Sight picture change during bullet time in barrel?

[leam]

I'm shooting an M28 with a 6" barrel. Assuming I don't have an iron grip, which I don't, won't the sight picture change before the bullet exits the barrel? Given the mass of the bullet being pushed forward while the rest of the gun is being pushed backwards against the web of my hand, doesn't the gun start to flip up a little while the bullet is still moving through the tube? So you'd not want the sights to be perfectly aligned with the bore, but you would want a good, consistant, grip and the sights aligned for your grip.

Or am I again totally off and need more coffee?

Leam

[Joe4d]

well yes you are right in your observation but you are wrong on your conclusion, Your gun is zeroed to it's position when the bullet leaves the barrel, Thats why a bullet traveling at 800 fps will hit in a slightly different point than a bullet traveling 900 fps, SO you aim at the target, pull trigger the gun starts to flip up before it leaves the barrel so the bullet hits a little high, but basically the exact little high every time, so you crank down on the rear sight to zero, which compensates for the little bit of muzzel rise. You also will compensate for the arc of travel of the bullets since we arnt shooting lasers yet.

[GrumpyOne]

As far as the recoil messing with your sight picture, I don't think it's an issue, EVER. At 800 FPS, that bullet has left the barrel in less than 1/1000th of a second, and in fact travels 9.375" in the first 1/1024th of a second. Your eyes cannot register anything even remotely near that fast, and the recoil of the gun does not even begin to affect the actual point of the gun until after the bullet has left the barrel (or it seems, we're talking thousandths of a second here).

[leam]

I'm not sure that I get it. The bullet must move forward with something similar to the force of the gun moving backwards. If the inertia of the gun can't be overcome, that makes sense, but I'm not sure that's the full case given the fleshy parts supporting it. Of course, there are lots of things I don't understand at all...

[JFlowers]

Leam,

What they are saying is that the very act of sighting in your gun, accommodates that shift. You line up the sights, fire, adjust. Any recoil-based deflection is accounted for, naturally, in the process. Grumpy's point is that the amount of time the bullet is in the barrel is so small that the recoil-based deflection is also very small.

Now, Quit worrying about the small stuff and SHOOT!

[Gatekeeper]

Leam,

What they are saying is that the very act of sighting in your gun, accommodates that shift. You line up the sights, fire, adjust. Any recoil-based deflection is accounted for, naturally, in the process. Grumpy's point is that the amount of time the bullet is in the barrel is so small that the recoil-based deflection is also very small.

Now, Quit worrying about the small stuff and SHOOT!

I'd agree, too little movement to be concerned with there would actually probably be more movement caused by your trigger finger between the time it trips the sear the hammer falls and the bullet leaves the muzzle. Don't sweat the little stuff, consistent form would be more important to worry about, then you sight in for point of impact.

Here is a pretty cool video I found on youtube, shows muzzle just barely starting to move as bullet exits barrel

Real good view about 38 seconds in

Edited January 31, 2011 by Gatekeeper

[50GI-Jess]

Well, not so fast !

Yes I enjoy shooting more than thinking about the mechanics behind it. But in some ways, knowing the mechanics behind it, will also make you a better shooter...right !

Put it this way...if the bullet and gun had the same weight, they would move away from one another with the same speed. Since the gun weights more than the bullet, the gun recoils with a force that is calculated different than the FPS for the bullet.

Even though the bullet spends very little time in the barrel, the amount of gripping strenght/technique still plays a major role on where the bullet will hit the target. Theori is nice, but i stick to the facts.

[Gregg K]

I used to shoot IHMSA years back and found that the amount of grip pressure made a huge difference on POI when shooting handguns at 200 meters. We also used longer barrels so the bullet spent a little more time in the barrel. That is an extreme example as the amount of difference for our games in USPSA would be small due to the closer target distance.

[leam]

Real good view about 38 seconds in

Even better view at .27 to .29. It shows the revolver moving significantly before the bullet leaves the very short barrel and even more so right after it leaves. Given the length difference of that barrel and a 6 incher, I'm still wondering about the movement. I understand USPSA is not very problematic for extremely small moves, but to get the old girl to hit where I point I have to crank up the rear sight. Even for slow controlled fire, and that's what confuses me.

