Understanding recoil: 9mm+ versus 40 S&W

Understanding recoil: 9mm+ versus 40 S&W

This is a discussion on Understanding recoil: 9mm+ versus 40 S&W within the Defensive Ammunition & Ballistics forums, part of the Defensive Carry Discussions category; First time post, long time lurker. I have a Glock 22 and love it. Looking for another gun and debating between 40 and 9mm. Please ...

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Thread: Understanding recoil: 9mm+ versus 40 S&W

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    Member Array globetruck's Avatar
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    Understanding recoil: 9mm+ versus 40 S&W

    First time post, long time lurker. I have a Glock 22 and love it. Looking for another gun and debating between 40 and 9mm. Please help me understand recoil.

    From my understanding of physics, recoil is the "equal and opposite reaction" from the bullet exiting the gun. So in my mind, it's directly related to muzzle energy. It will be dampened by the weight of the gun, strength of the recoil spring, etc. It will feel stronger when shooting a smaller gun, or potentially even the same gun with smaller grips, since the force will be distributed across a smaller area.

    Now going back to the endless debate about 40 versus 9mm. Lots of 9mm proponents argue that it's cheaper than 40 (it is), and it has similar ballistics (not quite), and that the +p rounds have more power. I found some ballistics data here:
    9mm Ballistics Chart | Ballistics 101

    And I made a quick scatter plot for comparison:
    Picture 3.png

    As you can see, there is a difference between 9mm, 40 s&w, and 9mm+, at least in terms of muzzle energy. Going on my premise that recoil is directly related to muzzle energy, it would seem that the 9mm+ offers the most recoil.

    Is this true? Has anyone shot 9mm, 9mm+, and 40 S&W in comparable guns? In other words, comparing a Glock 26 versus a Glock 27 is probably more accurate than comparing a subcompact 40 recoil to a full sized 9mm.

    Thanks!


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    VIP Member Array Bad Bob's Avatar
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    Whether or not the 9mm +P has more power than a 40 S&W. Pick the best from each for comparison VS cherry picking to make a point.

    This is the same thing already running and should be closed.
    My rifle and pistol are tools, I am the weapon.

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    Senior Member Array Happypuppy's Avatar
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    Quote Originally Posted by globetruck View Post
    .

    Is this true? Has anyone shot 9mm, 9mm+, and 40 S&W in comparable guns? In other words, comparing a Glock 26 versus a Glock 27 is probably more accurate than comparing a subcompact 40 recoil to a full sized 9mm.

    Thanks!
    I have a 19 and 23 Glocks to compare. The 40 s&w has the sharpest recoil. The 19 with +p+ is close behind. The only thing I care about is you quick I can get back on target.


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    Numbers on paper are useful, but unfortunately are only one-dimensional when it comes to describing recoil. You're correct in that recoil will be related to recoil; if you had two identical guns with one firing the 9mm +P and the other the .40, the objectively measured recoil would be higher for the 9mm (given the rounds you selected).

    However - the recoil impulse is delivered over a period of time - see the attached graphic. The total impulse is related to the area under the curve. Thus you could have two rounds, one with a much higher force delivered over a shorter duration, the other with a lower peak force but extending over a longer time, and have the same total recoil. But the recoil of the two rounds would feel substantially different in your hand. That's why you can't simply judge recoil based on external ballistics numbers. The difference in recoil between .40 and .45 is a good example. To a lot of shooters (including me), the .40 S&W recoil seems "snappier" than that of the .45, and part of the reason is that the .40 delivers its recoil over a shorter period of time.
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    Member Array eagle00's Avatar
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    Calculating "Recoil"

    Regarding recoil calculations, check out this site: Recoil Calculator

    It is a recoil calculator, giving you the recoil energy in ft. lbs., and velocity of the recoil. You have all the variables to enter into the calculator with perhaps the exception of the powder charge. But, you can get the powder charge from the manufacturer.

