In mid-to-late 2022, the 10mm round experienced a renaissance of sorts. It seemed like everyone was offering something chambered in .40 S&W Magnum. Hunters, people who hike in areas with bears and cougars, and people just looking for more power than most mainstream semi-auto handgun rounds were all giving the full centimeter a second look.
While most self defense buyers and law enforcement had moved back to 9mm, I was one of the stubborn people clinging to .40 S&W. With all of the interest in 9mm, ammo was increasingly plentiful and used police guns could be had for cheap, too. But having grown up shooting magnum revolvers, I saw no need to go to 9mm. Life was good.
But after several high-profile shootings in 2022, I got to thinking about the limitations of the .40 S&W round. I was confident in my ability to do the Dicken Drill, but I wanted something with a little more “oomph” going out to 100 yards and an optic that could make that kind of a shot more realistic and speedy.
A full-power 10mm round from a full-size pistol still has .40 S&W power at 100 yards, and the Primary Arms Holosun 507C X2 with the ACSS Vulcan reticle has a chevron instead of a dot, making for an infinitesimal point of aim and some limited ability to compensate for drop.
I was already a big fan of M&P pistols in .40 S&W and .45 ACP, so the same gun in 10mm seemed like a great choice. Plus, the M&P 10mm comes from the factory cut for an optic, so it was a natural fit for this project.
But I’m not the kind of person to run down to a gun shop and slap cash on the counter without doing a lot more homework. One thing I figured out right quick was that some people were having trouble with feeding, especially with full-powered rounds. So, it seemed pretty obvious that I’d need a heavier spring. I went with the Wolff 22-lb. spring and guide rod kit made for the M&P .45 ACP (it’s a direct fit for the M&P 10mm).
Once everything came in, it all went together just so. The Wolff spring and guide rod were a perfect fit and they were quite a bit stiffer than the weakling factory recoil spring. With a torque screwdriver, some thread lock, a little paint for witness marks, and the included polymer adapter plate, the Primary Arms Holosun red dot installed perfectly.
When I first went to the range in late 2022 with the full kit all put together, zeroing was a snap. With the tip of the ACSS Vulcan chevron, I set up the most precise pistol zero at ten yards that I’ve ever done, and it made for some extremely tight groups that were very easy to reproduce even in low light. Then I went for some 100-yard shots on dimly-lit 4-inch steel targets, and was able to ring them pretty consistently.
Since those first days, I’ve had the gun out to the range a number of times. Even shooting the occasional spicy Underwood round, the 22-lb. springs have always made for perfectly reliable feeding. Like all 10mm guns with loads at the limit, recoil is brisk, but with my experience shooting hotter guns, it’s still very manageable.
Happily, there’s really not much else to report on the last year-plus of ownership. Other than one defensive use that didn’t require pulling the trigger (helping a neighbor clear out some sheds that fentanyl-addicted homeless people were squatting in), the gun has been boringly reliable. No malfunctions. No hiccups. No problems holding the zero. No problems with the Holosun’s screws backing out.
All in all, I’d definitely recommend picking one up if you’re into 10mm or are looking at getting into it. But, definitely get the Wolff spring kit.
2 Responses
I’m curious to see the process you took to replace that spring and guide rod. I ordered it, and found the spring wouldn’t work with the guide rod like that. I was cutting a quarter coil off at a time until I could get slide lock. That wouldn’t allow my pistol to lock in battery. I ended up trimming the back of the guide rod and then trimming a quarter coil at a time until I could get slide lock. I ended up ordering everything twice.
Thank you for this third update, Jennifer. I have two M&P 2.0 .40s, one of which is optic-ready. I probably would’ve gotten the 10s instead if they were around back then. I still might get them. .40 ammo ain’t exactly cheap (compared to 9mm). It just so happens that a Holosun with the ACSS Vulcan reticle is also the optic I’m interested in when I decide to go that route. I’m a little hesitant because everything I’ve seen about it indicates that irons tend to be faster at close distances, while the optic helps maintain accuracy with longer shots. Almost all defensive shots occur at close range.