Compressed load question:

D

disseminator

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Hey guys,

So I'm looking into some loads for my 357 SIG using a Speer 125 TMJ and the max load listed in my Speer reloading manual is given as 11.2C of vvN105

Imputing this into Quickload says it will be a load density of 116.3%!

I've loaded a bunch of compressed loads before so that's nothing new but 116.3% seems like a LOT of compression.

What do you think?
 
Some powders are fine with compression, and N105 appears to be one of them.

I'd suggest you start well below that value and work up with a chronograph.
 
I don't know about handgun loads, but I have had the bullet in rifle loads back out of the case. I don't bother with them anymore.
 
I don't know about handgun loads, but I have had the bullet in rifle loads back out of the case. I don't bother with them anymore.
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Yeah, I don't think I would do it in a rifle either. I use a few slightly compressed loads but were talking 1-4% max, not 16% over.

Loading manual data for the Vihtavuori powders is a bit sporadic.

This data is right from Speer, the start load of 10.1 is also compressed around 6%.

I think I'll use a different powder. I have some vvN350 that will do.

I don't think I have seen any other loads in my manuals that are compressed to this level.
 
Quickload says it will be a load density of 116.3%!
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I have discovered (over time) that a QL designation of ~108% fill means the bullet/powder have made firm contact.
After that, real compression.

Not-to-worry for "116%"
Try it to get Comfortable-w/-the-Crunch. ;)
 
Wouldn't pay any attention to anything QuickLoad says about anything. Speer actually tested that load. The programmer who invented QuickLoad just guessed.
 
Computers use math to solve complex computations. Math is an exact science so one would think that you could get exact results from a computer. The problem arises when you use math on a topic that has so many variables that it can not be well defined. Internal ballistics is just such a topic. No matter how good your algorithms are, a certain number of assumptions have to be made. There are also estimations made that are not exact. The size of the bore, the coefficient of friction between the bore and the bullet, the specific heat of the burning propellant, and the heat absorbed by the barrel. These things change with outside conditions in the same gun and bullet and the changes between different guns and bullets can be extreme.

With all the variables it is impractical to get exact data to work with so, no matter how good the algorithms are the results can be very far from the real world. That is why there is a note at the bottom of the data that tells you to double check the computed suggestions with published data that has been tested.
 
Wouldn't pay any attention to anything QuickLoad says about anything. Speer actually tested that load. The programmer who invented QuickLoad just guessed.
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You serious? Come on now.

I think I'll load up a few dozen and see what happens. I'll let you all know how it goes.
 
Thing I always understood is that if you get a compressed load, the powder is to slow, that is with rifle's. I would guess that it's the same for handgun's. I like a powder that will give my a min of 80% to a max of about 90% At 90% I have never had a compressed load. Another thing you'll find is the cartridge will likely not get up to Performance with a compressed load.
 
Thing I always understood is that if you get a compressed load, the powder is to slow, that is with rifle's. I would guess that it's the same for handgun's. I like a powder that will give my a min of 80% to a max of about 90% At 90% I have never had a compressed load. Another thing you'll find is the cartridge will likely not get up to Performance with a compressed load.
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While this may or may not apply to my specific question in the OP, I can try to paint a picture of why a compressed load can be superior.

If you have ever seen a graph of the pressure wave that occurs when a primer is detonated you will notice that in general the pressure happens very quickly and then tapers off almost immediately.

By using a slower burning powder, which will often mean some compression due to it's volume, we can make the pressure pulse last longer and thus impart higher total velocity to the bullet - sometimes with lower pressures as an added bonus. ( I have seen this with IMR 800X in the 10mm for example )

That said, I have never loaded a small pistol load at nearly 40,000 psi with a 116% load so we will see what happens.

:cool:
 
All sources of information have their own value.

Quick load does fine to let you know the general setup and a lot of other factors with a load. Its not junk by any means.

For an actual load, tested ones by an mfg are the best as they have the exact data on each one for that set of circumstances.

While I would not jump to a max quick load, if it says its ok otherwise and its been tested by Speer I would have no issue working up to it as long as I was as close as possible to their test specification for brass mfg, dead on for primer and carefully about the gun its fired in.
 
All sources of information have their own value.

Quick load does fine to let you know the general setup and a lot of other factors with a load. Its not junk by any means.

For an actual load, tested ones by an mfg are the best as they have the exact data on each one for that set of circumstances.

While I would not jump to a max quick load, if it says its ok otherwise and its been tested by Speer I would have no issue working up to it as long as I was as close as possible to their test specification for brass mfg, dead on for primer and carefully about the gun its fired in.
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This is one of those very rare cases in which I am actually using the exact same components as the manual. Same bullet, brass, primer, and powder. I don't think that has ever happened before. Of course the items are all from a different lot so that is why we work up from the minimum.

