Using that calculator, the recoil energies did not surprise me much but I was amazed that the recoil velocities for the Nitro express calibres were faster than smaller but higher-velocity rifles.

I had previously thought the elephant numbers gave a long push rather than a short, fast shock.

quote:

Originally posted by sambarman338:

I had previously thought the elephant numbers gave a long push rather than a short, fast shock.

The rifle achieves its recoil velocity in a very small distance, just a fraction of an inche, that is why the G forces on the scope and mounts are so high.

The rifle moves back, while the bullet and powder are in the barrel, by the ratio of the rifle weight and the combined weight of the bullet/powder.

So take a 10 pound 458 with 24" barrel and 500 grain bullet and 70 grains of powder so 570 grains all up and moves 21.5" with a 24" barrel. The rifle weighs weighs 70,000 grains so 123 times the weight of bullet and powder. So while the bullet and powder move forward 21.5" the rifle will move back 1/123 X 21.5"= .175"

A 30/378 with 180 grains and 120 grains of powder, so 300 grains all up will be the same as a 358 Winchester with 250 grains and 50 grains of powder. However, the recoil will be much higher with the 30/378 because the rifle will get to a higher velocity in the same distance.

Of course the final velocity the rifle gets to is the extra velocity they rifle gets as the bullet exits and the velocity of the gas speeds right up.

As you can see from how far the rifle moves back when fired, the gun has finished accelerating to its recoil veloicty in a very very small distance.

All recoil formulas are based on the momentum of the rifle being equal to the momentum of the bullet and the powder gas. The variation in formulas is becaus eof the velocity assigned to the gas. The common figure for the average veloity is 4700 f/s and undoubtedy that was based on on early30/06 military ammo.

While the gas is in the barrel the gas jusg behind the bullet is obviously right at muzzle velocity. The gas at the head of the case is zero velocity. So an average will be about half the muzzle vleocity. The the bullet uncorks the barrel and the gas speeds right up, maybe 6000 f/s. Something like a 30/378 will be higher than a 30/06 or 458 because of the muh higher pressure in the barrel when the bullet exits.

If yo ever you get the chance to put weights that can slide behind rifle you soon see there is no such thing as fast and slow recoil It is a mental thing, physics rules the day. The way the gun is shot also influences things. People with a458 etc are more likely to fire a few shots offhand at a rock or tree whereas a 300 Winchester etc. is likely to be all very deliberate shooting, measuring lots of groups and firing a lot more shots.

I picked a 404 Jeffery over the 416 Rigby because I was building on a 1917 Enfield and the bolt face rim would have been thinner with the Rigby. It was a toss-up on the actual round as folks have said. I think easier to get one more round down on the Jeffery as well, at least in an Enfield.

With that said, a the 416 Ruger is a better modern choice all around, I'd assume more snappy, and less nostalgiac.

Sort of like my off-road vehicles. My FJ40 is cool, but my Polaris Ranger Crew is less $$$ and more practical. And just look at the price of a Ruger 416 African! Just ditch that fugly muzzle brake.

quote:

Originally posted by Mike McGuire:

quote:

Originally posted by sambarman338:

I had previously thought the elephant numbers gave a long push rather than a short, fast shock.

The rifle achieves its recoil velocity in a very small distance, just a fraction of an inche, that is why the G forces on the scope and mounts are so high.

The rifle moves back, while the bullet and powder are in the barrel, by the ratio of the rifle weight and the combined weight of the bullet/powder.

So take a 10 pound 458 with 24" barrel and 500 grain bullet and 70 grains of powder so 570 grains all up and moves 21.5" with a 24" barrel. The rifle weighs weighs 70,000 grains so 123 times the weight of bullet and powder. So while the bullet and powder move forward 21.5" the rifle will move back 1/123 X 21.5"= .175"

A 30/378 with 180 grains and 120 grains of powder, so 300 grains all up will be the same as a 358 Winchester with 250 grains and 50 grains of powder. However, the recoil will be much higher with the 30/378 because the rifle will get to a higher velocity in the same distance.

Of course the final velocity the rifle gets to is the extra velocity they rifle gets as the bullet exits and the velocity of the gas speeds right up.

As you can see from how far the rifle moves back when fired, the gun has finished accelerating to its recoil veloicty in a very very small distance.

All recoil formulas are based on the momentum of the rifle being equal to the momentum of the bullet and the powder gas. The variation in formulas is becaus eof the velocity assigned to the gas. The common figure for the average veloity is 4700 f/s and undoubtedy that was based on on early30/06 military ammo.

While the gas is in the barrel the gas jusg behind the bullet is obviously right at muzzle velocity. The gas at the head of the case is zero velocity. So an average will be about half the muzzle vleocity. The the bullet uncorks the barrel and the gas speeds right up, maybe 6000 f/s. Something like a 30/378 will be higher than a 30/06 or 458 because of the muh higher pressure in the barrel when the bullet exits.

