Why Polyagonal Rifling ????

[Uncle_Steve]

I have seen this as an option on some of the uppers lately. Why is it any better than cut rifling?

 

[rockinbbar]

Have a look at this thread:

http://www.m4carbine.net/showthread.php?t=22848

 

[doggin coyotes]

I read page one and got a headache. Done overloaded my pea brain. No way I'm doing page 2.

 

[dogmessiah]

Simplest way to think about it is because polygonal rifling doesn't have sharp grooves the bullet does a better job of sealing the barrel when the [beeep] of the bullet expands. Consequently you get more velocity, however shooting lead bullets makes them foul quicker and can cause dangerous pressures.

 

[Uncle_Steve]

Thanks for the info, It helped a lot.

Steve

 

[CastleRocker]

I'm really curious how polygonal rifling would cause the barrel to foul quicker with cast lead bullets. I shot nothing but cast bullets back when I shot IPSC, and I had to go TO polygonal rifling to help PREVENT excessive lead fouling. There aren't any lands and grooves to fill up with lead in a polygonal rifled barrel. That's just been my experience, but my cast bullets were pretty hard in order to shoot major power factor, so maybe that made a difference. (Although it would seem to me that to softer the casting the more fouling at a given load, not the other way around). So like I said, I have to wonder about that one.

 

[Brandon Sneed]

Originally Posted By: dogmessiahSimplest way to think about it is because polygonal rifling doesn't have sharp grooves the bullet does a better job of sealing the barrel when the [beeep] of the bullet expands. Consequently you get more velocity, however shooting lead bullets makes them foul quicker and can cause dangerous pressures.

Quite the contrary. Polygonal actually reduces pressures, and allows for greater loading capacity in cases that allow it, without increasing the pressure signs. The same can be accomplished by increasing the number of grooves of a lapped barrel as well.