Series 80 firing pin safety? Variable ratio recoil spring Vs. Conventional?

[coltsr]

Question #1: Can you remove the firing pin safety plunger and spring from the frame, but leave the leaver in the frame and the pistol still function?

Question #2: Will a 16.5 lb. Variable ratio Wolff spring be just as reliable in a Colt Gov. model as a 16 lb. Conventional Wolff spring?

[stumbler]

For #1: Even though I am against disabling any factory safety, I would look to replace the frame parts with small spacer washers.

For #2: There should be no problem with reliability

Good luck

[wichaka]

There's a lot of talk when it comes to the subject of recoil springs for the 1911 Auto.

How is a recoil spring’s weight measured? The amount of energy stored by a conventional spring as it is compressed changes value in a straight line. For example, if you compress a conventional spring an inch, it has a pound of energy. Compressing it another inch will add an additional pound of energy. At three inches we would have 3 pounds of energy stored. The figures are for example only.

A variable-weight spring works differently. The amount of energy stored for each increment of compression changes on a curve. Example, compressing a variable weight spring one inch may have 4 ounces of energy, another one inch will add an additional 8 ounces of energy, the third inch will add another 12 ounces, and so on. A conventional 16 pound recoil spring and a variable 16 pound recoil spring will both store 16 pounds of energy but they get to that point at different rates. While 1911 Auto recoil springs are available in many weights, 16 pounds is considered the standard for full-size guns with 5" barrels. Just how is this figure of 16 pounds determined? In full recoil, the space available for the recoil spring to occupy is approx 1.625". At this point in its compression, its stored energy is 16 pounds. A 15 pound spring would store 15 pounds of energy when compressed to 1.625", and so on with other weights of springs that are compressed at the standard 5" 1911 of 1.625".

Similar pistols but with shorter slides, such as Commander or Officer’s ACP-length models, require springs that are not only shorter, but have different compression weights. A standard Commander spring is 18 pounds when compressed to 1.125", while the Officers ACP spring system must store 22 pounds of energy when compressed to .700". The free length prior to compression is not all that important, as long as it fits within the available space.

Hope this helps..........

[SMMAssociates]

Question #1: Can you remove the firing pin safety plunger and spring from the frame, but leave the leaver in the frame and the pistol still function? My own non-expert guess is that the lever that's supposed to activate the firing pin block may not like the hole in the slide. You'd think that some design effort had gone into this, but....

IAC, if this is a carry gun, you should not remove any safety devices. Ayoob may be a little too cautious, but it's cheap insurance. Keep the firing pin block (and the firing pin) lubed back there, and use something that doesn't mind temperature extremes.

Having said that, I'll agree with Stumbler - there are spacers available that should be used to replace the lever if you really want to. I would expect that just removing the lever would make for some odd things happening.

My Tac-Four functioned just fine when I managed to accidentally lose the little firing pin block spring, although what effect that has on the trigger, I don't know. Most people want to remove the pin block because the thing has an effect on the trigger. (I replaced the spring; the Para's LDA is sufficiently goofy that I don't think anybody would ever notice.)

[1911Tuner]

While I don't advise removing the Series 80 system on a carry gun, it's a matter of debate, and the final decision rests with the owner. Personally, I don't think it should have a bearing on the outcome of a legal action following a clean shoot...but one can never bet on a jury. A civil action is also a
much different animal to defend against, and they're rarely decided on legalities alone.

But...if you want to remove it, it's best to get the spacer and remove all of it. Stu made a good point. Depending on how high the plunger lever is lifted in the frame by the trigger pull...and they do vary...it could grab the leading edge of the hole in the slide during recoil. If it does, you can kiss your hammer pin goodbye, and possibly your frame or slide too...or both.

The spacer is available from Brownells for 4 bucks and change, and requires
disassembly of the frame to install. Not a hard task, even for the first-timer with good instruction. I believe the name of the part is TJ's Frame Blank.

Luck!

tuner

[RickB]

I would recommend, if you are going to remove the S80 bits at all, to remove them all, and install the frame spacer. I bought a S80 Commander that had only the slide parts removed, and there was a distinct rub mark in the slide, where the frame-mounted lever was rubbing. I decided it was not farfetched to imagine the tip of the lever actually protruding into the (empty) plunger hole in the slide, and thereby jamming the gun. If you remove the frame bits without installing the spacer, the sear can wander on its pin, and likewise lock up the works.
Progressive recoil springs are a help in unlocking heavy, compensated barrels, but for a standard barrel, you want the barrel and slide to remain locked as long as possible. The progressive spring actually works against you in two ways; it unlocks more quickly than a standard spring of the same rate, and it gets heavier as it compresses, which could cause weak ejection, or a malfunction if your thumb rides the slide as it cycles. Within the normal 1911 spring rate range (14-18 pounds), it probably doesn't matter too much, but if you are using light loads and a spring at the high end, or vice versa, it could cause problems.

