I cannot vouch for how accurate this statement is, but I did hear it from a certified instructor for what it is worth. He had said that the angle on the Glock ( the one gun everybody seems to reference when mentioning grip angle) gets it design from the idea of having a much more aggressive stance when shooting it. It has been described different ways but it is basically your knees slightly bent, you set on your hips and chest out forward of your waist and shoulders forward of your chest. That is supposed to bring you head down lower and better inline with the sights on the Glock.
I've also heard the some grip angles were designed with the expectation of the shooter having their wrists locked in different positions. It seems that there is a science to it, but like the poster before me said, it is up to you to find the gun that fits your method but handling the different guns like Glock, the M&P autos, and the 1911 will probably give you a better idea of how you will hold and shoot the gun since everybody has a different stance, grip and wrist position.
When it was first announced and presented to the public, the Luger was hailed as a very 'natural pointing' pistol. Probably because nearly all the serious handguns before the Luger were single or double action revolvers, which tend to have a grip angle similar to the Luger.
The Government .45 auto pistol broke that trend. Actually, John M. Browning did prior to the 1911; take a look at the early Browning designed semi-automatics like the .38 Automatic Pistol, the 1903 Pocket Pistol (in .32 ACP and .380 ACP), the 1905 .45 pistol, the 1908 .25 ACP Vest Pocket Pistol. They all have grip angles much closer to 90 degrees from bore angle than the revolvers or the Luger.
The 'old guys' said the grip angle was wrong on the .45 Auto and the gun would ALWAYS shoot low. My first serious gun was a WWII issue pistol - released to the public, of course - and after learning on that pistol, I found revolvers shot high.
The late Jeff Cooper opined the .45 Auto (1911) was perfect in grip angle, as one could shoot with a 'locked grip'. For all the late Brother Cooper's intellect and experience, the wrist is a near 'ball joint' arrangement and it doesn't 'lock' anywhere. (Unless it's malfunctioning; severe arthritis, for example.)
The stance DustyDawg outlines is the 'gunfighter stance' that has been used since the first guy with a pistol realized a shot was coming at him. It is outlined in many places - Fairbairn's book Shooting to Live discusses the stance, as do Ed McGivern, Elmer Keith, Skeeter Skelton and any number of newer guys. It has been used with all manner of handgun; in the cartridge era, single and double action revolvers and all manner of auto pistols. Having shot the Glock and a number of other pistols, I can't see any particular advantage with the Glock's grip angle. Sounds like a sales pitch to me.
Here's my certified findings based on shooting a whole bunch of handguns for over 45 years now: Grip angle itself doesn't mean squat.
Your hand and arm may like 'this' angle better than 'that' angle. But that's got more to do with you and your preferences - which matter a lot in the matter - than it does with some 'magic' grip angle.
Or, if you shoot them all well, pick the one you think looks the coolest.
Hold your arm straight out. Point your first finger and curl the other 3 back. The angle contained in the curled fingers is your ideal grip angle. The grip angle on the 1911 works well for me. When I pick up a new to me handgun I clear it and then look at an object on a wall. I square up with it, close my eyes and bring the handgun up. If it is not aligned with the object I dont bother with it. I will not adjust my grip. It has to point naturally. I was trained to do it this way 50 years ago and it has worked very well for me.
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