I would appreciate any and all information concerning "real life" polygon rifling tests concerning hard cast bullets.
I have no interest in jacked bullet results whatsoever.
I am very aware that H&K used this method, and yes the accuracy was great!
Don't do it.
The polygonal rifling won't hold the cast bullets.
I tried them in my H&K rifle years ago, and the accuracy went from 1" at 100Y to not staying in 4" at 50Y.
After trapping a few bullets after firing, the rifling marks had completely stripped off. I checked the case expansion at the head and found excessive pressure signs, the primer pocket had expanded and the case fluting was almost to the "cut" level.
Checking the barrel I found dramatic amounts of leading.
The nice thing about polygonal rifling is that they last longer than standard barrels with jacketed bullets. The seal only works with jacketed bullets.
A Glock that I used in my academy had a documented 60,000 rounds through it, before I put another 2700 through it. It still went into 3" at 25Y.
But there have been too many examples of Glocks blowing up, after using lead bullets. One example was a model 22 that blew up after 200 rounds. An independant group recreated the blowup using the same ammunition and an identical gun.
So far I have heard of 5 blowups of Glocks, and the last one is the only one that involved jacketed bullets.
There are people good people on both sides of this debate. I really like reading whatever the late great Gale Mcmillan wrote, and a guy that buys 60,000 cast bullets for his Glock cannot be ignored. Thirdly, Mike Mcnett is an expert in loading 10mm Glocks to the max. He says that Beartooth bullets are the best.
My Glock and several others that I am aware of digested Beartooth's cast bullets just fine. I'm sure it's possible to make a cast bullet not work with Glock or any other rifling, but I had perfect results. Good accuracy, good velocities, no leading, no pressure signs, nothing blown up!
Perhaps polyagonal rifling is more sensitive to bullet hardness, fit, etc., but it is not impossible to make it work.
First off, Wirlibird, I don't mean to be harsh but case expansion past specifications and blowing out primers would be the result of "dam hot loads", or twist rates "Way" more agressive than the norm.
My interest is in the accuracy of polygon rifling. I guess with all things being equal, how will it stand against conventional rifling? I would think that it would distort the projectle less, this would be awesome for cast bullet accuracy!
Unfortunately they weren't "Hot" loads when I started out, using Laser Cast bullets that were .0005" over bore dia. and book standard 9mm loading data. As I was firing the recoil got progressively higher and the leading got worse and worse. The rifle loads were worse, I quit after only 10 rounds the last try, the primers stayed in the cases, only because of the rifle design, but the pockets were nasty and the cases were useless.
I finally gave up for pistol when the primers were ejected at the same time the case was leaving the pistol. I was a great deal newer to reloading then, I still wonder why I still have all ten fingers.
I think there is a fine line between bullet to rifling fit and depth of rifling. Pope rifling was shallow but has great gripping surface, with multiple grooves with semi-rounded corners in them, this is still one of the best rifling styles.
Look at the 1950 and 1917 Smiths, these pistols have shallow rifling in comparison to the model 25's, and perform their best work with jacketed bullets as lead at any respectable velocity generally tends to strip out in the rifling.
Technically Micro-groove barrels should perform phenominally with lead, but most of the time this isn't the case. This is why Marlin brought back Ballard rifling in the Classic series and later the Cowboy guns.
I have always loaded for Auto's that have the poly rifling, H&K & Glock, and have found that even when I use hard cast, even water quenched bullets I get stripping of the lead when the velocity gets up to where the action will work.
My last Model 21 had an extra barrel fitted to it, a Wilson Combat with conventional rifling. The same ammo fired in each would leave a slight lead trace in the corners of the grooves right in front of the chamber and no other leading. Meanwhile the Glock barrel would lead heavily for 1-1.25" in front of the chamber and pressure signs were quick in coming, somewhere in the neighborhood of 50 rounds. This is with Laser Cast bullets again, 200gr moving at 900fps. This happened with my H&K also, although not as bad and the Gold Cup I still shoot doesn't lead at all with the same load.
I'd like to find out just how to make the cast bullets work in a Glock and such, without risking hand and weapon, but I still am leery of using lead at this time.
There is no ready available source for Beartooth Bullets around here, so I may have to order some and try them.
I'm no expert at reloading, only been doing it for 15 years now so I'm a relative beginner, but I have made my share of mistakes and try and not let others make the same ones or worse.
I had problems developing a load for my Glock 17 with cast bullets. The light bullets keyholed badly. I ended up with a 38 Super bullet weighing 160 gr. The only heavy bullet data at the time was in an old Lyman book and a little from AA. I decided to use AA#2 and started with 3.0 grains. Moved up until the pistol worked every time. This load shot about 3in at 25 yards in the Glock and seceral other 9mm pistols. Function was always perfect in the pistols and in a Marlin carbine. When shot in an Uzi carbine, it produced 1in 25 yard groups.
Please note that if you try this load you must use the longest OAL that will fit in your guns. Also you must use the Lee factory crimp die because you may get a case bulge from the long bullet.
I think the long bullet with its much larger bearing surface takes the Glock rifling better and at least allows a good practice load.
Whirlibird, please don't think I am arguing with you, you sound like you have a lot more experience with Polygon than I do (mine is 0). The hole idea around this posting was to consider that form of rifling for a 45 Colt (or bigger) revolver. The simple fact of less deformation of the bullet (cast) sounds great to me, and should work very well. That is why my intent is to get as much information as possible on the subject before deciding to lay out the bucks for further investigation. So if there is anything that you care to add or recommend I would appreciate it very much.
Super accurate .45 Colt, Ross Seyfried did an article in Guns And Ammo on his minute of angle Ruger.
He had Linebaugh line bore a cylinder, tighten everything up and make a set of barrels for it.
If I remember right it was a Pac-Nor barrel, with various throat lead-in's. He had great success with a Taylor throat in the barrel, it lets the bullet gradually size down into the rifling, here is a link to some info on it. http://www.sixgunner.com/dad/throat.htm
Not an article on accuracy specifically, but it links to some.
I don't know anyone who makes any polygonal barrels except Glock and H&K, I checked with my sources and they didn't know either.
I worked for two years as a professional pistolsmith, and fitted more than a few barrels.
If I was going to spend a few dollars on a high end pistol I'd either spend the money up front and get one of the Freedom Arms .454 or .45LC's or get a Ruger Bisley in any caliber and send it right to Bowen, Linebaugh or Morrison (QPR). Any one of these guys can make a pistol that you'd be proud to shoot.
I've had better luck by controlling the deformation rather than by eliminating it, by using the Taylor throat, perfect cyl throats, perfect allignment, and a barrel that gradually tapers about .0005"to.001" from the throat to the muzzle. I've made several pistols for customers that would produce 1 hole groups at 25 and 50 yards regularly.
For the best dollar value in smiths, I'd check with Milt Morrison at www.qpr-inc.com Milt does the best bluing bar-none and does a better trigger job than anyone in the business. Look into a Western Hunter conversion, not exactly cheap, but Taffin and Wilson both have had nothing but great things to say about theirs.
Whirlibird, thanks for your help, it seems you have walked across the ground I was trying to plough up again. I appreciate you not letting me make a time consuming (costly) mistake. Whichever route I take, I will owe you a lot for sharing your knowledge.
Not a problem, that is the purpose of these boards isn't it.
Do you ever get over to sixgunner.com board? Not a bad place and a lot of hte same people frequent it, J.Taffin, Paco etc.
Let me know what you come up with I'd like to know.
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