JFK Assassination Forum

TG-

I could never make heads nor tails out of what any of the audio experts said on the dictabelt, on any side of the issue.

Unlike the Z-film, where a layman can make a reasonable educated guess what happened, I suspect almost no one in the JFKA research community has any idea what the audio experts are talking about.

Who knows?

Maybe? Maybe not?

ME: Was H. B. McLain's motorcycle's radio stuck in the "on" position when he was travelling on Houston Street a few seconds before the first shot rang out?

Thought for 4s

GROK: No, according to H.B. McLain himself and significant later analysis; the HSCA initially concluded yes, but this is heavily disputed.

en.wikipedia.org

H.B. McLain (sometimes spelled McLain or McLean) was a Dallas Police Department motorcycle officer riding in the JFK motorcade on November 22, 1963. He was positioned on the left rear of the motorcade (near Vice President Johnson's car) and testified that he was on Houston Street, approaching the turn onto Elm Street, when he heard the first shot.

aarclibrary.org

HSCA Position (1978–1979)The House Select Committee on Assassinations (HSCA) used acoustic analysis of a Dallas Police Dictabelt recording (Channel 1) to argue there was a fourth shot from the grassy knoll, implying a conspiracy. They identified a ~5.5-minute "stuck microphone" transmission—where the mic button stayed open—as coming from McLain's motorcycle.

en.wikipedia.org

Timing and location match: The HSCA placed the open-mic motorcycle on Houston Street seconds before the first shot (impulses analyzed as gunshots), consistent with McLain's position and testimony.

jfk-records.com

McLain acknowledged in testimony that his microphone could stick open (it had happened before due to worn gaskets or relays), though he had no specific memory of it doing so that day. He normally used Channel 1 and didn't recall using his radio during the motorcade.

aarclibrary.org

McLain's Denial and Counter-EvidenceMcLain strongly disputed the HSCA's identification after hearing the recording:He said it was not his motorcycle because the tape lacks sounds of him revving his engine at high speed or activating his siren immediately after the shots (as he recalled doing while racing to Parkland Hospital).

youtube.com

The engine sounds on the tape reportedly match a three-wheeled motorcycle better than his two-wheeler.

en.wikipedia.org

Later Dallas Police analysis and critics argued his bike was not in the right position or that the acoustic matches were flawed. McLain maintained the stuck mic was someone else's.

independent.org

Subsequent reviews (e.g., by the National Academy of Sciences and others) have criticized the HSCA acoustics as unreliable due to issues with synchronization, crosstalk, and identification of the bike. The "stuck mic" theory remains controversial and is not universally accepted.

en.wikipedia.org

In short: The HSCA said yes (McLain's bike on Houston Street with stuck "on" mic), but McLain and many analysts said no—the evidence doesn't hold up under scrutiny of his actions and the audio. This remains a debated piece of JFK assassination lore tied to the conspiracy vs. lone-gunman arguments.


ME: After he listened to the Dictabelt recording, did he say that the motorcycle with the stuck radio sounded like a three-wheeler?

Thought for 3s

Yes.

en.wikipedia.org

After listening to the Dictabelt recording (following his 1978 HSCA testimony, where he had acknowledged the possibility of a stuck mic but lacked specific recall), H.B. McLain explicitly stated that the engine sounds on the tape came from a three-wheeled motorcycle, not his two-wheeled Harley-Davidson solo bike.

kenrahn.com

Key quotes and details:

McLain told author Dale Myers (in an interview recounted in Myers' work): “I told him, ‘It’s a three-wheeler that’s stuck.’ You can tell very clearly the difference between the sound of a solo motorcycle that we rode and a three-wheel motorcycle; it’s like daylight and dark. The solo engine has kind of a thump to it: CHUKE.. CHUKE.. CHUKE.., while the three-wheeler has more of a thrashing sound.. AAANG.. AAANG.. AAANG!”

kenrahn.com

He also said: "There's no comparison to the two sounds."

en.wikipedia.org

This was one of his main reasons for rejecting the HSCA's identification of his motorcycle as the one with the stuck-open microphone. He further noted the absence of his engine revving at high speed or his siren activating as he raced toward Parkland Hospital, and he believed the recording likely came from a different officer on a three-wheeler (possibly near the Trade Mart).

en.wikipedia.org

This point has been cited in Wikipedia summaries, books, and discussions of the Dictabelt evidence, reinforcing McLain's consistent post-recording denial. The three-wheeler distinction remains a key element in critiques of the acoustic evidence for a grassy knoll shot.


