Best way to find powder charge?

[WEATHERBY460]

Whats the best way to find the powder charge when testing for a new load. I have tried many ways, but not sure what way is best. Thanks

 

[asd9055]

Oh MY! You are opening a can of worms now.
I have tried many, and they work. My favorites are:
1. Modified ladder test. Shoot at 300 yards or more, tracking both velocity and POI (but only care for elevation). Round Robin with marker color on bullets. You are looking for the velocity node and the minimum elevation change
2. I pick a charge, fire 5 shots and measure velocity. Calibrate GRT (Gordon's Reloading Tool) or QL. Find optimu "modelling load) go test with that, a few crains below and few above.

I would NEVER call these the best. And I expect to be attacked. Works for me, but I spend my career modeling calibrating and validating computer models with hard physical data.

 

[QuietTexan]

Unless you specify best at what this is nothing more than begging for an argument between people with vastly different goals.

Best at making .100" groups from a bench?

Best for a 7 year old to use schwacking does under the feeder at 50 yards?

Best for shooting an elk at 600 yards when it's -15* outside?

Best at making a cold bore shot at a mile?

Best at ****ing off everyone who thinks differently than you do?

Some things are worth shooting 0.2 gn increments of 5-10 shots per weight. Somethings I just shoot until there are pressure signs and back off a grain to shoot as few rounds as possible. Some things I shoot whatever the book spits out as a middle load and never change the powder weight at all. Those are all the best ways for each of those situations for me; if they weren't I'd do something differently.

For anyone curious, the answers are: 38 clicks on my Harrel with LT-30, half a case of H4895 behind a 125gn SST in 30-06, anything with a magnum primer over at least 90gns of powder, anything loaded into a 6.5 Creedmoor, and BC doesn't matter just shoot it faster.

 

[WEATHERBY460]

Sorry..looking for .5 in groups at 100.

 

[QuietTexan]

What caliber and kind of rifle?

Don't be sorry, just joshing you around.

 

[WEATHERBY460]

300 prc.. custom

 

[nealm66]

QuietTexan is spot on. For hunting I will work up in 2shot .03 ladder till pressure and back off a little and then a 3-4 shot .03 seating shooting the shortest fist so if I find my accuracy early I can shorten the remaining. For competition shooting I will sometimes do a .02 powder ladder for accuracy, then fine tune with seating as velocity isnt high on my concern.

 

[nealm66]

What bullet?I'm on my second 300 prc and really like it

 

[QuietTexan]

The last three custom barreled rifles I've started working on have all posted 5-shot groups under 1/2" with the first loads I've made - 93% of max book load/projected max load in QL, 0.020" off the lands, loaded both in big batches of new brass, or by reloading the same 5 cases 10 times in a row. There's something to be said for playing averages, especially early in a barrel's life. They aren't the fastest loads ever, the aren't the most perfectly tuned loads ever, but they shoot well enough to break in the rifle and hunt deer to mid-range with.

At 100 yards none of the muzzle velocity stats are going to matter, either the powder/bullet combo will shoot small or it won't. Load up a pressure ladder, find the real top in your rifle, pick the speed you want, and run it. Seating depth you got to start somewhere, either something arbitrary like 0.020" off or mag length if you're limited (shouldn't be in a 300 PRC but you never know). I wouldn't bother with less than 1gn intervals on the ladder or seating depth changes of less that 0.010" unless you want to shoot 5-10 shot strings to really prove out the increments.

IMO shoot pairs instead of 3-shot groups to save on components, statistically speaking the third shot doesn't tell you much of anything. If two shots suck the third won't make it any better; if two shots are perfect you really need to shoot 5-10 shots total to make sure it isn't a fluke, the third alone doesn't move the needle much.

Shooting groups get's boring fast. Shoot long distance cold bores if you can, and dot patrols for practice. You either hit the dot or you miss - it's pass/fail, just like shooting at an animal is. Group aggregate is a nice stat to post on the internet about - hits are what really counts.

 

[Darryle]

I found this post by Alan Griffith very informative.

Since wood is so expensive now, I made a 4' square "quilting frame" out of 1"x2" lumber and braced at the corners. Start with one top corner and stretch the landscape plastic tight to the lower corner, then to the opposite side and finally to the remaining corner. Then I go back and staple between the corners pulling the plastic good and tight. Paint them after they have sat in the sun for a bit, paint dries faster. Smaller calibers require higher magnification to see the hits sometimes and I have reused the plastic after a simple repaint.

I have the Dirty Harry target stands from Targetmeister but they really only work on fairly calm days. For those really windy days, I had two 5 gallon buckets filled with concrete with a piece of 2" PVC pipe in the center for the frame legs. Either drill out the bottom of the bucket thru the pipe center or flip them over or you'll have to make a second set like me after they freeze and bust the concrete after they fill up with rain water. My next set I am removing the bucket afterwards and the center pipe will have a cross on the bottom to spread out width and keep me from having to verify that the center pipe is perfectly vertical. I will be putting a couple of rebar handles off to the side to make carrying them easier.

Anyways, here's Alan's post on the subject. The remaining thread is here:

1000yd Ladder Test and Video

On going on record to explain how I've changed the excellent Audette ladder load development system.

Using the different colored markers is an excellent idea. The problem i've run into with this is that depending up the distance, caliber size and quality/power of spotting/rifle scope, the shooter may not be able to see the impacts down range "while" shooing the ladder. When shooting a ladder it is necessary to see/know which shot/impact is which. In addition, if you call a bad shot, you need to know which impact is the bad shot.

