I was thinking of buying a Glock and then...

[redneck2]

UH, I'm just a simple country boy but I've got an idea.

Take the same ammo and shoot it in another G20. Take some different ammo and shoot it in the subject gun. Instead of doing hours of calculations you could find the answer in 5 minutes. But, what do I know? I'm just a pig farmer from Indiana.

FWIW, I've got a G20 thats popped off some smoking, and I mean smoking rounds. Ones that are equivalent to Double Tap.

I examined the cases under a magnifying lamp and never did find "the bulge". What does that mean??? It means my G20 doesn bulge cases. Yours might.

 

[1911Tuner]

Unlock

Jungle...you may be right about the angle of the barrel. Hard to tell, since it drops so little for the total travel, that determining the very beginning is something that is best measured with a pair of dial indicators....one at the rear of the slide and one on the top of the barrel. If the second needle budges even .001 inch...you've gone beyond the start of the sequence.

The sequence begins just at the point of link's arc that puts it AT the correct point and angle to unlock...and all the slack has been removed from the
clearance between the link holes and both pins...which can vary from gun to gun. It doesn't mean that the barrel has actually moved, nor has tensile
stress begun. It only means that the slide and barrel are in position to begin the sequence. All that takes time. Meanwhile, the bullet is screamin' toward the muzzle at velocities approaching 800 or so fps. GI Hardball specs call
for 830fps +/-25. Most of the popular factory hardball these days runs in the
800-825 fps range, and the 230 hollowpoints are from 850-870 fps.

Looking at the recoil spring's influence...The standard 16-pound spring has an
in-battery preload value of about 3.5 pounds +/- a few ounces. If we plug in a linear resistance...which it probably isn't...and use the rated 16 pounds for the other end of the calculation... .100-.120 inch of slide travel just isn't going to provide a helluva lot more resistance to the slide. Rough figures here...12 pounds of additional resistance in 3 inches of slide travel equates to
4 pounds per inch...or maybe a half-pound of extra resistance.

Note the many hundreds of IPSC limited shooters...basically the stock class...
who juggle recoil spring rates...generally much lower than the standard 16...
in order to keep the muzzle from dipping below their line of sight when the slide returns to battery, for follow-up shots. These guns fire many thousands of rounds per year...in competition and in range practice...yet they don't produce the bulged and blown cases that we see in these photos. Why? Headspace has a lot to do with it.
Even though the guns compete in the "Stock" classes...many are carefully built with match-grade barrels in which headspace usually runs close to minimum specs, or even below. For the ones that aren't...a bulged case
is a sign that there's something seriously wrong with the gun, and the shooters have the problem corrected...or at least they do if they've got sense enough to come in out of an electrical storm. Problems that a new or heavier recoil spring can't correct. I'd go a step further and suggest that if any gun is on such a fine line that a simple recoil spring change will take it from safe to dangerous...and bulged cases are dangerous...there is something seriously wrong with the design or the specs of the gun.

 

[jungle]

The guy doing the math in the link provided comes up with the right answer but doesn't show the equation correctly and then goes on to point out that velocity doesn't matter. Wrong.

I see the photo, but whether it is an unlocked or unlocking or locked barrel is not completely clear.

redneck, You sir, have common sense and that is an uncommon virtue. I suggested such a test earlier with no response, in the meantime we are just chewing the fat and trying to figure out how these things work.

Tuner, Agree, but let's not forget the term Superface, which originated when those near perfect guns encountered ammo that exceeded a very high limit.

 

[georgeduz]

very well said 1911tuner.

 

[1911Tuner]

Distance

Okay...Marking the distance from the base of the bullet to the muzzle as near as I can see by using the rear point of the cigar-shaped bright spot on the side of the bullet to mark the base...and comparing it to the tape marks on the slide and frame...the bullet is nearly twice as far from the muzzle as the
distance between tape edges. If the witness marks are truly .130 inch apart...and assuming that my assumption on the bullet base are a bit off...
the slide had moved about .070 inch when the base of the bullet was just at the end of the muzzle...at the point of breaking into air.

