quote:

That is a simple formula that will give an idea of the recoil for most cartridges. Unfortunately it has a built in error factor that makes it useless for this discussion because "grain for grain, the powder has more effect on recoil than the bullet weight."

This formula is easy to use ... just plug the values in for each component. The escaping gas velocity at the muzzle is 4700 fps (the best approximate value). In fast photography one can see that the gas is ahead of the exiting bullet for the first few inches, as the bullet's velocity is slower.

Free Recoil = [(weight of the bullet x muzzle velocity) + (weight of powder charge x 4700)]squared
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64.348 X weight of gun in pounds

Warrior

quote:

Originally posted by JBrown:
"grain for grain, the powder has more effect on recoil than the bullet weight."

This statement has been supported by many posts on this subject and the issue is clearly that magnums do in fact recoil greater than a "linear" relationship to bullet velocity. (I used the word inordinately)

Not that JBrown needed his statement supported because his posts have always been high esteem in my eyes. It's more like icing on the cake as proof of what we feel when we take up shooting magnums.

Moreover this thread is confirming why I've grown so fond of the .30-06 case as a base for most of my hunting rifles.

quote:

Originally posted by Warrior:
This formula is easy to use ... just plug the values in for each component. The escaping gas velocity at the muzzle is 4700 fps (the best approximate value). In fast photography one can see that the gas is ahead of the exiting bullet for the first few inches, as the bullet's velocity is slower.

Free Recoil = [(weight of the bullet x muzzle velocity) + (weight of powder charge x 4700)]squared
------------------------------------------------------------------------------------------------------------------------------
64.348 X weight of gun in pounds

Warrior

Curious as to the basis for your claim that 4700 fps is the 'best approximate value' for the velocity of the escaping gas.

quote:

Originally posted by vapodog:

This statement has been supported by many posts on this subject and the issue is clearly that magnums do in fact recoil greater than a "linear" relationship to bullet velocity. (I used the word inordinately)

So if you go from 06 to 300 winnie you get a 30% increase in recoil. If you go one more step up to 300 RUM you get a 38% increase over the winnie and almost double the recoil of the '06.

So nonlinear would be a good way to describe it because as you add more and more powder you get less and less gain in velocity, and I would go so far as to say killing power too .

quote:

Curious as to the basis for your claim that 4700 fps is the 'best approximate value' for the velocity of the escaping gas.

Deadkenny,

I have seen 5,200 fps used as well. Lyman pitched it lower at 4,700 fps, and that is the one I used in the calculation and realised that opinions vary and that it is at best an approximate value.

I have also seen the figure of 4,000 fps of late. Somewhere else I found a statement of 4 times the speed of sound, making it:

1,116 fps ( at sea level at 59 degrees F) x 4 = 4,464 fps,

Here is another quotation ... " .... powder gas effective escape velocity constant, that equals 4,000 fps (1,220 for Metric) for smokeless powders and 2,000 fps (610 for Metric) for blackpowders;"

This opens up a debate that all powder are not the same in burning rate and energy potential, and so all powders will vary (single based vs double based powders, Hornady's new powder Superformance perhaps run at a different curve, etc.) So to quote a single figure can never be absolute, but merely approximate and broadly speaking indicative.

Somewhere else I see people are quoting a value of 1.5x the muzzle velocity, as if there is a direct correlation. Now that may be so, I am n actually not sure of the precise value. If this happens to be true then we have a totally different scenario, for example:-

7x57 mm: 175 gr @ 2,350 fps yielding a gas escape velocity of = 2,350 x 1.5 = 3,525 fps
30-06 Spr: 180 gr @ 2,650 fps yielding a gas escape velocity of = 2,650 x 1.5 = 3,975 fps
300 Win Mag 180 gr @ 2,950 fps yielding a gas escape velocity of = 2,950 x 1.5 = 4,425 fps
30-378 Wby 180 @ 3,420 fps yielding a gas escape velocity of = 3,420 x 1.5 = 5,130 fps
220 Swift 40 @ 4,213 fps yielding a gas escape velocity of = 4,213 x 1.5 = 6,320 fps

Nor can I vouch that there is a linear relationship in escaping gas behaviour.

If someone have figures to share, based on actual research, it would be greatly appreciated.

