OPINION OF THE COURT
POMEROY, Justice.Following a jury trial, James Bennett, the appellant, was convicted of murder in the first degree and aggravated robbery. After the trial court denied his post-verdict motions, Bennett was sentenced to a term of life imprisonment for murder and to a concurrent imprison*422ment of ten to twenty years for robbery. This direct appeal followed.1
Bennett assigns four trial errors as mandating a new trial. Finding no reversible error, we will affirm.2
I
Appellant first objects to the refusal of the trial court to admit into evidence a statement given by an eyewitness to the crime, one April Young. Ms. Young, called as a Commonwealth witness, testified on direct examination that she saw the defendant shoot Calvin Turner. During the course of her cross-examination, defense counsel produced a statement allegedly given by Ms. Young to counsel prior to trial which in various particulars was inconsistent with her testimony. When confronted with the document, Ms. Young admitted that the signatures on it were hers, but denied having made most of the statements contained in it. The defense subsequently called to the stand one Joseph Prim, who testified that he had been present when the statement was given by April Young. He gave his recollection of the substance of that statement, and testified that the statement had been taken down by counsel in counsel’s own words.
When later the statement was offered in evidence, the court sustained an objection to it on the *423ground that the document had not been properly authenticated, since Ms. Young had denied making the statement and the scrivener had not been called to verify it as hers. We find no error in the court’s ruling. Furthermore, appellant was able to make substantial use of the statement in his questioning both of Ms. Young and of Prim. In this process the jury was made fully aware of the contents of the statement, the circumstances under which it was made, and that it had been signed by Young. The mere fact that it was not formally admitted into evidence was in no wise prejudicial to the defendant. See 1 Henry, Pennsylvania Evidence, § 1 at 4 n. 16 (1953 ed.).
II
Appellant’s next allegation of error relates to the testimony of a police detective who was present when the murder weapon was recovered from the victim’s bar, where it had been hidden by Bennett’s accomplice. The officer testified, over objection, that when he examined the weapon, a .38 snubnose revolver, it had a gray discoloration on the cylinder and barrel. He then testified, based upon his experience in firing weapons, that such discoloration indicated that the gun had been fired, although he could not say when it had been fired. The appellant contends that this testimony should not have been admitted because the officer had not been properly qualified as an expert in firearms. For three reasons we find no merit in this argument.
In the first place, the officer did not purport to testify as an expert, and his testimony was not “expert testimony” in the traditional sense. As the Superior Court has put it:
“[A] witness may state relevant facts known to him, because of experience, even though he is not regarded as an expert whose opinion would be admissible *424on a hypothetical inquiry.” Commonwealth v. Harris, 186 Pa.Super. 59, 63, 140 A.2d 344, 345 (1958).
The testimony was not intended to be determinative of whether the gun had been fired; it was, rather, in the nature of a statement of the officer’s observations.
Secondly, even if the testimony were to be considered expert testimony, the question whether a witness is qualified to testify as an “expert” is within the sound discretion of the trial court and will not be overturned except in clear cases of abuse. Commonwealth v. Davis, 466 Pa. 102, 115, n. 9, 351 A.2d 642, 648 n. 9 (1976) ; McCullough v. Holland Furnace Co., 293 Pa. 45, 141 A. 631 (1928); McCormick, Evidence § 13 at 29 (Rev. ed. 1972). We find no abuse in this case. The officer clearly was not a neophyte with firearms, and could be expected to have first hand knowledge concerning the firing of a weapon and its consequences in the appearance of the gun. His credibility, of course, was for the jury to pass upon.
Finally, the officer’s testimony was at best merely cumulative because appellant’s co-defendant, Barry Andrews, had already identified the revolver as the one used by Bennett during the robbery-murder.
Ill
Appellant objects to the fact that on re-direct examination of Barry Andrews, a co-conspirator called by the Commonwealth, the prosecuting attorney was permitted to question him concerning statements he had given the police before trial which were consistent with his testimony on direct examination. On cross-examination, defense counsel had attacked the credibility of Andrews by raising the inference that his testimony was motivated by self-interest in order to obtain more lenient treatment for himself. Appellant concedes that under these circumstances the Commonwealth was entitled to rehabil*425itate the witness by reference to prior consistent statements although such statements are not normally admissible. See, e. g., Commonwealth v. Gaddy, 468 Pa. 303, 362 A.2d 217, 223 (1976); Commonwealth v. Wilson, 394 Pa. 588, 602-03, 148 A.2d 234, cert. denied, 361 U.S. 844, 80 S.Ct. 97, 4 L.Ed.2d 82 (1959). He contends, however, that the rehabilitation in this ease was “overly broad” in that the prosecutor was permitted to ask Andrews if the statement which he gave the police shortly after his arrest was “substantially” the same as his testimony. Appellant argues that this was an improper conclusion because the statements themselves were not introduced into evidence so that the jury could judge for itself whether, they were “substantially” the same as Andrews’ trial testimony. In dismissing this claim, we need only point out that under our case law which recognizes the above exception as to the use of prior consistent statements, there is no requirement that they be introduced into evidence if they are referred to; nor do we believe that the trial court abused its discretion in permitting the questioning and the response.
IV
Appellant’s final allegation of error relates to a portion of the trial court’s charge to the jury. The court, in its initial charge, defined for the jury the crimes of murder in the first and second degrees and voluntary manslaughter. After three hours of deliberation, the jury requested that these definitions be repeated. The court did so and then, after the repeated definition of voluntary manslaughter, made the following additional comments:
“I have told you earlier3 that it is in your power to find that a defendant is guilty of voluntary man*426slaughter, under these circumstances. And it is within your power to do that.
