Which effects recoil more, bullet weight or bore diameter?

I ask because of some observations. Chief among these:

The pressure versus time trace for the 30-06 is very nearly identical to the pressure versus time trace of the 460 Weatherby magnum, which in turn is nearly identical to the 416 Rigby, etc, etc.

Thank you for your comments.

ASS_CLOWN

AC....what are you smokin?????....the bore diameter is only of issue in that it allows for larger/smaller amounts of mass to pass.....
Recoil is not effected by bore diameter at all...the omly two factors (IMO) are "ejecta" weight and "ejecta" velocity....."ejecta" being the combination of bellet weight and weight of powder gasses escaping.

I would call it three things. Bullet weight, velocity and powder charge.

"Ejecta" is everything that comes out the barrel.

Neither!

Bullet MASS, powder MASS, and their velocity...

Weight is just something we use to normalize mass to a familiar unit at sea level in normal Earth gravity.

Nitpicking over...for now.

Gentlemen,

Thank you for the replies.

I haven't been smoking much lately, perhaps that is the problem, eh.

I asked this question for the following reason.

I have looked closely at the following three curves.

Curve #1
Chamber pressure versus time
30-06
220 gr Rem Corelokt
IMR4350 powder
Muzzle velocity ~ 2527 fps
Peak pressure ~ 62,100 psi
Muzzle pressure ~ 16,200 psi
Time to muzzle ~ 0.0012 secs

Curve #2
Chamber pressure versus time
416 Rigby
400 gr Hornady SP
IMR4350 powder
Muzzle velocity ~ 2617 fps
Peak pressure ~ 61,700 psi
Muzzle pressure ~ 15,400 psi
Time to muzzle ~ 0.0012 secs

Curve #3
Chamber pressure versus time
460 Weatherby Magnum
500 gr Hornady SP
IMR4350 powder
Muzzle velocity ~ 2582 fps
Peak pressure ~ 61,900 psi
Muzzle pressure ~ 15,700 psi
Time to muzzle ~ 0.0012 secs

These three rifles recoil significantly different from one another; however, the pressure curves are practically identical.

Since the pressure signatures are SO very close, I was thinking that perhaps it was the bore that dictated the ACTUAL recoil.

Bullet sectional densities are:
220 gr (0.308") ~ 0.331
400 gr (0.416") ~ 0.330
500 gr (0.458") ~ 0.341

Anyway, that is why I ask the question. Further comments are greatly appreciated.

ASS_CLOWN

The free recoil of your firearm can be found using the formula below:

((weight of the bullet in pounds x the velocity of the bullet in feet per second)+(4,700 x the weight of the powder in pounds))squared / (64.348 x the weight of the gun in pounds)

At my time in life it becomes rather academic. The small calibers and light bullets treat me better to a days shooting than larger heavier did in days gone by.

When the adrenaline is flowing the unpleasantness from a couple of rounds out of a .375 super pooper plus won't even regester on my charged brain. roger

I agree with those that say it's all about ejecta mass and velocity, assuming guns of equal mass and stock configuration. Bore diameter and pressure are only relevant to the degree they affect the velocity of the ejecta.

Time-to-muzzle is also irrelevant as long as it's less than, say, .005 seconds, IMO. If your barrel is 20 feet long and the bullet accelerates at a constant acceleration from chamber to muzzle, the recoil will be spread out over a relatively long time. Maybe long enough to notice the difference. As long as the bullet exits the muzzle before the rifle has moved enough for you to begin feeling it, you won't feel the difference, IMO.

How far does a typical rifle move before the bullet exits?

Actually bore diameter would influence recoil because rocket thrust is about the mass of gass passing through the nozzle in a given time.

So a 458 and 257 Wby with 70 grains of powder each could result in the 458 having a higher recoil from the gas. The 458 won't have the same muzzle pressure but it has a much bigger nozzle diameter.

This can be seen with a garden hose. When the nozzle is set to a very fine spray the water is travelling fast enough to almost cut you. As you open the nozzle up the water velocity drops but the "recoil" of the hose increases as a greater mass of water passes trhough the nozzle in a given time.

Mike

quote:

How far does a typical rifle move before the bullet exits?

If you ignore the weight of powder then the gun will move back as follows

Bullet Weight/Gun Weight X bullet travel

In other words if we take a 9 pound 30/06 with 180 grainers then the gun at 63000 grains is 350 times heavier than the bullet.

So if we have a 24 inch barrel and the bullet moves 22 inches the gun will move back 22/350ths of an inch, about a 1/16th of an inch. A bit more in practice because we also have the powder weight.

The practical affect of that is seen with heavy barrel varmint rifles in 224 calibres and lighter weight 458s with 500 grain bullets. The latter is far more sensitive to consistent hold if flyers are to be avoided.

Mike

Pressure x area = force

soooo if an equal pressure is applied to a larger area wouldn't that equal more force.

eg

62000 psi x .0745 = 4,619 psi/in2 (.308 cal)
62,000 psi x .1963 = 12,173 psi/in2 (.500 cal)

Seems to me that the same force applied to a larger bolt face would cause more recoil.

What say you?

Jim