RIFLING TYPE

[texas]

Ok I read about different types Cut,Button,Freebore and Polygonal any idea as to which is the best or is just personal choice?

Will one give faster spin or velocity? What about stabilizing the bullet longer?

If you have a question ask before its too late to ask . Or you might fail the test.

 

[Garrum]

Cut rifling and Button rifling refer to how the rifling was created in the barrel. Cut rifling is made by individually cutting the grooves, one at a time a little at a time. Cut rifling is supposed to impart little to no stress on the barrel.

Button rifling is formed by pulling a slightly oversize carbide 'button' through the bore, which presses the grooves into the steel. Button rifling is supposed to be a little 'stressful' on barrels, but I'm not sure how much.

Freebore is really just an extra long throat, and not a rifling type. Weatherby uses it to keep the pressure from peaking so steeply on their magnum rounds.

Polygonal rifling is primarily used in handgun barrels. It can only be used with jacketed bullets, as cast bullets lead the barrel very fast. It is however, supposed to give a slight velocity increase with jacketed bullets. I don't know of anyone who uses Polygonal rifling in rifle barrels, but that doesn't mean that no one does.

As far as one type rifling stabilizing a bullet better than another, I don't think it would. That would depend more on the rate of twist that your barrel has. A faster twist equals a more stable bullet(more or less).

Hopefully this answered some of your questions. If not, maybe one of the serious shooters will chime in, and set us both straight.

 

[texas]

Thanks for the info. As far as I know only I believe H&K does the polygonal rifling.
Reading another post I saw that the freebore system on Weatherbys is not the best but not the worst either. So that leaves the CUT or BUTTON RIFLING to choose from. Any idea as to which is more consistant and longer lasting for barrel shoot out.

 

[Garrum]

Supposedly, both kinds of rifling are pretty consistent, but if I had to venture a guess, I would think that cut rifling is a little more accurate. This isn't based on any actual evidence, just a gut feeling.

And as far as which kind would last longer, I wouldn't think there would be any difference.

 

[Brent]

Texas,
I saw my friend Erics 357 Sig H&K Poligonal barrel yesterday. They look cool. He said it was chromed too.

I think Dave King has a Poligonal bore in a rifle, can't remember what caliber if I'm even remembering correctly to begin with. He has some thing different like that though.

 

[texas]

Dave King do you have a rifle with polygonal rifling and if you do how does it shoot compared to some of your other guns? Also who did it for you?

 

[Dave King]

Yes, many of my rifles have polygonal rifing, I get them from Tac-Ord in Meridian ID, the barrels are from Pac-Nor.

The rifles shoot very well but don't particularly care for the solid alloy bullets (Barnes, Lost River, etc).

My 338 RUM is a 1x8 338, my 223 Rem is a 1x7 and most of the 308s I've recently had are 1x10. I've been told that the twist needs to be a little faster with the Polygonal rifled barrels.

Overall ALL my rifles are sub .5MOA rifles, some get into the .25MOA range on occasion.

For more info on polygonal call Jim Ryan at Tac-Ord (208) 288 1450.

Some/all of Lothar Walther barrels are polygonal too (I believe).

 

[texas]

Dave thanks for the info, I'll give Jim a call. What I think I want is to neck up a 308 case to take a 338 bullet.
If they can do it with a 35 caliber bullet (358 win.) then a 338/308 should work. The 358is suppose to get about 2200 fps with a 300gr. bullet and 2250 with a 250gr factory load. I hope to get at least 2500fps out of a 22-24" barrel with this combination.