Load Density, Bullet Jump, Case Air Space

MagnumManiac

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Compressing a powder does not make it dangerous.
A normal rifle powder actually burns a little better when compressed.
Powders like TrailBoss are not normal, they are formulated to fill a case, without compression to get reasonable velocity for specific type shooting, it does not like being compressed and has been known to be dangerous.
When I look at info regarding case fill, such as what’s listed by Nosler, I test my own cases volume to the base of the neck with a Burette that is marked in tenths of CC’s.
I use isopropyl alcohol and I also load my comp rounds using CC’s rather than weight, as specific gravity changes with air temperature and humidity.
Consistency is key and I find this method of percentage to case fill works best for me. If I check weigh the charges I find on different days that the charge varies while the volume stays the same. I know the factories charge by volume and it is consistent.

Cheers.
 

Frogman77

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In general I agree, compressing powder is fine.

Retumbo is one powder I found out the hard way that compressing is fine until it is not and there is no warning. It goes from safe to bolt lock when other powders do not. Could be a one off, maybe. Could be my particular cartridge and chamber, also maybe.
Either way, I still advocate doing pressure ladders to be sure when experimenting into new territory.
 

Muddyboots

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Load density that I have gone by from Nosler:
"Load density is a calculation of case capacity versus powder bulk density. Case capacity is measured by taking a piece of firedbrass, filling it up with water and then loading a bullet into the case neck at the tested OACL listed in Nosler’s Reloading Guide #7. The weight of water left in the brass after the bullet has been seated is the case capacity. Powder bulk density is how many grams of a particular powder fit into one liter. "

As result of this thread, I have altered my understanding of load density. Another Eureka! from LRH!

My thoughts were that load density calculated at bullet SAAMI COAL is the standard load density for the cartridge case volume. When the bullet is seated farther out, the load density is changed but seating it deeper than SAAMI COAL you are compressing the powder but not changing the load density which was wrong thought process. No clue why I thought that? I get seating bullet out further changes load density but no clue why I didn't think it seating deeper affected it same way. Never too old to get knuckles slapped!😂

This thread was started based upon the thought the "best solution for rifles is to choose bullet/powder combinations that come close to filling the cartridge to the base of a seated bullet. This will typically reduce standard deviations and accounts for one of the reasons why slower powders, and their fuller cases, tend to produce the best accuracy in rifles." (Western Powders).

The interesting thought is how to measure the case volume under the bullet in a "easy button" method that is accurate and reproducible for consistency.

Is there another thread on load density calculation methods?
 

asd9055

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Load density that I have gone by from Nosler:
"Load density is a calculation of case capacity versus powder bulk density. Case capacity is measured by taking a piece of firedbrass, filling it up with water and then loading a bullet into the case neck at the tested OACL listed in Nosler’s Reloading Guide #7. The weight of water left in the brass after the bullet has been seated is the case capacity. Powder bulk density is how many grams of a particular powder fit into one liter. "

As result of this thread, I have altered my understanding of load density. Another Eureka! from LRH!

My thoughts were that load density calculated at bullet SAAMI COAL is the standard load density for the cartridge case volume. When the bullet is seated farther out, the load density is changed but seating it deeper than SAAMI COAL you are compressing the powder but not changing the load density which was wrong thought process. No clue why I thought that? I get seating bullet out further changes load density but no clue why I didn't think it seating deeper affected it same way. Never too old to get knuckles slapped!😂

This thread was started based upon the thought the "best solution for rifles is to choose bullet/powder combinations that come close to filling the cartridge to the base of a seated bullet. This will typically reduce standard deviations and accounts for one of the reasons why slower powders, and their fuller cases, tend to produce the best accuracy in rifles." (Western Powders).

The interesting thought is how to measure the case volume under the bullet in a "easy button" method that is accurate and reproducible for consistency.

Is there another thread on load density calculation methods?
We are all here to learn from each other and share experiences. I have both QuickLoad and Gordon's Reloading Tool (GRT is free for now), so as long as I enter the fired case capacity it calculates my load density for a given powder, bullet and COAL. I am sure there are are tools out there.
Personal preference (advice given to me by old time reloaders) I look for load densities in the 90+% and have occasionally used compressed load, give sufficient data and personal testing.
 

Muddyboots

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Another Twizzler moment:

If you take a fired (not sized) case, place your powder load into it, gently place your bullet into case onto the powder, you will have the bullet "resting" on top of the powder column minimizing air space. It is not "compressed" just "resting". I wonder if this would provide an interesting ES SD since the air space is minimized? You could measure the COAL and resulting CBTO easily for reproducibility of loads?

The assumption here is you have enough magazine COAL to accommodate this resulting COAL. Later today I will try this for a couple of cartridges I have fired brass on bench ready for loading process and see where the COAL ends up relative to my magazine capacity.
 

asd9055

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I would still stick to Twizzlers! There are a few things to consider before trying that, because you might end up with too much pressure, locked bolt or even worse. I just wouldn't try it my self.
 