    You can use the calculated recoil figures to compare the different calibers you have with their particular firearms. Once you calculate the recoil for your specific load and firearm, knowing what that recoil feels like when you shoot it, you can calculate ( +/- ), and get an idea, what another caliber and firearm might feel like.

    * as an addendum; as I understand it (please correct me if I'm wrong), evidently it is the velocity of the recoil that actually produces the "pain" of the recoil. Also, as pointed out by gasmitty and msc 8127, the lower the recoil impulse, the lower the velocity of the recoil and the recoil energy of the particular round, with the respective firearm.
    Last edited by eagle00; July 23rd, 2012 at 03:18 AM.

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    Senior Member Array surefire7's Avatar
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    No stats here but I have shot the PM9 and PM40. Same gun, lots more "snap" from that 40.
    "Good decisions come from experience;
    experience comes from bad decisions"

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    VIP Member Array BigJon10125's Avatar
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    It is in my mind very subjective. As others have shown, and from my experience, .40 is snappy. 9 and .45 to me feel like more of a push. I do not feel the snappiness is an issue, just a thing you need to be aware of. Stats and #s are nice, but until you have shot both its just ink on paper or a screen.
    BigJon


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    Member Array msc8127's Avatar
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    Smitty, bringing in this physics talk....good stuff!

    300 win mag vs 300 weatherby mag...the win mag is tolerable to most shooters with a decent amount of training. However, the weatherby mag is past the threshold that most shooters care to deal with. The reason being exactly what smitty's post addresses. The weatherby mag produces a larger impulse and does so in a shorter time frame. Increasing the numerator and decreasing the denominator in the equation force = impulse / time results in an overall great recoil force felt by the shooter. The whole purpose of recoil reducing devices is to make the denominator in the impulse over time equation larger which decreases the force felt by the shooter. Using some generic figures here 300 / 1 = 300 whereas 300 / 3 = 100. The bigger the denominator (time in this case) the weaker the force applied to the shooter becomes.

    Likewise, a 12 gauge with 3 1/2" turkey loads produces a very significant recoil impulse. However, it is a slower (or longer perhaps is a better term) impulse than either of the aforementioned rifle cartridges, thus making it more tolerable to many shooters than either of the rifle cartridges, even though the actual recoil impulse in and of itself is greater.

    I'm falling asleep as I type this, so hopefully I didn't flop any variables around and screw things up. If so, I'll correct when I'm in a more conscious state.

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    Senior Member Array BamaT's Avatar
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    I have a Glock 19, my brother has a Glock 23. We've compared recoil with similar types of ammo, i.e. WWB ball in both, premium HP in both. The 40 had sharper recoil every time, definitely more snappy as some have said.
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    Distinguished Member Array CDW4ME's Avatar
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    Same size guns and same make ammo, average for 5 shots:
    Glock 26: Ranger T 124 gr. +P @ 1,162 fps / 372# KE / PF 144
    Glock 27: Ranger T 165 gr. @ 1,116 fps / 456# KE / PF 184
    Power Factor (PF) is a calculation that can be used to compare recoil out of similar pistols, as above.
    projectile weight x projectile speed = ______ / 1,000 = PF
    The 40 S&W does kick more than an equivalent 9mm loading, 22% in this case.
    I can feel the extra recoil.

    I used a shot timer to compare those two pistols recently. The greater recoil of the 40 did not cause a large difference in avaraged 1st - 2nd shot times like I thought it would (.25 vs .26) essentially the same; it did however, take more effort on my part to stay on target and the effect was that misses landed further from a 6'' circle in my little 6 - 7 yard comparison.
    If you only shoot slow fire you will just know that the 40 kicks more.
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    Ex Member Array oldrwizr's Avatar
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    Unless the recoil is injuring your wrist, hand, or fingers, it's only a question of does it affect your accuracy? I wasn't very accurate with my G23 (.40) until I learned about "accidental discharge". That's my term for slowly pulling the trigger while keeping the sights on target and then BAM! it goes off in your hand. Because it was a "surprise" the recoil has less of an effect on your shot. I improved instantly when I started trying that and just keep getting better. Mind you, this is a range, not a defensive strategy for sure but I'm a range jockey anyway so what the hey. Don't laugh (too hard) but I learned this watching Top Guns, the off-season follow-up to Top Shot. Some guy who could shoot his butt off gave that advice to Colby Donaldson and it's also in the book Michael Murphy gave away at this site (which is an excellent book on defensive carry, BTW). So it won't reduce recoil but it sure can reduce the effect of it.

