DG Bullets, COL and Load Volume Density

[chilehed]

I’ve got two guns chambered in 9mm Luger: a stock M&P 2.0 Shield and a Zaffiri 80% G19 kit which I’ll be assembling over the next few months. My intent is to develop soft-shooting, reliable target loads for each.

With DG Bullets 124gr round-nose coated lead, the plunk test yields a max COL of 1.107” in the Smith, and 1.059” in the Zaffiri.

By my measurements, that gives an assembled cartridge internal volume of 0.63 cc in the Smith, and 0.56 cc in the Zaffiri. Calculations with DG 145gr bullets yield volumes of 0.46cc and 0.39 cc (assuming that the nose profile is identical with the length being 0.105 greater)

I’ve got a bunch of Winchester WMR. The Hodgdon data center indicates starting loads of 4.0gr for the 124s, and 3.7gr for the 145s. Assuming a powder density of 11.6 gr/cc, this produces starting volume load densities ranging from 55% (with the 124s in the Smith) to 83% (with the 145s in the Zaffiri), and a max volume load density of 92%.

My questions are:

- What’s the correct average density value for WSF?
- How sensitive is WSF to variations in volume charge density? I know that excessive pressures can result from both excessively low and excessively high load densities, and I want to avoid that.
- I realize that WSF might not be able to cover both applications. What other powder should I be considering, and what is its average density? Autocomp? (I do intend to build the Glock as a competition-style gun with a compensator.)
- Why does the load data reference OAL to the exclusion of cartridge internal volume? It seems to me that peak pressure would be a function of powder speed/chemistry, load mass, load volume density and bullet mass/material, and not give a rip about OAL.​

What am I missing that’s really important? Yes, I will have a chronograph.

Thanks for your help.

 

[Rule3]

Maybe I have not had enough coffee but sure sounds like you are overthinking this and have TMI !

Just go with the start rates for the powder you have for one weight bullet. Try that, then move on to the other weight bullet.

You notice that Hodgdon loads them all at the same COL which is the MAX OAL for a RN bullet. and a 1.000 MIN

https://saami.org/wp-content/upload...FP-and-R-Approved-2015-12-14-Posting-Copy.pdf

 

[NWcityguy2]

Use the published load data.

Look for pressure signs.

Confirm results over the chronograph.

 

[higgite]

By my measurements, that gives an assembled cartridge internal volume of 0.63 cc in the Smith, and 0.56 cc in the Zaffiri. Calculations with DG 145gr bullets yield volumes of 0.46cc and 0.39 cc (assuming that the nose profile is identical with the length being 0.105 greater)

What brass is that?

 

[LiveLife]

M&P 2.0 Shield ... Zaffiri G19 ... intent is to develop soft-shooting, reliable target loads ... DG Bullets 124gr round-nose coated lead, the plunk test yields a max COL of 1.107” in the Smith, and 1.059” in the Zaffiri.

What am I missing that’s really important?

Max OAL/COL that "plunks" in the barrel and spin without hitting the start of rifling may not reliably feed/chamber from the magazine.

While Max OAL may work as Working OAL, you may need to incrementally decrease length (Say by .005") until dummy rounds (No powder, no primer) reliably feed and chamber from the magazine when the slide is released.

I also found coated lead bullets sized same as regular lubed lead bullets work well using lead load data.

WSF is a great powder for 9mm but it is a "relatively" slower burning powder that produces higher max velocities and flexible enough to produce accuracy at mid-range load data (Like BE-86). For decades, I used WSF for USPSA match loads and practice duplicate premium JHP rounds and recently replaced with BE-86 due to even higher velocities and greater accuracy.

For lower velocity target loads, you really need to look at faster burning powders than W231/HP-38 with sufficient powder burn efficiency to produce accuracy at lower velocities (Slower burning powders tend to produce accuracy at high to near max load data).

And I am one of those OCD reloader who sweats the details regarding consistent OAL (More specifically to bullet seating depth), case powder fill, bullet setback etc. as small internal case volume 9mm accuracy is more influenced by reloading variables, even small variations. And if I am using shorter OAL (Note deeper bullet seating depth) than published OAL, I will consider reducing my start/max powder charges by .2 to .3 gr.

BTW, here's step-by-step I use for load development you may want to check out - https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11419509

 

[chilehed]

Maybe I have not had enough coffee but sure sounds like you are overthinking this and have TMI !

Just go with the start rates for the powder you have for one weight bullet. Try that, then move on to the other weight bullet.

You notice that Hodgdon loads them all at the same COL which is the MAX OAL for a RN bullet. and a 1.000 MIN

https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.3-CFP-and-R-Approved-2015-12-14-Posting-Copy.pdf

Guilty as charged, I’m an engineer so it’s in my blood to try to understand the underlying principles. I absolutely plan to work on one load/gun combination at a time beginning at the start rates, but given the current market I’d like to get an idea for what other powders I should keep an eye out for. Thanks for the link, I copied that to my hard drive.

What brass is that?

It’s mixed brass. I based the internal volume calculations on PI * NominalCaseID^2 * (OAL – BulletLength – BaseThickness) / 4.

