Robert Ofcky was convicted of unlawful possession of a firearm by a convicted felon in violation of 18 U.S.C. § 922(g)(1). On February 4, 2000, following a sentencing hearing, Ofcky was sentenced to 78 months in prison, three years of supervised release and a special assessment of $100. He appeals his sentence, and we affirm.
During the week of March 16, 1998, Nancy Ofcky, the defendant’s wife, left the family home in fear and sought the counsel of Stanley Jablonski, a divorce attorney. Nancy informed her attorney that her husband was a convicted felon and that there were numerous firearms and ammunition hidden throughout their home. She also told Jablonski that she had been “straw” purchasing firearms for Ofcky, meaning that Ofcky gave her money and directed her to purchase particular firearms and turn them over to him. Jablonski forwarded this information to the United States Attorney’s Office. A federal search warrant for Ofck/s residence was obtained and executed on March 17, 1998. Recovered from Ofcky’s home was a tidy arsenal- — 13 rifles, more than 1,000 rounds of ammunition, 23 ammunition magazines, miscellaneous gun parts, The Anarchist Cookbook and gun literature.
The district court found that in addition to the items found at Ofcky’s home that day, there had previously been two M-ll firearms in a hidden compartment in the bathroom. The court based this finding on the testimony of Ofcky’s wife, Nancy, and his son, Christopher, who both testified that they were familiar with the characteristics of a fully automatic machine gun.
The district court determined that the total offense level under the U.S. Sentencing Guidelines was 26. It started with an offense level of 20 because the offense involved a machine gun and the defendant was a “prohibited person.” 1 The judge *907 added four levels for the number of weapons and two levels for obstruction of justice. See U.S. Sentencing Guidelines Manual §§ 2K2.1(b) (number of weapons), 3C1.1 (obstruction of justice).
Ofcky appeals on three grounds. First, he argues that the district court erred in finding, as relevant conduct, by a preponderance of the evidence, possession of an automatic weapon. This enhanced his base offense level from 14 to 20, thereby nearly doubling his maximum base sentence from 24 to 46 months. Second, Ofcky contends that the district court was clearly erroneous in finding him guilty of obstruction of justice. Third, he argues that the district court failed to give proper consideration to the mitigating factors that he believes mandated a downward departure in the sentencing calculations.
I.
Ofcky’s first claim is that the district court erred in enhancing his sentence based on his possession of an automatic weapon. When reviewing the decision of a district court to enhance a sentence based on relevant conduct under U.S. Sentencing Guideline § lB1.3(a)(2), we accord deference to the district court:
Our review of a district court’s sentencing decision is deferential. We will uphold a Guidelines sentence “so long as the district court correctly applied the Guidelines to findings of fact that were not clearly erroneous.” United States v. Duarte,950 F.2d 1255 , 1262 (7th Cir. 1991), cert. denied,506 U.S. 859 ,113 S.Ct. 174 ,121 L.Ed.2d 120 (1992); see also United States v. Rivera,6 F.3d 431 , 444 (7th Cir.1993). The determination that uncharged activity constitutes “relevant conduct” ... is a finding of fact, which we will not disturb unless it is clearly erroneous.
United States v. Sykes,
Ofcky challenges the district court’s application of a “preponderance of the evidence” standard in determining his relevant conduct. Because Ofcky failed to object to the use of the preponderance standard at the time the district court determined his relevant conduct, he waived this issue on appeal.
See United States v. Rivero,
Under the Sentencing Guidelines, possession of a firearm by a prohibited person has a base offense level of 14 points and a sentence range of 18 to 24 months. U.S. Sentencing Guidelines Manual § 2K2.1(a)(6); ch. 5, pt. A.
2
After a finding of relevant conduct, the district court increased Ofcky’s base offense level from 14 to 20, giving him a sentence range of 37 to 46 months.
See id.
ch. 5, pt. A. This, Ofcky contends, was such a dramatic increase that it warranted a finding of relevant conduct only by clear and convincing evidence. Ofcky argues that our decision in
United States v. Hardin,
The government correctly notes that “simply a preponderance of the evidence is all that is required for a factual finding under the Sentencing Guidelines.”