If yo ever you get the chance to put weights that can slide behind rifle you soon see there is no such thing as fast and slow recoil It is a mental thing, physics rules the day. The way the gun is shot also influences things. People with a 458 etc are more likely to fire a few shots offhand at a rock or tree whereas a 300 Winchester etc. is likely to be all very deliberate shooting, measuring lots of groups and firing a lot more shots.

So, do you think the recoil velocities in that program are wrong?

I tried to take your examples back to that calculator but, having no exact velocities or all the rifle masses, was missing parts of the equations. But guessing the velocities and also giving the 30/378 a 10lb rifle, the 458WM still seemed to have the greater recoil velocity.

Also, how did you come by that movement of 21.5 inches?

Does the rocket-blast aspect affect the simple equation based on velocity and various masses or just the way it all plays out - eg could a rifle that burns most all the powder within the barrel give a shorter, sharper felt recoil while one spewing heaps of as-yet unburnt powder out behind the bullet give some part of the recoil as an extended push?

quote:

Originally posted by Mike McGuire:
... People with a 458 etc are more likely to fire a few shots offhand at a rock or tree whereas a 300 Winchester etc. is likely to be all very deliberate shooting, measuring lots of groups and firing a lot more shots.

Sir,
I resemble that remark, NOT !

Paul,
21.5" = 24" barrel length MINUS 2.5" brass length,
The effective length of barrel down which the bullet moves is that barrel length from breech face to muzzle
less
the distance from breech face to end of brass in chamber,
neglecting all seating depth and throat effects beyond maximum brass length, of course,
roughly speaking.

quote:

Originally posted by sambarman338:

So, do you think the recoil velocities in that program are wrong?

I tried to take your examples back to that calculator but, having no exact velocities or all the rifle masses, was missing parts of the equations. But guessing the velocities and also giving the 30/378 a 10lb rifle, the 458WM still seemed to have the greater recoil velocity.

Also, how did you come by that movement of 21.5 inches?

Does the rocket-blast aspect affect the simple equation based on velocity and various masses or just the way it all plays out - eg could a rifle that burns most all the powder within the barrel give a shorter, sharper felt recoil while one spewing heaps of as-yet unburnt powder out behind the bullet give some part of the recoil as an extended push?

No ....my post does relate to that calculator. My main point was the velocity of the rifle is achieved in an extremely short distance as in a fraction of an inch. Once the rifle has stopped accelerating it does not matter if a very heavy and slow bullet was fired or a light and vry fast bullet. The rifle is simply a 10 pound mass.

With the calculators that is 4700 f/s for the powder/gas velocity they will probably overstate the recoil of a 458 etc. and understate the 30/378 etc. However, ther is another factor that will have influence and to get this one right you need to contact NASA The thrust of a rocket is based on the mass of gas that passes the nozzle in a given time, This will be a product of both diameter and pressure inside the barrel/combustion chamber. If we conssider a 257 Wby and a 458 both with 80 grains of powder and same peak pressure then the pressure in the barrel/combustion chamber will be much smaller in the 458 than the 257 when the bullets exits the muzzle. The volume inside the 458 barrel will be 3.175 time great than the 257. As a side note that is why the 458 can get much more KE to the bullet from 70 grains of powder because the gas has done a lot more work. Moving bacl to recoil, so the gas pressure is much lower for the 458 but the are for the gas to escape is much larger. Somit might well be thay the rate at which gas passes "the nozzle" in the 458 is greater than the 257. This might well be the reason that muzzle brakes reduce recoil of calibres like 458s more than would expected.

If you have good water mains pressure a simple experiment will show what happend with the variables of pessure and nozzle area. If you put the hose's nozzle on the finest spray the velocity of the water feels like the water is almost cutting your leg. As you open the nozzle up the "recoil" of the hose will increase but the velocity of the water will drop. However, get an empty bucket and you will see with the nozzle opened up you will fill the bucker much faster.

However, if you take the nozzle off the hose (depending on your mains pressure) the recoil of the hose will be less than when the fully opened nozzle was used and it will take longer to fill the bucket. What has happened is taking the nozzle off has caused the pressue in the hose o drop right off and so the rate of water mass exiting per "time" is now less.

Of course another factor in how we perceive recoil is muzzle blast and of course the 30/378 is a big timer in muzzle blast.

Thanks for that, guys. I have at least your 21.5-inches explanation crystal clear, RIP.

quote:

Originally posted by sambarman338:

Does the rocket-blast aspect affect the simple equation based on velocity and various masses or just the way it all plays out - eg could a rifle that burns most all the powder within the barrel give a shorter, sharper felt recoil while one spewing heaps of as-yet unburnt powder out behind the bullet give some part of the recoil as an extended push?

