So defective factory ammo is just as as bad as defective re-loads.
Yes and no. One of the things that I have not seen addressed here concerning reloaded ammunition fired in Glocks involves the cases, not the bullets themselves. Glocks feed ammunition very well. Any ammunition. Hardball, as well as all of the flat point, personal defense ammo. They do this because of the unsupported chamber design that is incorporated into every Glock pistol, regardless of caliber.
As is often said in engineering, you don't get something for nothing. While this heavy throating delivers excellent feeding, and high shot to shot reliability, it causes the cases to bulge severely at the base upon firing. This is especially true with the heavier +P and +P+ ammunition all Glock pistols are rated for. When these cases are run through a full length resizing die the brass at the base of the cartridge case is worked very heavily in order to bring it back to factory SAAMI specifications. When brass is worked it becomes work hardened and brittle. This can cause the case to rupture on the next firing. This is especially true in heavy, major power factor handloads, and if the case should just happen to chamber in the same rotational position it was in when fired originally.
This is the reason Glock specifically states reloads,
any reloads, regardless if they contain jacketed or lead bullets, should not be fired in their pistols. Yes, many people do shoot reloads in Glocks without incident, just as many drink and drive and get away with it. But with that said, the odds are against you if you choose to do it. For me the risk doesn't equal the reward.
The brass that has been fired in Glocks is by no means useless, it just needs to be fired in a supported chamber after reloading. There are aftermarket barrels avaliable for Glocks that have these type of chambers. This will negate the problem. I simply segregate my factory brass that has been run through my Glocks, and after reloading it, I shoot it in my Sig's, or other weapons that have a more supported condition in the rear of the chamber area. I also keep the pressure down in these reloads as well. All of this helps in not winding up with a ruptured case that can damage your firearm, as well as you, should it let go. Bill T.