recoil v accuracy

[ken snyder]

Small caliber rifles have such as 30 cal. have minimal twisting ability. Multiple layers of clothing that are slick such as a wool shirt under a nylon windbreaker can allow the rifle butt to twist and slide wherever it wants to. The second is grip and pocket. Grip is self explanitory. Pocket: If your elbow is too far back then your arm will not create a pocket to capture the Butt and this will promote twisting. I would work on the corkscrew first and then see how much of the problem goes away.

 

[rscott5028]

There's lots of info throughout this thread. However, the thing that seems to be missing is perspective. Without perspective, facts can be misleading.

The rifle moves before the bullet leaves the barrel. Is it the same amount of movement and same influence for a 22LR with a 20" barrel @ 50 feet vs 50 BMG with a 32" barrel @ 2000yds? Not likely.

Nonetheless, a properly setup shooting system tracks straight to the rear to help stay on target. A 1/2" rearward motion is less detrimental than a 1/16" muzzle rise. Hence, the effectiveness of rail guns.

For this reason, small people shoot just as well as big people. So, shooter mass is largely irrelevant unless you're not only large, but dense. Pulling the rifle into your shoulder with a death grip will not help stay on target.

Barrel vibrations are an important factor. While this is not the same as recoil, it can't be ignored.

Palma shooters turn in some amazing scores and it's not because they prevent the rifle from recoiling or vibrating.

Sorry I can't contribute any formulas or big words. But at some point, the theory needs to translate to technique.

JMO
-- richard

 

[bigngreen]

I believe this statement to be true.

I was in a long range match a couple of years ago shooting my 7mm-08, with a bipod. At my home range before the match it wa dead on shooting .5moa or less. When I went to the sighter board at the match, I couldn't keep my groups under 1 MOA. I couldn't figure out what was going on...thought maybe the scope went bad, fouling ,me,etc. A guy came over and handed me a sheet of plexiglas to put under my bipod legs and I instantly Restored my original accuracy. My practice range bench had a smooth wood surface so during primary recoil the rifle came straight back not effecting my accuracy. The bench top at the match had a carpet on it that had a course weave base. This caused the bipod legs to not come back smoothly effecting the accuracy on primary recoil. The guys at the club said they have seen this happen on numerous occasions. The difference wasn't that big, but I would have had no chance of winning this match with a 1moa rifle. It was a 200 yard egg shoot. A week later I confirmed this effect at my home range with a price of carpet.

Actual results trumps theory every time!

I have a very similar story, I was shooting of the bipod at a 550yrd target with known good loads and just shooting to stay tuned up. There were a few shots that I noticed the rifle touch the back of my bag hand with the grip during recoil, not hard and all I had to do to not get hit was to move the rifle just a touch forward. At the target I had two nice groups 18in apart. So I shot a few more and found that just that little contact during recoil was the cause.

I've also seen the interaction of the bipod with the terrain change POI and accuracy, it seems abundantly clear that during recoil there is the ability to influence accuracy and POI.

 

[lightwind]

Greyfox: That is a great example of the application of the physics we have been discussing. Examples like that are what I signed up for this list for. Application tricks like this are things that require years of experience. It is learning from experienced shooters that make getting involved in the discussions worth while.

 

[nwolf]

WOW! I would have never asked the question if I knew it would go like this. I'll try some of the helpfull tips I got on here (what few there were). But for those of you who beleive that physics do not apply in a closed system. Try this, Hook up a sealed electric motor laid loose on the ground and turn it on. The motor housing will rotate the opposite direction of the stator. Why? Becouse it reacts to the forces against it.

Better still, for the slower among you. Press your finger against a wall and see if you feel anything. You do? Guess what, that is the wall pushing back, or resisting with the equall and opposite force that you are aplying to it.

There are no exceptions to laws of physics.

Or this. Why does the bullet leave the brass? Its the same reason that the rocket efect happens. Expanding gass pushing against something. In the case of the rocket, its pushing against air, and pushes against the rifle with equal force. For the bullet, it is gass pressing against it and the brass with equal force.

 

[nwolf]

Wait. I thought of a simpler one for those who may actually take the time to educate themselves rather than rely on the word of someone who was also wrong.

1)Take a section of pvc pipe and cap one end.
2)Drop in a rubber ball smaller than the pipe.
3)Cap the other end.
4)Turn the pipe letting the ball roll from one end to the other.

You should not be able to feel the ball hit the ends of the pipe. What? You did. How can that be? There is no exposure to "the outside world" therefore, physics does not exist.

