Rifle torque??

[MagnumManiac]

G’day all,
How many of you shooting light hunting rifles notice the rifle twist from the torque imparted by the bullet?

I have several lightweight hunting rifles in some pretty potent cartridges, ie 270 Weatherby 6.5lb scoped, 264WM 7.2lb scoped, 300WM 7.5lb scoped, 338WM 7.5lb scoped and 375 Weatherby 8lb scoped.
They all torque to differing degrees, the 264, 300 and 375 seem to be the most noticeable, however, the others do it too.

What are your experiences with this?

Cheers.

 

[Bc'z]

I was reading your post thinking this guy shoots a lot of magnums, then I saw your handle.
Im'ma gonna say it's inevitable, probably more pronounced with with lite rifle in heavy caliber.

 

[XTR]

Most noticeable I've ever had was shooting a 45-70 with 535 gr bullets. It will rotate 45 degrees in your hands if you don't hold on. (very noticeable with that tall sight on the back)

 

[mikegaiz]

This is how I counter for competition guns.

 

[Sniper338]

My 338 lapua torqued pretty bad. A wide f class bipod fixed it. Needed a good bipod anyways back then.

 

[MagnumManiac]

I also shoot F-Class with 3 cartridges, a 22-250AI, 264WM and 300WM. Depending on range and conditions.
I also use a wide bi-pod because when I was using a front rest, no matter how tight I had it the 300 would twist in the rest, it still came straight back though.

The reason I asked initially is due to my buddy firing my Kimber 8400 in 300WM with 200gr Accubond and the rifle twisted to just less then 45 degrees in his hands and he asked if it ALWAYS did that!? Which I replied it does if you don’t hold it tight enough.

Cheers.

 

[K22]

My Browning X Bolt synthetic stalker, 223, torques (twists to the left) when I shoot it off my shooting sticks. I believe it's due to the rubberized factory stock not providing sufficient stable contact with the sticks combined with the light weight of the rifle. Interesting the same model rifle in 243 but with a wooded stock does not exhibit any torquing.

Since I could not find any after market stock to fit their "super short action" I solved the problem by attaching a bipod to the rifle to more weight, moving the rifle on the sticks so the thicker part of the rifle, near the magazine, sits on the sticks and paying close attention to my hold keeping it firm throughout the shot. Admit not ideal but works.

 

[Clark]

Doing a Google search I can see it is easy to calculate the torque the bullet imparts on the gun about the bore axis.

Much harder is calculating the moment of inertia [remember freshman physics?] of the rifle shape and mass.... to solve for the rifle free recoil rpm

Here is italics is some work I stole from the benchrest forum:
determine the amount of torque the moving bullet will apply to the gun is:

M = (1.7x10^-9 x W x R^2 x n )/T
M= torque in lb ft
W = bullet weight in grains
R = radius of bullet diameter in inches
n = RPM of bullet
T = time bullet is in barrel in seconds
I applied this to a 50 grain .22 caliber leaving barrel at 300000 RPM with a barrel time of 1 millisecond. I got .31 lb ft torque. Determining how much the gun will move before the bullet leaves could be figured but it depends on so many things that would be hard to pin down that I wonder if you could ever get close. For example, friction at the gun support would probably be very tough to predict.

I had a job doing electrical designing of a starter generator for a jet engine 12 years ago, but the mechanical guys designed the flywheel, which was the test load. We measured the torque with a strain gauge on the shaft and sent a battery powered radio signal to our non spinning world. That flywheel had an easy moment of inertia to calculate.

 

[Bart B.]

Some 50 odd years ago or more, an article in the American Rifleman on the guy who won the big 1000 yard prone match at the Nationals mentioned him noticing the scope reticle slighty twisting from the 200 grain loads in his 30-06 ammo.

A lot of the rifle shooting sports magazines comments on it were all over the map in disbelief. Impossible, in so many words. Left hand twists would unscrew the barrel.

Easier to see with 50 caliber BMG ammo.

 

[steve123]

A good way to counter act the motion is to push your left foot into the bench just next to you and hold onto the rifle very tight/

When I do this I always beat that guy just to the left, that is if he doesn't get to beating on me with some object he has near his bench.

Or get a left twist barrel and use your right foot.

 

[ShootDots]

I have found that torque increases in direct proportion to: 1.) Case capacity; 2.) twist rate of the barrel and 3.) the length of the bearing surface of the bullet. L-O-N-G bullets shot in a fast twist barrel with a large case is difficult to control. However, if shooting off a pedestal style rest i.e. NEO, you can tighten the ears against the sides of the stock, you can generate enough resistance by this tightening to control the torque. I am sure there is a point of no return, however, that point may be reached by the B-I-G, as in Chey-Tac BIG! Even then the NEO MAXI may be able to help.. I don't know. But everything from WSMs and SAUMs down can be controlled in this manner..

 

[6MMsteve]

A good way to counter act the motion is to push your left foot into the bench just next to you and hold onto the rifle very tight/

When I do this I always beat that guy just to the left, that is if he doesn't get to beating on me with some object he has near his bench.

Or get a left twist barrel and use your right foot.

that's funny lmao

 

[6MMsteve]

I offset my stocks bout 4inches , offset rails to left, stock barrel to right, all 3 guns shoot much better than I can

 

[6MMsteve]

This is how I counter for competition guns.

View attachment 1076084 View attachment 1076085

Nice

 

[savagedasher]

I expiermented width the barrel lower the the rest what a difference that made

 

[muleman69]

My Browning X Bolt synthetic stalker, 223, torques (twists to the left) when I shoot it off my shooting sticks. I believe it's due to the rubberized factory stock not providing sufficient stable contact with the sticks combined with the light weight of the rifle. Interesting the same model rifle in 243 but with a wooded stock does not exhibit any torquing.

Since I could not find any after market stock to fit their "super short action" I solved the problem by attaching a bipod to the rifle to more weight, moving the rifle on the sticks so the thicker part of the rifle, near the magazine, sits on the sticks and paying close attention to my hold keeping it firm throughout the shot. Admit not ideal but works.

So your rifle has right twist rifling and torques left?

 

[muleman69]

My 338 lapua torqued pretty bad. A wide f class bipod fixed it. Needed a good bipod anyways back then.

What would be a good wide bipod?

 

[Sniper338]

Rempel, phoenix, joypod, majestic... f class bipods

 

[K22]

So your rifle has right twist rifling and torques left?

I only thing I know for sure is this rifle twists to the left when I fire it off a shooting cross sticks. I can minimize this affect by positioning the rifle on the thick part of the stock, i.e. near the magazine (which is not ideal for shooting off a cross stick) and use a firm hold and follow though with the shot.

The stock is a "rubberized", i.e. "sticky to the touch" factory stock. I want to replaced it but can't find an after market replacement wooden or composite material stock for a Browning super short action.

My 243, same model, with a factory wooden stock, does not exhibit this tendency to twist to the left.

 

[muleman69]

I only thing I know for sure is this rifle twists to the left when I fire it off a shooting cross sticks. I can minimize this affect by positioning the rifle on the thick part of the stock, i.e. near the magazine (which is not ideal for shooting off a cross stick) and use a firm hold and follow though with the shot.

The stock is a "rubberized", i.e. "sticky to the touch" factory stock. I want to replaced it but can't find an after market replacement wooden or composite material stock for a Browning super short action.

My 243, same model, with a factory wooden stock, does not exhibit this tendency to twist to the left.

Do you think the rifling could be a left twist? Sounds like you have it figured out though. Really hard to shoot off of sticks at magazine for sure