does the boberg pistols fire +p+ rounds ?

I know they can fire +p, but how about +p+ ?

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Permalink Reply by Arne Boberg on January 23, 2012 at 10:01pm

I have shot the PowrBall in the XR9 guns. They seem to work well and sound and feel a lot like the +P+ rounds I shoot for durability testing.

Should you shoot +P+ rounds in an XR9-S? No - it will invalidate the warranty. SAAMI has no standard for the pressure in +P+.

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Permalink Reply by VMole8 on January 24, 2012 at 2:43am

Well, strictly speaking, it simply can't have the same "ballistics" (broadly) as a .45, but regarding what's probably your point, no 9mm has the expanded frontal area potential and penetration of .45, and certainly not apples to apples with the same projectile. However typical modern hollowpoints of all service calibers which expand reliably will typically get between 12 and 15 inches of penetration with 1.5-1.8x expansion. DPX is tuned to perform similarly, though it does have some unique terminal characteristics because the petals are widely separated, but longer than usual, and utilize a cutting mechanism more than lead core hollowpoints. The effect is that, while they can reach farther out into the wound cavity and do cutting damage along the length of the wound track, they don't necessarily displace/crush as much tissue volume due to the petal gaps moderating the total frontal area. The cutting mechanism and limited frontal area also seems to explain how such fast, light bullets can achieve 12" of penetration. There is an odd result as well regarding velocity, and it can create tradeoffs. The petals, being spread apart but long, tend to open broadly and stay that way at lower speeds, however, they peel back more and proportionally to the impact velocity while retaining the same open spaces between the petals. This means that DPX bullets lose frontal area at higher velocities. Contrast this with lead hollowpoints which tend to grow in total surface area with higher impact velocity. The result is that driving DPX rounds faster will provide greater penetration, however, because their wounding capability relies on cutting and reach rather than total frontal area, you lose benefit the more the petals fold back regarding reaching out to cut vascular structures along the wound track. So again the bullets tend to be tuned to expand with minimal curl back of the petals while reaching just past the FBI minimum of 12" in 10% gel. Go faster, and you lose significant wounding diameter at typical vital structure depths but you get some extra penetration.

There is one potentially problematic characteristing of DPX rounds. Because of the length and stark angle of petals combined with their light weight translating into a lack of momentum, when they hit glancingly on bone after beginning expansion, this can bend a single or pair of petals back on one side only, causing a rudder effect which can drastically redirect the path of the bullet in the body, even to a virtual 90 degrees, which means excellent shot placement becomes a crapshoot regarding terminal effect in that case. Considering ribs and arm bones are frequently encountered barriers to the internal organs, this can be a problem. And this tendency is completely opposed to the tendency of 230gr lead .45 ACP bullets which tend to greatly resist bone deflection though they may yaw or deform. 9mm 147gr is better in this regard than 127gr, or 115gr, but total weight as well as expanded sectional density from various angles and retained weight are the keys, and 230gr .45 will win that contest under the most circumstances, and light copper will always lose.