Another point that's been overlooked in the pressure and unlock debate is that, the rifling isn't cut all the way to the edge of the muzzle because of the slightly countersunk crown. Gasses would start to vent, dropping the pressure before the bullet base is dead flush with the edge of the muzzle...so we're probably back to roughly .060 inch of slide movement at bullet exit...or maybe less. Without measuring, the crown on the Kart barrel in my Springfield
looks to be about .030 inch deep. Adding that distance to the approximate
point of slide travel when the pressure starts to drop...the bullet has exited
about a 32nd inch earlier than the photo suggests.

Jungle...If you can follow all this without gettin' Excedrin Headace #1911,
plug the figures into your equations and give us a final score!

 

[jungle]

Tuner, Going to stick with my figures, which were predicated on the bullet base being at muzzle for the slide travel distance given, but I do believe that friction(slide, magazine round to slide, barrel to bushing, and whatever else is there) may contribute 10-20% to the mass, and therefore reduce slide travel somewhat.

The fact that it all works and works well with a fairly wide variation in spring is telling. The equations came from a former head of Army Ordnance and I do believe he knew what he was doing.

Haven't weighed the Glock recoiling mass(nor the 1911s for that matter, just going on what was given), but I'll bet the Glocks is heavier than the 1911s, being quite a bit thicker and lacking the restraint of the 1911's hammer.

 

[1911Tuner]

re: Figures Given

Jungle...Look closer at the bullet base in relation to the edge of the muzzle.
If you lean to the left a little, you can see the base a little more clearly.
It's at least 75% further from the muzzle as the distance between the witness marks...and that's not even accounting for the muzzle crown.

You can also do a direct ratio equation. Mike the length of a 230 hardball bullet, and take measurements on the gun pictured. Apply the direct ratio to determine more closely where the bullet base is.

When you find the bullet base, use a scale to measure it as closely as you can...then do the same with the tape, and compare. Then, if you're inclined...add another 32nd inch to the distance that the bullet has moved
from the muzzle...the point that gasses began to vent into the air.

I've worked with Navy Ordnance myself...and found that some of those boys really didn't have a clean grip on how the thing works until some of the old armorers finally got'em clear on it.

oorah...

 

[jungle]

I see what you are saying, but also consider what a bullet would do leaving an unlocking barrel- accuracy would be in the crapper and the amount of unlock would not be consistent, not to mention the wear and tear. It isn't happening and it wasn't designed to.
A rough ratio of bullet movement at 800FPS and slide movement at 27.1 FPS could be juggled around, but it isn't going to change much.
I've been flying all night and this has been fun, but I've got to hit the rack.

 

[1911Tuner]

I see what you are saying, but also consider what a bullet would do leaving an unlocking barrel- accuracy would be in the crapper and the amount of unlock would not be consistent, not to mention the wear and tear. It isn't happening and it wasn't designed to.
A rough ratio of bullet movement at 800FPS and slide movement at 27.1 FPS could be juggled around, but it isn't going to change much.
I've been flying all night and this has been fun, but I've got to hit the rack.

I understand...Did the Midnight Killer Shift for 15 years myself.

You said:

>I see what you are saying, but also consider what a bullet would do leaving an unlocking barrel- accuracy would be in the crapper and the amount of unlock would not be consistent.<
*******************************

Exactly so. That's part of the reason that match pistol armorers delay the
unlock for as long as possible...to get the bullet closer to the muzzle before the barrel starts to drop. The other part being that they want primary extraction to begin in a straight line, before the barrel starts to drop. Of course, on doing that...because it was delayed...once the unlock starts, the barrel has to drop quickly in order to get out of the way.

In any case, if this photo is a pretty close representative of the event...the bullet has broken free into the air at a maximum of about .075 inch of slide travel...well before unlock starts. Looks like we're on the same page. Now all we gotta do is beat John with a brickbat until he can see it.

 

[JohnKSa]

the the bullet has broken free into the air at a maximum of about .075 inch of slide travel...well before unlock starts.