A friend of mine from Albuquerque taught me a new technique; home made DirtyBird or Shoot N See targets. Targets that leave a large black impact on a light/white colored backing. I take an 8'x4' sheet of plywood or similar sheet of stiff backing material and cut it in two so I have two 4' x 4' sheets. I then buy a roll of black plastic. Mine was about 20' x 8'. I cut that down to 4' x 4' sheets which are stapled to the plywood. I then take a $.97 cent can of white spray can and spray the entire sheet of black plastic, white. Let it dry and add bright orange aim points. Select your desired distance to shoot at and let fly. With my Zeiss 15-45x spotter I can easily see 22 cal hits at 660 yds. When the bullet hits, the white paint, directly around the impact hole, chips off, exposing the black plastic, easily seen at extended distances.



Above you can easily see my LV Steel 1/2 silhouette, used as a sighter target then looking at the right 4'x4' DirtyBird target you can see my ladder; 3 shots upward, 3 shots across (accuracy node) and 2 more shot above that.

That's my target. How I bring loads to the range is new as well. We all know that BR shooters load their ammo at the range. I modify that by bring prepped and charged cases to the range and seat bullets "as necessary". Below is an MTM ammo boxes with 100 prepped and charged cases.



The first row across is my starting row; for example all are 40 gr. The 2nd row has a .2 gr increase (6.5x47Lapua) and so on and so on until the 10th row has 41.8 gr. I take small, light, handheld press to the range with me with the seating die already pre-adjusted to my desired setting depth. At the range, I fire one round at my steel target to confirm a hit and so I can adjust closer to my intended point of impact. In this case the center orange dot on the 4'x4" DirtyBird target. I then start up the ladder, seating one bullet and shooting; marking the POI on a separate sheet of paper. Even with my NF scope set at 22x I can see the hits. Once the ladder has been shot the MTM ammo box should look something like this.



This ladder showed that 40.4, 40.6 and 40.8 gr showed promise. Now, I take the next 3 unloaded, charged, cases from the 40.4, 40.6 and 40.8 gr rows and seat bullets. I shoot each 3 cartridges at individual aiming spots for 3, 3-shot groups to see which group better. I'm especially looking for zero to nil vertical spread. Once I've done that the MTM box should look like this.



At this point I'm hoping to have narrowed it down to 1 or 2 different powder charges; say 40.6 and 40.8 gr. I then want to play a bit with seating depth; loading up 3 more of the same powder charge. Once I've shot those, my MTM box looks like this.



Now I may want to play a bit more with seating depth; going in or out a bit more….or……in the opposite direction. My box now looks like this.



At this point, it's time to pack up and go home where I don't need to pull any bullets. I might want to play a bit more with seating depth or try different primers but the majority of my Audette Ladder testing is done and all in one trip and I've only shot a max of 31 rounds; saves on components and barrel life.

Questions?

Alan

Ladder testing at 1k- Detailed article and video

 

[StumpyJohnson]

Oh MY! You are opening a can of worms now.
I have tried many, and they work. My favorites are:
1. Modified ladder test. Shoot at 300 yards or more, tracking both velocity and POI (but only care for elevation). Round Robin with marker color on bullets. You are looking for the velocity node and the minimum elevation change
2. I pick a charge, fire 5 shots and measure velocity. Calibrate GRT (Gordon's Reloading Tool) or QL. Find optimu "modelling load) go test with that, a few crains below and few above.

I would NEVER call these the best. And I expect to be attacked. Works for me, but I spend my career modeling calibrating and validating computer models with hard physical data.

I'm interested in you grt process, I do something similar lately.

 

[manitou]

.

 

[asd9055]

I'm interested in you grt process, I do something similar lately.

Quit Texan had excellent advice

I am still learning GRT and first with the heat, then with the cold here in Houston, plus the scarcity of supplies, I have not done any testing in a while, but this is my process
I will load at least one set of 5-10 rounds, same charge, same everything, if I have data of a "good safe load" I'll start with that.
I will shoot those over a chrono. Take the fired cases and get the average volume of water.
I use the data I gathered (bullet, charge, case volume, cartdridge length and fill in the tables.
I got to measurements and fill that table
Follow the procedures in GRT guidlines for obt, node, charge.
Make three sets of 5 with suggested load, one at, one below, one above.
Shoot over chrony, and look for the best group.
Repeat if necessary.

I do expect strong reactions to this. I did simillar with QL, but its a manual calibration

 

[StumpyJohnson]

Quit Texan had excellent advice

I am still learning GRT and first with the heat, then with the cold here in Houston, plus the scarcity of supplies, I have not done any testing in a while, but this is my process
I will load at least one set of 5-10 rounds, same charge, same everything, if I have data of a "good safe load" I'll start with that.
I will shoot those over a chrono. Take the fired cases and get the average volume of water.
I use the data I gathered (bullet, charge, case volume, cartdridge length and fill in the tables.
I got to measurements and fill that table
Follow the procedures in GRT guidlines for obt, node, charge.
Make three sets of 5 with suggested load, one at, one below, one above.
Shoot over chrony, and look for the best group.
Repeat if necessary.

I do expect strong reactions to this. I did simillar with QL, but its a manual calibration

Yea, GRT and the whole OBT thing seems like a bit of voodoo, BUT, I do like it for various reasons. Namely, once calibrated a bit, finding powder/bullet combo's.

To calibrate, once the various measurements are in place (case volume, barrel length, etc.) do you do your calibrating with Initial Pressure values alone?