Gunsmithing Lothar Walther polyg.barrels
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Re: Lothar Walther polyg.barrels
I got a LW barrel with polygonal rifling, but can't comment on the velocities, since I don't have a chrono.
I'd like to hear an answer to this thesis, too.
I got a LW barrel with polygonal rifling, but can't comment on the velocities, since I don't have a chrono.
I'd like to hear an answer to this thesis, too.
Re: Lothar Walther polyg.barrels
..
I know, lets kick a bees nest!
This is a controversial issue with either side fully able to defend their position. Polys were designed originally to attend to the issue of high volume fire and its impact on jacketed bullets being torn up. There is so much more I want to puke. All the way to conversations about the inability to properly measure wear on the mandrel used to make them. Forget about it, its mental masterbation. Worry much much more about your chamber and lead in. Throat erosion, gas cutting, etc.
Here...
"I don't want this to be taken as a flame and is not directed toward anyone, only I felt compelled to reply because IMHO there is just too much incorrect information being put out about polygonal VS conventional bores. I do not understand how people think that conventional land and groove rifling lets gas escape around the bullet. Throat erosion and gas cutting that occurs right in front of the chamber happens because of a combination of several things, not just the very tiny amount of gas that might be going around the bullet before it completely obturates, but from the burning of the powder and the tremendous heat and peak pressures that occurs in those first few inches the barrel. If gas were shooting past bullets all the way down the barrel, barrels would burn out in no time flat, accuracy would non-existent, and extreme spreads would be sky high. None of these events are seen in conventionally rifled bores any more so than they are seen in polygonal bores. If you slug a conventional rifled bore you will find the groove diameter is the same as the bullet's diameter. And don't think for a minute that a jacketed bullet will not obturate to fill the bore if slightly undersized, say shooting a .308 bullet in a .309 bore. They will completely obturate and seal the bore the same as a soft lead slug will. We are talking about pressures here that will blow a barrel apart if obstructed; you don't think that it won't obturate something as soft as a bullet, hogwash. In a .45 ACP you shoot a jacketed bullet of .451 to .452 diameter. The groove diameter of the .45 ACP conventional rifled barrel is .451 but can vary as much as .001 inch in a crummy barrel. The land diameter is several thousands less than that. The bullet does NOT ride on top of the lands, the rifling cuts into the bullet. No gas escapes around the bullet any more in a conventionally rifled barrel than does a polygonal bore. Also, if polygonal bores are so much more accurate which I often hear stated, how come you do not see them showing up in all the BR guns and LR guns? You don't. People who shoot LRBR will pay any amount for a barrel if it will give them an edge, and polygonal bores do not. They are accurate, sure, but they are not more accurate than conventionally rifled bores. Sure, you can find an individual polygonal bored barrel that is more accurate than an individual conventionally rifled barrel, but that is purely anecdotal, meaning nothing to the overall picture. If polygonal boring were more accurate you would see Lothar-Walther, K&P, Lilja, McMillan/Wiseman, Shilen, Wilson...all the top barrel makers going to polygonal bores. They aren't. You don't get better barrels than what these makers produce, so while there MIGHT be advantages to polygonal bores on a combat rifle/pistol there are none when it comes to accuracy. That is just pure sales propaganda, period. Sure, one can find all the anecdotal "evidence" one wants to make a point such as my HK out shoots my Colt, but that proves nothing. Look at what the top barrel makers in the WORLD produce, and an "ain't" polygonal bores. And furthermore, if polygonal bores are just as accurate as conventionally rifled bores but offer less throat erosion, then do you think for one minute that if these top barrel makers could sell a barrel that is just as accurate but last longer without having to be set back and rechambered they wouldn’t? Of course they would because if it were true, a barrel maker that came out with a barrel that was just as accurate AND held its accuracy longer would put the others out of business in a heartbeat. In the world of LRBR shooting, what works is used, they will do or try anything to give them any edge at all, even if it means killing a chicken at midnight under a new moon. They hold few loyalties.
