For various reasons, it can be difficult to get accurate results of this type with self-testing. Fortunately, there's a large reservoir of information available on the internet that provides just this kind of results.
GSSF outdoor match scores are posted online and GSSF has a category called Heavy Metal. Competitors in that category
must shoot a pistol chambered in .45ACP, .45GAP or 10mm. There is also a category called Amateur Civilian and most shooters in that category compete with 9mm pistols although it’s legal to compete with any caliber in that category. Both categories use exactly the same course of fire.
Scores combine time and accuracy, so this provides just the kind of data that is of interest.
This means that we can look at shooters who compete in both categories and see how their scores differ. Of course, it’s important to understand that this will UNDER estimate the performance degradation since it’s not a straight comparison between 9mm and .45/10mm. That’s because Amateur Civilian has no caliber restrictions and therefore a shooter could compete with a 9mm, .357SIG, .40S&W, .45GAP, .45ACP or 10mm if he/she wished to. Still, because most shooters compete in Amateur Civilian with 9mm pistols, it should provide some useful data even if it underestimates the factor we’re concerned with.
Awhile back, I pulled up the results from several of the larger matches and compared the scores of all of the shooters who shot an entry in both categories. So if "Frank Smith" shot in both categories, his scores from each category would be compared. If "Ann Jones" shot in only one of the categories, her score would not be included in the comparison.
On average, the scores (time combined with accuracy penalties) from the Heavy Metal category, when compared with scores from the
same shooters in Amateur Civilian were about 20% worse.
Also interesting is that shooters in "Master Class" are identified--this allows a comparison of scores from higher level shooters as well, to see if maybe their skill can overcome the additional recoil. Turns out that skill does make a difference. It doesn't eliminate the difference but it does cut the advantage for the smaller calibers to about 10%.
What a surprise, right? Lighter recoil does make a significant difference when time/accuracy comparisons are made. Who would have thought... Well maybe the folks who put caliber and/or power factor restrictions on various pistol competitions to try to level the playing field. And maybe the LE departments who have noted that their officers shoot better with lighter calibers. Maybe competitors like Rob Leatham who states that he shoots better with a 9mm. Ok, maybe it's not really such a big surprise.