United States v. Porter,
Ofcky’s second challenge to the enhancement is premised on an argument that— even under a preponderance of the evidence standard — the evidence lacked sufficient foundation, credibility and corroboration to warrant a finding of possession of an automatic weapon. Ofcky was not in possession of an automatic weapon at the time of his arrest. The only evidence presented at trial on this issue was the testimony of Ofcky’s wife, Nancy, and son, Christopher.
Ofcky claims that the testimony of both these family witnesses lacks credibility. Nancy he deems incredible because she is estranged from him and because she was granted immunity from prosecution in exchange for testifying against Ofcky. Christopher’s testimony is supposedly incredible because he loves his mother, comes from a broken family and fears the
*909
loss of both his parents, Ofcky argues. App. Br. at 14-15. This is not enough to ascribe error to the district court in crediting Nancy’s and Christopher’s testimony. We give credibility determinations a lot of deference.
See
18 U.S.C. § 3742(e)(4);
United States v. Moutry,
Ofcky next challenges the testimony of Nancy and Christopher on the grounds that it lacked sufficient indicia of reliability.
See United States v. Morrison,
Ofcky also claims that his possession of the fully automatic weapons was in doubt because there was no evidence to corroborate Nancy’s and Christopher’s testimony. This argument, too, fails to register. It is well established that a conviction may be based solely upon the uncorroborated testimony of an accomplice.
See United States v. Henderson,
Ofcky’s strongest argument about whether the enhancement was appropriate is that the government failed to establish that the relevant conduct had sufficient similarity, regularity and temporal proximity to the offense of conviction, as required under
United States v. Sykes,
II.
Ofcky next argues that the court’s enhancement of his sentence for obstruction of justice was not supported by the evidence, as provided by § 3C1.1. of the U.S. Sentencing Guidelines. When a court makes a finding that a defendant obstructed justice, we review for clear error.
See United States v. Webster,
The court found at the sentencing hearing that Ofcky committed perjury and willfully obstructed justice. Citing
United States v. Buchannan,
Ofcky argues that the district court must make specific separate findings sufficient to establish an obstruction of justice claim.
See
Here, the court found that Ofcky committed perjury in testifying that he was an expert in firearms, that he did not own or have access to the firearms nor possess the keys to the gun cabinet and that he did not purchase guns from Paul Wright. This testimony was directly contradicted by the government’s witnesses. The government correctly notes that an obstruction of justice enhancement is appropriate where the trial judge weighed the testimony of the defendant against that of others and determined that the defendant’s testimony lacked credibility.
See United States v. Pedigo,
III.
Ofcky’s final argument is that the district court erred in not decreasing Ofcky’s sentence because the Indiana code at the time of Ofcky’s arrest permitted a convicted felon to possess a firearm in his home.
See
Ind.Code § 35-47-^Mt (repealed 1999). A district court may depart downward from the Guidelines if the judge finds a “mitigating circumstance of a kind, or to a degree, not adequately taken into consideration by the Sentencing Commission in formulating the guidelines.” 18 U.S.C. § 3553(b). But the government correctly notes that this court lacks jurisdiction to review a sentencing court’s refusal to exercise its discretion to depart downward from the sentence prescribed by the Guidelines.
See United States v. Sinclair,
For the foregoing reasons, the judgment of the district court is
Affirmed.
Notes
. U.S. Sentencing Guidelines Manual § 2K2.1(a)(4)(B). For the purpose of this Guideline, one may satisfy the definition of "prohibited person” by meeting one of several standards. Here, Ofcky qualified as a prohibited person because he had "been convicted of[ ] a 'crime punishable by imprisonment for more than one year,' as defined by 18 U.S.C. *907 § 921(a)(20)...U.S. Sentencing Guidelines Manual § 2K2.1, cmt. n. 6 (1998).
. This is based on Ofcky’s criminal history category of II, pursuant to § 4A1.1 of the U.S. Sentencing Guidelines.
. A sentencing factor, as we know from
Apprendi v. New Jersey,