The other claim often made is the polygonal bores offer less resistance so they shoot the bullet faster. Again, hogwash. Take a bullet in a conventional rifled barrel. Shoot a particular load over a chrony and get a velocity. Now, take those same bullets and coat them with molly and shoot them over the same load in the same gun, what happens? Velocity goes down because of LESS resistance to the bore, and because less resistance means less pressure develops in the barrel. To get the pressure back up to where it was before, you add more powder. More powder means more gas expanding, and by the time you add enough powder to get the pressures to where they were before you have a larger volume of expanding gas and the end result is that the bullet is going faster with a molly coated bullet when loaded to the same pressure. That is why you cannot take a load worked up with molly coated bullets and substitute a non-coated bullet. The non-coated bullet will raise pressures sky high. So, if one sees higher velocities with a given load out of a polygonal bore versus a conventional bore, then it must be because HIGHER pressures are being developed in the polygonal bore, not less, so the polygonal bore must be creating MORE resistance to the bullet, NOT LESS.
I have shot loads though many .45s in polygonal and non polygonal bores, and the velocity difference between barrels of the same length are well within the standard deviation of individual barrels. One HK might shoot a hair faster than the conventional bored barrel, another HK shoots a little slower, same as with the normal variation found between any set of barrels. I know HK and Glock make all kinds of claims about the superiority of polygonal versus conventional bores, but nothing I have seen proves any, and some of the claims made by supporters are against the laws of physics. You cannot decrease resistance which lowers pressures and increase the velocity of a bullet, it ain't gonna happen.
The only claim often made that could hold any water is that they last longer. IF the polygonal bore offers less resistance, then less pressures develop in the barrel, then of course that barrel is going to last longer, same as with shooting molly coated bullets in match barrels with conventional rifling.
IMO if there is any advantage of one method over the other it has to do with manufacturing costs. If anyone can make a barrel that is just as good as another barrel but make it cheaper, then that is what they are going to do. HK and Glock went the polygonal route and the barrels work. Why change. Same with all the others. They chose the other route, their barrels work, why change. I think what we see here are two methods to achieve the same end.
We’ve all heard raves about new barrels that come out from time to time, gain twist, tapered bores, RH vs. LH twist, more or less number of lands and grooves…and as yet has any one method proven to be light years ahead of the other? No, they have not. Marlin invested tons of money in their Micro-Groove barrels and they work. But yet they don’t work as well with all bullets so they have gone back to conventional rifled barrels for those who regularly shoot lead. And while with jacketed bullets the Micro-Groove works very well, it does not work any better, not when you get right down to the brass tacks of it. And don’t forget the gain twist and tapered bored barrels which are rare birds indeed. They work sure, but do not offer the hoped for results often claimed, but once invested, the makers continue to make them that way for as long as they can because as with any venture, there is a client base that will swear by this or that without any real evidence to support their prejudice (sort of like me with the .45 ACP). If any of them offered any real gain, then those barrels would dominate the shooting industry and the firing line, they do not. In fact, the only barrels that do dominate the world of firearms IS the conventionally rifled barrel. Many other barrels are good, some very good, but other than the occasional anecdotal story, there is no solid, irrefutable evidence that I have seen that suggests any one method is any better than the other.
OK, now take all the above with a grain of salt. It is worth exactly what you are paying for it."
..
I know, lets kick a bees nest!
This is a controversial issue with either side fully able to defend their position. Polys were designed originally to attend to the issue of high volume fire and its impact on jacketed bullets being torn up. There is so much more I want to puke. All the way to conversations about the inability to properly measure wear on the mandrel used to make them. Forget about it, its mental masterbation. Worry much much more about your chamber and lead in. Throat erosion, gas cutting, etc.
Here...
