Recoil Springs-2: The Free Lunch

[1911Tuner]

Rather than bury this one on the Spring Rate thread, I decided to start a whole new one. I hope that everybody finds it interesting.

It's said that there ain't no free lunches, but sometimes, we can eat
pretty cheap. The matter of balancing good functional reliability
with frame/slide/lower lug protection is one such lunch...

There are two more, largely ignored factors in reducing the slide's
rearward momentum and speed. The mainspring, and the slide's
mechanical advantage in overcoming the mainspring's load in order
to cock the hammer. The recoil spring is just one factor, albeit the
biggest one. Like everything else, nothing is everything, but EVERYthing
is SOMEthing.

A friend of mine approached me at the range a few weeks ago with an
intermittent hammer followdown problem. Just a once in a while thing.
His pistol was a gamer...tricked out and complete with a 3-pound trigger.
Examination revealed the need for a little dressing on the hammer hooks, but the mainspring was either badly fatigued, or it was too light to begin with. From what I've seen of the hack that USED to do his trigger jobs,
my guess is the latter, with a little of the former adding to the issue.

I cleaned up the hooks on site, and installed a new 23# mainspring.
Presto! No more hammer follow, and the trigger was still sweet. We
noticed that the empty brass was kicking out about 1/3rd the distance
as it was before the tuneup...which I half expected, and then came the
clear sign that the slide wasn't moving rearward smartly...the stovepiped
empty brass on the last round. As it turned out, he had just replaced the
recoil spring with a nice, new Wolff 18# number. The gun functioned
well with the spring, until I installed that new mainspring. Watching
the gun cycle, the slide was moving markedly slower in recoil. His ammo
just barely made major, so we fired some honest hardball in the gun.
Much better...but the brass still wasn't getting far from the gun.

We cocked the hammer to let the spring take a little set for about an hour.
Better, but still not quite there. A fresh 16-pound recoil spring set things
straight. (I always keep spare parts in my range box) The brass was
landing a good distance from the gun, and it was runnin' like a Singer
sewing machine. The extra resistance provided by the standard mainspring
made the heavy recoil spring unnecessary. The lower barrel lug as happy,
Jim was happy, I was happy.

On to...the mechanical advantage thing. The firing pin stop has a fairly large radius. The flat area makes contact with the hammer at point A.
If the contact point is moved lower on the hammer, there is a reduction
in the mechanical advantage in cocking the hammer, and the 23# mainspring provides as much resistance as a 25# mainspring...or maybe more. Trying to explain it to him proved to be a little frustrating. "The
mainspring load is what it is." or so he thought. I happened to have a
used EGW square-bottomed firing pin stop in the box that I had radiused just a little. I checked it in his slide, since they come oversized to
allow for a file-to-fit...and it slipped in with just a little effort.

He loaded up and went to the firing line. Bingo! The brass was landing at
his feet again, but the stovepipes didn't occur. I went and opened up a
14# Wolff spring and installed it. Aha! back in the saddle again! The
brass was still falling a little short of the mark, but it was almost there.

The point was made, and he began to understand. There is ALMOST
a free lunch here. The one drawback is a slight increase in felt recoil
with the firing pin stop, and he noticed just a bit with the new mainspring,
even without the stop. Not so much as to make the pistol unpleasant, but
noticeable.

Lesson: The slower that the slide returns to battery, the more time the magazine has to catch up, and the less critical the magazine spring tension. When one thing speeds up, everything else has to speed up.

Lesson 2: The slower the slide returns to battery, the less impact on the lower barrel lug. If the pistol is right, it doesn't need a heavy spring to
return to battery.

Lesson 3: It is possible to slow the slide in recoil and limit impact between the slide and frame, without going to a heavier recoil spring. The best
of both worlds can almost be achieved with just a little experimentation.
This is the essence of fine-tuning...Finding the middle ground...Striking the
balance.

Happy day!

Tuner

 

[BigG]

Thanks again, Tuner. You can be my .45 blacksmith any time!

 

[stans]

This all makes tons of sense. I went down the road of heavy recoil springs, now I am heading down the road of sensible recoil and mainsprings. At one time I was up to a 20 pound recoil spring firing loads that just made a 180 power factor. What have I learned? I learned that John Moses Browning was a brilliant firearms designer and maybe we just should not be straying so far from his specifications for the 1911.

 

[Delmar]

Guess we will have to start calling you Dr. 45, Tuner
Question for you on springs-because I like to reload, I'd like to keep the brass in the same county as where I am shooting. Where, or at least how far should the brass be landing in a properly sprung 1911 assuming standard factory pressure?

 

[1911Tuner]

Slingin' Brass

Delmar asked:

Where, or at least how far should the brass be landing in a properly sprung 1911 assuming standard factory pressure
-------------------------------------------

The standard answer is 6-8 feet, 90 degrees to the axis of the gun...What the gurus don't tell you is how to get to that. to happen consistently There's more than the spring involved in the direction and distance that the brass flies.

