By Bullseye
The newer Mark III series pistol has the magazine release on the grip frame just like a Ruger 22/45 series pistol. This button holds the magazine securely in place by means of a dimple located on the right side of the magazine body and not by the base block like a regular Mark II’s heel latch release. This release button on the Mark III is also responsible for properly indexing the magazine so the feed lips are in correct position relative to the feed ramp for smooth operation of the pistol.
But what if your Mark III doesn’t feed or eject properly? Is a magazine defective, or does more than one magazine cause feeding and ejection problems? If multiple magazines fail to function, the feed lips may be improperly positioned inside the pistol because the magazine is not properly seated. This is especially true if the left rear magazine lip knocks the cartridge case off the bolt before it ever reaches the ejector, causing stovepipe failures.
There can be a couple of reasons for the failures. The magazine release button may be slightly misshaped. Or, the release button mounting hole might have been bored slightly off center when that particular grip frame was manufactured.
The first thing to do is look inside the pistol's ejection port with a magazine installed. A properly positioned magazine should have a gap immediately underneath the ejector pin. This gap is measured where the magazine rear feed lip sits underneath the ejector. (See picture) There is about a 1/16" gap between the feed lip and the bottom of the ejector. The rear feed lip slopes upwards but only reaches a point that is about even with the bottom of the ejector pin’s bottom edge.
One can duplicate this situation if they force the magazine base upwards with their finger and crunch the feed lip right up against the ejector pin. Of course, the magazine isn't supposed to sit that high when it's properly installed.
If your magazine is not positioned correctly then next inspect the magazine release button for irregularities. Remove the magazine release button from the grip frame by removing the left grip panel and then 3/8ths inch hold down screw just to the right of the release button. The button will now slide out of the grip frame. Inspect it for any flash (metal sticking up). You should look on the back side and see two rounded pins. (See drawing)
One has a larger diameter, and is flat topped. The other one is a smaller diameter, rounded on top, and spring loaded. When looking at the back side of the release, just above the larger, flat topped pin, you should see a cut out. It should look like a pie chart with approximately 1/4th missing. The cut out should be 90 degrees or square and the edge should go down flush with the base of the larger round flat topped pin. If this metal on this edge isn't exactly flush with the pin base, then there's your problem. Any extra metal here and the magazine will lock in the grip frame slightly higher than it should, causing feeding and ejection problems.
There are few options to fix this type of problem.
One way is to file or grind about 1/16th inch of metal off of the rear of the magazine release button right where the magazine body bump sits on the metal edge. This metal edge should be flush with the base of the larger diameter pin. If you’re not comfortable with grinding or filing, then make a call to Ruger with a detailed explanation of what you found. They will likely send you a new magazine release button in the mail.
Another way could mean sending the gun back to Ruger for customer service. The grip frame may need replacing if the magazine button doesn’t have any excessive metal on the rear edge, and multiple magazines are sitting up too high, because the frame’s magazine release button’s hole might be miss-positioned.
Customer service is your only remedy short of modifying each individual magazine to operate smoothly in that pistol. Taking a grinding wheel and taking the 1/16th inch off the bottom of the right side bump will make the magazine fit. The problem with cutting the magazine is; it will only operate properly in that specific pistol.
All in all, if your Mark III is suffering from feeding or ejection problems, then inspecting it for proper magazine positioning is one possible way to get it running smoothly.
Hope this helps.
Bullseye
