tension
now try them at distance

 

[6bra1k]

the real big problem is you are new to loading AND you have chosen long range.......tuff to learn two things at once that rely on each other

 

[6MMsteve]

the thing is if your not running a good barrel, all those numbers r out the window, usually a decent barrel will cut things in half, sometimes cut 2/3, but when you get the good barrel and find what it likes it can get boring

 

[Florida Wally]

I look at point of impact where groups line up vertically when ladder testing powder charges. If I get two or three groups that have the same or close vertical point of impact I will pick a load somewhere in the middle. I also consider average velocity and often the velocity flat spots will line up with the flat points of impact. I only use es and sd to verify my loading technique and maybe to feed my ego if they are low. I will then start testing seating depth until I find a seating depth that shoots a group I am happy with. I then use that load and seating depth and see if it produces consistent results over several groups. I’m not nearly as experienced as most members here, but this method works pretty well for me. I learned this method from other members, so I can’t take credit for it.