Extractor tension plays a role...Ejection timing plays a role (Where in the
recoil stroke is the brass hitting the ejector? Think extended ejectors)
The extended ejectors on Commanders and the Officer's Model/Defender
class of pistols isn't just about reduced slide travel. It's related to the
timing of the ejection too.

The length of the extractor hook is one that's often overlooked, and a
little can make a big difference in where and how far the brass goes,
and which direction. Want to see one go bonkers? Adjust the hook to
about .040 inch long and watch the brass fly straight up and forward about
45 degrees. If you get it just right, you can almost hit your brass with the
follow-up shot.

The shape of the ejector face and where on the rim does it hit? Rule of
thumb: The lower it hits, the more straight up the brass flies. The higher
it hits, the more straight out. Ideally, the brass should exit the port at
2 O'clock and land 6-8 feet away. If it kicks out at 1 O'clock, the brass will
land closer...3 O'clock, and it will fly farther. Likewise, if the ejector face
has a light angle on it, the brass will follow that angle as it twists sideways
on the hook.

The bottom corner of the hook can also make a big difference. Is it square
or lightly radiused? Is the inner part square at the bottom or beveled? Everything means something when it comes time for the extractor to release the case.

The diameter of the rim is a player. As brass goes through the fire/reload
process, the rim gets wider. Wider means more extractor tension. The
brass that landed 6 feet away when it was new won't land in the same place 10 firings later. Burrs or rough edges on the rim? That'll affect it
too.

One important thing is...Is the brass clearing the port before the slide
hits it? Everybody has experienced or heard of having the brass come straight back and whack them in the head...or in the eye..or go down the
back of their shirt. When that happens, the case is being bounced off the
slide while it's in the air.

Fine-tuning at its tedious best. Maddening, ain't it? What's more, no two pistols will produce the same results with a given tuning. Each one has to be approached as a law unto itself.

Again, since all my concerns are geared toward dead reliability, I'm not
overly concerned with the ejection. As long as I don't get hit in the face
more than on occasion I don't care if the brass lands at my feet or in Virginia. I do prefer that it stays within 10 feet though.

Luck to ya!

Tuner

 

[BigG]

How does "FoofKeenTuner .45s" sound for a new start up company? I've got a couple nickels to invest.

 

[1911Tuner]

Company Logo

ROFL BigG...Lemme see the money!

 

[Jammer Six]

ROFL BigG...Lemme see the money!

How much?

Keep the profit, I only want one small return- you have to train me!

 

[InTheBlack]

Well, the design ratio between the two springs is 23/18 right? about 1.28.

Can you think back to various tunings you have done and see if the ratio falls into a narrow range?

What's the design ratio for Commander and Officer sizes?

Then the height of the hammer stop is a tweak. It might be interesting to tune a gun with the hammer stop in a middle position, and then see what exactly happens when you change the stop to the highest and lowest positions you can achieve.

 

[1911Tuner]

Ratios

IntheBlack said:

Well, the design ratio between the two springs is 23/18 right? about 1.28
----------------------------
Not sure where the 23/18 comes from. Commander spring 23 coils and 18 pounds load rating? The loading at full compression is only part of the story. The rate...loading per inch of compression...determines how fast the
spring will slow the slide's momentum and how fast it will unload its
stored energy. Change the distance between coils at free length, and you've got a completely different spring from the same lot of tempered wire.



Can you think back to various tunings you have done and see if the ratio falls into a narrow range?
----------------------------------------
Nope. When I cut a GM spring to fit in a Commander, I cut it long enough to coil bind...cut enough to eliminate the coil bind, and go from there.
If I get to 22 coils and still have problems, I drop to the next level
down and start again. Most Commanders will run with a 16 pound Wolff
GM spring (32 coil original length) that's been cut down to the range
noted in the other thread.
.

What's the design ratio for Commander and Officer sizes?
---------------------------------
Never worked out a ratio. I generally play it by ear...whatever works
in a particular gun.

Then the height of the hammer stop is a tweak. It might be interesting to tune a gun with the hammer stop in a middle position, and then see what exactly happens when you change the stop to the highest and lowest positions you can achieve
--------------------------------------

The higher the contact on the stop, the faster the slide will recoil due to the
increased mechanical advantage working against the hammer. Think of
a lever, and what effect moving the fulcrum closer to the load would have.
(Less effort to move a given load.)

I remember reading an article about the square-bottomed firing pin stop in a Delta Elite. Turned out that by using a square bottom with the corner just barely radiused, they were able to drop the spring load rating by 2-3 pounds.

'Bout all I can tell ya.

