Bullet Exits Barrel Before Felt Recoil

[joejoe05]

I was looking through some footage from my range session today and thought the timing of this shot did a good job of showing a bullet exiting the barrel before any felt recoil.

This is probably obvious to most folks here, but it's something I remember thinking about a lot when I started shooting.

https://youtu.be/pmsXZWqRDvA

[Rock-it3]

It's interesting to think about the physics of it, yes. If a bullet leaves the barrel at about 1000 feet per second (12,000 inches per second), and the barrel is 4" long, then (discounting acceleration from 0 to 12,000 inches per second), then the bullet is only in the barrel for .00033 seconds. That is 1/3rd of a millisecond. That's why the bullet hits where it was aimed when the trigger was pulled, not 10" high.

Great video BTW. It all happens so fast, even in the super slow motion it almost appears the slide is moving backwards before the hammer is fully down.

[M1A4ME]

Discussion on another forum without the video I just finished reading.

Over there (Brian Enos's forum, or what ever it's called, but it's a competition oriented forum) and there's lots of responses.

Some shooter's say different brands shoot to different POA/POI than others.

Some shooter's say there's not difference.

Some shooter's say one of their pistols gets different POI with 115's vs. 124's and their CZ75 does not.

Difference it the way the pistol locks up/unlocks on firing?

I can say that many years ago, when we got all new S&W 686 4" revolvers in the department I was in at that time we saw a vertical difference between 125 grain hollow points and 158 grain hollow points (.357 magnum) with the heavier bullets hitting higher on the paper by about 3 or 4" at 25 yds.  Everyone who tried the heavy bullets got similar results (3 or 4 out of .

I've shot so few 124's from my 9MM pistols I couldn't say one way or the other.  All I do know is that different brands shoot the same ammo differently (larger/smaller groups and/or not to the same POI even when the sights are lined up the same way.

[Joe L]

I have observed the POI shifts with changes in load or changes in bullet weight.  For bullseye pistols I can detect changes in POI between single hand and double hand grips and between tight grip and light grip, even on my .22 Kadet pistol.  A heavier bullet will generally leave at lower velocity than a light one, so the recoil motion is a little larger before exit, so they will hit higher than a light bullet.  A hot load at higher velocity at muzzle exit will hit lower than a light load due to the difference in barrel rise in recoil due to the velocities. 

These differences show up clearly at 50 yards and greater shooting distances.  I no longer experiment much with different box ammo, so I hope I am reporting these years old results correctly. 

I remember one experiment I did with the 97B at 200 yards where the 185 gr hot load and the 185 gr light load ammo seemed to have about the same POI, and that was a surprise to me.  Apparently, the higher velocity of the hot load (less drop at 200 yards) cancelled out some of the recoil exit difference so that the POI wasn't much different.  But that was at 200 yards.  At 50 yards, the hotter load would hit lower than the light load. 

Joe