Everyone let's take a time out = Deep Breath =
So a company who's primary success is built on supplying cut-rifled barrels for Glocks -- so that folks can shoot lead bullets without quaking in fear of the Kaboom -- has to be told to make them with loose tolerances so you can shoot lead bullet through them?
I found Lone Wolf barrels to be match grade and with the tightest chambers of all barrels I have measured (I practically use them as my case gauge as if loaded rounds chamber in a Lone Wolf barrel, they will chamber in any other factory barrel). They have been very good barrels for me right out of the box without any modifications.
Shooting lead bullets in Glock barrels raises several issues that can easily be "resolved":
1. Lead build up in barrel - I have shot both hard cast lead bullets with hardness of 18 and 24 and have not experienced lead build up (in any barrels, to include Glock). What I have found is that during seating of bullet, sometimes a sliver of lead is shaved by the case neck and is pushed around the bullet. As bullet is shot through the barrel, this sliver lines the barrel (usually in the grooves) as streaks.
I have found that if your flaring is sufficient and you are setting the base of the bullet flat and not tilted to the side, this slivering of lead is minimized. I do inspect and clean barrels I shoot lead out of more often and usually Hoppes #9 solvent with copper brush cleans out any lead lining/streaks. Be sure to clean the chamber and the transition area to leading to the rifling really well as this area collects much of fouling from powder burn/bullet lube.
I recommend using aftermarket barrels with conventional squared off land/groove rifling over the Glock's hexagonal rifling because the larger grooves between lands seem to allow more buildup and allow more excess pressure to escape.
2. If you are shooting Gen3 or Gen4 Glock barrels, chamber support is much better and the past concern over bulged Glocked cases is no longer applicable. If you are shooting older Glocks with less supported chambers and lead reloads, bulged case bottom may lead to failure if the fouling buildup around the chamber/rifling transition area is significant (usually, lead sliver streaking occurs at the chamber/rifling transition).
So can you safely shoot lead bullets in Glock barrels? I believe you can if you follow the following guidelines:
- Keep your Glock barrels clean and inspect/clean the barrels often for fouling/streaks.
- If you can, use Gen3/Gen4 barrels with better chamber support to minimize bulging of case bottoms that leads to case failure and the dreaded KaBoom
- Use caution when flaring and seating of the bullet to minimize slivering by case neck that leads to streaking of lead in barrels
- Use 18-24 hardness lead bullets from "reputable vendor" and DO NOT shoot softer lead bullets as softer lead bullets WILL lead more readily.
- Carry a mini cleaning kit to the range and frequently inspect barrels/chambers when shooting lead bullets.
I have tried shooting moly-coated bullets to reduce leading in barrels, but found good hard cast bullet properly seated in sufficiently flared cases do very well.
Use your own discretion regarding shooting lead bullets in Glock barrels. For me, I shoot jacketed and plated bullets in Glock barrels and lead bullets in aftermarket Lone Wolf barrels. Following quote is an excerpt from Wikipedia:
http://www.thehighroad.org/showthread.php?p=6212826#post6212826
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.