 

[westcliffe01]

NWolf, I am in a similar situation as you. I recently purchased an 8mm Mauser (Remington 700 Classic Long Action). So far I have been shooting big bullets (196, 198, 220gr) and the gun recoils like a beast. It has a muzzle break on it, that the original owner had installed before he had a health crisis and then never shot the gun (heart condition). The brake is from Magnaport, it is called the "Mag-na-brake" Rather corny name...

This is the heaviest recoiling rifle I have yet shot, particularly with these loads. I don't think too much of the Magnabrake, frankly. The ports are all around the circumference, thus in a prone position it kicks up a lot of dust. Without the brake, I get quite a bit of muzzle rise, so no way one is going to be spotting your own shots. Thats bad, since I don't have hunting buddies, I will be on my own.

There are several other factors in my case: The rifle has a butt pad, but it is not a decelerator type pad. It is also very light with the wooden stock. Also, the range I typically shoot at is really only set up for bench shooting so one can't get your weight behind the rifle effectively.

I just started reloading and shot some 150gr loads for the first time today (whitetail ammo) and as expected the recoil was quite a bit less and flatter shooting. The 1:10 twist must be sufficient for 150gr, since these were some of the smallest groups I have shot with this rifle.

So I have a long way to go to make something of this rifle. 8mm bullets seem to be pretty problematic to obtain and limited in whats available. I may go with a Shilen match barrel chambered in 7x57 instead and rework my brass to the 7mm neck size. That caliber seems to have a lot more going for it today and it looks like it will take everything that can be done with the 8x57. The stock needs to be bedded and the recoil pad changed to a Pachmeyer. The action probably needs to be blueprinted, the witness mark is much more prominent on 1 bolt lug than the other. The cheap brass millsurp ammo that is out there shoots 4-6MOA at best, which may be OK within 100 yards, but is not going to make me excited....

I have already replaced the crap Remington "9lb" lawyer trigger with a Shilen unit and have left is as shipped so far. I will probably dial it down a little after some experience.

 

[WildRose]

Wait. I thought of a simpler one for those who may actually take the time to educate themselves rather than rely on the word of someone who was also wrong.

1)Take a section of pvc pipe and cap one end.
2)Drop in a rubber ball smaller than the pipe.
3)Cap the other end.
4)Turn the pipe letting the ball roll from one end to the other.

You should not be able to feel the ball hit the ends of the pipe. What? You did. How can that be? There is no exposure to "the outside world" therefore, physics does not exist.

You feel the ball hit at the end because it came to a stop. When it did it's momentum drove the piple a little furter in the same direction. The energy of that ball has to go somewhere.

A rifle with a plugged barrel acts in similar fasion with a much more dramatic effect because the pressure cannot be released otherwise.

Conversely if that pipe wasn't capped and the ball continued to exit, no such effect would be possible. The energy of the ball goes with it.

If you want to study inertia get on an old pinball machine. Launch a ball and see how far it goes vs how far the launch pin bounces back after impact.

For something similar to how things react inside your barral buy a large 50 cc syringe. Draw 50cc's of air, then plug the end with caulk and let it set overnight.

Now place the thumb end of the plunger on the table and depress the syringe downward. WHen you reach the point you can no longer compress the air release it. Of course there is no combustion going on with in the pressure vessel but it will expand quite rapidly until the trapped gasses cease expanding.

This will also give you a good idea as to why we use powders that continue burning and generating pressure to at least the end of the barrel.

 

[rscott5028]

NWolf, I am in a similar situation as you. I recently purchased an 8mm Mauser (Remington 700 Classic Long Action). So far I have been shooting big bullets (196, 198, 220gr) and the gun recoils like a beast. It has a muzzle break on it, that the original owner had installed before he had a health crisis and then never shot the gun (heart condition). The brake is from Magnaport, it is called the "Mag-na-brake" Rather corny name...

This is the heaviest recoiling rifle I have yet shot, particularly with these loads. I don't think too much of the Magnabrake, frankly. The ports are all around the circumference, thus in a prone position it kicks up a lot of dust. Without the brake, I get quite a bit of muzzle rise, so no way one is going to be spotting your own shots. Thats bad, since I don't have hunting buddies, I will be on my own.

There are several other factors in my case: The rifle has a butt pad, but it is not a decelerator type pad. It is also very light with the wooden stock. Also, the range I typically shoot at is really only set up for bench shooting so one can't get your weight behind the rifle effectively.

