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Posted: 3/22/2007 1:09:48 PM EDT
| Are there ant advantages to polygonal rifling vise conventional rifling? |
That is a polygonal bore and is a totally differnt thing. Polygonal rifling has a land and groove profile. Do not confuse the two. Polygonal bores can only be made through hammer forging the barrel. Polygonal rifling is made by button rifling a barrel. |
I think its advantages lie in the manufacturing process, and not as an improvement to conventional rifling. IOW, manufacturers do it as a way to save money and/or produce barrels faster. |
Why couldn't a polygonal bore be produced by button rifling like any other type of rifling? IME polygonal bores are the easiest cleaning barrel I've ever used, I'd list that as one of the advantages, along with higher velocity, theoretically greater accuracy due to less deformation/stress on the bullet, better wear characteristics, and better uniformity of bore coating/lining materials (chrome, etc) |
I thought so too, but have since changed my mind. I took a few peaks down "clean" polygonal bores using a borescope only to find a distictive pattern of "dirty" in them. Polygonal bores do not allow brushes to naturally follow the bore like conventional bores do. You have to twist the cleaning rod with your fingers to get it t follow the barrel's twist or you'll find it consistently skips entire sections of the bore. Otis Pull-through kits make cleaning them particularly difficult because you cannot guide the brush. |
I don't use brushes that much anyway, patches do most of the work, and with a snug fit they seem to turn with the rifling just fine (although for full disclosure, I have limited experience with rifle caliber poly bores) |
I think my Noveske came with a card that said all of that. I'm sure I've read it somewhere before, maybe it was on teh site of a vendor that sells them. |
If you cant understand why a polygonal bore cant be produced via button rifling I dont think I can explain it adequately but I will try. Button rifling makes little grooves in an already round bore. It presses them in directly. You cant make the groove the size of the bore like you are describing to get a polygonal bore. The button creates both lands and grooves. If you can design a tool that could do this in a single pass you would be able to make money either selling it or making your own barrels. Noone has created such an item to my knowledge and no such barrels exist. |
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Polygonal rifling != Polygonal bores. If I recall correctly, a polygonal bore is what Glock and HK uses for their pistols. Polygonal rifling is just standard button rifling where the lands/grooves are not squared, but are usually advertised to mislead the avg buyer into thinking it is the same as a polygonal bore. |
From what I understand this is true. As far as polygonal rifleing, I always understood that it was opposite from conventional rifleling, ie groves stick out into the bore and lands go away from the bore. |
Are you sure? I mean, you should know what you're talking about since you guys use their barrels, but I asked Woody to clarify this for me and he said that it was like the glock. Of course I also asked him how much to do a run of stainless 1/7 blanks and he gave me a quote + a set up charge for production, only to find out that he was already making exactly what I wanted for you guys. Do you have a photo from the muzzle of one of your barrels, so we could see the "rifling"? |
| Polygon rifling is when the lands are canted at angles and sometimes have a small radius at the edges. Schneider makes polygon barrels (buttoned) that David Tubb uses in all his rifles. It is explained on Tubbs websight. It gives slightly higher muzzle velocity due to better seal on bullet. Pac-Nor, Noveske and Broughton also make polygon barrels. Cut rifled barrels with the Obermeyer 5R rifling are basically the same as polygon rifling. Mike Rock, Border and Bartlein all cut barrels with the 5R rifling. |
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