The key question asked by the Portland officer is whether there have been similar "failures" with aftermarket barrels that more fully support the cartridge.
I've shot several aftermarket barrels in both .40 S&W and .45 ACP and been unable to measure and significant case expansion at the 6:00 position. Nor have I "heard" any reports of similar failures with aftermarket barrels.
The officer also asked about fully supported after-market barrels and their reliabilty feeding ammo. For one example, I refer you back to Sam's posting of the two barrels side by side showing the difference in support and his assertion a couple posts down that the aftermarket barrel has been just as reliable.
Around 97 or so I had a phone conversation w Mike Dunlap, then range master at the Amarillo TX PD about Glock kBs. APD had some probs w G21s too, he mentioned they tried aftermarket bbls in some. Might check w him/APD and see how they worked?
Was told on the phone by someone at Jarvis reliability might be compromised w the added support of their bbls in Glocks; why I decided against that route at the time in my 40s.