Question about riffling.

[Jadd]

Hi to everybody, I have a little question about the riffing of my revolver : I own a M&P R8 (great gun!!) I have read before buy it that it has a polygonal riffling, then in another thread, someone said, no, it's not a polygonal riffling, it's a EDM riffling...
So, I'm a little confused but very curious, can anyone could enlighten me about this point (and eventually about good points and bad points)
Thanks in advance

 

[bgrafsr]

If I'm not mistaken, the rifling in your gun barrel is done by the EDM process.

Glocks have polygonal rifling.

 

[OKFC05]

It is EDM rifling. (riffling is a different word)

It is very smooth and uniform, and reduces production costs.

 

[Jadd]

Thanks to correct me about the spelling

About the EDM rifling, could you tell me more about his features.
Is it OK to shoot lead bullets with it for example?...

 

[slickracer]

Thanks to correct me about the spelling

About the EDM rifling, could you tell me more about his features.
Is it OK to shoot lead bullets with it for example?...

It will shoot lead just fine.

 

[Jadd]

Thanks, I was worried about that!
For now I shoot lead wadcutter, and fmj bullets, but I would like to widen my possibities of reloading...

 

[Pisgah]

It stands for Electrical Discharge Machining, just another way to remove metal.

 

[Jadd]

It stands for Electrical Discharge Machining, just another way to remove metal.

Yes, I have read that in another thread : does it means any improvement?

 

[Bullet Bob]

Other than smoothness and the lower production costs mentioned above, no.

It is traditional type of rifling, just as S&W and most others have always had, just done by a different process.

 

[Jadd]

Other than smoothness and the lower production costs mentioned above, no.

It is traditional type of rifling, just as S&W and most others have always had, just done by a different process.

Thanks for the clarification !

 

[Neumann]

EDM is one way of cutting metal, by electrical discharge (spark between tool and object). Other methods include broaching, button, swaging and hammer forging (externally, against an internal tool). Polygonal rifling refers to the geometry, a series of flat surfaces in a spiral, as opposed to grooves and lands.

In general, polygonal rifling tends to strip lead from soft bullets, and foul rapidly. You can use hard cast bullets, however, as well as jacketed bullets. Cast bullets must be somewhat oversized so that they seal the bore properly. Undersized bullets will lead badly, whether hard or soft. That may be the principal obstacle to successful use in a polygonal barrel, since there is a larger difference between the minimum and maximum effective diameter of the rifling than with lands and grooves, and greater displacement of metal required.

 

[Jadd]

EDM is one way of cutting metal, by electrical discharge (spark between tool and object). Other methods include broaching, button, swaging and hammer forging (externally, against an internal tool). Polygonal rifling refers to the geometry, a series of flat surfaces in a spiral, as opposed to grooves and lands.

In general, polygonal rifling tends to strip lead from soft bullets, and foul rapidly. You can use hard cast bullets, however, as well as jacketed bullets. Cast bullets must be somewhat oversized so that they seal the bore properly. Undersized bullets will lead badly, whether hard or soft. That may be the principal obstacle to successful use in a polygonal barrel, since there is a larger difference between the minimum and maximum effective diameter of the rifling than with lands and grooves, and greater displacement of metal required.

Thanks, that's very interesting and perfectly logical!