<SOAP BOX MODE ON>
You will have to count me among those that give credence to this "fairytale"
There are so many engineering principles and delicate energy balances in play when a Luger is fired that it is certainly not beyond the pale of reality that failure to provide the proper resistance to the forces acting on the frame can upset that balance.
For every action there is an equal and opposite reaction. Remember that law of Newton? Well what happens when the action is mitigated by inadequate resistance (holding the Luger with less than a firm grip) to the recoil action? Is it not likely that the performance of the pistol may suffer if the recoil force is buffered by excessive movement of the frame caused by a limp wrist? I think so.
While the stories of improved performance by a firm grip may only be anecdotal and have not been scientifically proven, the sheer number of such anecdotal stories carries some weight in this community. Combine those stories with the questions I posed in the previous paragraph and you can easily start to form an opinion based on educated guesses and experience.
I spent almost 8 months as the coach (and participant) on a U.S. Army combat pistol team using issue M1911A1 .45 ACP pistols, frequently shooting thousands of rounds a week... and know first hand that your aiming point and point of impact are definitely affected by not using a "uniform" grip.
When competitively shooting my grip was practiced to be uniform, and after shooting you could easily see the impression of the mainspring housing and front grip strap in my hand. My target hits were always worse when I failed to maintain the proper grip.
While IMHO the design of the Colt .45 isn't as susceptible to "limp wrist-ing" as the Luger with regard to reliability, ---you will have to count me among the "believers."
<SOAP BOX MODE OFF>
