R relies only on a mis-cited Second Circuit case and an unpublished district court opinion. Second, Barr argues that he is not merely disputing a sentencing enhancement but is contesting his conviction on the second gun charge, which is proper under § 2241. Finally, Barr maintains that he is factually innocent of the second firearm conviction because an element of the crime was not proved. None of these objections is persuasive. The first objection is without merit because, even if the R & R did not properly cite any binding authority, it correctly identified the law in this Circuit. Subject matter jurisdiction under § 2241 is present only when the petition attacks the execution, rather than the validity of the sentence. See e.g. United States v. Barrett, 178 F.3d 34, 50 (1st Cir.l999)(<HOLDING>). Barr’s second objection is equally
holding that a  2241 petitioners claim was not cognizable under  2241 and therefore the district court lacked jurisdiction holding that subject matter jurisdiction under  2241 is present in the custodial court when the petition challenges the manner location or condition of a sentences execution holding that a petition under  2241 attacks the execution of a sen tence while a  2255 petition attacks the validity of a judgment and sentence holding that because henrikson is not challenging the fact or duration of his confinement subject matter jurisdiction is not present under 28 us  2241 holding that an attack on the computation and execution of a sentence must come in the form of a  2241 petition