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 am I missing that’s really important? Yes, I will have a chronograph.
Thanks for your help.
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.
- 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.