"I don't want this to be taken as a flame and is not directed toward anyone, only I felt compelled to reply because IMHO there is just too much incorrect information being put out about polygonal VS conventional bores. I do not understand how people think that conventional land and groove rifling lets gas escape around the bullet. Throat erosion and gas cutting that occurs right in front of the chamber happens because of a combination of several things, not just the very tiny amount of gas that might be going around the bullet before it completely obturates, but from the burning of the powder and the tremendous heat and peak pressures that occurs in those first few inches the barrel. If gas were shooting past bullets all the way down the barrel, barrels would burn out in no time flat, accuracy would non-existent, and extreme spreads would be sky high. None of these events are seen in conventionally rifled bores any more so than they are seen in polygonal bores. If you slug a conventional rifled bore you will find the groove diameter is the same as the bullet's diameter. And don't think for a minute that a jacketed bullet will not obturate to fill the bore if slightly undersized, say shooting a .308 bullet in a .309 bore. They will completely obturate and seal the bore the same as a soft lead slug will. We are talking about pressures here that will blow a barrel apart if obstructed; you don't think that it won't obturate something as soft as a bullet, hogwash. In a .45 ACP you shoot a jacketed bullet of .451 to .452 diameter. The groove diameter of the .45 ACP conventional rifled barrel is .451 but can vary as much as .001 inch in a crummy barrel. The land diameter is several thousands less than that. The bullet does NOT ride on top of the lands, the rifling cuts into the bullet. No gas escapes around the bullet any more in a conventionally rifled barrel than does a polygonal bore. Also, if polygonal bores are so much more accurate which I often hear stated, how come you do not see them showing up in all the BR guns and LR guns? You don't. People who shoot LRBR will pay any amount for a barrel if it will give them an edge, and polygonal bores do not. They are accurate, sure, but they are not more accurate than conventionally rifled bores. Sure, you can find an individual polygonal bored barrel that is more accurate than an individual conventionally rifled barrel, but that is purely anecdotal, meaning nothing to the overall picture. If polygonal boring were more accurate you would see Lothar-Walther, K&P, Lilja, McMillan/Wiseman, Shilen, Wilson...all the top barrel makers going to polygonal bores. They aren't. You don't get better barrels than what these makers produce, so while there MIGHT be advantages to polygonal bores on a combat rifle/pistol there are none when it comes to accuracy. That is just pure sales propaganda, period. Sure, one can find all the anecdotal "evidence" one wants to make a point such as my HK out shoots my Colt, but that proves nothing. Look at what the top barrel makers in the WORLD produce, and an "ain't" polygonal bores. And furthermore, if polygonal bores are just as accurate as conventionally rifled bores but offer less throat erosion, then do you think for one minute that if these top barrel makers could sell a barrel that is just as accurate but last longer without having to be set back and rechambered they wouldn’t? Of course they would because if it were true, a barrel maker that came out with a barrel that was just as accurate AND held its accuracy longer would put the others out of business in a heartbeat. In the world of LRBR shooting, what works is used, they will do or try anything to give them any edge at all, even if it means killing a chicken at midnight under a new moon. They hold few loyalties.
The other claim often made is the polygonal bores offer less resistance so they shoot the bullet faster. Again, hogwash. Take a bullet in a conventional rifled barrel. Shoot a particular load over a chrony and get a velocity. Now, take those same bullets and coat them with molly and shoot them over the same load in the same gun, what happens? Velocity goes down because of LESS resistance to the bore, and because less resistance means less pressure develops in the barrel. To get the pressure back up to where it was before, you add more powder. More powder means more gas expanding, and by the time you add enough powder to get the pressures to where they were before you have a larger volume of expanding gas and the end result is that the bullet is going faster with a molly coated bullet when loaded to the same pressure. That is why you cannot take a load worked up with molly coated bullets and substitute a non-coated bullet. The non-coated bullet will raise pressures sky high. So, if one sees higher velocities with a given load out of a polygonal bore versus a conventional bore, then it must be because HIGHER pressures are being developed in the polygonal bore, not less, so the polygonal bore must be creating MORE resistance to the bullet, NOT LESS.
I have shot loads though many .45s in polygonal and non polygonal bores, and the velocity difference between barrels of the same length are well within the standard deviation of individual barrels. One HK might shoot a hair faster than the conventional bored barrel, another HK shoots a little slower, same as with the normal variation found between any set of barrels. I know HK and Glock make all kinds of claims about the superiority of polygonal versus conventional bores, but nothing I have seen proves any, and some of the claims made by supporters are against the laws of physics. You cannot decrease resistance which lowers pressures and increase the velocity of a bullet, it ain't gonna happen.
The only claim often made that could hold any water is that they last longer. IF the polygonal bore offers less resistance, then less pressures develop in the barrel, then of course that barrel is going to last longer, same as with shooting molly coated bullets in match barrels with conventional rifling.
