October 18, 2023
Speaking frankly, the new .30 Super Carry cartridge debuted as a surprise to many of us in the shooting community. Somehow, in the middle of ongoing international health and political crises and a domestic ammunition shortage, Vista Outdoor convinced Smith & Wesson and Nighthawk Custom to modify handgun models to fire a totally new and extremely high-performance round.
Touted as “filling the gap” between the performance of the popular .380 ACP and 9mm Luger rounds, the .30 SC’s ballistics are clearly slanted toward the latter. Six different loadings are offered from Federal, Speer, and Remington. Factory bullet options include 100-grain FMJs and JHPs and 115-grain TMJs and Gold Dots. The lighter-weight bullet velocities range up to 1,250 fps, whereas the heavier ones top out around 1,150 fps.
At 0.312 inch, the .30 SC projectiles are the same diameter as typical .32-caliber handgun bullets. The .380/9mm bullets are 0.355/0.356 inch in diameter, so the smaller but equal-weight 0.312-inch bullet requires much greater pressure to achieve similar velocities.
SAAMI maximum average pressure (MAP) for the 9mm Luger is about 35,000 psi. To achieve about the same muzzle velocity as a 115-grain 9mm bullet, the .30 SC MAP is a whopping 52,000 psi.
The .30 SC propellant used in factory-loaded ammo is a standard OEM concoction made by General Dynamics’s St. Marks division that’s not available to the home handloader. In addition, as yet no factory bullets are available as components. So what was I to do to handload this new cartridge?
Here’s how I accomplished the task.
I purchased an S&W Shield EZ in .30 SC. My contacts at Vista provided samples of factory ammo; RCBS carbide reloading dies; Speer and Federal bullets (three types); and unprimed Speer, Blazer, and Federal cases. Hornady supplied some XTP bullets, and a technician at Federal suggested some suitable propellants. Using Small Rifle or Small Pistol Magnum primers also was suggested.
I still had one glaring problem. No one had yet developed lab-tested pressure and velocity data! On top of that, I was unable to safely disassemble any of the factory-loaded rounds so that I could weigh their powder charges. So I weighed the separate cartridge components, did some math, and estimated the Federal American Eagle 100-grain FMJ powder charge weight to be approximately 5.8 grains. Caution: This is not a typical practice because the primed cases varied enough to affect the estimated charge by +/- 0.5 grains, and Shooting Times does not recommend this procedure. It’s especially a big deal if you’re loading a small-capacity case and the “safe” charge weight is small.
However, proceeding cautiously, I selected nine propellants and assembled two rounds each with the estimated 5.8-grain charge. I intended to fire the “slowest” burn rate powder selection first and record the bullet velocities. Hopefully, I would avoid a “bullet-in-barrel” situation and get reliable velocity readings. Then I would proceed to fire each pair of the next “fastest” burn rate test loads and record velocities until I reached from 1,200 fps to 1,250 fps, hopefully, without experiencing excessive pressure.
Of course, I could measure only velocity, not pressure, so it was a calculated leap of faith that I would be firing safe handloads. After talking with a propellant engineer at Federal, I further reduced the initial test charges of the top four fast burn rate candidates. That turned out to be a good move because I stopped climbing the ladder before reaching the 5.8-grain sample rounds for those propellants. Please note that I fired a few of the loads listed in the accompanying chart for velocity only, so there is no accuracy reported for them.
Extrapolating the initial velocity results, I adjusted the powder charges and repeated the tests to obtain the target velocities. The slowest burn rate candidates were eliminated because the .30 SC case cannot accommodate enough powder without excessively compressing the charge.
The primers of the fired test loads looked identical to the factory loads; they were flattened with obvious cratering that was also flattened. The appearance of primers is often not a reliable indicator until safe pressures have already been exceeded; however, there were no gas leaks, which I took as a good sign that my test loads were safe.
Switching over to the 115-grain Gold Dot and TMJ bullets, I repeated the same process and again determined potentially suitable propellants and charges. Again, I closely matched the Gold Dot factory ammo velocities.
Silly me. Subsequent pressure tests performed in Speer’s lab shot several holes in my premise that matching the test loads’ velocities to the same bullet weight factory ammo would also indicate closely similar pressures.
The pressure data for my 100-grain test loads turned out to be safe, but that was only because the American Eagle FMJ ammo is loaded to a more modest average pressure level than the SAAMI MAP. In other words, there was already a built-in margin of safety that I wasn’t aware of as I test-fired batches of carefully assembled handloads.
The 115-grain Speer Gold Dot ammo however did not provide the same cushion. It’s loaded much closer to the SAAMI MAP, so of the test loads I first developed, more than half exceeded the .30 SC’s MAP by up to 121 percent! I unknowingly fired handloads generating 62,000+ psi, and I was fortunate to avoid injuring myself or the S&W Shield EZ. I’m impressed with how it handled those high pressures.
Let me repeat a caution I’ve made many times: Only use load data provided by a proven, reliable source.
Until my test loads were pressure-tested by a reliable source, I would not publish them. Fortunately, my industry contacts did just that for the loads listed in the accompanying chart. However, consider the charge weights as maximum and reduce your initial charges by at least a half-grain.