[wichaka]

I'm with ya there Rick except on one point........

".....and it gets heavier as it compresses, which could cause weak ejection,"

Remember the variable is still picking up tension as it gets compressed, but at a somewhat lower rate then a conventional....... so the slide is actually fighting less lbs in the spring during ejection, than a conventional spring would have. In other words, a conventional will stack up its weight faster than a variable.

Main point though.........if the gun is set up right.........it'll run with a 12lber or most anything just fine.

[1911Tuner]

Can't say much about variable rate springs because I've never used'em. I'd
tend to thing that they would allow a little wider variation in ammo and still provide acceptable function...within limits. Anything mechanical is a compromise...Nothing more, nothing less.

First off...The recoil spring load or rate has almost zero effect on the unlock timing of the barrel. The 1911 isn't really a locked breech system in the purest sense like a bolt-action or falling block rifle. Static on the bench,
the 1911 is only "locked" by recoil spring tension, and doesn't really lock until it fires. At that point, the barrel is pulled forward by the bullet, while the slide is driven rearward in recoil. The locking lugs on the barrel and in the slide are meshed while the two parts are pushed/pulled in opposite directions.
The result is an isometric lock, rather like a tug of war.

In a static condition, a 16-pound recoil spring holds the slide in battery under roughly 3 pounds of force. The unlocking begins when the slide and barrel have moved rearward about one-tenth inch. The average load rate of the spring is approximately 2.65 pounds per inch of compression. Even if the .100 inch of compression yielded the average....which it won't...that would add just a tick over a quarter-pound of resistance to the spring's static loading.
Not a lot when the recoil forces are considered. If we plug in the difference between a 16 pound spring and a 20-pound spring...25%...we add 25% of
a quarter-pound at .100 inch of slide travel. One ounce of added resistance
just ain't gonna have much of an effect at the instant the slide starts to move.

The mainspring will have more influence on unlock timing than the recoil spring...and even that is brief. The radius at the bottom of the firing pin stop will have the greatest influence of any single factor outside of the slide's mass and chamber pressure and pressure curve.

Cheers all!

Tuner

[John]

Tuner, those words, even though 100% true, are about to make a lot of 1911 shooters start yelling! I know so many of them who complained (at one time or another) that their pistol stop functioning when they went from 16 lbs to 18 lbs.

LoL, reading your posts is a revelation my friend.

Rgds

[1911Tuner]

Tuner, those words, even though 100% true, are about to make a lot of 1911 shooters start yelling! I know so many of them who complained (at one time or another) that their pistol stop functioning when they went from 16 lbs to 18 lbs.

LoL, reading your posts is a revelation my friend.

Rgds

Yep...A lot of'em do start pukin' when the spring rates go up...but it's
usually when the spring hits maximum tension in full compression that causes the problems. Short cycle induced stovepipe failure to eject...Bolt-over-base feeds caused by short-cycle or the slide outrunning the magazine on the last round, etc. Stem-bind failures to go to battery become more firmly jammed when the spring is stiffer. When the slide is rearward, the spring exerts its maximum influence. The average rate is 2.65 pounds per inch...but the tension starts low and builds as the slide moves so that the last half-inch of travel is probably something closer to 5 or 6 pounds per inch...or more. If the spring's load rate was constant from the time the slide moved until it reached maximum travel, life would be so much simpler for us tuners... :p

A hydraulic system could provide that...but it would probably double the cost and weight of the gun. :eek: :D

[richg]

.... The average rate is 2.65 pounds per inch...but the tension starts low and builds as the slide moves so that the last half-inch of travel is probably something closer to 5 or 6 pounds per inch...or more. If the spring's load rate was constant from the time the slide moved until it reached maximum travel, life would be so much simpler for us tuners...

Hate to be a new guy speaking to an expert, but you just described a progressive spring. A "straight" spring has a constant load rate ("spring constant" or "k" for us engineers) - each pound of increasing force moves the spring the same additional distance. They are regognized by constant coil spacing. The coils on a "real" progressive start wide at one end and gradually become tighter as you move toward the other (these can be seen on some motorcycle suspensions). Most of the "progressives" for I have seen advertised for the 1911 would be more propertly be considered "two stage" with part of the spring at one spacing, and the rest at another.

BTW, I *really* appreciate reading your operational descriptions and tuning tips for the 1911. Such a helpful attitude toward people you don't know, who have far less experience is refreshing. Thanks.