Tuner

 

[N3rday]

Ok...what are the standard spring pressures that come on a 1911? Are they the same in SA, Kimber, Colt, and how can I tell?

And what did JMB use in his original design?

 

[1911Tuner]

Springs

N3rd said:

Ok...what are the standard spring pressures that come on a 1911? Are they the same in SA, Kimber, Colt, and how can I tell?

"Standard" for a 5-inch gun is 16 pounds and 18 for Commanders-length
with the original style recoil spring plug. Reverse plug systems use a shorter spring, and that changes everything...

The only way to tell for sure is to use a spring tester. A little imagination
and some cobbling might net a reasonable facsimile on a bathroom
scale, but that won't read as close as a tester.

 

[JeffC]

1911Tuner posted:

"The length of the extractor hook is one that's often overlooked, and a
little can make a big difference in where and how far the brass goes,
and which direction. Want to see one go bonkers? Adjust the hook to
about .040 inch long and watch the brass fly straight up and forward about
45 degrees. If you get it just right, you can almost hit your brass with the
follow-up shot. "


Wonder if Bob Munden has tried that yet? .... hrm, what's his phone number

 

[Stinkyshoe]

Doc .45(aka 1911tuner)....regarding the ejection patterns...

I heard this guy talking at a gun show how his 45 ejects shells all over the place. Over his head, then to the right, then a different place. He said the gun started to do it when he replaced the old worn out extractor with a Brown Match extractor. What cause brass to be thrown "all over"?
Thanks
Ss

 

[JeffC]

Could be,

• lack of tension
• clocking
• hook geometry
• all of the above
  [/list=a]

 

[1911Tuner]

Brass, Brass everywhere...(Long)

Mah fren Jeff pretty much nailed that one.

Since it started with the extractor swap, it's gotta be the extractor.
Studying the design, the case can only go in one direction after the ejector smacks it. To the right. Up and right...straight out to the right..
right and back at an angle...or right and forward at an angle. If it
launches in these directions, it's bouncing off the slide, and sometimes
the case will bounce off the slide twice. Most of the time, it's once,
and unless the extractor hook is far too long, this usually sends it up
or back at your face.

Breaking the sharp corner on the bottom of the hook will change the direction, as will a directional angle on the face of the ejector. A
rollover notch at the back of the port will also have an effect. A lowered,
flared (at the front) port can provide a little more time for the case to get clear of the port and avoid the riccochet.

The extractor tension has a lot of influence because it affects how easily the case gets free of it. Think of this in terms of TIME. Things are happening fast during the cycle. It only takes a fraction of a second early or late to see a big change in where the brass goes. The extended ejectors found on Commanders and shorter pistols aren't so much about compensating for reduced travel as they are about getting the brass out at the right time.

Generally, the closer to the end of the recoil stroke the ejector hits the brass, the less chance of the slide knocking it back into your face, even if
the brass bounces off the front of the port. The recoil spring is stacking up
and slowing the slide down near the terminal point, so the energy is less.

Extended ejectors can help IF the extractor doesn't hang on too long. If
that happens, the slide is moving fast and the brass gets hit harder.

When all is well, the brass will exit the port straight out at 2 O'clock. Out
and backward or forward at an angle means that the slide is hitting it
at some point. Tuning a pistol for ejection direction is often a matter of
trial and error because no two act exactly the same. Then, when you get it
fine-tuned, a change of ammo will change it again. A variation in the size
of the rim changes the extractor tension. Reloads are particularly bad in this respect. Multiple fire/reload cycles spreads the rims out and makes tem
larger. Dents and dings on the edge of the rim will have a bearing, Even a
recoil spring change can have a big effect, especially when going above or
below standard after the ejection has been tuned. Add a shock buffer, and
everything changes again.

Some people get frustrated because their pistol doesn't pile the brass up neatly in the same place. I don't think the gun was ever intended to do that consistently from gun to gun. The most important thing is that the brass gets clear of the port. As long as I don't get hit in the face more than
once in a while, (which is pretty much expected, especially with reloads) I don't care if it lands at my feet or in the next county. When I start getting
half-moon cuts on my forehead and hot brass down the back of my shirt, it's time for me to start tweakin'. :banghead:

Ah...The essence of fine-tweakin' It do keep us on our toes.

 

[1911Tuner]

Just a Note

I wanted to add a little something about the EGW firing pin stop, but my
edit time was up, so I'll do it here.

The bottom of the stop is square, or nearly so. The bottom should be
beveled lightly, or if you can file a good radius, radiused lightly. At any rate,
don't leave it dead square. EGW recommends just breaking the corner
for the least mechanical advantage against the hammer without overdoing it. Remember...The farther down on the hammer the bottom of the stop
impinges, the less momentum available to operate the slide, and the slower the slide will move in recoil.

Cheers!
Tuner