Does recoil begin before the bullet exits the muzzle?

[Golovkin]

I'm experiencing POI shifts with a 338 RUM going from bench rest, to bi-pod, to shooting off my pack. I believe the main cause is recoil effecting POI before the bullet exits. My theory is that shooting off my pack allows the rifle to kick straight back, but on a bi-pod it "rocks" back allowing the butt to move down and the barrel to point up, and off the bench rest its causing muzzle rise as the gun has no where else to really go. All 3 positions are printing sub MOA groups, but each position is shifting the "zero'.

Bench POI is highest, followed by bi-pod, and shooting off my pack is the lowest POI. (All shots taken with front hand holding the forearm. POI change is about 6 MOA from Pack to bench.

Some people on here claim to have experienced similar issues, while others say that its impossible for recoil to occur before the bullet exits, so it must be parallax, flinch, body positioning or something else. The rifle did this with the factory synthetic stock and also with a wood stock that is piller bedded, glassed and floated.

I don't experience this with lesser recoiling rifles. I'm not an elite marksman and this rifle is a challenge to shoot (with over 50lb's of recoil). I did qualify expert marksman in basic training on my first attempt, my Grandfather was on the army shooting team and taught me well, but that was long ago and I'm just getting back into shooting a lot, so I won't rule out shooter error, but I think I've got the fundamentals down since this isn't happening with my little guns.


Anyone have any insight as to whether or not recoil occurs before the bullet exits?

 

[cohunt]

it takes about .0007 seconds for a bullet to exit the barrel, can you move that fast? does the rifle recoil and move you in that short amount of time? shift in poi often has to do with "outside forces" on the rifle, such as forearm pressure, sling pressure, bipod pressure (preloading etc)-- other thing is if anything is changed on the rife (such as muzzle brake) it can change the harmonics or muzzle exit gasses on the bullet which can sometimes change the poi
flinch or trigger jerking can affect the poi considerably also, might have some one watch you in different shooting positions to watch for flinch or trigger jerking, or video and play back in slow mo if possible

 

[Hand Skills]

@Golovkin - I believe it does. Maybe you can answer your own question though. Try putting your left hand on top of the scope when you shoot from these positions next time, and tell us if anything changes

 

[sea2summit]

Mathematically yes recoil starts as soon as the bullet starts to move.

I would say there are many many many culprits more likely affecting point of impact from changing positions which are far more likely than recoil.

 

[Orange Dust]

Cheek Weld? Do you get the same POI with the bipod on the bench as you do prone?

 

[Chuckrub]

Here is a couple video's

 

[bigngreen]

Your rifle recoils roughly 3/8th of an inch before exit. Getting poi the same from multiple positions at long range takes a lot of rounds down range paying attention to how the rifle tracks as it comes back and rides your rear bag and front rest.
With a bipod you want to load it so the recoil is stays at the top of the movement and does not come from the top and roll back and down a little. If you can get it tracking the same you'll maintain poi!!
This is why so many experienced long range shooter basically free recoil.

 

[carl1775]

Yes, recoil starts as soon as the powder ignites and the projectile starts its motion.

 

[Canhunter35]

Bigngreen explained it well.
Imo the proof is where the rubber meets the road, lighter recoiling rifles don't cause the same problem.
Don't punish urself with that hand cannon, get a brake on it and make it manageable to shoot.

 

[cervus]

@Golovkin - I believe it does. Maybe you can answer your own question though. Try putting your left hand on top of the scope when you shoot from these positions next time, and tell us if anything changes

Okay so what the likely outcome/outcomes with hand on top of the scope??

 

[Mt rummy]

For every action there is a reaction. First movement is forward. Firing pin and spring. Then rearward. You have ignition/departure from case, hitting the lead of chamber, and the add a rotational twist of the barrel.

Draw a dotted line from axis of bore. You want that axis to move in a straight reward movement. Simple?
Drop at heel in stock will or can have verticle POI influence. ( Why bench rifles are cut straight)

Dry fire on all positions and pay close attention to cross hair movement.

Here's a good rule, go back to the dotted line. Your body needs to address the bore at a 90 degree position. Example;

Place rifle prone on bipod aimed at Target. A right hander places his right foot on the " axis dotted line" behind the rifle. In a push-up position fall forward to the butt of the rifle. Stretch your right arm out to the side at 90 degrees to your body, then do a final alignment to the bores axis.

Elevation of the bores axis follows through your body. You are now " square". Again dry fire and watch those cross hairs. Burn that movement in your brain!!

Pay also close attention that bipod feet are not on hard rock or cement. You will get uncontrolled bounce. Same applies to trigger hand grip. Don't use down ward pressure. Old chunck gun shooters called this "bending the barrel". It was done to purposely affect POI.

When you learn a good address, then do some reverse engineering. Purposely, go off 90. See where your impact is. You will soon learn how to troubleshoot yourself. The axis rule applies to all positions.

The slower the pill, the more time to screw up. The bigger the pill, the more forces you have to fight. So go buy a 8 pounder and "work it out".

And last, always leave on a good shot or group and burn the feel of the platform in motion. Have fun and hope this may help.

 

[FIGJAM]

Your rifle recoils roughly 3/8th of an inch before exit. Getting poi the same from multiple positions at long range takes a lot of rounds down range paying attention to how the rifle tracks as it comes back and rides your rear bag and front rest.
With a bipod you want to load it so the recoil is stays at the top of the movement and does not come from the top and roll back and down a little. If you can get it tracking the same you'll maintain poi!!
This is why so many experienced long range shooter basically free recoil.

But the OP is talking about a 12" difference in POI at 200 yards (saw it in another thread).

 

[Hand Skills]

Let's assume a 24" barrel;

To see a 6moa change at the target, we are talking about a .042" difference at the muzzle (assuming a 24" bbl)

Do you doubt the barrel could move that much before the bullet exits @FIGJAM ?

 

[FIGJAM]

Let's assume a 24" barrel;

To see a 6moa change at the target, we are talking about a .042" difference at the muzzle (assuming a 24" bbl)

Do you doubt the barrel could move that much before the bullet exits @FIGJAM ?

I don't know if I doubt it or not, I have never experienced or seen what the OP is talking about other than when somebody has a bad flinch.