Right or Left Hand Rifling?

[striker]

Found this on the web. Hey, sounds good.


1. Newtons laws of physics hold within the firearms community. Thus, if a
bullet is caused to spin either by a lefthand or righthand twist rifled
barrel, it does so because there is an exact same force (less frictional
losses) exerted on the rest of the rifle. Hence, as the bullet accelrates to
(say) the right along a rifled barrel, the rifle itself is is accelerated to
the left. The rifle wights more than the bullet, so the degree of
acceleration is proportional to the bullet/rifle weight ratio as a function of
the exit velocity of the projectile from the rifle muzzle.

2. From the 1850's onwards the British tended to have an empire where
rifled sporting firearms came into widespread use in India and Africa, and
said empire was populated by large/dangerous animals, in turn requiring large
bore / high energy projectiles to safely dispatch. Shooting large bore
projectiles has the downside that said projectiles tend to pound the user.
The larger the rifle bore, the larger the energy (in general terms) and hence
the larger the energy able to be transmitted either left or right by the stock
.... into the users cheek.

3. Here is the crux of the topic. By choosing to rifle the bore either
with right hand twist or left hand twist rifling, the designer can choose to
have the rifle stock twist into the shooters face or twist away from their
face. By convention, the British chose to have the rifling of their large
bore rifles cause the stock (remember Mr Newtons laws here) to move away from
the shooters face, rather than twist into their cheekbones. The recoil energy
transmitted to the users shoulder remains the same in both cases.
Interestingly, many American makers at the turn of the century made barrels
with a twist opposite to the "standard" British pattern, thereby causing their
customers to directly experiece a triumph of fashion over physics.

4. For an interesting demonstration of the abovee, obtain two identical
rilfes, preferably with high combs for scope mounts ... one with left hand
rifling, one with left hand rifling. Obtain a very solid cheek weld and fire
the same ammunition in both rifles. One rifle will twist into your cheek, one
will twist away from your cheek. You will immediately be able to tell which
rifling is which, as one of the rifles will smash into your cheek while the
other will not disturb you at all. The author had the opportunity to observe
this at first hand some 25 years ago, a lesson not easily forgotton in heavy
recoilng rifles.

cheers
sankar

http://www.xdtalk.com/forums/xdtalk-cha ... fling.html

[raj]

I must say its a very informative article....
some nice facts n catches about the firearms..!!
real great stuff!!!

[timmy]

This is certainly interesting enough! Read thru your post and also the link you posted.

My Cartridges of the World shows that, for military rifles, the nations using left hand twist rifling were the UK, France, and Norway. Everyone else used a right hand twist. A quick peek at my SMLE 2A shows a right hand twist.

I am interested in the idea of perceived recoil being the reason here, as it seems plausible. I had not thought of this. I have seen other ideas, but this was connected with my interest in Colt revolvers, which almost always (but not always) had a left hand twist.

The reasons for this, so I've read, include: 1. The left hand twist offsets the direction the barrel is screwed into the frame. Supposedly, according to this theory, that is why Smith & Wesson revolvers have the barrels pinned, but Colts do not. 2. Another theory is that the left hand twist in Colts revolvers causes the downrange bullet drift to offset the natural tendency of a right-handed shooter to pull shots to the right.

The first theory has a little plausibility in my mind. Colts revolver cylinders rotate clockwise, and they use left hand threads in the cylinder mechanism to compensate for this and ensure that these joints stay tight.

The second theory seems a bit troublesome. The fact is that Samuel Colt was left handed, and you can see the legacy of this in many Colts firearms. For instance, the Single Action Army (the standard sidearm of US Western movies) is clearly intended for left handed operation (even tho Col. Colt was long dead by then): The weapon is held in the left hand and the loading gate is on the right.

If you note Colts double action revolvers, vs. Smith & Wesson, you see Colts cylinders rotate clockwise, but Smith & Wesson cylinders turn counter-clockwise. You also see the side plate of Colts on the left of the revolver, while Smith & Wesson's are on the right hand side.

(This is one reason why I prefer Colts double action revolvers to Smith & Wesson: the hand of Colts revolvers pushes the cylinder into the frame, while the hand of Smith & Wesson revolvers pushes the cylinder out of the frame. I believe that this is one reason why Smith & Wesson has to include a second lock at the front of the cylinder ejection rod and include a corresponding lug on the barrel.)

So, it seems to me that the twist of Colts revolvers could be more due to the handedness of the company's founder.

Strange? Consider that British autos, and often the nations that were in their empire or closely associated with them (like Japan) at the turn of the century are right hand drive. I understand that the reason for this was that jousting took place, along with wielding a sword, generally with the right hand. So, jousters passed on the each other on the right sides and the left hand was free (presumably to handle the shift lever).

Still, the list of nations that chose left hand rifling twist is interesting: Norway became independent in 1905 from Sweden and was closely aligned with the UK thru royal marriage. (King Haakon VII was married to Queen Maud, who was Britain's King Edward VII's daughter.) Discounting Britain and British influence, France's choice of left hand rifling is interesting. French engineering often chooses solutions that do not appear like the solutions of other nations, but are often quite rational and workable. I guess that, for this reason, the idea of felt recoil influencing the twist of rifling seems valid enough to me.

Thanks for sharing!

[TenX]

Very good info, and a great discussion Striker and Timmy.. Thanks a bunch