We are the manufacturer of unique vessels for hydrogen storage at 1000 bar. The clients often ask for the safety of hydrogen storage in steel vessels.
The main evidence that steel vessels are the safest and most durable solution for hydrogen storage at extremely high pressures compared to composite vessels is the shotgun test we performed in cooperation with VŠB - TUO. These vessels also doesn´t shoot through the caliber with a special tungsten core, which is available only to the Department of Rapid Deployment of the Czech Police. The Lapua Scenar shotgun 338 with a lead core (standard equipment in the interventional unit in the Czech Republic), OTM (Open Tip Match) and a narrowed "Boat Trail" shape was used during the shot.
For comparison, you can also have a look at a 200 bar cylinder shot (the Lapua Scenar shotgun 338 with a lead core) when the bullet passes through the cylinder casing, but only the gas escapes from the cylinder rather than tearing it.
The main advantage of using steel vessels and cylinders compared to composite ones is the resistance to such extreme mechanical failure under extreme conditions.