Muddyboots

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This process would be no different than any other load change that you would have to address but may be a process to improve ES SD. When various load jumps are being tested, similar process. This is just different perspective of setting jump to case volume.
 

asd9055

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This process would be no different than any other load change that you would have to address but may be a process to improve ES SD. When various load jumps are being tested, similar process. This is just different perspective of setting jump to case volume.
Perhaps I missunderstood...
 

Muddyboots

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So just placed the load I shoot in my .270TH 156HH and the COAL was too long to try. But what was interesting was the 165ABLR with 59.5 RL26 was shot at 3.63 COAL with-a 0.037 jump. When I placed this load in fired case, set bullet on powder column, the COAL dropped to 3.530, full 0.100 below initial load. The jump would now be 0.137. But zero space below bullet. This is what intrigues me as how or if this change affects total load efficiency. Basically I see similar changes in cup and core and lighter weight mono style bullets. So now I will try a ladder working up to the new max COAL.
 

MagnumManiac

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Another Twizzler moment:

If you take a fired (not sized) case, place your powder load into it, gently place your bullet into case onto the powder, you will have the bullet "resting" on top of the powder column minimizing air space. It is not "compressed" just "resting". I wonder if this would provide an interesting ES SD since the air space is minimized? You could measure the COAL and resulting CBTO easily for reproducibility of loads?

The assumption here is you have enough magazine COAL to accommodate this resulting COAL. Later today I will try this for a couple of cartridges I have fired brass on bench ready for loading process and see where the COAL ends up relative to my magazine capacity.
This is where packing scheme really comes into play. If the powder height is all over the place prior to bullet seating, then pressure and velocity will change between shots and may result in very poor ES/SD numbers.
A powder doesn’t have to be compressed for packing scheme to be a game changer, it just has to be the SAME across all rounds.
If the bullet is just touching the powder, it will push some up around it’s base, if the powder height is the same in each case then the amount of powder below the bullet should be fairly uniform, this should result in better ES/SD numbers throughout the testing.
As dumped charges are fluffy, there is air space between the kernels and it can settle through handling and or transportation.
Example, I had a F-class load for my 300WM with a powder no longer available that was perfectly fine if I dumped the powder into all cases and seated bullets right away and then shoot those loads locally. The same load after a 6 hour trip to a national match resulted in a locked bolt, blown primer and destroyed extractor on the very first shot to foul the barrel….I was perplexed, that load had been perfectly safe for months when I shot them 15 mins down the road. It took me some time after pulling bullets to notice that some of the cases had very different powder compression, the one’s that had the most trouble removing the powder were the culprits. This is when I discovered the ‘swirl charge’ method. It is slower than just dumping the powder and really is only necessary for slightly compressed or properly compressed loads such as those in most 30 cal and up cases when using really long bullets, but I feel compelled to do it on everything I load now, even if I know the powder is gonna be loose in the case.
I have found on slightly compressed loads that it lowers ES/SD across the board when testing powder/bullet combo’s and powder/primer combo’s.
Try it, it works.

Cheers.
 

asd9055

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This is where packing scheme really comes into play. If the powder height is all over the place prior to bullet seating, then pressure and velocity will change between shots and may result in very poor ES/SD numbers.
A powder doesn’t have to be compressed for packing scheme to be a game changer, it just has to be the SAME across all rounds.
If the bullet is just touching the powder, it will push some up around it’s base, if the powder height is the same in each case then the amount of powder below the bullet should be fairly uniform, this should result in better ES/SD numbers throughout the testing.
As dumped charges are fluffy, there is air space between the kernels and it can settle through handling and or transportation.
Example, I had a F-class load for my 300WM with a powder no longer available that was perfectly fine if I dumped the powder into all cases and seated bullets right away and then shoot those loads locally. The same load after a 6 hour trip to a national match resulted in a locked bolt, blown primer and destroyed extractor on the very first shot to foul the barrel….I was perplexed, that load had been perfectly safe for months when I shot them 15 mins down the road. It took me some time after pulling bullets to notice that some of the cases had very different powder compression, the one’s that had the most trouble removing the powder were the culprits. This is when I discovered the ‘swirl charge’ method. It is slower than just dumping the powder and really is only necessary for slightly compressed or properly compressed loads such as those in most 30 cal and up cases when using really long bullets, but I feel compelled to do it on everything I load now, even if I know the powder is gonna be loose in the case.
I have found on slightly compressed loads that it lowers ES/SD across the board when testing powder/bullet combo’s and powder/primer combo’s.
Try it, it works.

Cheers.
MagnumManiac, can you please explain the ‘swirl charge’ method
 

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