This recoil calculator has also been programmed at 4,700 fps, using Lyman as the base, and the qualification is that it is applicable for bullets with muzzle velocities faster than 2,700 fps.

http://10xshooters.com/calcula...ecoil_Calculator.htm

Warrior

I am convinced that Lyman Reloading manual got their figure from Julian Hatcher. He was a noted firearms expert and is credited with several technical books and articles relating to military firearms, ballistics, and autoloading weapons. His premier works are Hatcher's Notebook and Book of the Garand. He has also authored the Textbook of Pistols and Revolvers and Pistols and Revolvers and Their Uses. He was a prominent man at Aberdeen Proving Ground, in 1941, and also the Commanding General of the Ordnance Training Center. when he retired from the United States Army as a Major General he served as Technical Editor of the National Rifle Association's "American Rifleman" magazine. His book Hatcher's Notebook is still availabe at ...

http://www.midwayusa.com/viewP...productNumber=710604

Back to the recoil issue under discussion:

Here is another quote ... " The high pressure gases, being lighter than the bullet, scoot right past it. Schlieren photographs show the muzzle blast sphere expanding out ahead of the bullet until air resistance slows it toward the speed of sound and the bullet then blows past its leading edge. Hatcher found about 4700 fps was a good number to use with the .30-06 and 24" barrel. I've seen up to 5,500 used with some slow powders or short barrels, where the pressure at the muzzle is higher."

Here we see again that pressure seems to be a key factor.
Also, that slow powders that generate higher velocities in longer barrels can be a factor.

Where Hatcher got the figures from I am not sure, but there had to be some basis. One suggetion put forward was ... "Since the calculation precedes more modern measuring methods, I assume that was deduced by firing a rifle mounted to a ballistic pendulum or some other means of measuring free recoil, then working backward to account for it."

Warrior

I compiled some notes from various sources and added my own understanding along the way with regard to felt recoil and how calculated free recoil energy can be reduced.

Calculated free recoil is not the same as felt recoil. Free recoil is the momentum or impulse imparted to the gun on firing. This momentum is equal in magnitude and opposite in direction to the momentum imparted to the bullet and propellant powder charge. Recoil has 2 components - the rifle's reaction to the bullet moving down the barrel and the second element by the hot expanding gasses that exit the barrel, causing a jet effect. The jet effect of the escaping powder gasses makes up about 25% to 50% of the total recoil of a modern rifle.

By using a muzzle brake for example, it diverts some of these gasses out to the sides through the vents or ports. The redirection of the gasses which is at an angle to the muzzle, creates a force which helps to counteract the rearward movement of the barrel due to recoil, as well as the upward rise of the muzzle. Another recoil control device is the mercury filled or weight and spring loaded anti-recoil tube mounted in the buttstock. These devices will help to reduce perceived recoil.

Put another way, felt recoil is mainly a function of the kinetic energy of the gun's rearward movement and the total area over which its force is distributed where it makes contact and how freely the shooter can move backwards with the force or momentum of the gun. With proper stock design and a good recoil pad we can also lessen perceived recoil even though the gun is coming back at you just as hard.

First off, everybody's threshold limit of recoil is different, but each individual should determine his own limit, and the question then becomes to define that limit. Opinions may vary, but here is one view .... that limit is broadly speaking that one should find the recoil tolerable to shoot 3 volleys of 3 rounds off the bench in quick succession without any excessive discomfort and flinching.

Felt recoil will also differ based on one's shooting position. From the bench in a sitting position one typically leans into the rifle and recoil is at its worst. In a sitting position the body has little flexibility to move with the rearward push of the firearm, whereas in the standing position the shooter can roll with the punch making the felt recoil less punishing. One of the important things for controlling recoil is keeping the stock pulled in tight to the shoulder without tensing up any muzzles - just firm enough.

Stock design can play a big part in how we experience recoil, as the way the stock is designed and shaped will dictate how recoil is executed by virtue of the stock's drop in comb and heel, size of the butt, and the pitch of the stock. Pitch is simply defined as the angle of the butt to the line of sight. The pitch should be such that the butt sits squarely in the shoulder to avoid slippage. However if the top part (heel) is too far back and the bottom part (toe) is too forward the recoil will pound the shoulder in a smaller area and felt recoil will be more severe.

More stock designs can be seen here: http://www.gunstocks.com/Stockstyles.html

The worst example of stock design is to be found in the old 30-30 Winchesters and just as well it is a mild cartridge. Its drop at the comb is excessive and the pitch is wrong, causing the top of the butt plate to slant to the rear. With this combination the rifle is bound to move upwards in recoil and right into your face. That is why stockmakers almost universally insist on the comb being a little higher at the rear. And for the very same reason of stock design, the 7 lb Marlin 45-70 has an unpleasant recoil and it becomes progressively worse with the 45-90 that has so much more powder capacity.