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    Member Array Ljutic's Avatar
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    Sometimes data can be misleading. Other times it's right on the money. I had a similar question so I decided to run some tests and see what I could learn with high speed video. I learned quite a bit. I really feel that recoil is more about the design of the grip and it's fit in your hand than a pure physical measurement. This was an early test, but it does have the PM9 and PM40 in a side by side comparison. I learned the .40 not only has vertical lift but also much more axial spin to the left than the 9mm. Not sure what causes that, but it's worthy of deeper investigation and explains why time between shots is longer with the 40 vs the 9mm.

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    VIP Member Array Kilowatt3's Avatar
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    Quote Originally Posted by gasmitty View Post
    Numbers on paper are useful, but unfortunately are only one-dimensional when it comes to describing recoil. You're correct in that recoil will be related to recoil; if you had two identical guns with one firing the 9mm +P and the other the .40, the objectively measured recoil would be higher for the 9mm (given the rounds you selected).

    However - the recoil impulse is delivered over a period of time - see the attached graphic. The total impulse is related to the area under the curve. Thus you could have two rounds, one with a much higher force delivered over a shorter duration, the other with a lower peak force but extending over a longer time, and have the same total recoil. But the recoil of the two rounds would feel substantially different in your hand. That's why you can't simply judge recoil based on external ballistics numbers. The difference in recoil between .40 and .45 is a good example. To a lot of shooters (including me), the .40 S&W recoil seems "snappier" than that of the .45, and part of the reason is that the .40 delivers its recoil over a shorter period of time.
    Good info, but it doesn't tell the whole story. The graph shows the pressure curve, but the force is a function of the pressure and the cross-sectional area of the bullet. A .40 has about 27% larger cross-section, so even if the impulse curves were identical for a 9mm round and a .40, the .40 would have 27% greater recoil. Given that a .40 typically has slightly higher pressure, a larger cross-section and a steeper pressure curve, it's pretty easy to see why the felt recoil of a .40 is a good bit 'snappier' than a 9mm.

    Regards,
    Jim

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    Member Array hammer2213's Avatar
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    I don't mean to start any kind of problems, and I don't claim to be a genius by any means. However, I feel like this is getting a little complicated, take it back to high school science/math. Both guns are the same size/weight, Both bullets have very similar energy/velocity/etc, therefore in my opinion the .40 is gonna have a little more kick because you are forcing a heavier bullet out. Just my opinion. Sometimes we tend to complicate things.

    But I do appreciate all the data u all have posted, very good stuff!

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    Quote Originally Posted by Kilowatt3 View Post
    Good info, but it doesn't tell the whole story. The graph shows the pressure curve, but the force is a function of the pressure and the cross-sectional area of the bullet. A .40 has about 27% larger cross-section, so even if the impulse curves were identical for a 9mm round and a .40, the .40 would have 27% greater recoil. Given that a .40 typically has slightly higher pressure, a larger cross-section and a steeper pressure curve, it's pretty easy to see why the felt recoil of a .40 is a good bit 'snappier' than a 9mm.

    Regards,
    Jim
    The particular graph I chose was out of convenience, just to illustrate the impulse over time concept... it doesn't even have anything to do with a cartridge firing. I failed to completely "sanitize" it by removing the units of measure. The graph I chose could just as easily be pressure in a reciprocating water pump!
    Smitty
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