[1] In his first assignment of error the defendant contends the Superior Court erred in allowing an officer to read to the jury statements made to him by two of the State’s witnesses. He argues that the witnesses had not been impeached and the statements did not corroborate the witnesses. It is not necessary for a witness’ credibility to be impeached for prior consistent statements to be admissible in corroboration of a witness. State v. Perry, 298 N.C. 502, 259 S.E. 2d 496 (1979). The appellant does not say why the statements read by the officer did not corroborate the witnesses. We believe they do. This assignment of error is overruled.
[2] In his second assignment of error the defendant argues that the trial court erred in permitting the prosecutor to ask the defendant on cross-examination whether he had been convicted of several larceny charges more than ten years before the date of trial. He contends that because G.S. 8C-1, Rule 609 became effective the week following his trial the court should have followed *744that rule and excluded evidence of the defendant’s prior convictions that occurred more than ten years before the trial.
Before G.S. 8C-1 became effective, the rule was that for purposes of impeachment, the defendant could be cross-examined about prior convictions. This rule contained no time limits within which the convictions must have occurred. 1 H. Brandis, Brandis on North Carolina Evidence § 112 (1982). This rule remained in effect until the effective date of G.S. 8C-1, which applies to actions commenced after 1 July 1984. The court had no authority to implement a statute before its effective date. This assignment of error is overruled.
[3] In his third assignment of error the defendant contends it was error to submit to the jury a possible verdict of involuntary manslaughter as a lesser included offense of murder. This issue was addressed by our Supreme Court in State v. Greene, 314 N.C. 649, 336 S.E. 2d 87 (1985), and was resolved against defendant. This assignment of error is overruled.
[4] In his next assignment of error the defendant contends the court should have allowed his motion to set the verdict aside because there was not sufficient evidence to find him guilty of involuntary manslaughter. A death which is proximately caused by culpable negligence is involuntary manslaughter. See State v. Greene, supra. In this case the testimony of the defendant showed that he pointed a pistol toward Mr. Oden which fired when he tried to pull it back and that he fired the second shot in an effort to scare Mr. Oden away from him is evidence of culpable negligence. This evidence was sufficient to show culpable negligence on the part of defendant which proximately caused the death of Mr. Oden.
[5] In his fifth assignment of error the defendant argues that the trial court erred in sentencing the defendant for several reasons. The defendant first contends that the court improperly found as a factor in aggravation that the defendant had prior convictions punishable by more than 60 days’ confinement pursuant to G.S. 1340.4(a)(l)(o), since the convictions relied upon were more than ten years old and were for property crimes and traffic offenses. G.S. 1340.4(a)(l)(o) does not include any time limit within which the convictions must have occurred nor does it make any *745distinction among crimes of violence, property crimes and traffic offenses. The court properly found this aggravating factor.
[6] The defendant also argues that the court erred in failing to find in mitigation that the defendant acted under duress, coercion, threat, or compulsion which was insufficient to constitute a defense but significantly reduced his culpability, pursuant to G.S. 1340.4(a)(2)(b), that the defendant acted under strong provocation, pursuant to G.S. 1340.4(a)(2)(i), and that the defendant at the time reasonably believed that his conduct was legal, pursuant to G.S. 1340.4(a)(2)(k). The failure of the court to find a factor in mitigation urged by the defendant will not be overturned on appeal unless the evidence in support of the factor is uncontradicted, substantial, and there is no reason to doubt its credibility. State v. Hinnant, 65 N.C. App. 130, 308 S.E. 2d 732 (1983). The defendant’s evidence in support of these factors was contradicted by prosecution witnesses who testified that the victim carried no weapon and that the defendant held the victim by the collar and fired two shots in rapid succession. Therefore, the contended factors in mitigation were not shown by uncontradicted and manifestly credible evidence and the court’s refusal to find the factors in mitigation was not an abuse of discretion.
[7] Finally, the defendant argues that the court abused its discretion in failing to find that the two factors in mitigation outweighed the one factor in aggravation and in imposing the maximum permissible sentence.
While [the trial judge] is required to justify a sentence which deviates from a presumptive term to the extent that he must make findings in aggravation and mitigation properly supported by the evidence and in accordance with the Act, a trial judge need not justify the weight he attaches to any factor. He may properly determine that one factor in aggravation outweighs more than one factor in mitigation and vice versa.
State v. Ahearn, 307 N.C. 584, 596-97, 300 S.E. 2d 689, 697 (1983). This assignment of error is overruled.
No error.
Judge BECTON concurs.
*746Judge WEBB concurs in the result.