Does recoil begin before the bullet exits the muzzle?

[ATH]

One can factually demonstrate that the barrel dwell time stated earlier of 0.0007 seconds is ballpark correct. 3000fps and a 24" barrel yields 0.000667 seconds.

Remember that the inertia of the rifle must be taken into account. Since it is much heavier than the bullet, it will accelerate more slowly in proportion to the difference in mass.

Let's take a 3.5kg rifle shooting a 200gr bullet with 72gr of powder (so 17.5 grams total ejection mass) at 3000fps (914.4m/s).
- The rifle is 200X heavier than the ejection mass (3500/17.5=200).
- The bullet accelerates from 0 to 914.4m/s in 0.000667 seconds, so it's acceleration is 914.4/0.000667 = 1,370,914 m/s^2. Making an assumption that the acceleration is constant (close enough for this exercise).
- The rifle is 200X heavier, so its acceleration is 1,370,914/200 = 6854.6 m/s^2
- The distance the rifle travels is Distance = 1/2 X Acceleration X Time^2, so .5 X 6854.6 X 0.000667^2 = 0.0015 meters, or .06 inches

This 0.06 inches does not account for any friction forces from a rest; in that case movement would be even less.

I would be looking towards how each rest system is stressing the rifle differently versus the gun moving while the bullet is in the barrel as the cause of what you observe.

 

[FIGJAM]

Regarding recoil/bullet movement, the bullet cannot move without equal and opposite reaction against the bolt face/rifle receiver.....cannot violate Newton's Law of Motion....For every action there is an equal and opposite reaction.

Interesting comment on bipod loading. I've never been able to get anyone to explain bipod loading benefit.....including military trained shooters. They seem do it because they were taught to load the bipod.....without understanding why. I always questioned effect due to foreshortening the vertical height component under loading....like a clock hand moving toward one o'clock from straight up 12 o'clock. The "lost" height from foreshortening loading, has to be regained under recoil raising the bore equal to the lost height. I understand your comment to mean to account for the height change via consistency of height (recoil) at instant of bullet exit from bore. Am I understanding your point correctly?

Bipod loading is extremely over rated and unnecessary. If you have good form, you do not need to load the bipod. No idea who started that - i used to believe it until somebody educated me on it. My groups have tightened significantly since I quit doing it. And i find I can get back on target extremely faster without loading.

 

[Canhunter35]

While the brake will help with the punishment of recoil, it won't help with the effect of primary recoil effecting bullet impact. The bullet has left the barrel by the time the brake reduces secondary recoil.
Depending on the particular rifle, the muzzle can move 1/8-1/2" before the bullet exits the barrel. Last week I had an un-noticed, loose bi-pod open my typical .25MOA groups on my 6.5x284 to 2.5MOA!!! Tightened it up and it went right back to .25MOA.

I agree but a brake will help in addressing the errors in his form. At 50ft lbs of recoil how is he supposed to realize if the gun is recoiling straight and inline and settling to its original position. Not saying a brake will fix everything but it'll certainly help imo

 

[nkyshooter]

My personal experience has been that a different rest approach can move POI. Eye position on the optics MUST remain EXACTLY the same ... forestock pressures must remain the same and body to stock angles must remain the same. (plus lots of other factors, powder temperature, air temperature, altitude, etc, etc, etc)

If you plan to shoot from a bi-pod, you should zero from the same bi-pod. A rock solid bench with high quality rest and bags is best for load dev just to minimize variables for group size ... then finish the final zero from the bi-pod (or backpack or whatever you'll most likely use in the field) and in the same position you are most likely to fire from. Under a few hundred yards, this is definitely less critical ... once you pass 500 yards, this is all very important.

BTW ... barrel/ammo temps and clean vs dirty bore can also impact these things ... best approach is to experiment with your intended usage ... if hunting, zero for the first shot POI and know how it moves afterwards for a follow up (if it does). Then - practice the scenarios. NOTE: POI on an 80 degree day will be different than POI on a 25 degree day ... some powders are designed/developed to minimize it, but there is always going to be some 'creep' due to varying velocities associated with powder temps. Altitude will also have a significant effect if you are changing elevation. There are calculators that will help to get you close so you know what to expect but there is simply no substitute for practicing/experimenting with your equipment/loads in as many different scenarios as you can duplicate. THIS is the sort of 'learning/education' that is FUN though

Again - this is based on my experiences alone and since I didn't read all 3 pages of posts, no intent to contradict or repeat anything anyone else may have posted ...

