Differences in 1911A1 behaviors?

[19112XS]

I've noticed that with the hammer resting at half cock and the grip safety compressed that the hammer will completely fall without being fully cocked if the trigger is squeezed on the recent models of Springfield Model 1911A1 and Colt Series 80 Gold Cup I have experimented with. The fall (so far) is too weak to cause a discharge. The hammer does not budge from half cock on the Kimber pre-Series II and Remington Rand 1911A1s or the Colt 1911 I have tried this with. Although this action will not become a habit for me: 1) is this a safety issue 2) is it harmful to internals and 3) what is the difference between these pistols that allows this to happen?

Also, what is the difference in the function of 3 leaf and 4 leaf mainsprings?

Thanks for the patience of all respondents.

 

[1911Tuner]

Behavior

Howdy 19112X, and welcome to THR.

What you described is the result of the hammer having a shelf instead of a captive half-cock notch, and while the hammer will fall when you pull the trigger, it won't fall hard enough to light a primer. This redesign was first
used on the Series 80 Colts, and others have followed suit for a couple of
reasons. One is that it's cheaper to machine the hammer...One less step and less complicated to do.

The other is that, in the event of a followdown to half-cock, it's not as
rough on the sear nose as a captive half-cock...though I suspect that the
former is the primary reason and the latter a by-product.

The 3 leaf sear spring is standard design, and has been pretty much unchanged since 1912. The one of the far right powers the grip safety.
The center one resets the trigger and disconnect. The left one resets
the sear into the hammer hooks.

The 4-leaf sear spring is a recent design that does exactly the same thing,
except that it splits the center leaf's duties to allow the smith to get a lighter trigger pull because the tension on the trigger is theoretically
halved. Since the disconnect's operation is independent of the trigger return, the smith can tune the one that resets the trigger to the minimum
amount required to reset the trigger, thus shaving a few ounces off the pull.

It sounds like a simple way to get a good trigger, but simply dropping in a
4-leaf spring may bring on headaches unless other components of the trigger group are taken into consideration...Actual weight of the trigger is the main one. A heavy steel trigger may not reset correctly or in time with
that little tension. A heavy trigger is also more likely to overcome the leaf's tension and cause a followdown when releasing the slide, inertial mass of the trigger being the mechanism that accomplishes this little trick.

Whenever something is changed, other things generally have to be changed to compensate. This caveat goes double-triple when dinking around with the trigger group. "Fools rush in where angels fear to tread"
applies here.

The mainspring is a coil spring inside the mainspring housing. It powers
the hammer by impinging on the hammer strut.

Hope this clears it all up.

Tuner

 

[19112XS]

Thanks Tuner for the clear response! Yes your post does resolve my concerns. I always learn when I read your posts.

Sorry to misidentify the sear spring as the mainspring. Glad you understood my question anyway.

This brings up another question…can trigger pull be affected by adding or removing coils from the mainspring and if so, what kind of balancing act with the other trigger group parts is required?

 

[1911Tuner]

Mainspring

19112XS asked:

This brings up another question…can trigger pull be affected by adding or removing coils from the mainspring and if so, what kind of balancing act with the other trigger group parts is required?

Since any change will have some effect, yes...but don't clip coils.
Wolff has a full line of mainsprings that vary in one-pound increments
from 25 down to ridiculously light.

The difference in trigger pull between a standard (23#) spring and a
19 pound spring will be minimal, and whatever you gain will be lost on the
other end with increased lock-time. Playing with the mainspring load is
a good way to tailor the slide's speed in recoil, since the mainspring offers
resistance to the slide as is cocks the hammer, but reducing the trigger pull is best accomplished by having a triggersmith tune the other parts of the trigger group. Dropping the mainspring load makes the sear and hammer more likely to bounce and damage the sear or cause hammer followdown to half cock during a reload.

I've always screamed about not overspringing the slide on 1911s, I've
often gone 2 pounds under the standard recoil spring rating and increasing the mainspring load to effect the same slide/frame protection as with standard springs. I'll edit and post a link to a thread that will go into more detail later.
EDITED: Try this link.
http://www.thehighroad.org/showthread.php?s=&threadid=57405

Tuner

 

[19112XS]

Thanks Tuner. I understand. The mainspring's role is more with the slide's rearward motion and less with trigger pull. Attempts to affect trigger pull by manipulating the mainspring will likely result in unintended timing consequences. The link was particularly enlightening. Thanks for your patient and informative responses.

 

[Jim K]

The mainspring load does affect slide motion, but not as much as sometimes thought, since (unlike the pictures in books) the hammer doesn't remain in contact with the slide during the first part of the cycle. Instead, the slide is moving so fast that it kicks the hammer back and down out of contact until the hammer hits the grip safety and bounces up to hit the bottom of the firing pin tunnel.

This is what causes the dents you often see in that location, and also explains why hammer "bite" happens even though in manual operation it looks like the hammer would not reach the hand.

It is also at that point, where the hammer is out of contact with the slide, the gun is in recoil, and the firing pin is still forward, that a loose firing pin stop can obey Newton's law and "remain in place", with the result that it comes partially out of the slide and ties up the gun.

Jim

 

[1911Tuner]

Bounce

Jim said:

the hammer doesn't remain in contact with the slide during the first part of the cycle.

Ah yeah! Jim nailed a point that I usually forget to mention when I get into
mainspring/recoil spring/timing topics. The mainspring's effect on slide movement is over as soon as the hammer is cocked, and any further
effect would be frictional drag on the slide from the hammer's nose
after it rebounds and comes back into contact with the slide. Although
there would be SOME difference between a 25-pound mainspring and
a 20-pound spring, the difference wouldn't be anything signifigant.

It's also possible, as was noted in the Free Lunch thread, to add to that
effect with a firing pin stop that reduces the slide's mechanical advantage
by moving the contact point lower on the hammer.

Anything that is changed has an effect on other things...especially when
we get into playing with different spring rates and the timing of the slide.
The best advice that I can offer is to remember that springs work both ways. A heavier than standard recoil spring slows the slide in recoil, but speeds it up on the return to battery. The mainspring has the same effect on the hammer.

Cheers!

Tuner

 

[Jim K]

Just a note on buffers. The 1911 is designed so the slide bounces off the recoil spring guide and some considerable portion of the recoil energy is returned. But some folks install a buffer, supposedly to keep the guide and/or frame from being marred. The buffer absorbs the energy of the backward slide movement and returns little or none of it, so the forward slide motion is not as rapid or forceful as it should be, leading to problems in feeding and return to battery. And if the buffer is too thick, it doesn't allow full slide travel and the slide may not lock back on an empty magazine.

In other words, you have a pistol that will look better, but won't work. So now you install a heavy spring, which also may not allow full slide travel, but which puts more strain on the slide stop pin and frame when the slide returns to battery.

Aren't we back to that "no free lunch" business?

Jim