That incorrectly assumes that the slide and bullet are travelling at the same velocity and they most certainly are not.

The picture shows the bullet about 0.3" in front of the barrel. And it also shows that the slide/barrel combo has recoiled 0.16" from battery. (According to the picture taker, the witness marks are 0.16" apart, NOT 0.13".)

The bullet has travelled about 4.4" in the time it took the slide to travel 0.16 inches. The bullet is travelling at LEAST 27.5 times faster than the slide. Jungle's calculations say that the rough number is closer to 29.6 times faster.

Moving the bullet back about 0.3" to put it back at the point of exiting the barrel is equivalent to moving the slide forward by about 0.01 inches--it's moving much slower than the bullet. That puts the total slide travel at the exit point at about 0.15" of rearward movement which is still WELL into the unlocking process according to our expert.

I'm not claiming that these calculations are exact, but they are close enough pose a serious challenge the idea that the gun has not begun unlocking before the bullet exits.

If you take away the other retarding influences on slide motion (recoil spring & hammer cocking effort) then it's only going to make the unlock come earlier since you're increasing the slide velocity.

match pistol armorers delay the unlock...to get the bullet closer to the muzzle before the barrel starts to drop

Isn't this an admission that it is accepted by match pistol armorers that the gun is unlocking with the bullet still in the barrel? Just as the photo suggests?

These guns fire many thousands of rounds per year...in competition and in range practice...yet they don't produce the bulged and blown cases that we see in these photos.

I believe that a very reasonable explanation for at least PART of this is that you're talking primarily about .45ACP pistols operating at 21Kpsi, not 10mm pistols operating at 37.5Kpsi--that's a 79% increase in pressure.

 

[jungle]

John, Many of the competition shooters were using rounds that exceeded .38 Super and SAMMI specs by a fair amount. This continues today with certain rounds. The bulging exists in certain guns because of a couple of factors.
1. Some guns have too much throat and that allows a bulge at a certain pressure level. This will be increased if excess headspace exists.

2. No matter how well the gun is built and assuming it stays locked, the brass will always be the first thing to fail if pressure is too hgh. This is true for bolt guns and recoil operated pistols.

 

[JohnKSa]

jungle,

Couple of questions--I can't really tell your position on all of this.

1. Do you concur that the evidence supports a reasonable conclusion that the 1911 in the picture is already unlocking (or at least beginning to unlock) before the bullet exits?

2. Do you think that early unlocking CAN cause, or at least exacerbate, case bulging?

3. Do you believe that altering the recoil spring weight can speed or delay unlocking?

I don't know for sure exactly what's going on with the excessive case bulging. I know that not all Glock 20 pistols bulge cases, and I have a hard time believing that we're seeing huge headspace variations in factory pistols. That sort of thing leads to lawsuits. Perhaps there are minor headspace variations whose effects are amplified by weak/worn-out recoils springs?

 

[1911Tuner]

re:

John, no. The bullet has traveled over 5 inches in the time it takes the slide to travel .075 inch...and the bullet is about twice as far from the end of the muzzle as the slide has traveled in the picture. It takes a little suintin' to see where the bullet bas is...but you can see it if ya squint long enough.
The bullet broke free...according to my redneck figgerin'...at around .075 inch
of slide travel.

Match armorers delay the barrel unlock and linkdown mainly as an extra precaution of ANY barrel movement...not to keep it from unlocking before the bullet exits. They want to keep it solidly locked and fully supported at the lockup points...as solidly as it is on ignition. Remember...the locking lugs aren't truly locked until the gun fires. They're touching under mechanical
pressure before ignition...whatever the recoil spring tension affords...but not pressure-locked.

Havin' a hard time tryin' to find a way to explain this...but I'll try it again.