Max OAL/COL that "plunks" in the barrel and spin without hitting the start of rifling may not reliably feed/chamber from the magazine.

While Max OAL may work as Working OAL, you may need to incrementally decrease length (Say by .005") until dummy rounds (No powder, no primer) reliably feed and chamber from the magazine when the slide is released.

I also found coated lead bullets sized same as regular lubed lead bullets work well using lead load data.

WSF is a great powder for 9mm but it is a "relatively" slower burning powder that produces higher max velocities and flexible enough to produce accuracy at mid-range load data (Like BE-86). For decades, I used WSF for USPSA match loads and practice duplicate premium JHP rounds and recently replaced with BE-86 due to even higher velocities and greater accuracy.

For lower velocity target loads, you really need to look at faster burning powders than W231/HP-38 with sufficient powder burn efficiency to produce accuracy at lower velocities (Slower burning powders tend to produce accuracy at high to near max load data).

And I am one of those OCD reloader who sweats the details regarding consistent OAL (More specifically to bullet seating depth), case powder fill, bullet setback etc. as small internal case volume 9mm accuracy is more influenced by reloading variables, even small variations. And if I am using shorter OAL (Note deeper bullet seating depth) than published OAL, I will consider reducing my start/max powder charges by .2 to .3 gr.

BTW, here's step-by-step I use for load development you may want to check out - https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11419509

Thanks for the feedback and link, that looks like a sound plan of attack. I had made a test batch of dummy rounds, they feed and eject well when I cycle both slow and fast but I know that best accuracy might come from reducing OAL from there.

Still though, your point about small internal volumes brings me back to my question about why load data isn’t more obviously correlated to that rather than (or at least, in addition to) OAL. I get that it’s not as easy to measure, but still it seems to me that it’s important. So much to learn!

 

[higgite]

It’s mixed brass. I based the internal volume calculations on PI * NominalCaseID^2 * (OAL – BulletLength – BaseThickness) / 4.

In your volume calculation, did you take into account that 9mm Luger uses a tapered case? And the case wall is thicker near the base than at the mouth? Did you use fired or resized case dimensions?

Just for information, I’ve measured a few different 9mm headstamps for internal volume. The average volumes of different headstamps after resizing varied from 12.76gr H2O (0.828cc) to 13.86gr H2O (0.900cc). Keep in mind that these are strictly eyeballed water levels in resized but untrimmed cases.

 

[Rule3]

Guilty as charged, I’m an engineer so it’s in my blood to try to understand the underlying principles. I absolutely plan to work on one load/gun combination at a time beginning at the start rates, but given the current market I’d like to get an idea for what other powders I should keep an eye out for. Thanks for the link, I copied that to my hard drive.


It’s mixed brass. I based the internal volume calculations on PI * NominalCaseID^2 * (OAL – BulletLength – BaseThickness) / 4.

Thanks for the feedback and link, that looks like a sound plan of attack. I had made a test batch of dummy rounds, they feed and eject well when I cycle both slow and fast but I know that best accuracy might come from reducing OAL from there.

Still though, your point about small internal volumes brings me back to my question about why load data isn’t more obviously correlated to that rather than (or at least, in addition to) OAL. I get that it’s not as easy to measure, but still it seems to me that it’s important. So much to learn!

That explains it, an Engineer!

The manuals and online data did the work for you but I understand. My Father was an Engineer
As they say powder burn rate is not linear, there are so many many factors that go into it.

https://www.leverguns.com/articles/ballisticians.htm

 

[chilehed]

n your volume calculation, did you take into account that 9mm Luger uses a tapered case? And the case wall is thicker near the base than at the mouth? Did you use fired or resized case dimensions?

I'd used the SAAMI ID at the case mouth, thanks for pointing that out. The external taper is 0.011" larger at the base, which could make as much as ~5% difference - probably not critical at the middle of the range but it might be at the limits. I know that, in many applications, combustion stability can go haywire in a hurry at the edges of operating ranges.

That being said: Yes! Start with published data and pay attention to pressure signs and the chronograph. Don't muck around at the edges when you've just started, and not for a long time after that.

 

[Demi-human]

It is though you are looking at a Georges Pierre Seurat through a magnifying glass.

Take a step back and the picture will come to you.

“The edges to muck about in” usually aren’t printed in a manual, it would be a waste of ink and space.
The powders that work are listed and tested with equipment that is a bit more precise than a chronograph, measuring the actual pressure contained, not just the speed. In fact, many engineers worked together over the course of decades to compile the data contained in a handloading manual.

Math is great. It can lead to concrete conclusions, provided all the variables are there. In reality, there is so much more to it than just the numbers.

A 75% fill powder could be more accurate or more pleasant shooting(very hard to quantify with numbers) than a “perfect” filling powder. Many bullseye shooters tilt their 38s up before firing for better ignition because the case is so empty.

H-110 fills the case and has more than enough energy packed in. It sucks in 9mm. That’s why it’s not written into the data.

Further, differing level of charge weight make the fill percentage pointless for much other than comparison. If a full case is too much to handle, or shoots poorly, it doesn’t matter if it combusts perfectly.
For instance, I am merely concerned with performance, not efficiency. If 20% more powder only gives me another 6% velocity(safely, of course), I’m doin’ it! I don’t care about what isn’t used in the barrel.