ME: Did he say that the three-wheeler must have been near another motorcycle that didn't have a stuck mic?

Thought for 5s

GROK: No, there is no record of H.B. McLain saying that.

kenrahn.com

In his detailed accounts (including interviews recounted by author Dale Myers and in The Deed by Gerald Posner), McLain consistently identified the stuck-mic sounds as coming from a single three-wheeled motorcycle (a Harley Servi-Car) operated by an officer known for whistling—likely Leslie "Les" Beilharz—stationed near the Dallas Trade Mart, about three miles from Dealey Plaza.

kenrahn.com

Key points from McLain's statements:He emphasized the distinct engine sound ("thrashing" AAANG.. AAANG.. vs. his solo bike's "thump" CHUKE.. CHUKE..) and other audio cues like the rider whistling, a loose manhole cover ("Bong...Bong"), and a sheriff’s car radio also assigned to the Trade Mart area.

kenrahn.com

He described the stuck mic as isolated to that three-wheeler, far from the motorcade and Dealey Plaza, which explained why no shots or relevant motorcade sounds (like his own siren or high-speed revving) appeared on the Dictabelt.

en.wikipedia.org

There is no mention by McLain (or in associated analyses citing him) of the three-wheeler being near another motorcycle whose mic was not stuck. He and dispatcher J.C. Bowles used the clues to pinpoint one specific officer and location, ruling out the motorcade entirely.

kenrahn.com

This aligns with broader critiques of the HSCA acoustics: the open-mic recording originated elsewhere, not from McLain's position on Houston Street. McLain's focus was always on disproving it was his bike by highlighting the mismatch with a solitary three-wheeler elsewhere.


ME: He said that in a January 4, 1979, interview to Helmer Reenberg which can be watched on YouTube.

Thought for 5s

GROK: Yes, in that specific January 4, 1979, interview with Helmer Reenberg (available on YouTube), H.B. McLain stated exactly that.

youtube.com

Relevant excerpt from the interview (transcribed from the video):"...it's going to have to come from some place where you've got two vehicles sitting fairly close together with one of them stuck because they have two tapes one of them is on channel one [and] one is on channel two and you can hear the same voice on channel one as [on] channel two..."
McLain was explaining why the Dictabelt recording could not have come from his motorcycle (or any near the motorcade in Dealey Plaza). He theorized the stuck mic was on one police vehicle (a three-wheeler, per his other statements) located near a second vehicle whose radio was operating normally on Channel 2, allowing cross-hearing of the same voice on both channels. This placed the source far from Dealey Plaza (e.g., near the Trade Mart), consistent with his rejection of the HSCA acoustics.

youtube.com

This detail aligns with his broader critique (distinct engine sounds, no siren/revving, etc.) but specifically addresses the dual-channel aspect in this early post-HSCA interview. Earlier and later accounts (e.g., with Dale Myers) focus more on the three-wheeler identification and location without always repeating the "two vehicles" point.

ME: Were any of the shells that were found in the "Sniper's Nest" on 11/22/63 dented? If so, does it present a problem for the official conclusion of the Warren Commission?

