I've had the 30SF for several years and have several thousand rounds through it at this point. Possibly the more accurate of my G-17 & G-19s. Great gun but as someone said pretty blocky for CCW, but definitely doable , especially if you're a big guy (6'3" / 230).
Ironically I had it at the range today, and experienced a blown out case (at the base). Quite the surprise! The blast blew apart the magazine, broke the mag release, and blew one-half (L & R) of the trigger off the gun. Otherwise the gun looks OK, although I need to disassemble and inspect it closely. I'm giving the Glock high marks today, especially since I still have all my fingers.
My thought is the cause is one of two that you are already thinking about
. It was not a squib, which was my first thought, because I clearly remember seeing the previous bullet on the target, and the bore was clear afterwards. That leaves an over loaded round or bad brass. I'm awfully anal about checking powder levels (yes, this was my own reload). Still, I can't absolutely rule it out. The brass was a CBC headstamp, and other than tight primer holes I haven't faulted these in the past. Again ironically, I have just sorted my loaded ammo to separate all the "off brand" brass to shoot and not recover (CBC, CCCP, Aquila, S&B, etc.). This was the lot of ammo I was shooting today. Not saying that this is bad brass, but I generally don't have a lot of it and I have been getting a lot of tight primers with much of this brass so I though I would just shoot it up and get rid of it.
Glasses saved my eyes, and I only got a couple of nicks in the face, and small cuts on my R thumb and R index finger, along with blood blisters on my finger and thumb, (I think from the blast coming through the gap between slide and the lower receiver). I'll try to post a couple of pics.
Edit: BY THE WAY does anyone know how to disassemble the Glock when the trigger in inoperative and the striker won't fall. (Working on Google now.). Thanks.