Shooting identical pistols in different calibers

[Uni-Vibe]

EXECUTIVE SUMMARY: In identical full size M&P guns, both 9mm +P and .40 S&W are more similar than I would have thought.

There are a lot of comparisons between calibers, but not too many are based on identical guns. I went to the range with two M&P full size, one in 9mm and one in .40. I'm used to the nine as it's my EDC gun. But I wanted to see how it compared to the .40.

.40 ammo was:

165 grain Winchester white box FMJ
180 grain hardcast handloads, max load in Accurate Arms reloading guide

9mm ammo was:

115 grain Winchester range fodder
115 grain FMJ handloads, loaded to max +P load in Accurate Arms reloading guide


This is not a quantitative test, just my impressions:

I fired not super rapid fire, but flash sight firing, about a round every second.

I expected .40 to be a whole different category of recoil. But it's really not all that much different. With a firm two hand hold you get some more muzzle flip. (Flip is much more noticeable shooting one-handed.) I think if you timed ten-shot strings you'd get ten off a bit quicker out of the 9mm, but not a great deal of difference. If I get a chance to do this test I will.

Firing at the rate I was shooting, accuracy at seven yards was equal. I was putting them in a fist-sized hole in the paper, with occasional outliers. Either one is combat-accurate at ordinary defense distances.



The 9 and the 40 are more alike than they are different, at least in full-size M&P. (Certainly neither is in the territory of my XDM 10mm with full power loads. That one is a bigger handful.) The M&P is known as a soft-shooting gun and you might have a different impression in some other pistol. I'd bet that there's a bigger difference, say, in 9mm Shield vs. .40 Shield.

I wanted to do a three-way test with the M&P45, but none was available.


In a full-size plastic pistol, either 9 or 40 should be fine for self-protection. I'd still give the edge to the 9mm. Save for possible barrier penetration, the 40 won't do a thing that the nine won't do on a bad guy, and you still have the advantage of more rounds, cheaper ammo, and less recoil.

[matemike]

I'd bet that there's a bigger difference, say, in 9mm Shield vs. .40 Shield.

This I can say yes to. I've personally had the paint in my shield 40 front sight chip and fall out due to muzzle flip. As far a my experience with a shield in 9mm, feels like any other polymer in 9mm.
The full size HG's were your friend in this test. Same goes with 1911's in 9mm and 45. Not THAT much difference in felt recoil due to more mass in the frame than shields or pocket guns of same caliber.

Same with long guns. A 12ga 870 and a 20ga 870 almost feel identical IMO. But then, a decked out inertia driven semi-auto 12 ga gives less felt recoil that a 20ga pump.

[ST911]

Good thoughts, OP. No criticism intended here, just adding to the conversation...

Don't discount the value of numbers, they matter - and comparisons are easy.

Establish a target, shoot a specified number of rounds to that target. Divide points by time for hit factor. Compare hit factors between the variables you're considering. If you use a par time, use a segmented target like a B8 bull and score the points.

When measured, the difference between 40 and 9 is typically significant in shooters of average ability. Difference between 45 and 9 is less than 40/9. Also, differences in full/mid/compacts, standard and high velocity ammo, etc are evident. No surprises.

"I shoot X as good as Y" is often seen, but not often true. Shooter ability or margin may not be great enough to matter, but differences are there.

[Disciple]

I fired not super rapid fire, but flash sight firing, about a round every second.

That rate seems a little slow for a flash sight picture. I bet you were faster than that. A timer as ST911 suggests would be interesting, if you can arrange this comparison again.

[MegademiC]

A timer and measured groups is a must.

That said, especially with the m&p fs, the 40 shoots just fine. With a small gun like a shield, or even the old m&p c (between g19 and 26 size), its a no-go imo.

[Failure2Stop]

For comparing effectively, I shoot at 25 yards on a B8.
10 shot string starting with gun aimed just below the paper.
Time only counts if all shots are in the black (9-ring or better).
Must have at least 3 clean runs.

[Disciple]

Why 25 yards?

[Failure2Stop]

Why 25 yards?

1: That's the distance at which timed and rapid fire stages are shot, which is what the B8 target is designed for, and is a "standard" distance.
2: At that distance the shooter must properly manage the sights and trigger well in combination.
3: It's my preferred zeroing distance for pistols.
4: It's far enough away that I can't see impacts without magnification, which encourages me to stay on the sights rather than focus shifting.
5: It's close enough that I can put several of them on a backer without risking stray shots from fouling other targets.

[Disciple]

Thanks