“But, it is my opinion, under the circumstances— and I give you my opinion. There’s no binding effect upon you. But, under the circumstances, the crime of voluntary manslaughter would not be an appropriate verdict in this case. Because, there is no evidence, as I recall it, that there was any scene between the deceased and the person who shot him, that would argue a provocation, that a person would be transported out of their mind and kill him.
“If there was anything that happened here — and you must determine that under the evidence as we have heard it, and you must decide what the evidence is. It seems to me that one could hardly say that a provocation was caused by someone who was being robbed, if you find that so.
“If, on the other hand, you find that there was a provocation not associated with the robbery in any wise, you could find the defendant guilty of voluntary manslaughter.” (Footnote added)
Upon completion of the supplemental charge, defense counsel objected, out of the hearing of the jury, to the trial court’s remark that “the crime of voluntary manslaughter would not be an appropriate verdict in this case.” The objection was overruled. It is renewed on this appeal on the theory that the comment was an improper expression of opinion by the trial judge which denied Bennett a fair trial. We do not agree.
The basis of the trial court’s view that a verdict of voluntary manslaughter would not be “appropriate” in this case was that there was no evidence to support such a *427verdict; all of the evidence having shown that the killing took place in the course of a robbery, the killing was, by definition, a felony-murder.4 In two recent cases we have been presented with the question whether a trial judge may indicate to a jury his opinion as to the insufficiency of the evidence to support a verdict of voluntary manslaughter when the evidence is in fact insufficient. In both cases we held that under the facts there present the expression of such an opinion was not error. Commonwealth v. Rivera, 470 Pa. 131, 367 A.2d 719 (1976); Commonwealth v. Gaddy, 468 Pa. 303, 318, 362 A.2d 217, 224-225 (1976).5
From those cases it is clear that two principal conditions must be met before such an expression of opinion may properly be included in a charge: (1) the trial court must fully inform the jury of its “power” to return a verdict of voluntary manslaughter, whether supported by evidence or not; and (2) the court must also instruct the jury that it is not bound by the court’s comments concerning the evidence because it is the jury which is the sole finder of the facts. Both of these re*428quirements were explicitly met in this case, and we find no error in the court’s charge in this regard. See Commonwealth v. Russell, 456 Pa. 559, 322 A.2d 127 (1974); Commonwealth v. Yount, 455 Pa. 303, 314 A.2d 242 (1974) .6
Judgments of sentence affirmed.
NIX, J., concurs in the result. ROBERTS, J., filed a dissenting opinion in which MANDERINO, J., joins.. Bennett’s appeal of the judgment of sentence imposed for murder was properly taken directly to this Court. See Appellate Court Jurisdiction Act of 1970, Act of July 31, 1970, P.L. 673, art. II, § 202(1), 17 P.S. § 211.202(1) (Supp.1975). The appeal of the judgment of sentence for aggravated robbery was originally taken to the Superior Court, which certified the appeal to this Court in order that the two appeals might be heard together.
. Although the sufficiency of the evidence is not challenged on this appeal, our review of the evidence convinces us that the Commonwealth established beyond a reasonable doubt that James Bennett shot and killed one Calvin Turner during the course of a robbery at Turner’s bar in the City of Philadelphia. See Act of February 15, 1870, P.L. 15, § 2,19 P.S. § 1187.
. In its main charge, following the definition of voluntary manslaughter, the trial judge had said, “Under the terms of the evidence as presented here, it does not seem to me that the crime of *426voluntary manslaughter is involved. You have that power, however, and I so instruct you.” The judge had earlier also charged that the jury “may find the defendant guilty or not guilty of voluntary manslaughter,” and again had stated, “[i]t is a possible verdict which you may return.”
. Appellant does not argue that the fault in making the statement was that there was, in fact, evidence which would have supported a verdict of voluntary manslaughter. Had this argument been made it would not succeed in this case. Our review of the evidence fully confirms the trial court’s opinion that evidence of passion and provocation was totally lacking. Cf. Commonwealth v. McNeill, 462 Pa. 438, 341 A.2d 463 (1975); Commonwealth v. Bailey, 450 Pa. 201, 299 A.2d 298 (1973).
. As we noted in Commonwealth v. Gaddy, 468 Pa. at 318-319, n. 15, 362 A.2d at 224, n. 15, at the time of the trial in this case, (February, 1974) the trial judge was not required to charge on voluntary manslaughter if in his view no evidence existed in the record which would support such a verdict.
See, e. g., Commonwealth v. Matthews, 446 Pa. 65, 285 A.2d 510 (1971). In Commonwealth v. Jones, 457 Pa. 563, 319 A.2d 142 (1974), cert. denied, 419 U.S. 1000, 95 S.Ct. 316, 42 L.Ed.2d 274 (1974), a majority of this Court, although for different reasons, held that a defendant, upon request, was entitled to a charge on voluntary manslaughter even absent such evidence. See also U. S. ex rel. Matthews v. Johnson, 503 F.2d 339 (3d Cir. 1974), cert. denied sub nom., Cuyler v. Matthews, 420 U.S. 952, 95 S.Ct. 1336, 43 L.Ed.2d 430 (1975).
. The appellant also contends that the trial court erred in its charge because it summarized the evidence to his detriment. Appellant took no jbjection to the trial court’s action and thus has not properly preserved this issue for appellate review. Pa.R.Cr.P. 1119(b); Commonwealth v. Dukes, 460 Pa. 180, 331 A.2d 478, 483 (1975).