Working up a good Load???

[jimbires]

how do you pick a powder charge for testing bullet jump first ? thanks Jim

Thats the reason I do an initial powder work up first.

I think you would want a powder charge that is not close to any node . this way you are only looking at the bullet seating affect . I also think this preferred bullet seating will hold constant while changing powder charge . I could be wrong on this , that's the reason I asked .

 

[BountyHunter]

Yep. I like the others do not load with the bullet touching the lands. Had a miss fire on a primer once and the force of the firing pin caused the bullets to stick in the lands and when I tried to cycle another the bullet pulled from the case and stayed in the rifling. Needless to say I lost a once in a lifetime muley. Always off the lands now.

Steve

highlights key mistake here.

1. Seating into the lands with almost no neck tension in a hunting rifle. Only way a firing pin strike ALONE could stick a bullet. Different for a comp gun.

2. Start either into the lands for a single shot or max COAL for a magazine gun. Crazy to start off the lands and then flip back and forth closer and further away to try and find a node. Work one way only: further away from lands. Think about it a little.

 

[jimbires]

Use a starting load. The powder charge will not affect the preferred seating depth. You can fine tune your seating depth, if you feel the need, after the powder charge workup. I have never needed to do that.

thanks , this is what I've thought . we must have been responding at the same time . I'm slow typing ! Jim

 

[engineer40]

I start by referencing multiple reloading manuals and see what they state the most accurate powder type and amount is for the cartridge plus+ bullet weight I'm shooting.

Mostly likely I'll have at least a 1lb jug of whatever powder they suggest.

From there I do some Googling and reading opinions from others to see if their accuracy nodes for the same cartridge+powder+bullet jives with the reloading manuals. Usually it does. This can usually cut way down on the quantity of loads you need to try before finding an accurate one. For example; a 30-06 size cartridge you should be able to narrow it down to about a 2gr window to start testing powder charges.

I find my OAL for the rifle, and note that. Then I load a dummy round with no primer or powder to exact magazine length; then measure to verify I won't be in the lands or uncomfortably close to the lands. Usually no problems and I'll load my initial testing ammo as long as the magazine lets me.

I'll tweak COAL after finding the best powder charge. Which doesn't take too long because usually I can narrow it down to a couple grain window to test.

Maybe I've just been lucky, but it seems like half of the time the most accurate COAL was the magazine max length anyways.

Anytime I've deviated from the above, it feels like my testing time, energy, and budget increase at a quick rate. I have spent A LOT of time testing combinations of reloading supplies trying to find the most accurate. Anymore, I'm quicker to try a different bullet if my initial testing doesn't end in positive results.

Hope this helps.

 

[benchracer]

I think you would want a powder charge that is not close to any node . this way you are only looking at the bullet seating affect . I also think this preferred bullet seating will hold constant while changing powder charge . I could be wrong on this , that's the reason I asked .

I normally do the Berger seating depth test at or near a starting charge. It has been my experience that the preferred seating depth will not only hold true while working up the powder charge, but even with a change in powders or primers.

I do this test at the beginning of every load workup, regardless of bullet brand and style, unless I am starting with a fixed seating depth (such as mag length on an AR). With rare exceptions, the preferred seating depth has typically fallen somewhere between .040 and .080 from the lands.

Below is an example of a seating depth test I did in 22-250 with a 53 VMAX and 8208 XBR, shot in round robin fashion. It turned out this powder charge was very near a node. It didn't matter. The preferred seating depth showed itself pretty dramatically. I have found that to be typical of this testing method.

 

[RockyMtnMT]

highlights key mistake here.

1. Seating into the lands with almost no neck tension in a hunting rifle. Only way a firing pin strike ALONE could stick a bullet. Different for a comp gun.

2. Start either into the lands for a single shot or max COAL for a magazine gun. Crazy to start off the lands and then flip back and forth closer and further away to try and find a node. Work one way only: further away from lands. Think about it a little.

That is why I said in my post before the one you quoted that I start at the max usable length and work back on seating depth. Never did I say work back and forth. Maybe you did not mean that to me.

Steve

 

[benchracer]

I also use the seating depth test to fireform brass for the powder charge workup. After I started using a chrono during load workup, I stumbled onto the fact that there is often a large difference in velocity produced by a given powder charge between virgin brass and once-fired brass. Unless you are working up a load only intended for use in virgin brass, you will be better served to do development with brass fired in your rifle.

Once the seating depth test is complete, I proceed with the powder charge workup. I have two different methods that I can follow: a non-instrumented method and an instrumented method.

The non-instrumented method I have used, with consistent success, can be found here:

OCW Overview - Dan Newberry's OCW Load Development System


The instrumented method I use came from information furnished to me by a fellow forum member: engineering 101 (pdf attached below). It is a method that revolves around using OBT (Optimum Barrel Time) to compute expected velocity nodes. It requires an accurate chronograph and a copy of Quickload (which generates barrel time data in its load charts).

It is simply a matter of finding a powder charge that produces muzzle velocities in the correct range. As powder charges progress, the ES and SD numbers typically become smaller as the node is approached, then bigger as it is passed. I have found this method to be useful, efficient, and effective. I have often been able to produce very accurate loads simply by tuning the velocity across a chrono, taking them to the range to verify them later.

Attached is an example of results I obtained using this method to tune a Mossberg MVP in 5.56 NATO, using 75 AMAX'S and CFE 223. The waterline on the target was shot at a laser-ranged distance of 344 yards:

 

[jimbires]

I've never played with the OBT method , or the OCW method . my chrony is not good enough for this . I'll probably buy a labradar when they are more available , and the tax man wounds heal . I have played with reduced loads for young shooters . what I've done is pick a powder charge from quickload that has the approximate recoil that I'm wanting , then I only adjust seating depth . this has worked well and would be the same thing as finding preferred seating first . yes , I use the Berger method . this is one of my reduced load work ups . only change is seating .

 

[barefooter56]

how do you pick a powder charge for testing bullet jump first ? thanks Jim

Jim,
I use the lowest powder charge listed for the bullet /powder/cartridge combination I am testing for. If the barrel length is 24-28 inches I kind of lean twords a medium-slow burn rate powder in the load data. 22-24 inch fast- medium burn rate.

 

[barefooter56]

Jimbires,
Very nice example !

 

[jimbires]

Jim,
I use the lowest powder charge listed for the bullet /powder/cartridge combination I am testing for. If the barrel length is 24-28 inches I kind of lean twords a medium-slow burn rate powder in the load data. 22-24 inch fast- medium burn rate.

that's easy enough . thank you Jim