I just started reloading and shot some 150gr loads for the first time today (whitetail ammo) and as expected the recoil was quite a bit less and flatter shooting. The 1:10 twist must be sufficient for 150gr, since these were some of the smallest groups I have shot with this rifle.

So I have a long way to go to make something of this rifle. 8mm bullets seem to be pretty problematic to obtain and limited in whats available. I may go with a Shilen match barrel chambered in 7x57 instead and rework my brass to the 7mm neck size. That caliber seems to have a lot more going for it today and it looks like it will take everything that can be done with the 8x57. The stock needs to be bedded and the recoil pad changed to a Pachmeyer. The action probably needs to be blueprinted, the witness mark is much more prominent on 1 bolt lug than the other. The cheap brass millsurp ammo that is out there shoots 4-6MOA at best, which may be OK within 100 yards, but is not going to make me excited....

I have already replaced the crap Remington "9lb" lawyer trigger with a Shilen unit and have left is as shipped so far. I will probably dial it down a little after some experience.

If that's a photo of your installed brake, the perspective may be distorted. But, it seems that the inside diameter of the brake may be too large. As such, too much gas is excaping forward and not being diverted to the ports.

The ID of the brake should be ~.020" larger than the caliber for best efficiency.

-- richard

 

[westcliffe01]

Richard, the photo is from the Magnaport website. The rifle was sent to them and they removed the barrel and turned it to fit the brake and the thread protector. If they don't know how to make and fit their own brake, then shame on them... The drilled holes in the brake were not deburred properly on the ID, so I quit using it until after i obtained some small circular section honing stones, with which I was able to deburr it properly. Now it no longer shaves fluff off the bore patches or bore mops when cleaning the barrel.

But as I said earlier, I don't find it to work particularly well anyway. It is disappointing coming from the company which was a pioneer in using ports to control recoil on handguns.

If that's a photo of your installed brake, the perspective may be distorted. But, it seems that the inside diameter of the brake may be too large. As such, too much gas is excaping forward and not being diverted to the ports.

The ID of the brake should be ~.020" larger than the caliber for best efficiency.

-- richard

 

[rscott5028]

Richard, the photo is from the Magnaport website. The rifle was sent to them and they removed the barrel and turned it to fit the brake and the thread protector. If they don't know how to make and fit their own brake, then shame on them... The drilled holes in the brake were not deburred properly on the ID, so I quit using it until after i obtained some small circular section honing stones, with which I was able to deburr it properly. Now it no longer shaves fluff off the bore patches or bore mops when cleaning the barrel.

But as I said earlier, I don't find it to work particularly well anyway. It is disappointing coming from the company which was a pioneer in using ports to control recoil on handguns.

Shame on them. It should be easy to replace. But, more money out of your pocket.

 

[WildRose]

Now that we all seem to be playing nicer again some thoughts for some of you who seem to be having problems managing recoil.

What caliber are you shooting, what does your rig weigh, and how much do you weigh?

A 200plus pound shooter vs a 160lbs shooter firing the exact same rifles are going to experience different levels of percieved recoil. The amount of force remains the same, but the mass being driven being larger is not going to move as far.

Also the mass of the rig relative to recoil force is going to greatly affect felt recoil. Heavier rig/less felt recoil, lighter rig, more.

Another is comb height relative to the line of the bore.

Something most modern military rifles share is that the comb is in line with or raised above the line of the bore.

The above are two great examples; mind you these are two of the five or ten longest range rifles in the world.

This design means that the recoil which does occur while the bullet is still in the tube will be directed straight to the rear.

The more drop you have on the comb, the more of that force is going to be directed upward creating a lever effect.

If your stock suits you as is, you can add comb risers to compensate for the difference.

Yes you'll have to raise your scope's mount/rings to match, but that will make a considerable difference.

There are also two other means.

One are recoil reducing butt pads. The decellerator is one that works pretty well, for those who need more there are some hydraulic compensators that are pretty pricey but certainly very effective.

Another, I wasn't even aware of still being available are shifing mass compensators including the mercury filled one's are still on the market.

They can be placed either in the stock or below the barrel in the forearm by either drilling it front to rear, or by routing out a groove and dropping it in after bedding in place.

Combine those with a quality muzzle brake, and you can tame the recoil of the most punishing magnums to a tolerable level.

 

[ken snyder]

Might be that we didn't answer his question and responded to his supportive data and gave fixes, physics lessons instead. The answer he's looking for might be this: Yes recoil is detremental to shooting accuracy, but makes no difference to the rifles accuracy.