By far the most popular stock style today is the 'modern classic stock' - it tends towards a straight comb with little or no drop at heel, a pistol grip with a medium curve, and a rounded or pear-shaped forearm. The straight comb line with minimum drop at heel is designed to align the eye with the telescope and to transmit recoil in a straight line to the shoulder, minimizing muzzle rise. The medium pistol grip is designed to provide good control without cramping the hand. The rounded forearm is designed to fit the natural curve of the hand that grips it. With muzzle rise, and more particularly so in high-recoil cartridges, we get a situation that the comb of the stock bucks upward and hits the shooter below the cheekbone and so transmit shock to the brain.

Modern classic stocks are basically designed for use with telescopic sights, but rifles so stocked often come with iron sights, which must remain useable. So the stock is somewhat of a compromise in that its drop at the comb is intended to favor optical sights, but still being able to accommodate iron sights. A lower comb height is more suitable for open sights, and so the old British Express Classic stock was more suitable for shooters who preferred open sights rather than a scope.

The Remington 700 stock is an example of the modern classic stock design. Notice how the comb of this stock is perfectly parallel with the barrel. This allows the rifle to recoil straight back along your face, but not into your face. With this design you will feel a great deal less recoil. The angle of this butt plate is also much better than the 30-30 Winchester, but still slanted slightly to the rear, and it delivers recoil lower on your shoulder where it's more comfortable.



Now let us look at Weatherby stocks. Roy Weatherby designed a fancy or striking looking stock, but he got it right . It is well designed and you will feel less recoil. Notice how the front of the comb on the stock slopes downward, allowing the rifle to recoil straight back, and in so doing away from your face that shifts now forward. The stock is designed expressly for the higher line of sight of an optical sight. This stock design delivers recoil to your shoulder the way it should, still with a slightly negative pitch. The only thing I do not like is the squarely shaped forearm that does not fit the palm of you hand as if made for it. A rollover cheekpiece design is also less sharp on the cheek bone.



The size of the butt and the type of recoil pad used either soft or hard, will determine how it spreads out the recoil impulse. The soft pad dissipates the energy less sharply on the shoulder tissue. A well designed recoil pad obviously reduces recoil even more and there is a multitude of designs available just in the Pachmeyer range alone. Also, it looks like there is a trend towards thinner and lighter 'modern-styled' rifle stocks, and as lighter stocks increase recoil energy, a good recoil pad would help to counter the effect.

A heavier weapon requires more kinetic energy to move backwards during recoil, than a lighter one. This results in a longer duration of recoil, which reduces the felt recoil considerably. All other things being equal, a longer barrel will result in more recoil, as the longer the bullet is in the barrel, the longer it's being pushed by the gasses and so more kinetic energy is being generated. It's worth noting that very short barrels typically exhibit far less recoil than longer ones, at the expense of muzzle velocity.

Warrior

quote:

The high pressure gases, being lighter than the bullet, scoot right past it. Schlieren photographs show the muzzle blast sphere expanding out ahead of the bullet until air resistance slows it toward the speed of sound and the bullet then blows past its leading edge.

This photograph captured it nicely:




Warrior

I absolutely believe the amount of powder is the main cause with the bullet weight being the same.

I had two 300 win mag loads that both sent 200 partitions to 2950 fps. One took 80 grains of powder compared to the other at 69. The 80 grain charge seemed to kick more.

Many times I will find the fastest couple powders for a given bullet then use the one that takes the least amount of powder.

quote:

Originally posted by Warrior:

quote:

The high pressure gases, being lighter than the bullet, scoot right past itonly after the bullet leaves the muzzle. Schlieren photographs show the muzzle blast sphere expanding out ahead of the bullet until air resistance slows it toward the speed of sound and the bullet then blows past its leading edge.

This photograph captured it nicely:




Warrior

i added text, in italics, clarifying your statement
cool pic though

Some interesting observations here from Don:-

Big Boomers

You've obviously never torn a retina in one of your eyes from shooting big boomers, and the 30-378 is a heavy recoiling cartridge, capable over time of tearing a retina, as I have done from shooting heavy recoiling rifles and shotguns. I'll stick with nothing bigger than a straight 300 H&H mag for a long ranger, as far as recoil goes; No more torn retinas for me.

I recommend against heavy recoiling rifles for any shooting, except for a few well spaced shots in Africa for dangerous game animals. A few shots from the big boomers would hurt, probably. But, for target shooting with lots of shots from big guns is not recommended. I'm a resident expert on torn retina's. Details of the retina repair on request.

