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13th Installment - Semi-Auto C5A1 Build - Left Extractor Cam Mods

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#1 ·
Left Extractor Cam Modifications - Casing (Receiver) Group

Feed Extractor Cam NSN# 1005-21-874-8292

When the .30 caliber M1919A4s were convert to the C1 the original feed extractor cams were not modified. During service the C1 suffered from a low round stoppage. The low round round stoppage which is not good for combat weapon could crack or break the T-slot on the breech bolt again not good in combat. The low round stoppage problem was traced back to the length of the 7.62mm NATO cartridge and the angle it was fed into the T-slot and the chamber of the barrel. This modification in the C5A1 upgrade process was to correct a problem with low round stoppages due to the use of the original .30 caliber Feed Extractor Cam which was retained on the remanufactured C1 guns. As part of the modifications to C5A1 upgrade from C1 the rear feed extractor cam were modified to correct the feeding angle of the 7.62mm NATO cartridge. The rear Feed Extractor Cams were removed and modified and reinstalled. This modification is easy and will require new rivets to reinstall the C5A1 extractor feed cam.

-fjruple
 

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#2 ·
I brought my 1919 into the base weapons shop to show the new guys what they looked like. (They were busy replacing locking blocks on a .50 at the time) and they were fascinated by the "mini" browning....they'd never seen the .30 BMG before, so they were, well, VERY interested.

The two old hands in the shop were holding back for a bit, but then Peppy (he's 68, and has been "playing" with military weapons for over 45 years) walked up. His eyes lit as he started talking, and it was truly beautiful to behold a master at work as he stripped it down. The first time he'd touched a BMG since the early 90's. He started telling me about the trials he was involved in MANY years ago when they discovered the low round stoppage. They had a 1919 (C-1/C-5A1) that they cut holes in to view the cartridge in motion. High speed filming was used, and they figured out the dynamics of what was happening inside the gun that caused the jams.

The angle to the cam was changed to resolve the issue, and basically it was an acceleration issue. The sharp angle on the original cam resulted in the 7.62mm bullets being "flipped" as they were cammed down into place. They changed the angle to slow the acceleration of the cam, and it fixed it up.

It was NEAT to see him talking about it. :)

NS
 
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