Find a powder that is listed with the cartridge, use a charge within the published range and try it.
It’s easier to use the math for budgeting powders, primers and bullets to buy.

 

[lordpaxman]

@chilehed, welcome to THR! I are an engineer 2. Retired.

My intent is to develop soft-shooting, reliable target loads for each.

You may want to explore QuickLoad or Gordons Reloading Tool, software that will keep you occupied for a fortnight. Or, as others have pointed out, start with the published data and see how it goes. You mentioned WMR, I’ve not seen that for 9mm on Hodgdon’s site. I have developed loads for WSF, it’s a medium burn rate powder, but for soft shooting target loads, for minor PF I prefer a much faster powder. N320 is really soft, Sport Pistol is my current load. I started with Titegroup as well, but the recoil impulse is quite sharp. I don’t shoot a comp gun, but all I know that do use Autocomp.
As to your calculations and observations above, published data specifies a COL, with a specific bullet, which implies a seating depth that is related to pressure. It would be ideal if published data specified the seating depth, but I’ve not seen it. If you’re extrapolating data to another bullet, if you know the OALs of both you can make a more informed decision. Good luck.

 

[chilehed]

It is though you are looking at a Georges Pierre Seurat through a magnifying glass.

LOL!! I literally did that when I first saw A Sunday Afternoon on the Island of La Grande Jatte at the Chicago Art Institute! Did it the second time, too.

It's a spectacular museum BTW, if anyone ever gets to Chicago they ought to schedule a full day to go there. I never understood why people would pay millions of dollars for a painting until I stood in front of Monet's Water Lilies - from twenty feet away they look as if you could jump in and go swimming.

You may want to explore QuickLoad or Gordons Reloading Tool, software that will keep you occupied for a fortnight. Or, as others have pointed out, start with the published data and see how it goes. You mentioned WMR, I’ve not seen that for 9mm on Hodgdon’s site.

My error, it's WSF. Thanks for the s/w and powder suggestions, I'll study them.

If you can't be good, be lucky. Or, at least, don't be stupid. It's my policy to not rely on luck.

 

[Demi-human]

They really are are all dots.
And they literally are more than the sum of their parts.

Or rather, components.
In the end, all published loads will give an acceptable cartridge. But it’s the tuning to the pistol, the recoil to the shooter, using a high gas powder for a compensator, or reaching a velocity requirement that is more important.
There’s so many other things that case fill is secondary, almost arbitrary.

In my opinion.

 

[Jim Watson]

It would be ideal if published data specified the seating depth, but I’ve not seen it.

Not really a help, but in 1937 Phil Sharpe showed seating depth. It has the advantage vs OAL of being directly related to powder space but the disadvantage of requiring arithmetic.

Lacking the sensitivity of the Princess and the Pea, I am quite content with HP38 (Win 231) for 9mm. It will deliver the sub-minor loads I shoot in GSSF Pocket, Minor for IDPA and USPSA, and factory equivalent for carry gun practice.

 

[LiveLife]

Why does the load data reference OAL to the exclusion of cartridge internal volume? It seems ... load volume density ... combustion stability

intent is to develop soft-shooting, reliable target loads

Another consideration for lighter powder charge target load and case fill is powder charge positioning when primer detonates.

For larger internal volume cases like .38 Spl, powder forward vs powder back can be a factor whether primer flash has to jump across air gap to reach powder granules.

With semi-auto cartridges like 9mm, when the round is chambered, powder charge is thrown forward and if case fill is less than 100%, primer flash may jump across air gap before igniting powder granules. This may have been confirmed during my load development testing where with certain density powders, using shorter OAL which seats bullet base deeper (closer to powder charge) better ensures powder granules are in contact with flash hole even after being chambered. But even when shorter 1.130"-1.135" OAL rounds produced smaller groups than 1.150"-1.155" OAL rounds, this could also be from another reloading variable of greater neck tension where case wall is thicker further down towards case base.

Anyways, your pursuit of lighter powder charge target load may benefit from testing shorter OAL so after powder work up identifies an accurate powder charge for your Working OAL, you may want to incrementally decrease OAL (Say by .005") to see if group size decreases. (But since 9mm is tapered case, using shorter than 1.100" OAL started to decrease neck tension to where bullet just dropped down into the case)

 

[Jim Watson]

I once loaded some very bad .38 Special with shallow seated bullets; at its worst a bullet stuck in the barrel because coming up from Low Ready the powder was against the bullet, out of reach of the primer flash. I reseated the remaining bullets and they shot normally.

Not something I worry about in 9mm. I am loading powderpuff .45s with Bullseye because it is easier to ignite with less position sensitivity than Titegroup which is advertised or that.

 

[LiveLife]

bullet stuck in the barrel ... Not something I worry about in 9mm

As Walkalong already "myth busted", any amount of powder charge in 9mm with locked breech, bullet will likely be pushed out of the barrel.

Lightest charge I tested pushed the bullet like 20 feet forward of the muzzle.