Polygonal rifling v land and groove rifling

I am not much of a fan of "luck". If two identical Glocks firing identical ammo behave differently, there is a reason. And it would not seem to be due to the rifling, since the rifling in the two guns would presumably be identical. I still think there is something we don't know.

The question to me is why Glock would continue to use polygonal rifling if the tests showing it to be dangerous are valid. Even if Glock warns against use of lead bullets and handloads, it is not good PR to have their guns blowing up.

Polygonal rifling is made by hammer forging, but any rifling style can be made that way, so why retain a potentially dangerous feature?

Jim
 
Identity is not certain at the micro level. Just because we each have the same make and model gun, loaded with the same brand and specification of ammo does not mean they are truly identical.

There are few if any lead bullet autopistol factory loads, the culprits are reloaders. Glock will not warrant their guns with reloads of any sort, nor will any other big maker. I assume they figure that takes care of the matter.
 
It was soon found that a cylindrical bullet would bump up enough to fill the Whitworth hexagonal bore.
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I'll bet that practice would result in much more leading than with the original mechanical fit bolts.
If two identical Glocks firing identical ammo behave differently, there is a reason. And it would not seem to be due to the rifling, since the rifling in the two guns would presumably be identical.
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Obviously, they were not identical. They were only APPARENTLY identical, as I stated. And that's the problem. The difference is there--it's just not apparent to someone without special instrumentation to measure the differences.

As far as it not being due to the rifling differences, that's true too, but that doesn't mean the rifling isn't a factor. The bore size and geometry contribute to higher pressures and to more/faster leading compared to a bore with standard rifling even if it's not one of the bores that leads super-fast. So when you get one of these unusual bores that leads faster than normal, you get into trouble a lot quicker because some of the normal safety margin that you would have with a typical land & groove barrel isn't there.
The question to me is why Glock would continue to use polygonal rifling if the tests showing it to be dangerous are valid. Even if Glock warns against use of lead bullets and handloads, it is not good PR to have their guns blowing up.
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This is part of what has led me to my "not unlucky" theory and why, in my opinion, this is such a difficult issue for many people to get their brains around.

A lot of folks seem to need this to be a clearcut case of black and white. They want it to be simple. Something like: "If you shoot lead in a Glock the gun with explode." Or maybe : "If you shoot X lead bullets through a Glock without cleaning the gun will blow up." Or they want a simple rule they can follow that will let them shoot lead without any fear of having an incident.

Life's often not that way. Think how many smokers there are who don't die of lung cancer. Think how many people don't have smoke detectors but don't die in a fire. Think about how many people are overweight but don't die of heart attacks. The fact is that you CAN do something that significantly increases your chances of a dangerous incident and still avoid the incident by being lucky (or not unlucky enough). Just like you can double your odds of winning the lottery by buying two tickets instead of one--and you will still probably lose.

Does that mean that buying more tickets isn't a factor in winning the lottery because it doesn't guarantee a win? Of course not--buying more tickets definitely changes the odds. It's just that changing the odds doesn't mean you've created a sure thing, it only means that the odds are different than they were before.

Same thing applies here. Shooting lead in a Glock creates a higher risk of a catastrophic incident than a person would run by shooting lead in standard rifling. Does that mean they're going to blow their gun for sure? CLEARLY it's not that simple because some people do shoot lead in Glocks and get away with it. Even Passamaneck did it for 20,000+ rounds before the numbers added up the wrong way one time and finally blew the gun.

If it were a sure thing that X lead bullets through a Glock bore would result in a catastrophic incident, Glock would have to put the "no lead" warning front and center in the manual and maybe even stamp it on the gun. The fact that they don't strongly suggests that it's not that likely to be a problem unless someone pushes the envelope or gets unlucky or maybe both.

That doesn't mean I'm going to tell people it's OK any more than I would tell someone that smoking is safe or that buying 100 tickets guarantees a lottery win.
 
I personally don't like polygonal rifling and it is one of the reasons I don't like glocks. I believe that there could be a slight increase in velocity in a polygonal barrel vs. A cut rifled barrel (with a copper plated or jacket bullet) simply because there is less friction, the bullet is not being cut into by the rifling, because there is no rifling. The steel itself is formed and shaped into a spiral- less friction, however with the absence of rifling, with solid lead bullet (which is much softer than copper) there is nowhere for excess let to settle and "clean" inself out out the bore. So after several rounds you will have build ups of lead that have nowhere to go, and can cause a catastrophic pressure increase. Now since lead has less friction (in a rifle barrel) you can make up for velocity lost over copper bullets in a polygonal barrel. I much prefer regular rifling, as it allows me to safely shoot much more solid lead bullets than a poly barrel, and solid lead bullets are much cheaper than fmj or Coated bullets.
 
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