1911Tuner
Moderator Emeritus
Howdy all. I ran this one about 6 months ago, but I figured that since
we've had a few new member since then it might be a good time to
redo it. More often than not, correcting a problem lies in understanding
WHY the pistol burps, and where the origin of the problem lies, so that
we can attack the real problem instead goin' at the wrong thing and
maybe creating a worse condition than the one we're tryin' to fix. I
hope this can help somebody along the way.
----------------------------------------------
Newton's First Law of Motion states that objects in motion tend to remain in
motion, and objects at rest tend to remain at rest. Inertia is alive and well
in the 1911 pistol. Start with a pistol in battery with one round in the magazine.
Bang! The slide moves rearward as the pistol begins to torque upward.
The weight of the round in the magazine fights against the magazine spring as it tries to push it upward. The pistol is still moving up and back as the mag spring struggles to do its job of nailing the round up against the feed lips. The cartridge is obeying Newton's Law to remain at rest, and the pistol moves away from it. The spring catches up, and the round is slightly ahead of where it should be in the magazine.
The second shock comes as the slide hits the impact surface in the frame,
and the magazine spring's tension is again overcome, and the cartridge "floats"for a fraction of a second. The impact jerks the pistol rearward and upward a second time, and the round gets even farther ahead of its optimum feeding position. If the magazine spring has seen enough use, the second shock comes before the round can settle into the feed lips. Here is where the round escapes from the magazine, and is left lying loose on top before the slide can get past the stop notch, and is locked open because it has read an empty magazine condition.
If the mag spring is in the twilight zone, the round is still in the magazine, but toofar forward for the breechface to make contact, and the extractor hits it instead, forcing the round into the chamber ahead of the extractor.
In some cases, the round gets up in time for the lower edge of the breechface to catch it in the extractor groove, and a rideover feed or a live-round stovepipe occurs. These can be dangerous. If the primer should
pressure-detonate, you have a miniature fragmentation grenade
at arm's length from your face.
A heavy recoil spring aggravates the condition, though the reasons are largely theory, but this is my take. A heavy recoil spring causes us to automatically pull harder downward as we fight the effects of the recoil AND the spring. This would seem to have the effect of helping the magazine spring push upward, but appears to have just the opposite effect. I've noticed that dropping to a lighter spring often makes the problem go away, with no other changes. Sometimes simply clipping a half-coil off a recoil spring can make a real difference.
It would also appear that the newer early-release feed lip design allows
a round to escape control of the magazine easier when compared to
the early, late-release "Hardball" magazine design, making the mag spring tension and placement of the dimple more critical. Which brings us to....
Magazine followers without the small dimple would also increase the tendency to let the round escape. The dimple is there to arrest forward motion of a round that is under the effects of inertia, and limit its movement. The dimple, coupled with the gradual release of the round is probably why so many pistols are so reliable with hardball ammo and GI magazines.
I've found that it's far easier to get a 1911 to run reliably with a lighter recoil spring than a heavier one, and I see far less extractor breakage and
need for retensioning as well. Getting the pistol to return to battery reliably with a lighter spring is more a matter of proper throat and ramp geometry and chamber dimensions than sticking in a gorilla-power recoil spring hoping that it will force-feed the gun.
To check for a push-feed condition, look to the once-fired brass. If there
is a small ding near the edge of the rim that sometimes kicks up a small burr on the edge, the gun is push-feeding and the extractor is being forced to snap over. Reloaders will recognize this as case rims that are difficult to
get into a shell holder after a few firings. The dings and burrs will be at the
rate of about one per magazine...usually on the last round.
John Browning was no doubt aware of all this, and he did three things to
compensate for it. He put the dimple in the follower...He kept slide
speed low on the return to battery with a 16.5 pound spring, and
he specified that the extractor be made of true spring steel to allow
for the occasional push-feed with extractor snapover without being
affected by the impact and being cammed open by the rim.
