I've observed something similar involving the G26/27's that I own. I've fired more than 10,000 rounds through the G27 and I'm approaching 11,000 rounds with my first G26, so I've had some time to experience and observe their functioning in my hands.
I've experienced upwards of maybe a dozen feeding & functioning issues with my G27. These have ranged from a couple of obvious ammunition issues, some magazine issues and the rest are what I'd categorize as shooter-induced. This last category includes using the G27 for fast & demanding training & practice drills which can introduce the opportunity for some unintended flex in my strong or weak hand grip, as well as my wrist not remaining locked.
I'd think it reasonable to consider that the increased felt recoil of the .40 might have an influence in this regard.
The only issue I've experienced and observed involving my G26 has been with the ejection pattern.
If I relax my grip ever so slightly, or allow my wrist lock to soften, I can get empty cases in my face, chest or even over my left shoulder (and I'm right-handed).
This condition can occur more frequently when using lower power loads and when it involves the last round. In the case of the former situation I'd think it has something to do with slide velocity and the strong recoil spring ... and in the case of the latter I'd think it likely also influenced by not having another live round in the magazine to help keep the empty case being extracted from slipping a bit lower before impacting the ejector. Neither of these things are exactly unknown to occur in other pistol designs and platforms.
I see a fair number of folks shoot both for qualifications. Discounting some parts breakage I've observed (which can happen with any mechanical device, including firearms
), I've seen some feeding issues arise when folks have been using G27's and G23 magazines. The slide velocity generated in the .40 can sometimes have an effect on such things when weakening or reduced recoil & mag spring tension is occurring.
In the wearable parts replacement schedule I received from Glock regarding .40's being used by LE, it's recommended that the recoil spring assembly is replaced every 3,000 rounds in the G27 and the magazine springs every 5,000 rounds. However, it's also listed as being recommended that the recoil spring is checked and tested using the Glock recoil spring field test at each range session or qualification, and the recoil spring replaced more often as may be needed.
The locking block pin & slide lock are a couple of other wearable parts recommended for replacement at 5,000 rounds, BTW. When I replaced the ones in my own G27, at 10,000 rounds, I noticed the locking block pin exhibited some noticeable wear and burred spots where it had been contacting the locking block. I saw another one I removed from another instructor's G23, which had supposedly only been fired upwards of 2,000 - 2,500 rounds, and it looked like it had been peened, burred and subjected to road rash, as well. I was told in my last Glock armorer class that Glock had changed the heat treating of the locking block pins more than a couple of years prior to that class (and that's coming up on 3 years ago).
I can't give you a definitive answer to your question about the G26 being more tolerant of human error (shooter influence), but I'd suspect the lighter recoiling G26 might experience less recoil-induced effects due to the G26 using the same recoil spring assembly (and other parts) as the harder recoiling G27. I can notice more felt recoil in my G27 when using 180gr loads than when I'm shooting 115gr +P+ & 127gr +P+ loads in my G26 ... (and standard pressure 147gr & 124gr +P loads seem rather mild by comparison, although it must be remembered that not all +P loads are the same) ... but it should also be remembered that how felt recoil is perceived by each individual can vary and is a somewhat subjective matter.
Something else to possibly consider is that shooting a pistol while standing comfortably on a firing line, taking plenty of time between shoots and making sure grip technique remains constant, resting when necessary, can be somewhat different than when shooting the same gun/ammo in a fast-paced, demanding and difficult training/qual situation which tasks the shooter to not only shoot the gun at an intended target, but do so while resolving tactical problems and making judgment calls about shoot/no-shoot conditions.
Adding movement (meaning shooting both during and between movement) , the use of 1 & 2-handed shooting (using the non-dominant hand for both) and effectively utilizing cover/barricade and perhaps while using a hand held light ... can all create potential conditions and introduce stresses which might distract a shooter from being able to calmly use their "optimal" grip & shooting techniques unless a lot of training & practice is frequently done. Even then a momentary distraction or physical influence can still occur and affect the shooter's ability to effectively use their skillset.
Now, think about what happens when the body is subjected to the physical and mental stresses induced by the hormonal fear response and how it might have an adverse effect upon gross & fine motor skills. It's been discussed by some authoritative sources that frequent & proper training can help mitigate this sort of problem, allowing ingrained training (reinforced by proper practice) to subconsciously be available under stress.
Hmmm, sorry if I got side-tracked. Hope some of my rambling might be relevant to your questions ...
I can also offer that I work rather hard with my various .40's, which includes my G27, to be better able to handle the increased recoil forces often felt over similar models chambered in 9mm. I've found that the more I work hard with my .40's, the better I seem to do when it comes to my 9's, too. Sort of a win-win for me, I think.
