For the benefit of the O. P., you should treat some of the generalizations & assumptions regarding Glock's "unsupported" chambers with a little skepticism as a lot of it is uninformed and repetitive internet lore. Its true that early Glock pistols, .40 caliber in particular, had a bit less chamber support than some other brands. Also true that some of these guns, when shooting full-house loads, could produce the bulged brass you hear so much about.
With that said, the problem is virtually nonexistent on current production models, .40 caliber included. Glock has increased their support at the 6 o'clock position substantially and its now as good as most any combat pistol you're likely to compare it with. I personally have six Glock pistols...4-9MM, 1-.45 and 1-.40 S&W. Of the six, the .40 has the best chamber support of the lot. I mentioned this to my local dealer and we compared the new models with some of the older, trade-in's on hand and found the current production gun's support markedly improved.
I can also say I have several thousand pieces of .40 caliber brass on hand (all range pickups) most, fired from Glock pistols. Having just processed every single piece of the range brass I can also say its very rare to see a bulged case and the few that did show up passed both Dillon case gauge and chamber just fine after resizing. FWIW, my G-35 produces no bulge even with full-house, max pressure loads.
IMHO, unless you just happen to want one, the only overbearing reason to acquire an aftermarket barrel for a current vintage Glock is if you want to shoot lead. Using plated or jacketed, the OEM barrell is just fine. If you have an older version, let the condition of the fired brass be your guide. Even with an older model with less support its not like the gun will know its shooting a reload and go into rebellion on you...if the load's reasonable you'll have no problem.