 

[Rogelio]

It could be harmonics / vibration of the barrel. Sometimes a barrel length, production method, metal alloy type will have vibration mode to close to the vibration caused by a round. To test put s non-maring collar, a weight or damper, on your barrel and shoot five rounds. Place the collar at the ends of the barrel and move it forward a 1/2 inch per group and see if there is a change on your spread. If it does, it's a vibration issue. Good luck.

 

[Greyfox]

I have mostly used the same rifle for my LR hunting ovrr the last nine years, Initially, I would adjust my sighting for different positions which I had pre-determined. For example, upright to prone I would aim .5MOA lower. Over time, working on my hold for each position to achieve the same POI, muscle memory took over and I no longer had to adjust. I do about half of my shooting off a Bipod. Whether I load it or not is dependent on the type of surface I'm dealing with. My holding pressure on the rifle is different as well. I'll load lightly off a hard bench, but apply no loading in the grass. Both shots shot hit the same POI. IMO, the key is to control the rifle such that it sends the bullet the same way each time. Lots of practice! I think this is easier then having to correct sighting for each position, and, once mastered, it has proven to be transferable to my other rifles with similar ergonomics.
Just some thoughts.

 

[bigngreen]

Loading the bipod can mean two things, some use it to load the system hard forward to control recoil and hold it in a straight back movement without bipod hop. Then you have taking the slack out of the system, I just take the slack out with barely any shoulder pressure, rear bag is firmed up and I just pull back straight on the grip and watch where my reticle goes, I make adjustments till the reticle is coming back and only moving vertical and always ending on the same spot then returning to the same. When I fire only my palm may be touching the stock and my cheek is just feeling the stock, this I can repeat from most positions and count on my POI being dead on.
I wacked a bull elk in the center of the neck at 825 one year with my front rest being a sage brush, did the same on a coyote siting at 960 but I was able to work with it and get the gun tracking so when I pulled the trigger the bullet went through the cross hair same as it would if I'd been on a bipod or my backpack. Tracking is the key, if you change how the rifle tracks during recoil you'll change POI.
I didn't really see how critical till shooting bench rest, you change the sand in your bags and you see it on the target, you change anything with how that gun tracks on the rest and bag and you can measure it easily, if you take that and apply it to long range hunting you can see how critical it since we vary our positions we have to look at how that guns moving before we take a shot to really know just how small and how good we can actually shoot cold bore!!
I've only see recoil with the bullet in bore calculated with all components once, my brother who is a has a PHD in Physics and Chemistry and is a shooter calculated, the roughly, with a whole list of things that can change that 3/8 ths of an inch, you have the bullet and powder weight but the bullet has significant resistance to moving, the bullet goes forward because its weight and time over comes the bullets resistance to move. We can see it it in chronograph numbers how consistently our gun moves under recoil so if we can measure the velocity difference between a firm hold and a free recoil there is major opportunity to effect accuracy and poi!!

 

[Mt rummy]

Though its a lot, not uncommon. I have a 300 rum, with a stout liadlbehind a 210 it will shoot .3 all day in prone with a sendero style stock. Put it on a 24 inch or so bipod, sitting, it shoots about 10 inches high and six inches right at 300 yds.

Big bores need to be addressed correctly and most will find a very firm and tight hold. All preasures exerted on the axis.

The fact the writer spoke to the ft lb of energy at the butt tells me he is thinking about it. Very well may be the first issue.

 

[Danny Butler]

Anytime you change shooting positions with a heavy recoiling rifle you change poi...it's because you are holding the rifle differently and it's recoiling differently...

 

[WiscGunner]

As stated, the scientific answer is yes yes recoil stats at ignition not at exit. It sounds to me like the OP has a lot of compounding issues but suspects recoil as the main culprit.