The locking lugs...slide and barrel...are butted together under intense pressure. Something on the order of 20,000 psi. Barrel nailed forward...slide hammered backward. The pressure is trying to shear the lugs off the barrel
and out of the slide...under some 10,000 pounds of pressure, if we assume a half inch square of surface area. The link, link pin, and slidestop pin simply aren't up to the task of forcefully separating the lugs for thousands of rounds
under that kind of pressure. And...even if those components were able to withstand that sort of tensile stress...once the lugs disengaged, the slide lugs would rake across the barrel lug corners as the slide hurtled rearward. Press your hands together hard and have someone jerk one of your arms down until your hands disengage. That is what would happen if the barrel could be unlocked under pressure, and the corners of the lugs would be eaten away quickly.

Again...Visualize trying to jerk a 5-ton weight off the ground by a barrel link,
attached to the weight by a .156 diameter pin on one end and a .200 diameter pin on the other. Somethin's gotta give...and it won't be the weight.
Even imagine trying to drag a 5-ton weight...which would be a closer approximation of the event...by the link and the two pins. I've seen half-inch
steel cables on a tow truck snap while trying to upright an overturned car that weighed less than half that. I'd venture a guess that those cables are quite a bit stronger than that tiny link and the pins.

There's probably a formula to determine the frictional resistance of trying to
separate a half square inch of surface under 5 tons of compression...but I don't know what it is. Jungle? You seem to have a good handle on the math.

 

[jungle]

John, Here is what I think.

1. The photo doesn't show us enough to conclude whether the pistol is locked or in some stage of unlock.

2. I think the bulges seen are for the most part caused by excess pressure in combination with excess throating, either of these can cause bulging and together they make it worse. It is a dangerous condition. Headspace problems will make it worse.

3. I believe spring weight has little to do with unlock timing.

4. Tilting barrel recoil operated pistols by design intent delay unlocking until pressure is well below that which would cause a case to bulge.
The bullet leaves the barrel before unlock happens.

 

[1911Tuner]

Headspace Variation

Okay...On to the other question:

"I have a hard time believing that we're seeing huge variations in headspace..."

Believe it, mah fren. I've seen static headspace vary as much as .020 inch in
new and/or lightly used Colts. Seen several brand new pistols go to battery easily on SAAMI standard NO GO gauges...pistols that would have failed and been returned to unit armorers for repair...and Colt doesn't have the market cornered on this observance. In these...all it would take is a little over-zealous barrel ramping and throating to produce bulged and blown cases...
and several have.

Why don't more pistols with max headspace bulge or blow cases? Simple.
Headspace can be excessive because the chamber was cut too deep,
and the case just moves further forward...or it can be out in the other direction...in which the case moves backward when the gun fires because
the breech is partially open under pressure as the slide is driven backward.
The case follows the slide...exposing the thin area forward of the web...
and it balloons. Sometimes the pressure exceeds the elastic limit of the brass...which varies with case construction and material...and it blows out.

 

[JohnKSa]

The bullet has traveled over 5 inches in the time it takes the slide to travel .075 inch...

Ok, the picture taker claims that the measured slide travel in the photograph is 0.16 inches. I don't think that is in question, it can be verified by reading the original thread, or if we need to, we can extrapolate the actual number by measuring parts of the gun in the photo and doing a comparison.

The bullet can be seen in the picture, and one can see that the base of the bullet is about twice as far from the end of the barrel as the slide has travelled. I believe we are also in agreement at this point. Using the slide travel number (provided by the person who actually took the picture) as a reference, we are force to conclude that the base of the bullet is about 0.32 inches from the end of the barrel. Still in agreement.

That means that to get the bullet back into the barrel, we need to move it backward by about 0.3 inches.

The picture taker says the bullet has travelled 4.4 inches, you say 5 inches. Whatever--by the picture taker's numbers the bullet is travelling 27.5 times faster than the slide, by your number for the bullet travel distance, it's going 31.3 times faster, by jungle's calculation it's going 29.6 times faster. I'll use your number. That means that at the point in the picture, the bullet is travelling about 31.3 times FASTER than the slide.

