Load work up...seating depth test first OR charge weight first?

[barefooter56]

Mikecr, have you found the optimum seating depth to remain constant regardless of powder or other components used?

I assumed it would but what Rhovee said makes me wonder and I have not done enough of my own testing to know.

Lonewolf74,
In my experience it does remain the same. I have always done my bullet seating depth testing first. Then worked up the powder charge. The issue with this is magazine fit after the bullet seating accuracy node is found especially with the long bullets like the VLD or Elite Hunter. Now there are cases where shooters have gotten these bullets to shoot accurately at magazine length. Your result will be based on what YOUR RIFLE LIKES. Some fixes can be installing a Wyatts extended magazine box (don't buy one until you do your bullet seating depth testing to make sure you need it and to have a COAL so you get the right unit.) Or try the CLASSIC HUNTER bullets that are designed to be used at magazine length. If you are building a rifle. Always build it around the bullet.

 

[Korhil78]

You know...it would be a fun little test to take a rifle that isn't a hot rod and burns barrels out fast and have one guy load up test loads using powder charge as the starting factor and then fine tune with seating depth. Have him record his most accurate load that he comes up with in his book. Then have his buddy, using same lot of brass, powder, bullets and primers work up a load using seating depth as the starting factor and fine tune with powder charge.

Each person doesn't tell the other what their final load is until the end and see how close they are to one another.

 

[J E Custom]

JE, when first testing for powder are you using several different powder and primer combos at a lower charge to see which yields the lowest ES and SD?
Then from there do you test seating depth then do a ladder with your chosen powder to find the charge weight node?

Do you find with a particular powder primer combo if SD is good at a light charge it will continue to have good or better SD as you climb in charge weight to find a node?

Also if you find a good powder primer combo in virgin brass have you found it to remain good in fire formed brass? What I'm getting at hear is could you do this step (finding a good combo not a node) while fire forming your brass?

I first approach the powder selection based on what a maximum charge
would be at 98% to 100% Case capacity and yield the highest or close to the highest velocity with pressures within SAMME pressure ratings using the preferred bullet weight. Normally there are 3 0r 4 choices.

Then with the bullet seated at Magazine length minus .010 thousandths I start with 2 grains less that the maximum listed (This gives me plenty of room to move up or down with these powder charges during testing, plus I can change the seating depth later To tweak the accuracy.

Next, based on the powder type and burn rate I decide what I think the best primer Brisance (Heat) is for the most complete burn would be and ease to start the ignition. (This does not always mean the hottest primer will be the best because some powders ignite easier than others).

With 5 loads of each of these powders in hand, I shoot them through a chronograph Looking for the best SDs (This tells me if I have a good powder/ primer combination). If I shoot two rounds and the SDs are poor (I prefer single digits, but can live with SDs below 15 to start with)
I cease shooting that load and move on to the next (No reason to just burn them up when I can pull the bullet and reload with a better combination later).

Then once I have found an SD to my liking (Normally 03 to 07) I move own with moving the powder charge up by .3 grain increments, Chronographing as I go for SDs and velocity looking for best SDs and accuracy without pressure signs. This has to be done carefully, because some powders will go critical (Go from a normal pressure to well Over Maximum with one slight increase.

Once my records show I am where I want to be with the bullet weight, powder and charge plus the primer and with the best SDs and velocity, I look at the best bullet for accuracy and its seating depth (First I find the most accurate bullet and then I test to find the optimum seating depth.

It sounds like a long drawn out procedure, But it works for me and normally I can find a great load with less than 25 or 30 test firings. The old way (Hit and miss) could take 50 to 100 rounds depending on how lucky I was.

NOTE: Only make one change at a time or you will be chasing your tail.

J E CUSTOM

 

[barefooter56]

J.E.,
Your NOTE: ONLY CHANGE ONE THING AT A TIME .OR YOU WILL BE CHASING YOUR TAIL. Should be hung above every reloaders bench. I would only add " THEN TEST" to this.
Bravo!

 

[Rhovee]

Here was my latest experience. Loaded some coal. Increasing charge weights. All three shot groups looking at lower set. Pretty clear that the groups changed when leaving seating depth the same. Just my experience. This was with a 28 Nosler and 195s.

 

[Lonewolf74]

JE I am following what your saying.

The question I have is how do you figure out what powder will give you the fill ratio that you want? How do you figure out if powder x will be at 98-100% fill at xx grains?

And how do you know what Brisance (heat) will work best for a given powder?

 

[barefooter56]

Here was my latest experience. Loaded some coal. Increasing charge weights. All three shot groups looking at lower set. Pretty clear that the groups changed when leaving seating depth the same. Just my experience. This was with a 28 Nosler and 195s.

Did you use the same cartridge overall length or the same cartridge base to ogive? There can be a big difference in the CBTO between cartridges if just using the COAL for testing.

 

[Lonewolf74]

Here was my latest experience. Loaded some coal. Increasing charge weights. All three shot groups looking at lower set. Pretty clear that the groups changed when leaving seating depth the same. Just my experience. This was with a 28 Nosler and 195s.

