Or...Why Johnny's Magazine Misbehaves.

I found an old post that I did over on THR and did a cut and paste for this one. The Spring Things threads probably need to be moved here, since this
is probably where they belong...Commandante?
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As we've laready seen, 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

Tuner- as always, you have provided us with with excellent food for thought. Most of my loads are in the 800 fps range. Do you think I should go to a 14 lb. recoil spring (I am currently using a 16)? Also, I notice that some who shoot target loads (probably in the 750 fps range), are advocating very light springs- like 10 lbs. Can you expound on the potential adverse consequences of going too light? Thanks, WB

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NRA Endowment member
"I used to do nothing; now I'm retired." from the movie "Trouble Bound"

Howdy WB,

None that spring to mind (pun intended)

I've kept a running tally of recoil spring load ratings on every new Colt that I can get my hands on for 20 years or more...Several dealers used to call me when they'd get one in so I could bring my handy-dandy tester and check'em before they were sold.

I've never found a 5-inch Colt with a recoil spring that tested at over 15 pounds...ever...and most are in the 14 to 14.5 range. Never found a Commander that checked at more than 16 pounds, with most of those
in the 15.5 pound range...A few have been as low as 14 pounds even.

I've also noticed a good number with different coil counts in identical pistols...which strongly suggests that somebody is tuning the springs to the guns for function in the test-firing stage. maybe a stroboscope is involved. So far, I can't get anybody at Colt to admit to this...

Finally...if you'll go to the Colt section of your Brownells catalog and look
up recoil springs...you may be surprised to see that the part numbers for
.45 and .38 Super are identical. The standard for .38 Super is 14 pounds...
and most that I've checked run to 13.5 or so...Interesting...what?

Luck!

Tuner

El Commandante is always listening.

The Springs thread has been moved in here, in the Gunsmithing forum.

Keep up the good work Tuner, and at the end, I bet you people would expect their 22LR conversion to run without a spring!! LoL

Just joking of course, your articles are a true wealth.

Rgds

__________________
John Caradimas SV1CEC
The M1911 Pistols Organization
http://www.m1911.org

Da Big Bossman said:

I bet you people would expect their 22LR conversion to run without a spring!! LoL

Nahhhh...That's a straight blowback desing on the newer ones...They need more spring than a locked breech set-up. Just check out the spring strength
on a blowback .380 autopistol. If a 1911 was straight blowback with not other
changes, the spring would need to be in the 40+ pound range.


Salute'!

Tuner

Yap, yap, I know!

We are living in a ... springy world.

LoL

__________________
John Caradimas SV1CEC
The M1911 Pistols Organization
http://www.m1911.org

Sir Isaac Tuner? That's got a nice ring to it!

__________________
Dave Berryhill
Berryhill Custom Gunsmithing & Parts

I have a title! I owe it all to Al Gore and his invention...The Internet!

Think I oughta get a new suit?

Yes. You can always wear it to funerals.

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Dave Berryhill
Berryhill Custom Gunsmithing & Parts

Nice to find someone who agrees with me. I have been using 10 to 14lb springs in my 1911s and clones for years with excellent results. When I mention this fact in other forums, I am treated like the Anti-Christ. BTW a shock buff is a great diagnostic tool when reducing recoil spring power. If thew spring is too light, you will experience accelerated wear on the buff. My current IPSC Limited gun is a Para P-16 with a Nowlin bull barrel and a 12 lb recoil spring. After 2000 rounds of 165 power factor ammo the buff was barely worn.