Don
JPFO
NRA Benefactor Life Member
NSSA Life Member

----------------------------------------------

I was curious to relate Don's comments to the figures relative to the other .300 calibers:

Cartridge --------------- Bw x Velocity --------- Gw ------- Recoil Energy ------ Recoil Velocity
30-06 Spr ------------ 180 gr @ 2700 fps ---- 8.0 Lb ------ 20.3 Ft-Lb ----------- 12.8 fps
300 Win Mag -------- 180 gr @ 2960 fps ---- 8.5 Lb ------ 25.9 Ft-Lb ----------- 14.0 fps
30-378 Wby Mag --- 180 gr @ 3300 fps --- 9.75 Lb ----- 42.6 Ft-Lb ----------- 16.8 fps

quote:

Originally posted by RMiller:
I absolutely believe the amount of powder is the main cause with the bullet weight being the same.

Yup....seems a lot of physical evidence here to support that.....

That said....I can't say that I actually notice much (if any) less recoil between the .308 and the .30-06!

Could anyone share with us scopes that failed on high recoiling rifles - say 300 Win Mag and up. Not that the 300 Win Mag has such high recoil, but just to set a base line.

More particularly on scopes that fail from 40 Ft-Lbs and up in relative short order or within the first 300 rounds. Let us see if we can quickly pool some experience together to identify scope failures.

Warrior

Most scope tests don't include durability testing anywhere close to the degree Rob has done it as can be seen below. It would be rather nice is scope manufacturers can publish on each scope box to what standard a scope has been tested for recoil, much like it is mandatory that consumers must know the ingredients or nutritional value of food stuffs by way of the print on the label.

Warrior

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ILya, for the past 6-8 months I have been playing with other testing apparatus in between hunting.

As of now, I have designed and built a recoil simulator and have sent the patent info in for publication. I can simulate up to 260 lbs/ft of recoil, muzzle lift, reverse recoil, both for and aft recoil. Some of the scopes that I felt wouldn't impress have really impressed me. At 75 lbs/ft recoil with 2.2" of travel in 21 milliseconds. I have a Vortex Viper 3-9 that has taken over 2200 simulations and still hasn't failed. I have a 3-9 Diamondback that failed after 1500+ recoils and was fixed and returned in 9 days without question.

They will all fail, just a matter of when:

Sightron SII Big Sky 4-16X42... 1630 impacts... erector screw ... had Loctite, put on the screw, and it's over 1200 impacts for the second time around.

Sightron SII Big Sky 3-9X42 .... 1260 impacts ... erector assembly

SIII.............. 3.5-10X56 ...... 1571 impacts

Conquest.......... 3-9X40 ...... 1056 impacts

Conquest ......... 4.5-14X44 ... 996 impacts

Leupold VXII...... 2-7X33 ......... 66 impacts.erector assembly failure...Fixed and went 1077 impacts

Leupold VXIII..... 3.5-10X40 ... 521 impacts

Nikon Monarch..... 3-12X42 ..... 336 impacts

ILya, these are a few of many scope I have broken. The nice thing about broken optics is you get a real good feel for customer service.

I got a VXL 3.5-10X50 from a friend of mine that has sent it back 3 times, parallax issues and erector that I cant get to go over 170 impacts. Leupold sent me a brand new one 2 months ago and it's back for the second time for erector issues. I would recommend against the VXL.

Haven't had a chance to put the VX-3 on there yet but will after I'm convinced my optical testing is complete, I'll recoil test it.

Just Having Fun
Rob

The Bushnell Elite scopes for example are tested to pass:

1,000 rounds with the equivalent impact of a 375 H&H for the Elite 3200 model, and

10,000 rounds with the equivalent impact of a 375 H&H for the Elite 4200 model.

Would it not be nice to have a statement like this say on a leaflet inside the box, telling you and me what we have bought, together with notes on the particular scope & its use. This may have particular value and comfort in knowing that the scope is fit for use on big-bores with more recoil. Or am I am asking too much?

Warrior

quote:

The Bushnell Elite scopes for example are tested to pass:

1,000 rounds with the equivalent impact of a 375 H&H for the Elite 3200 model, and

10,000 rounds with the equivalent impact of a 375 H&H for the Elite 4200 model.

I'll accept that as true....but mind you that I've put extremely cheap scopes such as Bushnell banner and Tasco scopes on a .375 H&H and have never had a nickel's worth of trouble....granted....I didn't fire them 1,000 times as proof.....but they survived quite well for the period I used them.

I consider the above advertising helpful but not incredibly so!