In things like this I enjoy combining theory and practice. Yesterday's practice was the first I've gotten in a long time, for various reasons. Mostly stopped 'cause I was past my hand endurance and my back was killing me. The 21 day's practice will be on dry-loads as I'm hoping to smooth out where I'm at currently, and getting back to working out at the Y.

Leam

Edited January 31, 2011 by leam

[50GI-Jess]

Hi Leam,

How are you. Look, first you need to keep it simple, and break down whatever problem you have. First off, never mix how mechanics work with the ability to shoot well. Test your gun by the book first. If you're a bad shot, let someone else test it for you. Let's say your gun will make 2" groups at 25 yfs. with quality ammo. Then thats the end of that problem. Then sight it in. Your front sight may be too high, or the rear not the original etc.

Scattered grouping on a target is most likely one of the following reasons. Holding the gun using wrong technique, working the trigger wrong or too fast.

Remember the front sight is also your accelerator. You simply can't hit well if you can't see exactly what and where you're shooting at.

In 9 out of 10 times when folks have poor performance, it's related wrong grip/trigger technique, and visiual impatience.

The main difference between action vs. precision (IPSC/Bianchi) shooting using wrong grip technique, is that your shot cadence in action will be slower and inconsistent, but in Bianchi your grouping will open up and look like a shot gun pattern.

Save youself time, and talk to some known hot shot shooter friends at the range, they can show and tell you why in 5 min.

Jess

[Matt Griffin]

Leam's right, and everybody else is right, too. Nothing to worry about, but yes the gun rises while the bullet is in the barrel. It's nothing to concern yourself about in USPSA since any difference you could make in POI is too small to matter at our ranges. But I get about 4" lower POI when I switch to ICORE ammo in my .45, and you can see a massive difference if you shoot some plastic primer-only rounds for fun.

Matt

[Bubber]

The only thing I could add to the discussion is that consistency is the key. If you hold the gun the same way each time it is fired the barrel will be at the same angle each time the bullet leaves it. Thus you will zero on that. And if the sight pictue is at the same point when the trigger breaks the rounds should impact at much the same point. It is a good discussion though. Different disciplines have different measurements of accuracy and different outcomes of small changes. Latter rdd

[G-ManBart]

Real good view about 38 seconds in

Even better view at .27 to .29. It shows the revolver moving significantly before the bullet leaves the very short barrel and even more so right after it leaves. Given the length difference of that barrel and a 6 incher, I'm still wondering about the movement. I understand USPSA is not very problematic for extremely small moves, but to get the old girl to hit where I point I have to crank up the rear sight. Even for slow controlled fire, and that's what confuses me.

In things like this I enjoy combining theory and practice. Yesterday's practice was the first I've gotten in a long time, for various reasons. Mostly stopped 'cause I was past my hand endurance and my back was killing me. The 21 day's practice will be on dry-loads as I'm hoping to smooth out where I'm at currently, and getting back to working out at the Y.

Leam

I wouldn't call the amount of movement shown at .27 to be significant. I held a pencil at the top of the front sight on the screen then quickly left clicked on and off on the play button until I got the bullet just leaving the muzzle, and it hadn't risen very much at all.

Still, are you shooting .38spl ammo in your Model 28? The sights were really set up for .357Mag, so they're going to use up a lot of their range to compensate if you're shooting mild .38Spl...or at least that happens frequently.

The amount of sight picture change while the bullet is in the tube really is insignificant. You want to watch the front sight rise off the target, and you'll know where it was in the last instant before it moved...that's all that really matters.

I'm not sure, but you seemed to say that you had to crank the rear sight up high "even slow fire"....slow, fast, doesn't make a difference. It's purely a matter of the bullet weight/shape (BC), velocity, and to a very minor degree, your grip. R,

[John Z Sr]

Way too much to think about, I have enough trouble thinking about what part of my glasses to look through to see the sight or the target !!!!

[Mover480]

No, Leam is absolutely right.

The barrel is coming up as the bullet is traveling down it. That is why consistency of grip is so important. Just ask any bullseye shooter! And, I remember shooting standards at Area 4 at 50 yards. We do it in ICORE too. Try NRA Action Pistol and you'll know that accuracy is very important.

