Importance of Load Density

[butta9999]

My understanding of load density is to have a near 100% powder density in the case with the bullet seated. It gives a uniform ignition when fired and best accuracy. If so then it wise to go for the slower burning powders to get that density rather than the fast burning powders which require less weights.

Members is this something that all of you try to achieve when reloading for your rifles or something that can be overlooked.
Especially for the larger calibers the powder charge can vary up to 15 grains, example i can use 67gr of AR 2209 in my .300 mag or i can use 80gr of RE-25. Verlocities are not much to talk about with only 100fps or so the difference. Powder charges are for a 180gr bullet.

Looking forward to your opinions

[SL1]

Loading density is often misunderstood, because we talk about powders in weight (grains) instead of volume. So, two charges of different powders might fill different fractions of a case, but weigh the same. OR, they might fill the same fraction of the case but have different weights.

There seems to be some good effect on uniformity of buring when the powder mostly fills the case, compared to filling only a small fraction of the case. But, when the case is 100% full and more powder is added to make a "compressed" load, different powders can behave very differently. Some seem to get even more uniform, and may seem to be somewhat "slower" (frequently in the case of "extruded" powders), while others can get "spikey" and cause wide variations in velocity and pressure (more typical of "ball" powders). But, there are no real "rules" except what the powder manufacturers find out for each powder from their testing. For example, Hodgdon says "don't compress ball powders" while Accurate shows lots of compressed loads for their ball powders in their manuals.

Max velocity within safe working pressure is another issue. Powders that have a higher "bulk density" can get more WEIGHT into a specific case volume. But, weight alone is not a measure of ENERGY in the charge. Two powders of different composition can have different amounts of energy in charges of the same weight. (Typically "double-base" powders that contain nitroglycerin as well as nitrocellulous have more energy per grain than "single-base" powders composed of only nitrocellulous.) So, finding the maximum charge weight that fits a case at max pressure levels still is not the complete answer. Typically, really slow double-base ball powders can get the highest amount of energy into a case because they have both high bulk density and high per-grain energy content. But, they may also produce less uniform buring , or more fouling, or bright muzzle flash, or some other less desireable characteristics that make them less suitable for YOUR application than another powder that gives slightly lower max velocity.

SL1

[Sevens]

There are some powders in some calibers where it makes a lot more difference than it ever will in many others. With that in mind, I don't worry even a little bit about it.

Some folks here in this forum flat-out refuse to use Bullseye powder for any application because it uses a small weight, small volume charge and they worry about double or triple charging their cases. I also can't get on board with that line of thinking because I feel my methods have many checks in place to prevent such a catastrophe.

Some folks pick a powder because it uses the lightest weight charge of any other, thus "saving" them money in the long haul. I also think this is crazy when you consider how very little money we are talking about for most shooters.

Some folks pick a powder because it meters better than others. Some folks pick a powder based on the price per pound. Some pick a powder because they have a slew of data available for it. Some folks have found a powder that returns the recoil level, velocity and accuracy they seek.

I tend to choose a pistol powder based on the accuracy it gives me, and I choose a rifle powder based upon the chamber pressure it runs compared to others that do the same job.

I don't condemn anyone's choices, but I have a hierarchy of what matters to me when picking a powder, and powder density is way, way down on the list.

[Loader9]

For me, a load must be at or better than 80% loading density. I prefer for the load to be at or near compressed. Some powders are position sensitive and this gets around the issue. If you point the barrel up and then lower it to a level shooting position and shoot versus lowering the barrel and then raising it to level can, with some powders, have and effect on the ignition. That's going to effect pressure and accuracy. I avoid the issue by loading high density loads.

[Shoney]

All the hunting loads I use are either very close to 100% or just slightly compressed. This will keep loads accurate, wheter shooting up or down hill at steep angles, or having your weapon barrel down and coming up on target.

However, in my 222 accuracy loads, some are around 50%. Whether bench rest shooting or shooting prairie poodles, you must raise the weapon to verticle and slowly brng it to rest with each shot to get best accuracy.

So to answer the question, do the loads need to be near 100% for best accuracy?
It depends on what you want out of them, what you are going to do with them, and how you "set up" each shot.

[Dave P]

This will keep loads accurate, wheter shooting up or down hill at steep angles, or having your weapon barrel down and coming up on target.


I have had problems with 30-06 with powder position, when the case was about 70% full. Different positions resulted in different ignition, resulting in less accuracy. Less problems when I get more powder in there.

[BigJimP]

I'm with Sevens on this one ......I don't worry about it one way or the other in terms of density / as long as it is a published recipe.