Rich G.
Tillamook, Ore.

[1911Tuner]

Howdy Rich!

You're spot on. Lookin' back on that, I realize what i meant...I just didn't express it well. Sorry, and thanks for the heads up.

The RATE is constant in a straight spring. It's the load that changes as the spring compresses. One inch of compression equals 2.65 pounds...2 inches
equals 5.30 and so forth. The malfunctions occur at full slide travel because the entire load of the spring is bearing on the slide as it nears that point in its travel.

But...I have noticed one thing in my "spring studies," and that is...
A non-progressive spring does tend to increase its rate of loading as itcompresses, although by a very small amount...at least in 1911 recoil springs. So it would seem that they're all progressive to some degree, and it's probably due to the fact that there's a variation in the coil spacing. Tolerance...just like there's no such thing as a perfect dimension, there's no such thing as a perfectly-wound spring. In the case of a straight spring, the progressive change in loading isn't enough to make any sort of practical difference the way that a true, progressively wound spring does.

This is a good discussion. If you will...go into some depth on spring behavior.
It's been a while for me, and I need a refresher. I believe what I'm looking for is something called "Shear Modulus."

[richg]

Howdy Rich!

You're spot on. Lookin' back on that, I realize what i meant...I just didn't express it well. Sorry, and thanks for the heads up.
<snip>
This is a good discussion. If you will...go into some depth on spring behavior.
It's been a while for me, and I need a refresher. I believe what I'm looking for is something called "Shear Modulus."

Yeah. The formulas look quite hairy at first, but are really not that bad. But rarely does anyone (except a spring-maker) really need to use them.

Basicly, a spring's rate is related to:
Modulus of Elasticity in Shear (G expressed in PSI/Radians) - This is a property of the material the spring is made from, and the user has no control over it.
Diameter of the wire (d, in inches) - thicker wire = stiffer spring
Radius of the coil (r, in inches) - larger coil diameter = softer spring
Number of coils (n, just count 'em) - more coils = softer spring

The free length of the spring or the coil spacing do not change the spring rate. That is, until one or more of the coils "bottom out". Stretching the spring only increases the starting load when the spring is installed to its working position. Same thing happens with spacers, but the spring bottoms out sooner.

Many coil springs have the end windings touching to provide a better seating and force transmission to the coils - most cars with coil spring suspensions have formed spring seats, while valve springs have the ends ground flat. These will tend to make springs non-linear to some degree.

What is more difficult to quantify is the friction on the spring. In my P13-45, the stock, short guide rod has considerable friction on (inside) the first few coils. This effects the spring by uneven load transmission to it. Other effects (that I cannot see) come from friction inside the the slide, plug or against the guide rod or frame if the spring does not compress perfectly straight. I know my recoil spring tends to buckle if I try to load it without some form of confinement. This is not surprising considering its length/width ratio.

Oh, well. This is interesting theory, but I don't fully understand how much this makes a practical difference in the operation and usability of my particular gun. I will leave it to people with greater experience actually shooting and tinkering before I try to cut off coils, stretch springs, put in preload spacers, or what-have-you.

BTW, what kind of spring would you recommend for a Para 13-45? I generally shoot factory 230gr. RN. I do not (yet) roll my own (I've only done rifle ammo). Sometimes try out Rem. GoldenSabers, occasionally PMC, Triton or ProLoad 165gr. HP? I have even tried grouse hunting w/ the occasional CCI shotshell (only fired 2 or 3 times) - but I never got a second shot.

Thanks for your patience.

Rich G.
Tillamook, Ore.
--------------------
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. - C.S.Lewis

[1911Tuner]

That's it!

I've had a hard time convincing some that a 16-pound, 32 coil spring,(GM Length) can be cut down to operate in a Commander-length tunnel...and actually produce a higher compressed tension than its original length when installed in a 5-inch gun. They don't consider the difference in the pre-load
of ths spring when the gun is in battery.

On your Para13 spring question...I tend to go in the opposite direction on
recommended spring rates...lighter rather than heavier. Of course, that
depends on the gun's intended use. Heavy range use calls for a slightly heavier spring than carry...but not so far outside the window that the spring's
unload rate causes other problems. For carry in a 5-inch gun, I like 14-16 pounds. Range use...500-1000 rounds per month...16 pounds in alloy-framed guns and 18 in steel-framed guns if the magazine timing is up to the task. Commander-length, steel-framed guns...16-18 pounds for range use and
15-16 for carry. For alloy-framed guns, 14 pounds for carry and 16 for range use.

Keep the engineering aspects comin'. I have some engineering experience,
and I can understand what you mean. 15 years as a toolmaker has helped.

Have a safe and happy New Year!

Tuner