Polygonally rifled barrel for 1911?


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Boberama
January 27, 2010, 05:12 PM
Does anyone know where I can get one? I knew Glock, HK, and Magnum Research used polygonally rifled barrels in some or all of their firearms but what I didn't know was that it increased the velocity.

Since there is less friction the round moves faster. In an artiicle on the 357 SIG, Massad Ayoob noted that the Glock barrels were about 100 fps faster than the conventional SIG barrels.

So if I put 185 gr +P in my 1911 and the same held true in .45 caliber, then I would be getting about 1250 fps. That's 642 ft-lbs. It could also send a 200 gr +P to around 1150 fps, and a 230 to about 1050 for 587 and 593 ft-lbs respectively.

Double Tap's 185 gr Nolser would go 1325 fps with 721 ft-lbs.
Double Tap's 200 gr Bonded would go 1225 fps with 666 ft-lbs.
Double Tap's 230 gr Bonded would go 1110 fps with 629 ft-lbs.

You'd definitely need to do something about recoil though. If a 185 gr went out the muzzle at 1325 fps that would be almost equal to a .460 Rowland defense load, which puts out a 185 at 1350.

Food for thought.



Bobthinkingofpolygonserama

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mljdeckard
January 27, 2010, 05:42 PM
Why do you want to increase the velocity of a bullet/barrel combination that was designed specifically to work at 850-875 feet per second?

JoeSlomo
January 27, 2010, 05:47 PM
Don't believe anything you read until you chrony the load in YOUR gun...

Boberama
January 27, 2010, 06:04 PM
Well, I've read many chronographs of short barreled Glocks, and the velocities are very high for their barrel length.


.45 ACP CCI 230gr------------------Glock 21: 829 fps------------------Glock 30: 796 fps
.45 +P Cor-Bon 185gr ------------------Glock 21: 1218 fps------------------Glock 30: 1088 fps



10mm Cor-Bon 135gr ------------------Glock 20:1390 fps------------------Glock 29: 1297 fps
10mm Cor-Bon 180gr------------------Glock 20:1170 fps------------------Glock 29:1108

mljdeckard
January 27, 2010, 06:15 PM
That wasn't what I was asking. What advantage do you want to gain from increasing the velocity?

HisSoldier
January 27, 2010, 07:10 PM
Plus it generally limits you to jacketed of plated bullets.

SlamFire1
January 27, 2010, 07:15 PM
No such thing as a free lunch. If velocity goes up, you can bet that the pressure went up.

Aren't most semi auto pistols delayed blowback? http://en.wikipedia.org/wiki/Blowback_(arms) Increase the pressure and mess up the recoil dymanics.

BHP FAN
January 27, 2010, 07:17 PM
Why would you want to give up home cast lead rounds?

wild cat mccane
January 27, 2010, 07:26 PM
interested in someone answering his question :)

bds
January 27, 2010, 07:29 PM
Polygonal rifling achieve greater velocity by minimizing pressure lost from conventional rifling grooves.

Good match barrels have lower lands to minimize pressure loss and also allow you to shoot lead (also better chamber case support over Glock chambers).

I will take a good match barrel over polygonal barrel for cheaper practice (trigger time with good training methods I believe is key).

bds
January 27, 2010, 07:30 PM
- Duplicate post - Guess my smart phone is not that smart.:(

CWL
January 27, 2010, 07:37 PM
Why go for polygonal when standard rifled barrels have worked fine for a century already?

Why do you feel the need to bump velocity by 100fps when it probably won't do anything to help with increasing performance in an already excellent design? Remember that the .45ACP is meant to be "big & slow", and it has gotten the job done in wars, police actions and HD/SD.

People trying to "hot rod" the M1911 platform is the principal reason why there are so many unreliable M1911s around.

Floppy_D
January 27, 2010, 07:44 PM
I gotta ask... why is the extra velocity needed? If you want it, go for 460 Rowland. My favorite 1911 loads were usually slow, accurate and easy to shoot. 45acp is a playground for cast lead bullets; they are less expensive, and work well within the velocity range of the 45acp.

