Striker drag is an issue that became a popular critique of the Sig P365. However, this is not the first pistol I have seen that gives striker drag on the primers. For instance, the M&P Shield has always done that for me, and I never really saw it as an issue because it wasn't really a topic that came up until the Sig P365 came out.
WHAT IS STRIKER DRAG?
Striker drag is basically when the striker is dragged along the primer as the barrel unlocks and starts cycling. The primer is literally scraped by the striker, which is held forward with exceptional tension until it is retained by the sear at the end of cycling.
IS IT A COMMON OCCURENCE?
This is something commonly seen in subcompact pistols, but it is also seen in pistols that have strikers that do not have rebound striker springs, which push the striker back inside the breechface after it strikes the primer. On the left is a primer from the P365 and the right is from the full size Glock model 20. Neither pistol has striker rebound springs. I have seen some striker drag even on the full size P320.
Basically, my theory is that the some guns have a striker that does not have a rebound spring, and this fast cycling is so forceful, that the striker isn't able to be pushed by the moving cartridge back into the breechface before scraping occurs. The faster the cycling, the more dramatic the scraping is on the primer face, which is displayed below on two different rounds out of the Glock model 20. The Herters has less power that the Starline brass next to it, which is known to be used in high powered loads. The scrape on the primer of the Starline brass is deeper and dragged about twice as far.
IS STRIKER DRAG HARMFUL?
The idea of striker drag being a potential cause for firing pin damage is something that has become a common concern thanks to the new Sig P365. The pistol has brought out that concern and brought it into the limelight, but it apparently is not something new. However, I do not know of many other subcompact pistols that have suffered from constant firing pin breakages. I do not know of any reports that the firing pins are flimsy or weak in pistols like the Glock which uses triangular strikers. I feel that the angle relieves some of the pressure on the striker, allowing it to endure the stresses with more ease than a round striker. Sig Sauer has come to a conclusion that the striker breakages were a result of the metallurgy not being correct, but has not said whether the striker drag was the culprit, as far as I know. Perhaps we can reduce the wear on the striker by just strengthening the metal a bit.
FINAL THOUGHTS
Striker drag on most pistols has never been a main concern until the Sig P365 came out. Sig claims that they have solved the issue, but only time will tell. Time and thousands of hot rounds being shot out of the pistols.
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