IMO if there is any advantage of one method over the other it has to do with manufacturing costs. If anyone can make a barrel that is just as good as another barrel but make it cheaper, then that is what they are going to do. HK and Glock went the polygonal route and the barrels work. Why change. Same with all the others. They chose the other route, their barrels work, why change. I think what we see here are two methods to achieve the same end.
We’ve all heard raves about new barrels that come out from time to time, gain twist, tapered bores, RH vs. LH twist, more or less number of lands and grooves…and as yet has any one method proven to be light years ahead of the other? No, they have not. Marlin invested tons of money in their Micro-Groove barrels and they work. But yet they don’t work as well with all bullets so they have gone back to conventional rifled barrels for those who regularly shoot lead. And while with jacketed bullets the Micro-Groove works very well, it does not work any better, not when you get right down to the brass tacks of it. And don’t forget the gain twist and tapered bored barrels which are rare birds indeed. They work sure, but do not offer the hoped for results often claimed, but once invested, the makers continue to make them that way for as long as they can because as with any venture, there is a client base that will swear by this or that without any real evidence to support their prejudice (sort of like me with the .45 ACP). If any of them offered any real gain, then those barrels would dominate the shooting industry and the firing line, they do not. In fact, the only barrels that do dominate the world of firearms IS the conventionally rifled barrel. Many other barrels are good, some very good, but other than the occasional anecdotal story, there is no solid, irrefutable evidence that I have seen that suggests any one method is any better than the other.
OK, now take all the above with a grain of salt. It is worth exactly what you are paying for it."
Re: Lothar Walther polyg.barrels
Thank you thun51 my big conscern was i have seen a couple of comments or complaints of low vel. readings. I have pretty much settled on a LW.drop in ar10 308 ( not sure about chamber choices they have yet)due to reputation of steel and throat wear and ready drop in so since good 308 velocity is hard to come by i was just tryin to get some info out there.
Thank you thun51 my big conscern was i have seen a couple of comments or complaints of low vel. readings. I have pretty much settled on a LW.drop in ar10 308 ( not sure about chamber choices they have yet)due to reputation of steel and throat wear and ready drop in so since good 308 velocity is hard to come by i was just tryin to get some info out there.
Re: Lothar Walther polyg.barrels
A couple things to add to the mix:
I've had "Polygonal" barrels from both LW and Schneider. However, these differed from an HK or Glock polygonal barrel. When you looked down the barrel, it didn't look like a kaleidoscope like an HK barrel. It looked like a normal barrel. The reason for this, I was told by Schneider if I remember right (it was years ago), was that they weren't true polygonal, more like "rounded land". The LW appeared to be the same.
I will say I have run an LW to 10k rounds of 308 on a pretty rough firing schedule testing a semi-auto and while the throat eroded significantly, it was still holding around 2moa, which in a gas gun really isn't too bad. I didn't notice any low vel except as the barrel wore the velocity dropped relative to its original velocity.
Justin
A couple things to add to the mix:
I've had "Polygonal" barrels from both LW and Schneider. However, these differed from an HK or Glock polygonal barrel. When you looked down the barrel, it didn't look like a kaleidoscope like an HK barrel. It looked like a normal barrel. The reason for this, I was told by Schneider if I remember right (it was years ago), was that they weren't true polygonal, more like "rounded land". The LW appeared to be the same.
I will say I have run an LW to 10k rounds of 308 on a pretty rough firing schedule testing a semi-auto and while the throat eroded significantly, it was still holding around 2moa, which in a gas gun really isn't too bad. I didn't notice any low vel except as the barrel wore the velocity dropped relative to its original velocity.
Justin
Re: Lothar Walther polyg.barrels
..
Don't even really want to go there, but there is Poly, Reverse Poly and a whole series of "semi" polys that are really angle, canted or ramped leading lands. They can all be outstanding barrels...or not.
Bingo on the throat issue.
.
..
Don't even really want to go there, but there is Poly, Reverse Poly and a whole series of "semi" polys that are really angle, canted or ramped leading lands. They can all be outstanding barrels...or not.
Bingo on the throat issue.
.
Re: Lothar Walther polyg.barrels
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">..
Don't even really want to go there, but there is Poly, Reverse Poly and a whole series of "semi" polys that are really angle, canted or ramped leading lands. They can all be outstanding barrels...or not.
Bingo on the throat issue.