• A good muzzle break will of course make the rifle more manageable.
• Better form to better manage recoil.
• Possible stock flexing under bipod load
• Parallax shift from change in head position /LOP when changing positions.
• Rear support not sufficient to allow straight recoil
• Stock shape not sufficient to allow straight recoil
• Recoil management in different positions even affects velocity

So, yes, the answer to the original question is very simple but it does nothing to solve the problem.

There are great resources available today via the internet from people like Phillip Velayo, Caylen Wojcik, Frank Galli, Jim See, Scott Satterlee, Jacob Bynum, Todd Hodnett etc. Phillip Velayo has some on youtube but a metric ton of knowledge bomb on his Facebook page, many specifically on recoil.







At the end of the day, it is important to take some of these tips and try them for yourself.


Perhaps the OP can share pictures of his positions behind the rifle, pictures of the stock profile, about of barrel float, etc. that way the "internet" isn't guessing blind.

 

[Mt rummy]

I concur. What has taken sometimes near a half century cannot be translated into typed words. All platforms are different as well as body types. Each unique unto each other.

There are founded foundational principals. When things aren't right, you go back to those rules and move forward. This is a rule as well. Narrow your focus, and hang in there. On a side bar, lot guys think it's cool to touch off the cannons. It is, but with out good foundation you might find yourself just boring holes in the air or worst yet, coming home with a detached retina.

 

[codyadams]

This isn't always the answer - I have seen more people flinch because of the excessive noise from a brake than recoil.

It is the answer if you want to reduce 50 ft.lbs or recoil. My 6 year old son, 12 year old niece, wife (first time shooting guns in her life was with me), and sister have never shown signs of flinching due to the brake, and none have complained of it. I have however, seen nearly every person shooting a heavy recoiling rifle (including myself) flinch at times.

It may not be THE answer in this scenario, but it would help with recoil management.

 

[ATH]

Loading the bipod can mean two things, some use it to load the system hard forward to control recoil and hold it in a straight back movement without bipod hop. Then you have taking the slack out of the system, I just take the slack out with barely any shoulder pressure, rear bag is firmed up and I just pull back straight on the grip and watch where my reticle goes, I make adjustments till the reticle is coming back and only moving vertical and always ending on the same spot then returning to the same. When I fire only my palm may be touching the stock and my cheek is just feeling the stock, this I can repeat from most positions and count on my POI being dead on.
I wacked a bull elk in the center of the neck at 825 one year with my front rest being a sage brush, did the same on a coyote siting at 960 but I was able to work with it and get the gun tracking so when I pulled the trigger the bullet went through the cross hair same as it would if I'd been on a bipod or my backpack. Tracking is the key, if you change how the rifle tracks during recoil you'll change POI.
I didn't really see how critical till shooting bench rest, you change the sand in your bags and you see it on the target, you change anything with how that gun tracks on the rest and bag and you can measure it easily, if you take that and apply it to long range hunting you can see how critical it since we vary our positions we have to look at how that guns moving before we take a shot to really know just how small and how good we can actually shoot cold bore!!
I've only see recoil with the bullet in bore calculated with all components once, my brother who is a has a PHD in Physics and Chemistry and is a shooter calculated, the roughly, with a whole list of things that can change that 3/8 ths of an inch, you have the bullet and powder weight but the bullet has significant resistance to moving, the bullet goes forward because its weight and time over comes the bullets resistance to move. We can see it it in chronograph numbers how consistently our gun moves under recoil so if we can measure the velocity difference between a firm hold and a free recoil there is major opportunity to effect accuracy and poi!!

I've got my graduate degrees too, I've taken graduate level mathematics in three disciplines, and I listed my math explicitly, if there is a specific flaw in my logic I'm happy to have it pointed out. More qualitatively there are plenty of quality slo mo videos of rifles firing on YouTube and the barrels do not move meaningfully before the bullet exits, certainly not anything approaching half an inch. Yes the bullet has resistance to moving but the rifle's resistance is 200-fold that number, hence drastically reduced acceleration rearward and therefore movement.

 

[villagelightsmith]

Here is a couple video's