Question about the physics of recoil: CZ 75B vs 9mm 1911

[TMann]

I have a question about felt recoil: Why would two pistols that weight the same and fit essentially the same in my hand feel significantly different when shooting the same ammo?

Last night at the range, I was shooting a CZ 75B and an RIA 9mm 1911. I was shooting the same ammo in each (115 g, FMJ target ammo.) Both guns weigh about the same when fully loaded; the lighter weight of the CZ is offset by its higher ammo capacity (16 rds vs. 9 rds.)

While both guns were very easy to shoot, the 1911 felt a lot "softer" compared to the CZ; the recoil from the CZ had a sharper "snap" to it. Is this related to the weight of the slide? Is it a spring weight issue?

Just curious if any of you pistol gurus had a good explanation for my experience.

TMann

 

[BCRider]

This should make for an interesting thread. It's a very good question and relates to how some guns compare when shooting the same ammo. It's going to be doubly interesting to follow along as I've got a Norinco 1911 chambered in 9mm on reserve for when the shipment arrives. I've shot some STI Trojan 9mm guns and found that they are nice to shoot but I've never tried them back to back like you did.

I think you're right about the slide and barrel combo on one being heavier than on the other. The recoil spring will play a part as well but only a minor one if the spring rate is within the properly narrow range of being correct.

Keep in mind that first and foremost the recoil spring has to be chosen to match the ammo and slide/barrel mass to function properly. It has to be soft enough to let the slide cycle fully to properly eject the casings and to travel far enough back to hook the slide lock on the last shot. Yet it has to be stiff enough to avoid the slide hammering the frame at the end of the travel. If it hammers the frame even a little it'll be felt through the grips. Ideally it should be just the right preload and rate to cycle to within a millimeter or two of impacting the frame but not actually hit. But that's a tough one to achieve. But it's pretty cut and dry overall. Not much room for "customizing" on this front other than setting it up so it's doing the right job. The big point here being that before we can compare apples to apples both guns would need to be checked for frame slamming and sprung to minimize or avoid this issue. Only then will the recoil itself be consistently felt and able to be compared.

I don't feel that my own CZ's have a snappy recoil to a big degree. But I've tuned them to ensure that the recoil spring is as tight as I can make it and still achieve a good ejection power just to ensure that the slide doesn't slam the frame. I also prefer to shoot 124's because being a touch slower muzzle velocity it reduces the snap in the recoil.

When I begin to think about the slide and barrel to frame weight ratios my head starts to hurt. To cycle the slide some amount of energy is "stolen" from the chamber and barrel pressure to get the slide to cycle. And supposedly a lighter slide and barrel will move faster to have the energy required to eject, strip and chamber the empty casing and next round. Because a lighter barrel and slide may be moving faster does that make the perceived recoil feel sharper? Or should the lighter slide make it feel softer? I can see it going both ways in my brain. But I think we need measurements of light vs heavy slides to show some real world figures and then relate those to the felt recoil.

Some of it may be the nature of the grip shape and where it puts the pressure into your hand. The 1911 is well known for fitting a lot of hands with nice even contact pressure through the whole contact area in the hands. This may well affect how we perceive the recoil to some extent as well. I know that my own CZ's fit my hands well. But there's just something a little bit "righter" when I hold my single stack 1911. So this may be another factor that comes into play.

 

[Skylerbone]

Why does a 10 lbs. weight feel heavier when you extend your arm with it? It still weighs the same amount but you've lost your advantage over it.

Some pistols by design reduce recoil and some are designed to reduce perceived recoil. A low bore axis will assist with felt recoil which is what the 1911 has.

For a different perspective consider, but don't mimic, the gangster style over-the-head, high as you can with your wrist bent hold and imagine how the recoil would feel.

 

[Walt Sherrill]

Recoil springs may be different, and that can make a big difference in felt recoil.

CZs are typically sprung lightly (supposedly 14 lb., but sometimes lighter); a 16lb. spring will feel different and works fine with 9mms. I've used as high as 18lb in a CZ without problem with standard loads, when trying to explore what worked best with my guns.

 

[Mr.Blue]

Was the 75B modified in any way? CZ 75s are known as being one of the lightest recoiling 9mm out there. Even in .40 cal the platform is known for mild recoil. None of my CZs have a snap to them. That said, I'm sure a 1911 in 9mm must be very soft recoiling as well. I've only shot .45s in 1911s.

 

[CZguy]

This is an interesting thread. I've never shot a 1911 in 9mm, so I can't compair the recoil to my CZ 75B, but I've always thought that CZ's recoil was very mild.

 

[TMann]

Good evening, everyone. Thanks for all of the responses.

In regards to the setup for my CZ, it is a stainless 75B with a lightened hammer spring (mainspring.) I believe that it is a 15 lb. spring, while the stock spring is around 21 lb. (?) I didn't change out the recoil spring.

As I mentioned earlier, my 9mm collection includes a Glock 19, the 75B, an FN Hipower and the RIA 1911. The 1911 was my most recent acquisition, and I shot it exclusively for about a month (several trips to the range.) After the newness of my new toy wore off, I again took my CZ and my Hipower to the range and it was then that I noticed that they both had a bit more "snap" than the 1911. To be sure, all three of them are very smooth, soft shooters. But the 1911 was definitely the softest of the three.

TMann

 

[1SOW]

If your CZ is a da/sa, the reach to the trigger is way longer than the 1911-type trigger. This can affect your grip and percieved recoil/flip.
Weight distribution would be another issure. The 75B has the short slide, short plastic guiderod and lighter barrel unlike the SPO1 or Shadow.

The stock recoil spring in your factory B is designed to handle a wide range of loads and does. A heavier spring does lighten percieved recoil as Walt said above. If you point shoot multiple rounds very fast at a close target, your hits will travel/string up or down. Changing the recoil spring weight can shorten the string length or even reverse it-----just saying. The recoil spring can make a noticeable difference.

 

[woad_yurt]

WHile weight is important, one must figure in weight dispersal, angle of grip, etc.

I have a K98k and a friend has a Garand. Both shoot rounds that are relatively comparable in power (8MM vs 30.06) The Garand is 2-3 pounds heavier and is also semi-auto as opposed to the Mauser's bolt action. One would figure that the Garand would kick less as it's heavier and because the semi-auto action would absorb some of the jolt, but it thumps the shoulder quite a bit more harshly than the Mauser.

It seems that the Mauser's overall geometry is a bit better for handling recoil. I assume that one of the pistols you mentioned recoils less because of the same reason.