Can you pack powder too tight?


February 11, 2008, 04:24 PM
So now that I have the subsonic loads tailored for my .300 whisper AR-15, I am doing some experimenting with supersonic loads. They have ballistics very similar to an AK when fires supersonic.

My question is....... When I am loading these (110g-150g bullets), My powder charge is completely filling the case, and I really have to press down hard to seat the bullet. I can hear the powder crunching in the case. Is there anything negative to compressing your powder really tight like that?

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February 11, 2008, 04:35 PM
You can pack Black Powder to tightly...........

February 11, 2008, 07:52 PM
Moderate compression is one thing, and many powders like it, but breaking the grains smaller isn't good. When you crunch powder, you are turning coarse granules into fine granules. Fine granules decompose at a much faster rate, increasing pressure levels. I reload with Trail Boss, an intentionally low-pressure powder whose makers warn against this very thing. I suspect many other fluffy powders would also pressure-spike if significantly crunched...

February 11, 2008, 08:02 PM
I have read of some of the very tightly packed African class rounds swelling the powder in the heat of the summer and pushing the bullet up a bit.

February 11, 2008, 10:22 PM
I have a .458 X 2 American. I load a 350 grain bullet over 64 grains of 4895, and this is a fairly heavily compressed load. If I do not get the case neck crimped into the canelure the charge will push the bullet back out. I have never had any issues with this load. I have also loaded the same round with 65 grains of BLC2, and it too is pretty heavily compressed. No problems. I have read in one of the reloading manuals that this is not a problem. I can't remember which one...I will try to find it.

One consideration is that the .458 is a straight walled case. A bottle necked cartridge could certainly be different.

February 12, 2008, 01:39 AM
You can pack Black Powder to tightly...........

I think you can get in trouble if black powder is packed too loosely, but tight really isn't a problem there. With the last BP rifle I shot the drill was to bounce the rod off the round ball until it quit mashing and sounded solid. That's how you knew it had been obturated into the rifling.

For smokeless in the .300 whisper you might try a drop tube to get the powder compacted a little better before seating the bullet. You might also want to try a powder that is a bit faster or denser to fill the case less. A little powder compression isn't too bad, but I'm not sure about crunching a bullet into a full case unless the the charge has been verified in a reloading manual as a recognised compressed load.

Doug b
February 12, 2008, 09:13 AM
Have you tried a drop tube?

February 12, 2008, 01:17 PM
No, but I have filled it to the top, tapped it on the table to settle, then pouring the rest of the charge...

ken grant
February 12, 2008, 02:31 PM
Use a LONG drop tube!!!!!!
I made one out of 3/8 copper tubing that is 3 ft. long.
Just flare one end to fit over the mouth of the case and file the other end to fit your funnel.

February 13, 2008, 08:22 PM
It is also possible to bulge the case by compressing the powder too much.

The drop tube is a good solution. You might also try a dentist dental vibrator
table. Check ebay or a dental equipment supply house.

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