The .45 GAP
The .45 GAP was designed by Glock in cooperation with bullet manufacturer Speer/ATK in response to law enforcement̵7;s desire for a smaller duty pistol in a larger caliber. Glock achieved this by creating a .45-caliber bullet with a shorter casing then the traditional .45 ACP.
The .45 ACP
The .45 ACP was designed over 100 years ago to accommodate the Colt model 1911 pistol (the pistol used by the U.S. Army for nearly 80 years). The .45 ACP has been proven reliable and powerful. However, it is also a very large bullet.
G30 Magazine Capacity and Loaded Weight
The standard magazine of a G30 carries 10 .45 ACP bullets, giving the pistol a loaded weight of just under 34 ounces. Glock also produces optional 9-round and 13-round magazines.
G38 Magazine Capacity and Loaded Weight
The standard magazine of a G38 carries 8 .45 GAP bullets and has a loaded weight just below 32 ounces. Glock produces an optional 10-round magazine for the G38.
An Individual Choice
The similarities between the G30 and the G38 are such that choosing between them is purely an individual choice. The dimensions are nearly identical, the loaded weight varies by mere ounces and the bullets are comparable in performance. However, the G30 does provide the option of a higher magazine capacity. Ultimately, it̵7;s your call.