Kip Jones pleaded guilty to a cocaine offense, reserving the right to appeal from the denial of his motion to suppress evidence. See Fed.R.Crim.P. 11(a)(2). Police entered Jones’s apartment on the authority of a search warrant. Jones does not dispute the validity of the warrant, but he does protest the manner of its execution.
An officer pounded loudly on the door, shouting “Decatur Police! Search warrant! Open the door!” When the occupants did not respond, the officer tried the door, found it unlocked, and opened it slightly. A second officer hit the door with a battering ram, and it flew open. One of the officers looked into the living room and, seeing no one, tossed in a concussion grenade (which the police call a “flash-bang device”). A concussion grenade produces a brilliant flash and a loud noise designed to stun and disorient persons nearby, making resistance less likely. A member of the police team found Jones at a table approximately 15 to 20 feet from the front door and instructed him to “get down.” Instead, Jones stood up and was tackled, being struck on the right side of the neck in the process. Officers then handcuffed Jones, who had been unarmed, and conducted their search, finding marijuana, cocaine, and equipment for weighing drugs. No weapon was to be found in the apartment, though the officers did locate 26 rounds of ammunition. While the search continued, Jones initiated a conversation with some officers, who moved him to the bedroom, administered Miranda warnings, and took a statement in which Jones admitted dealing in these drugs and sought to open negotiations about the exchange of lenience for additional cooperation.
Jones does not contend that the officers violated 18 U.S.C. § 3109 or the fourth amendment, see Wilson v. Arkansas, 514 U.S. 927, 115 S.Ct. 1914, 131 L.Ed.2d 976 (1995), by giving insufficient notice before using the battering ram. What he does contend is that the entry was conducted in an unreasonable manner — that it was gratuitous to use a battering ram on a door already open, to throw an explosive device into the apartment (especially because the police knew that Jones’s girlfriend and her six-year-old child were present), and to tackle him when, perhaps stunned by the explosion, he did not immediately drop to the floor. The district court held that the officers’ conduct was reasonable in all respects. We are less certain. Richards v. Wisconsin, 520 U.S. 385, 117 S.Ct. 1416, 137 L.Ed.2d 615 (1997), rejects an argument that drug dealers are invariably so dangerous that no-knock entries are proper; by the same token, police cannot automatically throw bombs into drug dealers’ houses, even if the bomb goes by the euphemism “flash-bang device.” The police did not *838believe that Jones was an unusually dangerous drug dealer. True, his criminal record included a weapons offense (for which Jones had received a non-custodial sentence), and guns are common in the drug trade, but this was a given in Richards as well. Police had little reason to apply a battering ram to a door that was already ajar, and using the concussion grenade created a risk that people close to the detonation point would be injured. Children are especially vulnerable, and the officers knew that one was in the apartment. Although they peeked inside the living room, planning not to use the device if they saw the child, they could have missed someone in a corner or behind the furniture. A child who hears the door being broken down is likely to hide.
If this were a damages action seeking compensation for injury to the occupants or the door, the claim would be a serious one. But it is not a damages action, so whether one would succeed is not something we need decide. Jones wants us to hold that the fourth amendment precludes the use of the evidence that the officers found in his apartment. That argument must be rejected for a reason unrelated to the strength of the contention that the officers behaved inappropriately: the exclusionary rule depends on causation: A warrant authorized the entry, so seizure of evidence was inevitable. Murray v. United States, 487 U.S. 533, 536-41, 108 S.Ct. 2529, 101 L.Ed.2d 472 (1988). A battering ram, flash-bang device, or blow to the neck could affect the seizure only by surprising or stunning the occupants so that they could not destroy evidence. The principal function of a concussion grenade is to protect officers from weapons fire, not to uncover evidence otherwise concealed. An argument that the suspects would have destroyed the drugs, if only they had more time and full possession of their faculties, is not a good reason to suppress probative evidence of crime. See Segura v. United States, 468 U.S. 796, 813-16, 104 S.Ct. 3380, 82 L.Ed.2d 599 (1984). No other causal chain could be at work, so as in other inevitable-discovery cases the officers’ errors (if errors they were) do not lead to suppression. See Nix v. Williams, 467 U.S. 431, 104 S.Ct. 2501, 81 L.Ed.2d 377 (1984). See also United States v. Jones, 149 F.3d 715 (7th Cir.1998).
Jones’s statement similarly is admissible, for his custody was lawful, and he does not contend that 30 minutes after the entry he was still so disoriented by the explosion that the statement was involuntary. A confession that occurs during unlawful custody, or was influenced by unlawfully seized evidence, must be suppressed unless intervening events demonstrate that the illegality did not cause the confession. Oregon v. Elstad, 470 U.S. 298, 105 S.Ct. 1285, 84 L.Ed.2d 222 (1985); Brown v. Illinois, 422 U.S. 590, 95 S.Ct. 2254, 45 L.Ed.2d 416 (1975); Wong Sun v. United States, 371 U.S. 471, 83 S.Ct. 407, 9 L.Ed.2d 441 (1963). Because Jones was in lawful custody, cases such as Brown do not assist him. See New York v. Harris, 495 U.S. 14, 110 S.Ct. 1640, 109 L.Ed.2d 13 (1990). Given the inevitable-discovery doctrine, the police were not in possession of any forbidden fruit. If the police had used spray paint to decorate Jones’s door with graffiti, or stolen a family heirloom, these unlawful acts would not have spoiled a confession, because they would not have induced an innocent person to confess (or even made it more likely that a guilty person would do so). Just so here.
Only a link between the manner of the entry and the statement would set up a claim to suppression, and Jones does not try to establish such a link. His argument supposes that the discovery of the drugs was itself unlawful. Jones contends that the entry “was for the very purpose of trying to find illegal drugs, and then to use the finding of the drugs as leverage to obtain [his] confession”. The idea, in other words, is that a person knowing that the police had the goods on him would confess as part of a strategy to negotiate for terms. Jones, who initiated the conversation that culminated in his confession, does not suggest any other way in which the manner of entry led to his statement. Be*839cause both the seizures and the custody were lawful, the confession is admissible.
AFFIRMED