I pick a powder based on accuracy on my test firing at the range and cleanliness - but these days I'm almost exclusively into reloading for handguns and shotguns vs anything with rifles. I do look at the general recommendations of the powder mfg - in terms of what calibers, etc they designed a powder for vs trying to find some obscure recipe just because I have some powder. I also stay away from powders that don't meter accurately and consistently in my progressive loaders for a given recipe.

TiteGroup as an example, from Hodgdon, was designed so the position of the powder in the case didn't affect the performance - and on larger cases like .357 mag and .44 mag at around 6 grains and 9.5 grains respectively, the powder takes up probably less than 50% of the volume in the case - yet I find it performs very well.

[HOGGHEAD]

IMO you have hit one one of the most important parts of reloading.

I like the idea of filling the case with powder. That is my first priority when choosing a powder for a reload.

Whenever I fill the case I get lower SD's for the load. And as we all know a lower SD is a more accurate round.

A lot of relaoders go with the faster powder so they can use less powder and save money. For a lot of shooters they only reload to save money so they can shoot more. There is nothing wrong with that theory.

However I reload to achieve the highest accuracy that I can get from my firearm. And powder position in the case(if not full) will effect pressure if the powder is in a different position each time you pull the trigger. And we all know that consistent pressure is the most important(along with run out) part of an accurate round. Tom.

[SL1]

The idea that low SDs make more accurate loads is not a universal rule. I have produced myself and also seen some published data that shows that some unusually accurate loads have higher SDs than some of the less-accurate loads in the same sets of tests.

Also, some powders are really not very position sensitive. IMR 4759 is a powder that gives me exceptional accuracy in light loads in my 270 Winchester, even though I am only using 19 grains and it is mostly lying below the primer hole in the case.

SL1

[HOGGHEAD]

I realize that I live in my own little world of reloading. And I realize there is a big world out there. So I can only post my experiences.

In my way of thinking-consistency is KING in reloading. The more consistent I reload my shells, the better accuracy I achieve.

I prefer to achive consistent velocity out of my cartridges. IMO this yields better accuracy??

I am not sure how a higher SD could achieve better accuracy?? We are talking about velocity?? How could a higher velocity spread yield better accuracy??

I am only asking, not meaning to start an argument. But higher SD's make no sense to me. I guess I am just hard headed. Or after 34 years of reloading I may just be stuck in my ways.

I am sure there are exceptions to the rule. But for the little extra it costs me, I will try to fill the case. Tom.

[Loader9]

Okay SL1, the 4759 is a little deceptive now. That load is about a 60% loading density. I use a lot of it for the Boy Scouts. I have them load 19.0 grs in a 3006 and top it off with a 147 FMJ. When I hand them an 03A3, you can tell they're not real sure about getting kicked to the ground with it. But when the rifle goes off and there is almost zero recoil, you couldn't wipe the smiles from the faces with a Peterbuilt. It's a lot of fun for the little guys. SR4759 has about the same burn rate as IMR 4227 but is extremely bulky which is why it comes in a normal 1lb can but only weighs a half a pound- and the cans are full.

For more reading on loading density:
http://stevespages.com/powderdensity.html

[BigJimP]

ok, but its " Peterbilt " not built .......not to be a smart ass ...

[SL1]

Okay SL1, the 4759 is a little deceptive now. That load is about a 60% loading density.

Well, I'm not trying to be deceptive. Quickload doesn't have IMR-4759 as a standard powder, so I can't calculate my load density without spending more time than I have right now. But, putting 19 grains in a 270 Winchester case behind a 90 grain bullet seated out to 3.300 inches LOOKS like about 50% or so, compared to my full-power charges for 130 grain bullets. It is sure a far cry from a case-full. The position-insensitivity is not due to a high load density, but to the nature of the powder, as I said.

SL1

[butta9999]

Well saving powder is never an issue for me. i try to use slower burning powders for better load density. I wanted to see if it was important as i thought it was and it is.

Great opinions

[HiBC]

Different folks use different processes to reload.

I think the visual inspection of powder level in each case in the loading block is an important step before seating.Very small charges in big cases make this less reliable.It can be hard to see a double charge.(I know,we should never have a double charge)

While some powders are designed to be tolerant of low load density,other powders can achieve destructive pressure with low load density.Simply put,if a powder column is supposed to be ignited on one end,and instead,the primer flame flashes over the powder charge,you are burning the powder from both ends.(I know,ballistic experts,it is not a perfect explanation,but its close)
An effect a little like pinging in a gasoline engine occurs.Strange blow-ups have occured.
I stay away from compressing more than slightly.
On overbore cartriges,by definition you will probably be looking at 75-85% density.
A balanced cartridge,like the 30-06,will let you use the whole case.
A challenge,is with cartridges that have black powder origins.
Like 45 long colt and 45-70 or 45-90.
The cases are enormous,yet acceptable pressures are low.Density can be an issue with these.,

[Sevens]

The situation you described is termed "detonation" and though I've heard it discussed many times over the years, I've still never seen a report of it recreated in a lab environment. Detonation has gotten a reputation (deserved or otherwise) for being an urban legend. Many folks have read about it, many handloaders are aware of the possibility of it, but nobody has ever been able to say it's actually happened with any real data or proof to back it up.