I don't usually go all the way to the minimum load but in this case I am going to.

I have faster powders I could use but I love the n105 and I have two pounds of it so... :D

Thanks for all the input guys....
 
Just for grins (and a bet on another issue w/ another PhD friend), I set up a test for using cast in my Garand.

Having already calibrated IMR4759 in other cartridges (the big 45's, natch... but also the 30 carbine of all things :cool: ), I told QuickLoad to give me ~25ksi (for the alloy) and mid 1800s (for the ALOX).

This evening:
 

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First off, whoever trashed Quickload saying they just guessed must have no clue how a model works. QL is far superior to a reloading manual. I don't feel like typing a book explaining why but that's just ridiculous.

Next: full cases are almost always preferred to 80-90% case fill.... Especially in rifles. Again I don't want to type a book explaining but try tapping your 80% full cases on the head and fire them through a chronograph. Then do the same but tap them on the bullet (forward). You will see different average velocity.
But if it is full, it will not matter, velocity will stay the same.

On the flip side, I have a hard time getting consistent seating depth at over 110%. I have to lightly shake the case to remove the peak of powder in the middle.

I have never hit 116% , but my only concern would be consistent seating depth.
 
It has been many years since I was involved in a conversation that started with; "All you gotta do is dip the case into the powder to fill it up and then seat the bullet". I have never found anything entertaining about dipping cases to fill and I have never encouraged anyone to practice the bad habit; because? It must be understood the powder must be known. For me? I was always prepared because I am the one that uses all the bullet hold I can get, I want my necks to grip them necks, nothing fancy like tension. I would use tension if not for the lack of a way to measure tensions.

F. Guffey
 
Just a quick note on load density. Load density has two different meanings. The original meaning is tied to water capacity. If your case will hold 60 grains of water and you use 60 grains of powder the load density is 100% but because powder has a higher specific density (specific gravity) it will not fill the case. If you are using case volume in cc's and loading by volume then 100% load density is a full case of powder. The compression of a powder charge means that you have to settle the powder to remove excess space between the granules. Volumetrically a 116% powder charge would be very difficult to obtain but 116% of the water weight would require very little compression using a dense powder because some powders can have specific densities over 110% of water.
 
So I went to the range this afternoon and shot my test loads.

This data originated with Speer #14, but I also included some Quickload data so....

CAUTION: The following post includes load data generated by calculation in QuickLOAD software based on a particular powder lot, the assumption the primer is as mild as possible, and assumptions about component, chamber and gun geometry that may not correspond well to what you have. Such data should be approached by working up from published starting loads. USE THIS DATA AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL, nor QuickLOAD's author nor its distributor assume any liability for any damage or injury resulting from use of this information or information derived from it.
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They were indeed compressed! The last few at 11 and 11.2 grains I could really feel the powder scrunching down.

I was curious if the bullets would push back out without a heavy crimp so I didn't crimp them at all at first and after an hour measured them again and they were exactly the same: 1.135"

So I went ahead and put a normal light taper crimp on and shot them.

I am very impressed with this powder. Accuracy was good with all the loads but really tightened up at 11 and 11.2

Better yet, my gun was clean and cool even at 1400+ fps. I have good shooting loads with LONGSHOT but it runs hot and messy so I really appreciate the clean burning of this "Premium" powder. (vvN105)

I am gonna load some at 11.3 and 11.4 which will exceed 118% and see how they shoot.

Quickload says the 11.4 grain load will be 1500 fps and just under 40,000 psi, that should be fun!

:D
 
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Just a quick note on load density. Load density has two different meanings. The original meaning is tied to water capacity. If your case will hold 60 grains of water and you use 60 grains of powder the load density is 100% but because powder has a higher specific density (specific gravity) it will not fill the case. If you are using case volume in cc's and loading by volume then 100% load density is a full case of powder. The compression of a powder charge means that you have to settle the powder to remove excess space between the granules. Volumetrically a 116% powder charge would be very difficult to obtain but 116% of the water weight would require very little compression using a dense powder because some powders can have specific densities over 110% of water.
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So in this case, Quickload takes into account the space that will be used by the bullet in the case. Specifically: case volume is 19.50 grains H20 and the bullet will use 6.134 grains leaving 13.36 Grains H20 usable for the powder.

The 116% is of the 13.36, and not the total case volume. Obviously I would have a heck of a time if it were not so. :)

Based on what you are saying, my powder must have a density greater than water. ( But does it really since you can compress it? )
 
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