Try zeroing your sights at 25 yards by locking it down in a V rest. Then shoot it off hand at the same distance without changing the sights. It will probably shoot 6 inches high, maybe more depending on your grip. Revolvers are worse at this than autos because of the increased distance between the bore and the center of the hand. You can compensate somewhat by gripping the revo as high as possible (like JM).

Either way, maintain a consistent grip and zero the sights for the distance you shoot most often for accuracy.

[professor]

No, Leam is absolutely right.

The barrel is coming up as the bullet is traveling down it. That is why consistency of grip is so important. Just ask any bullseye shooter! And, I remember shooting standards at Area 4 at 50 yards. We do it in ICORE too. Try NRA Action Pistol and you'll know that accuracy is very important.

Try zeroing your sights at 25 yards by locking it down in a V rest. Then shoot it off hand at the same distance without changing the sights. It will probably shoot 6 inches high, maybe more depending on your grip. Revolvers are worse at this than autos because of the increased distance between the bore and the center of the hand. You can compensate somewhat by gripping the revo as high as possible (like JM).

Either way, maintain a consistent grip and zero the sights for the distance you shoot most often for accuracy.

To add my .02... or maybe more.

First, use a solid bench rest to check that your gun + ammo is consistent and grouping decently. 25 yds is a decent distance to check this. It's probably the distance best suited to zeroing in for IPSC shooting, because more than 90% of your targets will be inside this distance. For this testing, POI is not important, but grouping is, because you'll never get better grouping shooting off hand than shooting from a rest.

Second, shoot off hand [two-handed grip on the gun with a comfortable, stable standing position] at a classic target at that 25 yd distance. If you're new to shooting, this will produce an interesting comparison between your groups and the bench rest groups. All of the increased variability is due to your handling of the gun. Some tiny part of that is going to be attributable to the muzzle flip you're worried about. But it doesn't matter. Your goal is to get back on target, ultimately with a pattern no bigger than the lower A zone. Once you've got a decent grouping, you can adjust your sights to account for POI being slightly higher than in the bench rest case.

Third, you will be shooting much more deliberately [sLOWLY] at this distance, in order to get a decent grouping. That generally means that you've got a steadier, more solid grip on the gun, and that reduces muzzle flip. So now, you need to practice 2 shot sequences. This starts with a good point of aim for the first shot, and a controlled return to a good point of aim for the second shot. Forget the idea of 'double-tapping' a target. You need to engage targets with two aimed shots.

Fourth, if you can get decent groupings at 25 yds, you can do it at any closer distance. Then it amounts to determining for yourself how much time you need to take to get 2 aimed shots on target at those intermediate distances. Typically, these times will range from the 25 yd time interval down to as-fast-as-you-can-pull-the-trigger at distances as close as 2 yds.

Fifth, check what additional bullet drop your gun and ammo produces for 50 yds. My 45 Mod 625 has a drop of about 5" at 50 yds compared to POI at 25 yds. Knowing that drop, you can adjust point of aim accordingly. Intermediate distances will be between 0" and 5". The drop increases faster for more distant targets, because bullet drop is accelerating the farther out the bullet travels.

Sixth, Go back to the 25 yd target and see what you can do shooting at the upper A-B zone. It's about 6 inches square, and the previous practice ought to help keep on target, so long as you take your time to get aimed shots. Difference is that aiming at the head of the target means that you've got Mikes instead of Charlies for shots outside of the 6" grouping in 3 directions.

Seventh, go back and repeat the Second through Fifth steps shooting strong hand only and weak hand only. In these tests, you will NOT be adjusting your sights, but you will note how SHO and WHO affect your POI at different distances, and the time to get 2 aimed shots on target. [i left out the Sixth step because I don't know any course designers diabolical enough to require head shots SHO or WHO at 25 yds. ]

Have fun.

[leam]

I'm shooting Minor loads with 158 and 180 grain bullets. No speed records and there's probably some more drop than the previous owner's Major loads. To get on POI I have to lift the rear sight up fairly high. The comment on "slow fire" was to point out that the deviation is not high speed; I'm watching the front sight as she goes bang. Still don't see it rise, but working on that.

Grip consistancy is a big issue! Sunday's practice was nice, the bit of rapid fire I did saw her dropping right back into alignment with the target. Now if I can get enough trigger discipline to not knock her around so much, it'll be much better...

Leam