FloppyImissWildAlaska'sPostsWhenHeUsedToDoThatAsaSignatureLine_D

Sapper771
January 27, 2010, 09:08 PM
I think it would be interesting to see what it could actually do. The velocities that you quoted seem a little high, but you never know. There are several other variables that are involved as well.

When I do load development for my Glock 21 and my SA TRP, the glock's 4.6" barrel usually maintains a 25-30fps increase over the TRP's velocities using the same load. This was shown through chrono'ing 6 separate loads that were tested through each pistol.

ol' scratch
January 27, 2010, 09:20 PM
Well, I've read many chronographs of short barreled Glocks, and the velocities are very high for their barrel length.


.45 ACP CCI 230gr------------------Glock 21: 829 fps------------------Glock 30: 796 fps
.45 +P Cor-Bon 185gr ------------------Glock 21: 1218 fps------------------Glock 30: 1088 fps



10mm Cor-Bon 135gr ------------------Glock 20:1390 fps------------------Glock 29: 1297 fps
10mm Cor-Bon 180gr------------------Glock 20:1170 fps------------------Glock 29:1108
If these are accurate, could it explain why SOME Glocks have been known to kaBOOM? Could the Poly rifling (and the bump in velocity it creates) be part of the problem?

cyclopsshooter
January 27, 2010, 09:24 PM
in all my years futzing with 1911s i have never come across a polygonal 1911 barrel.

KurtC
January 27, 2010, 09:35 PM
Polygonal rifling exists because it is a cheap and easy way to create useable rifling in a barrel. Rifles have been made with it for generations.

So, to answer the original question: The odds of someone manufacturing a cheaper barrel than the one supplied from the factory are pretty thin. Aftermarket companies usually try to make something "better" than the original, not lesser.

Regarding Glocks: Some kaboom because the design can allow a cartridge to fire when it is out of battery. An out-of-battery condition is often caused by fouling in the chamber throat prevent the cartridge from headspacing properly. I believe the jury still out on whether the chamber throat and polygonal rifling is causing Glocks to foul more often or quicker than other pistols. The out of battery conditions might be occuring at the same rate as more traditional pistol, it just might be a design flaw that allows the cartridge to fire during such a condition.

19-3Ben
January 27, 2010, 09:40 PM
I'm actually really interested in this. As a recent Kahr K40 owner, I'm kinda taken (though not blown away) with the idea of polygonal barrels.

For all the people asking why one would want an extra 100fps... really? you have to ask?
More FPS=More energy dumped on target and more reliable expansion.

Yes I know, energy isn't everything. Energy is not the be-all-end-all of stopping power (assuming there is such a thing). Shot placement and penetration are much more important. But, assuming the shooter can still put shots on target, and you can get an extra 100fps in velocity to push that bullet harder and make it expand better, and dump more energy in the target, why the heck would you NOT want it?
Look, I'll take any advantage I can get. I mean, isn't that the purpose of having a gun in the first place?

Jim Watson
January 27, 2010, 09:46 PM
I think Peters Stahl in Germany makes polygon bore 1911 barrels. I can't be sure because they do not appear to have a site in English.

ol' scratch
January 27, 2010, 09:56 PM
How about a .45 Super? They shoot the same round, the Super cases are just beefier in the case head.
.45 Super velocities taken from the net-185-grain (12.0 g) bullet propelled at 1,300 ft/s, a 200-grain (13 g) at 1,200 ft/s, and a 230-grain (15 g) at 1,100 ft/s.

Standard barrels, I might add. Springfield builds one-I'm sure there are others, but I have read a few places online you can modify a .45 into a .45 Super.

Grayowl
January 27, 2010, 10:59 PM
If you want to become a really good shooter with a polygonal barrel, you had better be rich. If you are going to shoot 500 rounds a week (and that's not much, some shooters I know shot 100,000 round a year) you not only need to reload, but need a progressive press (like a Dillon 650). Reloading with jacketed bullets is still too costly. To keep the cost down, you need to shoot lead bullets and polygonal barrels don't handle lead very well. I cast some of my bullets from alloyed wheel weights, but due to the lack of time, I have to buy most of my lead bullets. Reloading is fun hobby.