Rhovee, food for thought. What do you think would be the outcome if you used the same charge at different coal or even tested each charge weight at several different coal?

What I mean is it is clear by your target that groups changed but that is expected while changing charge weight, the same is true of changing coal.

So using some hypothetical numbers; say your worse group was .020 off the lands and 50 grains powder, best group was .020 off lands and 52 grains powder. Now if you took the 50 grain charge and did a seating depth test do you believe you would find where that combo shoots better at a coal other than .020 off the lands? Or is it possible that's the best 50 grains is gonna shoot meaning the bullet is at optimum seating depth it's just a bad load at that charge?

I think a real test would be to do the Berger seating depth test at several charge weights and even powders and see if you come up with the same optimal depth or if there's differences.

 

[joep17]

Great questions and great answers.
One point that I almost forgot about until Barefooted asked an important point.

Bullet dimensions change based on lots.

When I bought my first 5000 lapua scenars I did the load development. Found a great load and COAL

When those were gone I ordered another 5000. The new tooling for that lot have a different measurement when measuring "jump" with the same barrel with about 1200 rounds of 308 through it. There was about 10 thousanths change measuring ogives touching the lands. When those were gone, I had to get another 5000 last year and again slight differences so back to square one.

Two "points" to make. If you get a load you like try to get enough bullets from the same lot to last that barrel. Tooling wears and gets replaced. Dimensions change slightly. For hunting bullets we never notice. For match bullets you sure do.

Second "point" is that a half dozen years ago or so I purchased a Whidden pointing system and meplat trimmer. My scores at 700, 800, and 900 metres went up. Great product from a real shooter. Great customer service. Just in the process of a new insert as I picked up a couple thousand Berger 185 match hybrids to test this summer.

 

[Gord0]

I do a rough seating depth with the Berger method, then charge weight. After that I do fine depth adjustments.

 

[Rhovee]

All my rounds are measured off ogive. I have seen it when shooting a ladder as well. I have had a lower node shoot a triangle size group. Then when you get to the higher node it goes horizontal and ends up being a small change in seating depth. I do seating depth first to get close. Then shoot a ladder. I am no expert. There are plenty of people with way more experience than me. Just sharing what I have found in doing load work up. But trying to shoot a ladder for charge weight and having a cbto way off won't help much either.

 

[barefooter56]

All my rounds are measured off ogive. I have seen it when shooting a ladder as well. I have had a lower node shoot a triangle size group. Then when you get to the higher node it goes horizontal and ends up being a small change in seating depth. I do seating depth first to get close. Then shoot a ladder. I am no expert. There are plenty of people with way more experience than me. Just sharing what I have found in doing load work up. But trying to shoot a ladder for charge weight and having a cbto way off won't help much either.

How small are the seating depth changes you make?

 

[Rhovee]

If I had great luck on .020 on a lower powder charge and was shooting a ladder and had things go horizontal, it would be .015-.018.023

 

[J E Custom]

JE I am following what your saying.

The question I have is how do you figure out what powder will give you the fill ratio that you want? How do you figure out if powder x will be at 98-100% fill at xx grains?

And how do you know what Brisance (heat) will work best for a given powder?

More good questions.

First. Most good reloading manuals will show where a compressed load starts with that powder it will say xxxC for grains and that it is compressed. Armed with that Information, I then look at the case volume to the base of the neck. (Usable powder volume with that powder simply by filing the case with the powder I want to use to the shoulder neck junction. as pored, I know that I can get more powder using a drop tube if I have to, and if I half to cut the powder charge I have a basic 100% number of grains for that powder. (Different powders will require different capacities based on size and shape)

Now that I have a good volume 100% density with that particular powder in my case, I can evaluate if it is to slow or reaches maximum velocity at or near 100% case density. This will also be an indication of other powders volume needs. The reason I like densities of 98 to 100 % is that normally the SDs are better/more consistent. Also loads with less than 85% can be tricky (Another word for dangerous).

As to brisance selection, it is mostly experience rather than a science
but again, the good reloading manuals will have the primer that they recommend, or that they tested with the load, The brisance chart will tell you where that primer falls in the chart so you can substitute with in range of the tested primer. I would warn anyone not to substitute
a hotter primer without reducing the powder charge. If you switch brands, and it is very close in brisance to the tested primer I would still recommend reducing the charge by 1/2 grain.

Lots of new reloaders try to use one primer for everything and have problems. The hottest primer will not always get the best results and some of the big cartridges that hold 70 to 80 grains often have much better SDs when a non magnum primer is used. In extreme cold sometimes a magnum primer may be necessary, so leave all of your options open. cartridges that hold over 90 grains will normally do better with a magnum primer. Cases with 110 grains to 145/150 will need the hottest primer available.

So for those that have not been loading long, I recommend going by the loading manual for everything, The manual are normally conservative and will for the most part keep you out of trouble.

J E CUSTOM