July 2020 GUNS Magazine, pages 70 & 71. Cast Bullet Accuracy, by Jeff "Tank" Hoover.
An article where Hoover uses a Ed Brown EVO-KC9 9mm to test accuracy of like-loaded rounds using cast bullets of 130 gr. weight, but sized at 0.356, 0.357 and 0.358 inch. The loaded bullets all chambered fine. Guess which were the most accurate?
Whether pushing bullets slow or fast, the .38 Super can deliver outstanding accuracy.
One can also use 0.357-inch bullets in the .38 Super. Yes, those traditional revolver bullets can be fired in your semiautomatic pistol, if they fit properly in your gun’s chamber, and many chambers handle them just fine. In fact, Hornady’s handloading manual includes 0.357-inch bullets in the load data for the .38 Super, specifically 125-grain and 140-grain XTP bullets, along with 0.355-inch bullets, and their one remaining 0.356-inch bullet, the 125-grain HAP. Hornady also has load data for the 110-grain .357 XTP for the lower-pressure .38 Automatic.
The thing to watch for with revolver bullets is exposed lead at the nose. That exposed lead might cause feeding problems because it doesn’t bounce off the feedramp like hard copper jackets.
If you’re wondering if 0.357-inch bullets are too large, the answer is no. Here’s why. The groove diameter of few barrels exactly match their prescribed bullet diameters. Most of the barrels are oversized compared to their usual jacketed bullet diameters. The nine .38 Super barrels I’ve slugged encompass a range of 0.355 to 0.357 inch. I see the same range in my 9mm Luger barrels. I’ve slugged 18 of them, and they range from 0.355 to 0.3575 inch. Only two of those were less than 0.356 inch.
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The Hornady 125-grain HAP bullet is one of the best bullets for target shooting. This 15-shot group, powered by W572 powder, was the smallest, measuring just 0.81 inch, center to center.
Schuemann Barrels makes 1911 barrels and recommends jacketed bullets 0.001 to 0.002 inch larger than the barrel’s groove diameter and lead bullets 0.002 to 0.003 inch larger for the best accuracy. World-class shooter Doug Koenig, 18-time winner of the Bianchi Cup Action Pistol Championship, shoots a .38 Super and uses 0.357-inch Hornady 110-grain XTP bullets. Are you convinced? The benefit is that you have a wider range of bullets from which to choose: 9mm, .38 Super, and .38/.357-caliber bullets.
My test gun is a hybrid: a Para high-capacity frame, Caspian slide, and Kart Xact Fit 5.0-inch barrel with a 1:16-inch twist. This one has a groove diameter of 0.3548 inch. (SAAMI calls for a groove diameter of 0.355 to 0.359 inch.)