bds
January 27, 2010, 11:47 PM
Partial repost from another thread that has pertinent information regarding shooting lead bullets in polygonal barrels: http://www.thehighroad.org/showthread.php?p=6212826#post6212826

"Conventional barrels have squared off (lands and grooves) rifling and newer pistols (Glock, H&K, Kahr) have hexagonal/polygonal rifling (hills and valleys).
http://upload.wikimedia.org/wikipedia/commons/3/3b/Polygonal_vs_normal_rifling.svg

When shooting bullets in conventional barrels, pressure is lost through the grooves while the lead bullet rides down the lands. Due to the heat/pressure of powder burning, some softer lead bullets can leave smears of lead and lead slivers/fragments in the grooves along with the carbon fouling (it is for this reason modern lead bullets are not soft pure lead, but an alloy of various metals and are hard cast with hardness of 18-24 to reduce leading in the barrels). The grooves allow some build up of lead/fouling and still allow the bullet to travel down the barrel on lands while allowing the pressure to escape through the grooves.

Of course, more frequent barrel cleaning is required if you shoot lead bullets instead of plated/jacketed bullets as plated/jacketed bullets only leave fouling in the barrel. I have shot lead bullets with 18-24 hardness in my Lone Wolf barreled Glocks and they do not lead my barrels (I clean my barrels with Hoppes #9 solvent/copper brush and barrels come out clean without any deposits).

Because the intent of the polygonal rifling is to reduce the void between the bullet and the inside of the barrel to increase contact and reduce pressure loss, there is less void in the valleys to accommodate the buildup of lead/fouling deposit and pressure increase inside the barrel becomes more of a problem as more and more lead rounds are shot.

Following is an excerpt from wikipedia: http://en.wikipedia.org/wiki/Polygonal_rifling


The manufacturer Glock advises against using lead bullets (meaning bullets not covered by a copper jacket) in their polygonally rifled barrels, which has led to a widespread belief that polygonal rifling is not compatible with lead bullets. Firearms expert and barrel maker, the late Gale McMillan, has also commented that lead bullets and polygonal rifling are not a good mix.

One suggestion of what the "additional factor involved in Glock's warning" might be is that Glock barrels have a fairly sharp transition between the chamber and the rifling, and this area is prone to lead buildup if lead bullets are used. This buildup may result in failures to fully return to battery, allowing the gun to fire with the case not fully supported by the chamber, leading to a potentially dangerous case failure. However, since this sharp transition is found on most autopistols this speculation is of limited value. The sharp transition or "lip" at the front of the chamber is required to "headspace" the cartridge in most autopistols.

Another possible explanation is that there are different "species" of polygonal rifle and perhaps Glock's peculiar style of polygonal rifling may be more prone to leading than the particular styles employed in the H&K and Kahr barrels.

Leading is the buildup of lead in the bore that happens in nearly all firearms firing high velocity lead bullets. This lead buildup must be cleaned out regularly, or the barrel will gradually become constricted resulting in higher than normal discharge pressures. In the extreme case, increased discharge pressures can result in a catastrophic incident.

Of course, shooting reloaded plated or jacketed bullets in Glocks is less of a problem in regards to barrel fouling, but if you have older less supported barrels, case bulging/case failure is still an issue.

You can shoot reloaded plated/jacked bullets and/or reloaded lead/moly coated lead bullets more safely in Glocks (especially older Glocks) by simply changing out the barrel with newer factory Glock barrels for better chamber support or with aftermarket barrels that have the conventional land/groove rifling to shoot lead bullets."

ol' scratch
January 28, 2010, 04:38 PM
If you want to become a really good shooter with a polygonal barrel, you had better be rich. If you are going to shoot 500 rounds a week (and that's not much, some shooters I know shot 100,000 round a year) you not only need to reload, but need a progressive press (like a Dillon 650). Reloading with jacketed bullets is still too costly. To keep the cost down, you need to shoot lead bullets and polygonal barrels don't handle lead very well. I cast some of my bullets from alloyed wheel weights, but due to the lack of time, I have to buy most of my lead bullets. Reloading is fun hobby.
I shoot nothing but jacketed. My costs aren't that bad. It costs me $17 a hundred. I just don't want the fuss of messing with the lead.

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