- 01: Introduction
- 02: History
- 03: Propellants, Firearms, and Ammunition Development
- 04: Modern Firearms Manufacture
- 05: Small Arms Ammunition
- 06: Evidence Handling Procedures
- 07: Equipment and Instrumentation
- 08: Examination of Firearms
- 09: Cartridge and Shotshell Examination
- 10: Characterization and Evaluation of Fired Projectiles
- 11: Bullet Comparison and Identification
- 12: Gunshot Residue and Distance Determination
- 13: Toolmark Identification
- 14: Communicating Results
- Resources
Ejection Port and Feed Ramps
Home > Modern Firearms Manufacture > Parts Fabrication > High Stress Load Parts > Ejection Port and Feed Ramps
The areas of the receiver that can produce identifiable marks for firearms identification are the ejection port and feed ramps. Ejection port marks on cartridge cases fired in Colt Model 1911 pistol slides are well recognized among examiners. Milling produces these marks in the gun.
For some firearms, the receiver or frame is stamped from sheet metal. It can be a flat sheet formed into a box as seen in the UZI submachine gun or two mirror-image pieces that fit together like a clamshell. In either case, some provision must be made for support of internal parts. Some support rails can be built into the stamping die so the rail becomes integral with the stamping; others require an index mark for adding a separate part later.
The .22 caliber Ruger Standard Auto pistol is a successful commercial product with a stamped frame. Two mirror-image half shells are stamped and joined with a weld. A separate trigger guard and latch bar help to stabilize the structure. The metal stock used for the stampings is of high quality. After welding, polishing, and finishing, the frame that started as two precision stampings has the same quality external appearance as a forged or investment cast frame.
Whether forged or cast, final forming operations (such as drilling holes for pins and screws) must still be performed. Today, this once tedious operation is performed on frames, receivers, and other large parts by CNC machining. At this stage, the gun part has an abundance of accurate index points. If the part has been CNC-processed all the way from a raw casting, the program will normally specify drilling as the last operation.
The operations and techniques discussed in this section are also used to make large parts (discussed in the low-stress part topic) that are not subjected to firing stress, including trigger guards and floorplates.
Click here to view a high-speed video of the ejection and reloading process of a semiautomatic handgun. Video courtesy of Kurzzeit.