. </div></div>
This is an intresting thread. But I have a quick question/observation, here it goes. Rollingthunder you seem to point out the throat has a tendency to errode faster in a polly barrel. Is this because the area that you are measuring aginst (what would be the lands) are very thin and there for are less resistant to errosion? Kind of like the theory behing a 3 grove barrel being more resistant to throat errosion because the lands are aprox. 2x as wide as a 6 grove. Am I understanding this correctly?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RollingThunder51</div><div class="ubbcode-body">..
Don't even really want to go there, but there is Poly, Reverse Poly and a whole series of "semi" polys that are really angle, canted or ramped leading lands. They can all be outstanding barrels...or not.
Bingo on the throat issue.
. </div></div>
This is an intresting thread. But I have a quick question/observation, here it goes. Rollingthunder you seem to point out the throat has a tendency to errode faster in a polly barrel. Is this because the area that you are measuring aginst (what would be the lands) are very thin and there for are less resistant to errosion? Kind of like the theory behing a 3 grove barrel being more resistant to throat errosion because the lands are aprox. 2x as wide as a 6 grove. Am I understanding this correctly?
Re: Lothar Walther polyg.barrels
Well im reading quite a few higher Vel.reports in various threads with modified if you will polyg. land desighns ( 5R )in particular and snieder,pacnor but i guess were at the mercy of here say. Anyway I hear LW throats wear 1/2 as much as others... I do know a rough bore along with crappy steel that gives off much harmonics will slow the bullet down thus less Vel. but only trying to get more educated on this subject.
Well im reading quite a few higher Vel.reports in various threads with modified if you will polyg. land desighns ( 5R )in particular and snieder,pacnor but i guess were at the mercy of here say. Anyway I hear LW throats wear 1/2 as much as others... I do know a rough bore along with crappy steel that gives off much harmonics will slow the bullet down thus less Vel. but only trying to get more educated on this subject.
Re: Lothar Walther polyg.barrels
..
Didn't mean to suggest that a poly bore impacts the throat. Sorry. Meant to suggest that he is better off spending less time on the rifling and more time on the chamber and throat of any great barrel (traditional or poly.)
..
Didn't mean to suggest that a poly bore impacts the throat. Sorry. Meant to suggest that he is better off spending less time on the rifling and more time on the chamber and throat of any great barrel (traditional or poly.)
Re: Lothar Walther polyg.barrels
..
Sorry, you are right, I should have put it in there...let me see if I can find it (as he grabs any part of the quote and drops it into Google.)
Yep, still out there in the ethersphere...
http://lmgtfy.com/?q=polygonal+bores+offer+less+resistance+so+they+shoot+the+bullet+faster
HKPRO.com 2004, one of many, many....
..
Sorry, you are right, I should have put it in there...let me see if I can find it (as he grabs any part of the quote and drops it into Google.)
Yep, still out there in the ethersphere...
http://lmgtfy.com/?q=polygonal+bores+offer+less+resistance+so+they+shoot+the+bullet+faster
HKPRO.com 2004, one of many, many....
Re: Lothar Walther polyg.barrels
Outstanding, and thank you.
I think the argument about 'It works, why change?' carries a lot of the weight regarding the scarcity of polygonal barrels.
I admit some interest in the concept. I agree; pressure and velocity should be, and probably are, independent of a bore's cross section shape, and more a factor of cross section area.
It makes sense to me that they should be less expensive, lending themselves rather especially well to hammer forging. But I also don't see enough being made to flesh out the economies of scale.
A lack of sharp edges and deep grooves would tend to support claims of longer life and easier cleaning, but who really knows for sure?
Still, fortune may smile, and I just might end up with one someday.
Greg
Outstanding, and thank you.
I think the argument about 'It works, why change?' carries a lot of the weight regarding the scarcity of polygonal barrels.
I admit some interest in the concept. I agree; pressure and velocity should be, and probably are, independent of a bore's cross section shape, and more a factor of cross section area.
It makes sense to me that they should be less expensive, lending themselves rather especially well to hammer forging. But I also don't see enough being made to flesh out the economies of scale.
A lack of sharp edges and deep grooves would tend to support claims of longer life and easier cleaning, but who really knows for sure?
Still, fortune may smile, and I just might end up with one someday.
Greg
