1911 Reliability Overview: Introduction To The Magazine Part 2, by John Travis
Magazine release timing. What does it mean? First understand what is meant by "Controlled Feed." The cartridge is held captive from the time it goes into the magazune until the empty case is kicked out of the port. If the round is allowed to escape the complete control of the gun at any point prior to that event...reliability can and often does suffer.
Simply put, it means the point at which the feed lips turn loose of the base of the cartridge and allow it to slip under the extractor. This step occurs just after the extractor begins to take control of the round, as the cartridge begins to climb the feed ramp. The angle on the ramp causes the round to move nose up, and forces the rim to engage the very bottom of the extractor claw...or hook, as it's often referred to. This serves two purposes. It works to keep the rim in contact with the breechface, so that the round is always under control, and it helps to "pull" the round farther into the contrrol of the extractor as the slide pushes forward.
The release point of the feed lips causes the magazine to relinquish control of the round, and hands it off to the extractor, slide and barrel chamber. As it releases...the magazine spring tension pushes up on the feeding round and helps to kick the rim further up onto the breechface, and aids in breaking the round over to horizontal so that it can enter the chamber smoothly. If it releases too early, the full control of the round can be lost. If it releases too late, the slide's forward momentum may not be enough to force the round up the ramp and change its angle to horizontal. A failure to go to battery often results.
A too-early release can also cause premature extractor failure because the cartridge is bumped ahead of the extractor, chambering the round and forcing the extractor to snap over the rim. While the gun will tolerate this occasionally if it has a proper extractor, it wasn't designed to operate that way. Many times, the round will chamber, without the slide being in battery because the extractor can't cam open and snap over the rim.
The first event causes the extractor to lose tension quickly, while the second generally breaks the extractor hook sooner rather than later. So we see that correct magazine timing can have a very real effect on extractor function and service life.
The release point of the magazine is determined by the exact place that the feed lips will let the rear of the round start to move up. In the older magazines--often referred to as "GI" or "Hardball" magazines-- the lips are tapered, and release the round later and more gradually than the timed magazines, with the flared lips that release the round earlier and more abruptly.
When the round reaches the release point, it starts to move upward under the extractor. As the slide pushes it farther forward, it finishes its release and the round is held captive by the extractor hook, breechface, and the feed ramp/barrel throat area. Finally, the round moves far enough into the chamber to break over to horizontal just as the rim is forced completely under the extractor hook and centers on the breechface. If everything happens at the right time, you have good feed reliability, assuming that all else is good. Release the round a little too early or too late, and reliability suffers.
There are three things which affect release timing:
The fixed point of release at the magazine feed lips...The overall length of the round...and the power of the magazine spring itself. A greater OAL causes the round to release a little later, and a shorter round causes it to release a little earlier. A weak spring can delay release, but mainly because it's slower in pushing the rear of the round into the extractor. The feed lips are fixed, and while there is some adjustment that can be made to cause the magazine to release the round slightly earlier, it's mainly a fine-tuning operation, and not very much adjustment is available.
Releasing too early and too abruptly can cause a nose-dive failure to feed, as can weak magazine springs. Releasing too late can cause a failure to go to battery by effecting a Three-Point Jam, or as it may be more commonly known: Stem Bind.
Stem bind failures can also be caused by excessive OAL--late release. Nose-dives can also be caused by insufficient OAL--early release. Generally speaking, .45 ACP caliber pistols operate best with cartridge overall lengths of 1.210 to about 1.260, depending on the bullet shape and style. Hardball configuration needs to be a little longer at 1.250-1.260 inch, while the semi-wadcutter and hollowpoint rounds do better at something less. 1.230-1.240 inch. Truncated cone bullet shapes can do very well all the way down to 1.200 inch, but most pistol/magazine combinations will tend to feed these more reliably at lengths from 1.210 to 1.230.
Excessive cartridge length can also cause difficulty in ejecting live rounds in pistols with extended-length ejectors, and most factory hardball runs to slightly excessive lengths--up to 1.275 inch can often be found. For reloaded or handloaded hardball equivalent rounds, I normally set the OAL at 1.250-1.255 inch. For truncated cone, about 1.220 seems to do the trick. Semi-wadcutters with the Hensley & Gibbs nose profile, do well in most pistols at 1.230-1.240 length.
The last, and most often overlooked part of release timing is the follower configuration. The original design incorporated a small "tit" on the center of the follower. That tit is an important part of maintaining full control of the last round in the magazine when spring tension is at a minimum and recoil forces that are imposed on the pistol are at a maximum due to the weight reduction. Whenever someone asks me about a magazine that has a follower with the tit omitted in the design, my response is to remind them that John Browning put it there for a very good reason, and to remove it by design or modification causes changes in the function of the magazine that may not be immediately apparent. Take note that the tit location closely coincides with the release point of the magazine. Wadcutter magazine followers, with their earlier release points have a slightly different location for the tit than do hardball magazines with their tapered feed lips.
In law enforcement circles, that's known as a clue.
John Travis is a North Carolina gunsmith who has spent decades studying 1911 pistol problems. He regularly takes questions on TheHighRoad.Org forums, where he posts under the username 1911Tuner. Reprinting or redistribution of this article without John Travis' permission is expressly prohibited.