Steve in Allentown
New member
The top picture below is of a fully loaded magazine locked into the magazine well. The bottom picture shows a failure-to-feed of the first round where the nose of the bullet is jammed against the frame feed ramp. This malfunction is commonly known as a nose dive stoppage.
Many folks will suggest switching magazines, switching ammo, checking the slide stop for bullet contact, or replacing the magazine catch with an EGW Higher mag catch. While one or more of these may fix the issue none of them address the underlying problem which is most often due to geometry problems with the frame feed ramp. Specifically, the feed ramp angle and/or the ramp depth are not correct.
The image below shows the correct angle of the feed ramp as specified by John Browning. Unlike most of the dimensions for the pistol, the feed ramp angle has no +/- tolerance. It is to be exactly 31.5 degrees. In practice it is a magical number. Too steep and cartridges won't feed. Not steep enough and cartridges may escape the magazine due to inertia. The Goldilocks Principle is in play here. Not too much, not too little, just right.
In addition to the correct angle the frame feed ramp must extend far enough down into the frame to make contact with cartridges that nose dive. Ideally, the ramp should extend from the top of the frame rails downward .400" which is just about at the bottom of the frame cut out for the slide stop. The longer the ramp, the better but often a ramp that is .360" is sufficient. It all depends on other dimensions within the pistol.
The barrel bed itself must not under any circumstances measure less than .246" from the top of the ramp to the VIS. Otherwise the structural integrity of the pistol will be compromised. The longer the barrel bed, the better.
Below is a collection of pictures showing bad ramps and good ramps in terms of ramp length for .45 1911s.
#1 - bad ramp. Does not extend far enough down into the mag well.
#2 - good ramp. Extends to the bottom of the slide stop frame opening.
A - good ramp.
B - good ramp.
C - bad ramp. Does not extend far enough down into the mag well.
If you want to get a rough idea of the angle of a feed ramp you can get one of these Empire protractors from Home Depot for something less than $10. You'll have to shorten the arm enough to allow it to fit in the magazine well. While it's not a highly precise machine tool, it will let you know if the angle of a feed ramp is grossly wrong. A real machinist/1911 'smith will have the right tools (expensive) to determine the exact angle and depth of a frame feed ramp. They can also correct ramps that are bad. Correcting feed ramps is a job best left to a professional.
FYI, here's how a professional 1911 'smith fixes an out-of-spec frame ramp.
Many folks will suggest switching magazines, switching ammo, checking the slide stop for bullet contact, or replacing the magazine catch with an EGW Higher mag catch. While one or more of these may fix the issue none of them address the underlying problem which is most often due to geometry problems with the frame feed ramp. Specifically, the feed ramp angle and/or the ramp depth are not correct.
The image below shows the correct angle of the feed ramp as specified by John Browning. Unlike most of the dimensions for the pistol, the feed ramp angle has no +/- tolerance. It is to be exactly 31.5 degrees. In practice it is a magical number. Too steep and cartridges won't feed. Not steep enough and cartridges may escape the magazine due to inertia. The Goldilocks Principle is in play here. Not too much, not too little, just right.
In addition to the correct angle the frame feed ramp must extend far enough down into the frame to make contact with cartridges that nose dive. Ideally, the ramp should extend from the top of the frame rails downward .400" which is just about at the bottom of the frame cut out for the slide stop. The longer the ramp, the better but often a ramp that is .360" is sufficient. It all depends on other dimensions within the pistol.
The barrel bed itself must not under any circumstances measure less than .246" from the top of the ramp to the VIS. Otherwise the structural integrity of the pistol will be compromised. The longer the barrel bed, the better.
Below is a collection of pictures showing bad ramps and good ramps in terms of ramp length for .45 1911s.
#1 - bad ramp. Does not extend far enough down into the mag well.
#2 - good ramp. Extends to the bottom of the slide stop frame opening.
A - good ramp.
B - good ramp.
C - bad ramp. Does not extend far enough down into the mag well.
If you want to get a rough idea of the angle of a feed ramp you can get one of these Empire protractors from Home Depot for something less than $10. You'll have to shorten the arm enough to allow it to fit in the magazine well. While it's not a highly precise machine tool, it will let you know if the angle of a feed ramp is grossly wrong. A real machinist/1911 'smith will have the right tools (expensive) to determine the exact angle and depth of a frame feed ramp. They can also correct ramps that are bad. Correcting feed ramps is a job best left to a professional.
FYI, here's how a professional 1911 'smith fixes an out-of-spec frame ramp.