If you're going to move the bullet back 0.3 inches to get it back into the barrel, you have to move the slide forward a corresponding amount since both objects are moving in the picture. If the bullet moves 0.3 inches then the slide, which is moving 31.3 times SLOWER than the bullet, moves a distance that is 31.3 times SHORTER--that would be about 0.01 inches using your number for bullet travel.

So, we have now moved the bullet BACK by 0.3" to get it back into the barrel and moved the slide/barrel FORWARD 0.01 inches from their positions in the picture. Since the picture taker says the slide is positioned at 0.16 rearward in the picture, moving it forward by 0.01 inches puts it at 0.15 inches when the bullet is exactly at the point of exit. 0.15" is well into the unlocking process according to your numbers.

Rather than simply saying "No", please point to the problem in this math and we can go from there.

Jungle,

I would invite you to do the same.

 

[jungle]

John, I don't fault the math or the distance the photo maker measured, but it is entirely possible that that particular pistol's slide has to travel a little further than the norm to unlock and it is impossible to conclude from the photograph exactly in what stage of lock/unlock this pistol is in.

Let us presume for a moment that the bullet still has an inch to go to exit the barrel and unlock is complete at that point. Examine a pressure curve and note that pressure is highest just as the bullet starts to move down the barrel and then ramps down rapidly as the bullet travels down the barrel and velocity builds. Even if this unlock happens with the bullet yet to travel an inch to clear the bore, the residual pressure would not be enough to bulge the case.

In considering time of travel we have assumed 800fps, but an argument could be made that the average velocity is 400fps= 0 at start and 800fps at finish, a simplification that doesn't depict what happens, but one that could skew the velocity of the slide quite a bit in the early stages of movement.

 

[JohnKSa]

jungle,

According to Tuner's numbers, 0.15" of travel is well into the unlocking cycle. He lists 0.125" as being sort of an outside limit for the beginning point of unlocking with 0.1" as being the normal start. I think we're sufficiently OUTSIDE of his listed outside limit to be pretty comfortable saying that the pistol is already unlocking.

skew the velocity of the slide quite a bit in the early stages of movement.

Agreed, but we're not examining the early stages of slide movement. At the point the picture was taken, the slide and bullet are both at maximum velocity. So at best, I'm going to underestimate the amount of slide travel. Furthermore, your numbers based on accepted/typical slide/bullet velocities agree well with the numbers provided by the picture taker that I am using. Everything about the picture supports the numbers as I've laid them out, and while I don't think we can expect exact results, the margins are sufficient to support the conclusion I've reached.

For the bullet to exit before the slide reaches the 0.125" travel point that Tuner says is pretty much the outside limit, we'd have to have the slide moving 3.5 times slower than what the picture suggests--or about 7.7fps at the point of MAXIMUM slide velocity. If you play around with those numbers, you end up having to say that it takes more than an eighth of a second for the slide to cycle--way too slow. It's even worse if you assume that the pistol was already unlocking around 0.1" of travel. You'd be saying that the maximum slide velocity is only 5fps and that it would take around a fifth of a second for the slide to cycle.

Here is an independent mathematically intense post on another forum that basically verifies my analysis of the photo.

http://forums.1911forum.com/showthread.php?t=2977&pp=25

It also concludes (and the numbers are remarkably similar) that unlocking has begun before the bullet exits. His numbers show bullet exit takes place at about 0.13" of rearward slide travel. His calculated value for slide velocity (25.7fps) agrees well with the number extrapolated with the picture. His calculation also suggests that spring forces are applying over 9lbs of force at the moment of firing--also agreeing well with my estimates.

 

[jungle]

John, Just to clarify, your conclusion is that the bullet always exits in this type of pistol after slide unlock is complete? Or the bullet exits sometime during the unlock process? And bulging is because high slide velocity speeds unlock? High pressure, headspace and throating are not factors?

From a mechanical standpoint, unlocking gets easier as pressure drops and as the bullet nears the muzzle it is valid that pressure has dropped off 90% or so. If the pressure has dropped that much, how can it bulge the case at that point.

