Lets talk ballistics for a minute. The bookshelf is rated to withstand:
- 9mm Hangun
- 5.56mm Rifle
- Shotgun
Of the three, the 5.56mm Rifle is likely the highest power round. (Well, the shotgun could be, but a birdshot load cannot even penetrate drywall, and we have no idea if the claim is .410, 20 ga, 12 ga, or 10 ga...)
5.56 x 45 is the NATO round used in AR-15 and M4 rifles. The story goes that Secretary Robert McNamara pushed for this caliber to replace .308 (a bigger round) to serve two purposes: give solders the ability to carry more ammo, and to inflict wounds not kill outright. The enemy spends more resources tending to a wounded comrade than a dead one, etc...
With that said, almost any modern 30 caliber rifle round, especially a cheap steel core type bullet, has a good shot a squirting right through this bookcase, just like they do bulletproof vests (TV doesn't show you that.)
Indeed 'terrorists' stereotypically carry 30 caliber rifles, ie: AK-47s, which have been produced in the tens of millions and ammo in the hundreds of millions of rounds. Some of the least expensive rifles available today shoot rounds with more power than the high-end and fickle AR-15.
Summary: Say I buy lots of these bookcases and spend loads of money in the process. They may prove to be insufficiently protective based on how the active shooter is armed.