Thought for 23s

GROK: Yes, one of the three spent cartridge cases (shells) found in the "sniper's nest" on the sixth floor of the Texas School Book Depository had a dent. The three cases recovered by Dallas police on November 22, 1963, were designated as Warren Commission Exhibits (CE) 543, 544, and 545. CE 543 had a noticeable inward dent on the mouth (the open lip where the bullet had been seated).

educationforum.ipbhost.com +1

This dent has been documented in photographs taken at the scene (and later in Commission exhibits) and was examined by the FBI and, later, the House Select Committee on Assassinations (HSCA) Firearms Panel. The other two cases (CE 544 and CE 545) were undamaged in this way.

aarclibrary.org

No, this does not present a problem for the Warren Commission's official conclusion (that Lee Harvey Oswald fired three shots from a 6.5 mm Mannlicher-Carcano rifle in the sniper's nest, with the three cartridge cases ejected from that rifle). The Warren Commission itself relied on FBI ballistic analysis showing that all three cases had been fired in Oswald's rifle (CE 139), based on matching firing-pin impressions, extractor marks, and bolt-face marks.

archives.gov

The dent on CE 543 prompted criticism from some researchers, who argued it was so severe that the case could not have held a live bullet beforehand (implying it could not have been one of the three shots fired during the assassination, or that the case was planted or previously damaged).

jfk.boards.net +1

However, the HSCA Firearms Panel (a team of independent firearms experts) directly addressed this in 1977–1978.

They concluded:

The dent on the mouth of CE 543 was produced during ejection from the rifle (specifically, from rapid operation of the bolt/ejector mechanism), not before firing or from manufacturing/loading.

They duplicated an identical dent in test firings with Oswald’s rifle (one of four test cases showed a comparable dent when the bolt was worked quickly).
Microscopic comparison confirmed that all three cases (including the dented CE 543) were fired in the CE 139 rifle, with no evidence of multiple chamberings or prior firings.

aarclibrary.org +1

The panel explicitly rejected the idea that the dent would have prevented the case from being fired in the rifle (or any rifle).

ronaldjlilek.medium.com

The Warren Commission (1964) did not dwell on the dent as an issue—the FBI’s initial matching of the cases to the rifle was sufficient for their conclusion of three shots from the sniper’s nest. The later HSCA analysis reinforced this by resolving the dent question through direct experimentation. While some conspiracy-oriented analyses continue to dispute the replication or point to minor chain-of-custody details (e.g., CE 543 was turned over to the FBI a few days later than the others), the official forensic examinations found the dent fully consistent with the three-shot scenario.

documents3.theblackvault.com

In short, the dent is real and well-documented, but it has been explained as post-firing ejection damage and does not contradict (or undermine) the Warren Commission’s ballistics findings or lone-gunman conclusion.

Short cycle.  Shooter error.

Oswald fired off a shot and in the act of operating the bolt, did not pull the bolt back far enough (focusing only on speed instead of operating the bolt properly).  This caused the spent shell casing to not eject as it should, getting caught and therefore dented before a second action of operating the bolt finally ejected the shell casing.

I still see people using the misnomer Mannlicher-Carcano to refer to Oswald's Carcano rifle. Carcano is a family of bolt action rifles designed by Italian gunmaker Salvatore Carcano in the late 19th century. Mannlicher refers to the feeding system that used an en bloc clip to load into the fixed magazine.
The following paragraph explains the various names used for these Carcano rifles.

"Although this rifle is often called "Mannlicher−Carcano", especially in American parlance, it was officially the Fucile Modello 1891 (Model 1891 rifle).[5] The "Mannlicher" title came from the en bloc loading clips system, having nothing to do with the action itself, which was a modified Gewehr 88 action (which itself was a combination of the action from the Mauser Model 1871 with the Mannlicher en bloc loading);[6] in Italy the rifle was commonly reported by army and civilian sources as "Carcano−Mannlicher" since the action engineer is usually named before the magazine designer's in Italian nomenclatures (like with Vetterli-Vitali and others)."

In general, the HSCA was skeptical and reasonable in their JFKA findings.

While the WC/FBI may have leaned on evidence, I think the HSCA mostly played it down the middle.

I accept the HSCA conclusions regarding the dent.

The WC/FBI leaned on evidence to reach its conclusions? What a novel idea. What did the HSCA use. A Ouija Board?

In general, the HSCA was skeptical and reasonable in their JFKA findings.

While the WC/FBI may have leaned on evidence, I think the HSCA mostly played it down the middle.

I accept the HSCA conclusions regarding the dent.

Do you agree with its analysis of the Dictabelt sounds or "sounds"?