Weighing each powder charge vs trusting a dispenser

[Metal god]

The late Dan Hackett reported a load that worked great when he put it together at home, but when he loaded it at the range he got sticky bolt lift. Same load. He finally worked out that the vibration of transporting the load to the range from his home packed the powder down enough to reduce its burn rate enough to be a good load.

I remember you talking about that before . I believe it was when I talked about the 2 mile dirt road I take to get to my range . At times it seems my teeth are about to rattle out my skull driving to the range . After reading about powder settling in transport . I started placing my ammo in my box and or bag on it's side . Hoping this would keep the powder from settling and even if it does a little I shake the whole ammo box back and forth before I start shooting to fluff the powder back up in the case .

Not sure if it actually has any effect but my SD/ES have been consistently lower since I started doing that . How ever there have been a few other things I've changed in the way I shoot that could effect my SD/ES so I have no real data either way but in my head it helps and sometimes that's all the help you need

That's one of the secrets of Federal GM .308M ammunition. The 4064 used is very slightly compressed. So even though the charge weights I've measured vary by 0.4 grains from one case to the next, the fact it is slightly compressed means the powder is locked in position as-dispensed and doesn't settle in transport to alter the burn rate.

I'm not buying that . Mostly because just last week I loaded some new loads that were compressed . So much so that I was unable to seat the bullet deep enough . This was using AR-comp powder which is like RL-15 size stick powder . Compressed so much that the bullet would no longer seat deeper even after multiple attempts to seat deeper with the die set at original setting . Meaning as the charges got more and more compressed through out this load spectrum the bullets just stopped being seated at the correct depth like they were at the lower charges . To the point I was .010 longer at the max charge then I was at the start charge .

Using the logic that those heavier charges should be locked in place by the compressed charge . I should not have been able to tap the side of the head on the bench 15 or 20 times to settle the powder to allow me to seat the bullet another .010 deeper with out removing the bullet first . How ever that's exactly what I did and it worked just fine . Thank god the best load out of those was just barely compressed so I should not have an issue with seating depth later on .

 

[Stats Shooter]

Using the logic that those heavier charges should be locked in place by the compressed charge . I should not have been able to tap the side of the head on the bench 15 or 20 times to settle the powder to allow me to seat the bullet another .010 deeper with out removing the bullet first . How ever that's exactly what I did and it worked just fine . Thank god the best load out of those was just barely compressed so I should not have an issue with seating depth later on .

When compressing a load, you should do the tapping and settling before attempting to seat the bullet. Also, it depends on the powder. Longer stick=more space. With my H1000 hunting loads in Norma Brass, I actually used a small screw driver to make a divit in the powder to get a good bullet seat.
. I Also noticed that Federal GMM varied by as much as 0.4 gr. And it was compressed. When I made the clone load, it was also compressed.

 

[Metal god]

I agree , how ever i did not know they were going to be compressed . Well i knew there might be some at the heavier charges but did not think it was going to be as much as it turn out . It was the first time i used this combo of components. Either way i was able to get the powder to settle while the bullet was still compressing the powder .

 

[T. O'Heir]

A ladder test doesn't test the accuracy of individual loads. It tests a load's MPI in comparison with other loads.
.2 grains up or down absolutely affects end results. .1 can do that. My '03A4 168 HPBT load went from an inch to touching with .1 of a grain.
"...all done by volume..." In volume, not by. Smokeless powder is not loaded by volume.
However, the whole thing depends more on the type of match you're shooting. The 'X' ring for F Class at 800 to 1,000 yards is 5". It's 10" in NRA High Power Rifle. Loads for the latter don't need to be giving one hole groups at 100.

 

[Unclenick]

I'm not buying that…

I've pulled a lot of the Federal Match ammo, which is only about 0.5% compressed (10% would be very heavy compression), and it is still compressed when I pull the bullets (you see the boattail shape depressed into it), despite having been manufactured, packed, shipped, handled in the store and carried around by me as spares for a match that I drove to and back from with it rattling around in my trunk. If it were vulnerable to further packing by vibration in that configuration, I should think I'd have seen it level out at the top.

I'll speculate that what may be happening when you tap the highly compressed powder hard 15 or 20 times with the bullet heavily pre-loading (stressing) the charge column is you may either be breaking some grains inside or some are effectively spring-loaded by that much compression to overcome inter-grain friction and pop between other grains like peas from a pod. Either way, you'd get more give. The Federal load compression just isn't very hard.

This is useful information to hear, as it suggests there may be an optimal compression range beyond which the charge bulk density may no longer be preserved by the compression. Food for further experimentation.

You might want to consider a tall drop tube. Here's what it does to 4064: