Expert Witness Profiler

Category: Firearms Expert Witness

  • Firearms Expert Allowed to Opine on Air Rifle

    Firearms Expert Allowed to Opine on Air Rifle

    This is a products liability case arising from an alleged injury caused by an air rifle. Plaintiff Brian Cornwell (“Cornwell”) ordered an air rifle from Extreme Big Bore Air Rifles on March 25, 2021. After regularly using the rifle for nearly two years, on January 11, 2023, Plaintiff injured himself while attempting to fill the air rifle with compressed air. He sustained an injury to his left thumb.

    Defendants Texas Machine Parts, Danny Duke, and John Wiley filed a motion to exclude Plaintiff’s experts, Kennith Comeaux and William Caster, or, in the alternative, to exclude any testimony from them related to medical causation.

    Firearms Expert Witness

    Kennith R. Comeaux has thirty-five years of experience as a gunsmith. Because of his familiarity with guns, in his other career as a certified ISO 9000 quality auditor, he “was allowed to audit firearms manufacturers and ammunition manufacturers” to determine if the companies could get ISO certified by meeting “an international standard associated with quality that is very similar to OSHA with respect to safety, but for quality.”

    Discover more cases with Kennith Comeaux as an expert witness by ordering his comprehensive Expert Witness Profile report.

    Air Mechanics Expert Witness

    William B. Caster, Jr. holds a certification from the National Balancing Council, “a group that educates and teaches in air balancing and hydronic balancing, which is airflow CFM delivery, pressure, and velocity.” He owns a consulting company for heating, ventilation and air conditioning, airflow dynamics, hydronic testing, and air testing.

    Want to know more about the challenges William Caster has faced? Get the full details with our Challenge Study report.

    Discussion by the Court

    A. Kennith Comeaux

    Though Comeaux acknowledged that he is not an expert in gun manufacturing, his experience in being able to quality-audit firearms and ammunition manufacturers underscores his gunsmithing experience.

    Comeaux also relied on sufficient facts and data to reach his conclusions and utilized reliable principals and methods. Importantly, he personally inspected the air rifle as well as consulted an American Society for Testing and Materials (ASTM) manual, looked at the subject air rifle’s owner’s manual as well as the owner’s manuals of other similar rifles, and researched other manufacturer’s diagrams.

    Comeaux also explained his methodology and how it comports with the ASTM and could be replicated by others. His decades-long experience as a gunsmith, combined with the foregoing, allowed the Court to find that Comeaux’s testimony is sufficiently reliable.

    It is also clear that Comeaux’s testimony will assist the trier of fact and is relevant. For example, one line of Comeaux’s report reads: “Further attempts to seat the exhaust valve without removal of the air chamber cap were unsuccessful including lubrication with Teflon oil.” This shows that Comeaux will provide testimony that goes beyond “common sense.”

    Moreover, this sort of testimony is relevant because Plaintiff’s claims are based in the alleged faulty function and design of the valves in the subject air rifle and a replacement valve assembly, and Comeaux’s testimony reflects his personal evaluation of the air rifle and its replacement valve.

    B. William Caster

    Caster’s testimony is based on sufficient facts and data. Like Comeaux, Caster personally inspected the air rifle at issue.

    He conducted research on the relevant parts included in his testing. Moreover, he limited his testing to his discipline, explaining that he did not operate or fill the air rifle during his testing because he “went there to find out if the equipment that [Plaintiff] utilized for filling the gun exceeded the capabilities or burst pressure of the gun.” As to reliable principles and methods, Caster did not conduct explicit testing like Comeaux, but rather researched and observed whether Plaintiff possessed the “tooling to be able to” fill the air rifle’s air tank beyond its PSI specifications. Caster explained that he based his conclusions off “the actual flow chart of the gun from the tank to the valve to the barrel” because “the only point of when air can enter into the chamber is when the valve is released.”

    Considering these circumstances, the Court found that Caster is qualified to testify at trial based on his experience and the nature and formulation of his opinions.

    C. Medical Causation Testimony

    Defendants asked that both Comeaux and Caster be excluded from offering medical causation testimony because they are not medical doctors.

    To the extent either expert anticipates opining on medical causation at the trial of this matter, the Court will foreclose them from offering any such testimony. Neither Comeaux nor Caster are medical doctors.

    Held

    The Court denied Defendants’ motion in limine to exclude the testimony of Kennith Comeaux and William Caster.

    Key Takeaway

    The fact that opposing parties do not agree with the facts relied upon by the experts or their interpretation of those facts does not render their opinions irrelevant or unreliable; challenges related to the basis of any of the experts’ opinions are thus best suited for cross-examination, not exclusion.

    Case Details:

    Case Caption: Cornwell V. Extreme Tactical Components, LLC
    Docket Number: 2:24cv926
    Court Name: United States District Court, Louisiana Eastern
    Order Date: January 15, 2026
  • Firearms Expert’s Testimony Excluded Because of His Limited Experience with Machineguns

    Firearms Expert’s Testimony Excluded Because of His Limited Experience with Machineguns

    Defendant Chase Farmer was charged and convicted of multiple firearms offenses in a trial spanning April 29, 2025, to May 6, 2025. Specifically, Defendant was charged with importing, possessing, transporting, and failing to keep proper records for drop-in auto sears (“DIAS”) and Glock switches from Russia, which are machinegun conversion devices regulated as machineguns under the National Firearms Act (“NFA”).

    Four days before trial commenced, the Government filed a motion in limine seeking to exclude various witnesses that Defendant proposed.

    The Court granted the Government’s motion in part. However, the Court took under advisement the Government’s request to exclude Defendant’s proposed firearms expert, Tyler Hilliker. The Court explained that it had doubts that Hilliker met the qualifications for an expert witness.

    Firearms Expert Witness

    Tyler Hilliker founded Hilliker Arms in 2021, and for the following two years was engaged solely in instructing on safe firearms handling and concealed carry.

    He has also completed several courses pertaining to firearms.

    Get the full story on challenges to Tyler Hilliker’s expert opinions and testimony with an in-depth Challenge Study.

    Discussion by the Court

    The Court found that Hilliker’s experience with DIAS and Glock switches is derived solely from watching others work with them, mostly on video, and relatively few times. Moreover, Hilliker’s experience with machineguns in general is limited. He has only manufactured three machineguns: two AR-15s modified with traditionalstyle sears and an Uzi.          

    Moreover, Hilliker based his conclusions in his expert report on modifying an AR-15 with what he called a “traditional” auto sear—not a DIAS. Thus, there was no “fit” between Hilliker’s proffered testimony and the pertinent inquiry in this case, which involves DIAS and Glock switches specifically.

    Held

    The Court granted the government’s motion to preclude Tyler Hilliker as an expert witness.

    Key Takeaway:

    While Hilliker may be knowledgeable about firearms in general, it does
    not mean he is qualified to be an expert witness about converting firearms into machineguns via DIAS or Glock switch.

    Case Details:

    Case Caption: USA V. Farmer
    Docket Number: 2:22cr20678
    Court Name: United States District Court, Michigan Eastern
    Order Date: May 07, 2025
  • Testimony of Firearms Expert Witness Emphasizing on Manufacturing Mistake Excluded

    Testimony of Firearms Expert Witness Emphasizing on Manufacturing Mistake Excluded

    This product liability lawsuit involves Plaintiff’s use of a single-shot Thompson/Center Encore Pro Hunter rifle with a barrel chambered in .460 S&W caliber. Plaintiff had purchased and installed this new barrel in 2017, and he proceeded to use the rifle without incident for the next four years, firing it on at least thirty separate occasions without incident. However, on October 9, 2021, while Plaintiff was attempting to fire a second shot from a shooting bench, the barrel on the rifle was damaged causing the rear forearm screw to be ejected from the rifle and fracture the forearm.

    Plaintiff subsequently filed a lawsuit against Thompson/Center alleging that the barrel was defectively designed and/or manufactured and that Thompson/Center otherwise failed to warn. During discovery, Plaintiff identified Ryan Spence as a witness. Spence is a gunsmith who visually examined the rifle for approximately two hours and then sent Plaintiff’s counsel an email stating that the incident was caused by Thompson/Center improperly drilling the hole for the rear forearm screw all the way through the barrel.

    Defendant filed a motion to exclude Spence from testifying as his opinions did not pass muster under Rule 702.

    Firearms Expert Witness

    Ryan Spence is a graduate of the Pennsylvania Gunsmith School who worked his way up to become the head gunsmith of the Remington premier warranty center for the east coast. He has performed warranty service for Weatherby, Henry, Marlin, and other firearm manufacturers. He now owns and operates Spence Gunsmithing.

    Discussion by the Court

    To begin with, Defendant argued that Spence was not a metallurgist and had no experience designing barrels.

    The Court decided that Spence’s report did not provide the key handholds of Rule 702.

    Reliability

    Spence did not examine a comparable exemplar barrel

    In his first conclusion, Spence wrote that “the cause of this weapons failure was due to the rear forearm screw hole being drilled all the way through the barrel.” Spence did not describe the methods he employed to arrive at this opinion. He had taken notes during his investigation, but he had not preserved them. However, it was clear from his testimony what Spence did not do: he did not examine a comparable exemplar barrel; did not perform any modeling or casting; did not perform any magnetized testing; and did not take any x-ray or other images of the barrel. Spence’s report also contained no measurements or other analysis. It did not explain in any way what his inspection method had entailed.

    Spence did not offer any comparison to establish what that industry standard was

    In his second conclusion, Spence opined that the screw hole “was a very obvious manufacturing mistake as it was industry standard to drill no more than 2/3 the thickness of the barrel when drilling and tapping barrels.” However, Spence did not offer any comparison to establish what that industry standard was. He did not explain why the claimed manufacturing mistake was obvious, and he did not explain how or why such a mistake would have evaded Defendant’s product testing. Spence never investigated or considered Defendant’s testing during the manufacturing process to determine whether it was flawed. Furthermore, Spence did not investigate and did not know Defendant’s manufacturing process for the subject barrel.

    Spence did not explain his methodology for his conclusion that his identified defect was the “only cause of failure ”

    In his third conclusion, Spence wrote that Defendants had drilled “at the very rear of the barrel where chamber pressures would be the highest. In our opinion, this was the only cause of failure for this rifle.” However, Spence did not explain his methodology for his conclusion that his identified defect was the “only cause of failure.” In fact, he recognized that there were many other likely causes for barrel failure. He testified that the barrel failure might have been due to a user loosening the forearm screw; an obstruction in the barrel; using an aftermarket screw made of a different material; using over-pressurized ammunition; or making post-production alterations to the barrel that changed its specifications.

    Held

    The Court granted Defendant’s motion to preclude the testimony of Plaintiff’s expert Ryan Spence.

    Key Takeaway:

    Spence’ inspection lasted about two hours. He concluded that Defendants were responsible for the barrel’s misfire and Plaintiff’s ensuing injuries. Spence did not examine a comparable exemplar barrel; did not perform any modeling or casting; did not perform any magnetized testing; and did not take any x-ray or other images of the barrel. Spence never investigated or considered Defendant’s testing during the manufacturing process to determine whether it was flawed. He did not explain his methodology for his conclusion that his identified defect was the “only cause of failure.”

    Case Details:

    Case Caption: James V. Thompson/Center Arms
    Docket Number: 3:22cv1781
    Court: United States District Court, Ohio Northern
    Order Date: March 28, 2024