ST barrel is better than traditional barrel when wind comes ？？？

[SocalTrail]

So I have to ask, do you have a primary source on an emperical test for barrel leading on polygonal vs. land and groove? I'm genuinely curious as I've spent years trying to run this down, and all I've found are a string of anecdotes and bad methodology all leading back to Glock saying they don't recommend cast bullets in their barrels but with the reasoning vague and un-testable. (I've also seen people run cast bullets through factory Glock barrels and have no problem, again a useless anecdote, but no clear causal link was obvious) Ignoring the vast differences in leading mechanics between centerfire weapons and airguns, I'm just genuinely curious to find a dataset or some good primary research on it anywhere. There are a whole bunch of possible mechanisms for and against leading in polygonal vs land and groove, so I'm genuinely curious to see how the chips fall on that one. Sadly good published primary research is hard to come by, so if you have some please share the love. 

Also I want to thank you for taking the time to have this chat with me. Typing up these responses is time consuming.

I actually read it in a book somewhere and I cannot recall exactly which one it was. A gentlemen conducted a controlled test where he measured the chamber pressure incrementally after firing a few hundred cast bullets through a stock Glock poly barrel. the chamber pressure gradually increased until stress fractures were induced in the barrel. The general consensus amongst people who actually get out and shoot these slugs is as long as you shoot hard cast bullets ( Greater than 16 Brinnel Hardness), you should be ok... at least for a few hundred rounds. The problem comes to light when people shoot soft cast slugs through the poly barrels and the lead essentially smears through the bore. I have absolutely no clue what BHN our JSB pellets come in at but I would suspect they are on the lower end of the scale.

This thread had truly piqued my curiosity about a couple things.... first, how hard is your standard JSB pellet? Second, how many rounds are people getting in the airgun specific poly barrels between cleanings? And last, I really want to get my hands on another impact or crown in .22 cal to test it alongside my .22 Wolverine R and see how the BC compares out to distance. The Marlin Micro Groove technology looks awesome, if you look at a slugged micro groove barrel, the distortion on the jacket is almost nothing. I almost want to start a little project to see if I could get one of these to shoot .22 slugs out of my Veteran!!!1

I'll keep my eyes out for the published research...

 

[SF-06]

A well written and interesting write up. You’re very well informed for a “random internet guy.” I will respectfully offer a couple points. True gain twist would not be possible with the cold hammer forged process, as removing the mandrel would destroy the rifling. The mandrel has to spin like a screw as it is removed. As another random internet guy, I’ve had my gunsmith spins barrels from button rifled Douglass and Bartlein blanks. For a mortal like me, I can tell the difference under careful bench conditions…but not noticeable in a match. I think you are 100% correct it has more to do with the craftsman building and fitting the barrel. 

 

[steve123]

A gentlemen conducted a controlled test where he measured the chamber pressure incrementally after firing a few hundred cast bullets through a stock Glock poly barrel. the chamber pressure gradually increased until stress fractures were induced in the barrel

HA, I was one of the first persons in AZ to get a new Glock 22 in 40 S&W many years ago. The manual stated not to use lead cast bullets but I didn't want to spend the extra money for copper jacketed so used to shoot lead cast bullets instead. Guess what = I was also likely the first person in AZ to blow up a Glock!!!! I thought may be I loaded them too hot but no that wasn't the cause, the next month an article came out in a gun magazine that stated DON'T SHOOT cast bullets in Glocks and there was a photo of a blown up Glock just like mine. I hadn't cleaned mine in who knows how many rounds, 3-4-5 hundred???, because I practiced a lot back then and hadn't cleaned my previous guns often. Glock was nice enough to replace a new one at cost pricing.