Cheers! (and happy tweakin')
Tuner
we've had a few new member since then it might be a good time to
redo it. More often than not, correcting a problem lies in understanding
WHY the pistol burps, and where the origin of the problem lies, so that
we can attack the real problem instead goin' at the wrong thing and
maybe creating a worse condition than the one we're tryin' to fix. I
hope this can help somebody along the way.
----------------------------------------------
Newton's First Law of Motion states that objects in motion tend to remain in
motion, and objects at rest tend to remain at rest. Inertia is alive and well
in the 1911 pistol. Start with a pistol in battery with one round in the magazine.
Bang! The slide moves rearward as the pistol begins to torque upward.
The weight of the round in the magazine fights against the magazine spring as it tries to push it upward. The pistol is still moving up and back as the mag spring struggles to do its job of nailing the round up against the feed lips. The cartridge is obeying Newton's Law to remain at rest, and the pistol moves away from it. The spring catches up, and the round is slightly ahead of where it should be in the magazine.
The second shock comes as the slide hits the impact surface in the frame,
and the magazine spring's tension is again overcome, and the cartridge "floats"for a fraction of a second. The impact jerks the pistol rearward and upward a second time, and the round gets even farther ahead of its optimum feeding position. If the magazine spring has seen enough use, the second shock comes before the round can settle into the feed lips. Here is where the round escapes from the magazine, and is left lying loose on top before the slide can get past the stop notch, and is locked open because it has read an empty magazine condition.
If the mag spring is in the twilight zone, the round is still in the magazine, but toofar forward for the breechface to make contact, and the extractor hits it instead, forcing the round into the chamber ahead of the extractor.
In some cases, the round gets up in time for the lower edge of the breechface to catch it in the extractor groove, and a rideover feed or a live-round stovepipe occurs. These can be dangerous. If the primer should
pressure-detonate, you have a miniature fragmentation grenade
at arm's length from your face.
A heavy recoil spring aggravates the condition, though the reasons are largely theory, but this is my take. A heavy recoil spring causes us to automatically pull harder downward as we fight the effects of the recoil AND the spring. This would seem to have the effect of helping the magazine spring push upward, but appears to have just the opposite effect. I've noticed that dropping to a lighter spring often makes the problem go away, with no other changes. Sometimes simply clipping a half-coil off a recoil spring can make a real difference.
It would also appear that the newer early-release feed lip design allows
a round to escape control of the magazine easier when compared to
the early, late-release "Hardball" magazine design, making the mag spring tension and placement of the dimple more critical. Which brings us to....
Magazine followers without the small dimple would also increase the tendency to let the round escape. The dimple is there to arrest forward motion of a round that is under the effects of inertia, and limit its movement. The dimple, coupled with the gradual release of the round is probably why so many pistols are so reliable with hardball ammo and GI magazines.
I've found that it's far easier to get a 1911 to run reliably with a lighter recoil spring than a heavier one, and I see far less extractor breakage and
need for retensioning as well. Getting the pistol to return to battery reliably with a lighter spring is more a matter of proper throat and ramp geometry and chamber dimensions than sticking in a gorilla-power recoil spring hoping that it will force-feed the gun.
To check for a push-feed condition, look to the once-fired brass. If there
is a small ding near the edge of the rim that sometimes kicks up a small burr on the edge, the gun is push-feeding and the extractor is being forced to snap over. Reloaders will recognize this as case rims that are difficult to
get into a shell holder after a few firings. The dings and burrs will be at the
rate of about one per magazine...usually on the last round.
John Browning was no doubt aware of all this, and he did three things to
compensate for it. He put the dimple in the follower...He kept slide
speed low on the return to battery with a 16.5 pound spring, and
he specified that the extractor be made of true spring steel to allow
for the occasional push-feed with extractor snapover without being
affected by the impact and being cammed open by the rim.
Cheers! (and happy tweakin')
Tuner
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