I'm not saying it's not possible. But it's not any kind of common occurance.

[HiBC]

Mr Sevans
With all due respect,I don't have the time to research my sources for detonation.
PO Ackley wrote of it,Hatcher may have.Mike Venterino and friends have discussed chamber ringing on black powder cartridge arms.I have seen the matter discussed at length on the pages of such publications as Handloader,Precission Shooting,etc and they did not give the impression it was urban legend.
As we are discussing a matter of safety before new reloaders,may we agree that detonation is a factor to consider,and that we should also not reduce loads below the recommended minimums in the load manuals?
Thanks,again,no disrespect intended
I may post a question on this in the research thread

[Sevens]

I'm sorry if my post came off unfriendly (not my intention!) -- and I do agree that it's worthy of repeating and duly noting, especially for anyone who is new to the game and can use more hints on safety.

It just seems like it really has the reputation of being somewhat of a ghost... folks have described it, but nobody can seem to get a real handle on it. Ballistic experts have tried to create detonation scenarios in test labs and consistently fail to do so.

There are some powders in particular that give very specific warnings not to reduce (H110 is the obvious one), but I don't think it's an across the board no-no to reduce loads under listed start loads. And though I hesitate to argue terminology, that's what they've always been given as: "start" loads, not "minimum" loads. A safe place to start, but not a bottom floor. Many rifle shooters who use cast lead bullets in modern centerfire rifles go well, well below start loads, and some of them even use common pistol powders in large rifle calibers.

Of course, going too low is a fine way to get a bullet stuck in your bore, and we all know what happens when you go ahead and shoot the next bullet. I'm certainly not recommending anyone go out and build powder puff loads for sport.

I was just trying to pass on the idea that detonation isn't quite as cut dried as having a light load laying across a long case that gets lit up and explodes. Is it possible? I agree with what you've said, I've certainly read about it from some very established folks. But what I've gathered from their writings is that detonation was perhaps a possible explanation for a scenario they've come across and haven't been able to explain it any other way. But it's not such a hard and fast rule that it's denoted in every load manual and powder guide.

I first read about the theory of detonation back in '88 when I started rolling my own, and since that day I've waited to come across the definitive answer, but nobody has ever come up with a stronger case. Each time it seems like they are describing the Bermuda Triangle.

No disrespect whatsoever-- I enjoy the discourse and am always hoping to learn from it!

[HiBC]

Sir,you did not seem unfriendly at all.We have no problem.
So often,when folks have a different way of looking at something,they think it is time to stop being gentlemen.
My intention was only to address you gentleman to gentleman.
Armed men have a paticular responsibility to be gentlemen.
It helps make the unarmed more comfortable with the Second Ammendment.

[Shoney]

My understanding of "Detonation" came from an article in American Rifleman well over 20 years ago, maybe longer. The article was entitles S.E.E. something???? The article made the point that SEE (Secondary Explosive Effect) is more commonly referred to as detonation, but that in reality it was not a detonation, rather it is a unique pattern of burning of the powder.

The phenomenon is theorized to occur in reduce rifle loads that are well below the minimum load. The greater the reduction, the greater the chance of catastrophic problems. Loading a good deal below minimum load has always been promoted as a dangerous and unwise practice since I started loading 48 years ago.

The article theorized when a small amount of powder lays flat in the horizontal case; that the primer ignition hits the rear portion of the powder igniting it, and then skips over the middle section of powder, igniting the front portion of the powder, and both ends burn rapidly toward the middle. The result is theorized to be an uneven but rapid burning of the powder, causing a very high pressure spike.

[David Wile]

Hey folks,

I, too, have been hearing about the danger of reduced loadings of slower powders for nearly fifty years. And just like everyone else, I have never seen any scientific research able to produce the results described. While I have loaded many cartridges with loads of slow powder that were perhaps 25 or 30 percent below the published starting loads, when I wanted to work up a completely new load with no published data, I chose to go with a medium or faster burning powder to start with really minimal squib loads.

As to load density of powder in charges, I have always prefered to use a powder that mostly filled the case. Right or wrong, one of my reasons was the idea of avoiding double charges. In the last twenty years, I have also moved to the idea of picking powders that meter beter. This was especially true after I started using progressive machines in both shotshell and metallic.

Best wishes,
Dave Wile