It doesn't matter what type of powder is used because the rifle's accelaration up to the velocity it achieves is always an extremely short distance. If you had a calibre that gave the greatest rifle movement during accelaration to its recoil velocity then if you were wearing a thicker coat by the time the rifle compressed the coat at the shoulder the rifle would be in free recoil. In short saying a rifle has long shove is in the shooter's mind. Apart from shooting bigger slow calibres differently we tend to think of 2000 f.s as just loping along when in fact it is extremely fast and we tend to imagine the recoil being slow. If the recoil form a 458 Win/Lott was a long slow shove then they would not tear up scoped and mounts.

Different powders and also loads can increase the velocity of the gas as it exits the muzzle but that only increase the velocity the rifle achieves before the accelaration stops.

The fact that rilfes that are heavier in reltion to bullet and powder weight is demonsrated in the field with accuracy. The heavier rifle in relation to bullet and powder weight is less influenced by hold. You also see it on the bench with bench style rifles of the same weight but different calibres. The calibre with the light bullet and powder charge moves back less during accelaration and so two different shooters will have points of impact that are much closer in say a 22 PPC than a bench gun in 270.

Not that you're likely to notice the difference but slow-burning powders generally require a greater amount than faster-burning ones, hence may put several grains more ejecta into the equation.

On the subject of scopes, I have heard that some makers have had trouble with heavy-kicking rifles and think the problem relates to the long travel under recoil.

The only explanation I can think for this might be that when the rifle rises under the first recoil impulse, causing the erector tube to bottom on the outer tube, the spring returns it to battery but then the second impulse (the shooter's shoulder arresting the rifle's rearward motion) sets off another ruction in the erector tube. In a faster, shorter recoil, those two reactions may be combined in just one movement of the erector tube.

Thinking about the recoil speeds from that calculator, though, if it is both quicker as well as heavier in the bigger calibre, then strain on the gimbal hingeing could also be a danger.

You know what I see as the answer to stuff like this, of course.

quote:

Originally posted by sambarman338:
Not that you're likely to notice the difference but slow-burning powders generally require a greater amount than faster-burning ones, hence may put several grains more ejecta into the equation.

On the subject of scopes, I have heard that some makers have had trouble with heavy-kicking rifles and think the problem relates to the long travel under recoil.

The only explanation I can think for this might be that when the rifle rises under the first recoil impulse, causing the erector tube to bottom on the outer tube, the spring returns it to battery but then the second impulse (the shooter's shoulder arresting the rifle's rearward motion) sets off another ruction in the erector tube. In a faster, shorter recoil, those two reactions may be combined in just one movement of the erector tube.

Thinking about the recoil speeds from that calculator, though, if it is both quicker as well as heavier in the bigger calibre, then strain on the gimbal hingeing could also be a danger.

You know what I see as the answer to stuff like this, of course.

Well the rifle firing a big heavy bullet moves back during acceleration.

The rifle rising sure not be any issue as that starts after rifle has finished acceleration. The rifle is only rising because the centre of the butt is "dropped".

The scope/mounts is a G force thing but of course there will be different combinations of "G Force X Time" Just like a man who can survive very high G forces in a car racing crash and because the G force is not actiong for very long. The G force does need to be high enough to actually cause damage so that G Force X Time won't meany much if G force is low even if it is there for a long time. A bit like Temperature X Time. Apply 1000 C to a steel bar all day and all night will not melt the bar.

The big rifle acceleration is in the first couple of inches of bullet travel. So a 460 loaded back to a 458 and a 378 loaded back to a 375 will (and is) a different deal.

As an aside I still think you (and most people) have in your mind that when you are being driven back by recoil that the rifle is being "pushed back". Once the rifle has moved back just a small fraction of inch it is "fee", the bullet and gas have long gone and any characteristic of the calibre are no longer an influence.

One thing I noticed many times over many years is rifles shooting reduced loads can still shoot well when bedding is not so good. I have often wondered if this is due to slower initial acceleration of the rifle and thus less of a hit on the bedding.

I have not found the 404 or 416 Rem or rigby to be punishing in recoil, and could never tell the difference between the two..Same for results on the live targets..I had a lovely Cogswell in both 375 and 404, and recoil was mild and less than my 375 7.5LB. Ruger 77 built in 2006 only then discontinued for some reason..Recoil only becomes a factor for me with the 458 Lott and up in bolt guns, the doubles I can stand up to a .470 but prefer the 450-400...return to battery is a important factor to me in a DG rifle..so its too each his own, and all calibers mentioned do what they are intended to do..Birsitas and hearing is what we paid for btw..