 

[1911Tuner]

re:

I ain't gonna argue with numbers too much. I'll let the mathematicians duke it out instead...but I will add that, in a measured time/distance experiment on a .45 caliber 1911 pistol, the average slide speed for the return to battery event was just a tick under 3 fps. (Wish I could remember where I read that...but it was on one of the forums.)


Three...fps. If we assume that the return to battery takes 2.5 or 3 X the amount of time that it takes the slide to complete the recoil cycle...7-8 fps isn't too far off the mark for the first 1/8th inch of travel.

John...You still don't seem to be considering the high load and frictional forces
that nail the locking lugs together. The link just can't jerk'em apart without snappin' like a twig. One sure way to find out is to take a link to a community college where MET is offered...and visit the metallurgy instructor.
They have a hydraulic tensile stress testing machine...or they should have.
Take'em a link and have'em test it as part of a class. I'd be interested in knowing how much stress it takes to break one. Bettin' that it'll break under a helluva lot less than 5 tons though...

 

[JohnKSa]

jungle,
The statement has been made repeatedly on this thread (and others) that it is impossible for the unlocking process to begin while the bullet is still in the barrel.

I think it's clear from the photo (and the other mathematical analysis in the second link) that 1911 unlocking DOES start with the bullet in the barrel at least some of the time. I think that makes it reasonable to assume that is also the case in other roughly similar designs.

I think that (depending on a lot of factors) sometimes the gun hasn't started unlocking, sometimes it's in the process, and sometimes it's completely unlocked by the time the bullet leaves the muzzle. I think that the latter case is probably unusual and likely to cause noticeable problems. However, clearly, the rigid stance that unlocking can't start while the bullet is in the barrel isn't supportable unless you work very hard to explain away the evidence in the picture.

That means that any analysis based on or depending on the idea that it's impossible for the gun to begin unlocking with the bullet in the barrel needs to be re-evaluated.

I think there are lots of things that contribute to case bulging, and your list seems reasonably complete. However, an earlier statement in this thread said that recoil spring tension was a non-factor in case bulging. I think that the analysis shows that it is unreasonable to completely rule out recoil spring weight as a contributing factor, but also shows that, in general, other factors must be present for it to become an issue.

Tuner,

3fps is way too slow and is not supported by the math. There are POINTS during the travel where it is that low but not at the point where the bullet is just leaving the barrel.

Ok, here's my whole point. You started with some basic assumptions. Your arguments throughout this thread are based on using your initial assumptions to explain away the evidence in the picture. That's not the way to look at an experiment. You can't interpret experimental evidence with the idea that you won't allow any of the conclusions to change or challenge your initial assumptions.

I understand your reasoning on the high load/friction thing, but I reject the conclusion because it is not consistent with the photographical evidence as supported by the mathematical analysis. It fails the test because it contradicts clear experimental evidence.

Obviously unlocking can start with the bullet in the barrel--I would say that evidence in combination with your comments about high friction due to pressure retarding the unlocking that drive us to the conclusion that either the pressure (and therefore the friction) has dropped significantly by the time the bullet is near the muzzle, or that there is something more to understand about how the pressure in the barrel affects the unlocking timing, or maybe even there's something we're missing altogether...

Ok, I learned some stuff on this thread...

In light of what I've learned from the photo (and the subsequent discussion), I would have to go back on the implications of my initial comment on this thread and say that the bulged cases that started this thread are not due exclusively to a worn out recoil spring or an under-sprung gun--in fact, the recoil spring tension is probably not even a major contributor to the problem. While the recoil spring can be a contributor, the evidence does not support it's being a major contributor. The gun in question has some other problems, and they need to be addressed before the gun is shot with any more hot loads.

 

[jungle]

John, The Link to TiroFijo's post in Post#93 is quite clear and one of the best reads on the subject. He is a formally schooled engineer and a spring specialist. I urge everyone who is interested to read it carefully.

His conclusions?
Springs don't effect the unlock timing to an appreciable degree. The bullet leaves the barrel prior to unlock unless something is abnormal with the design.

His writing and understanding is the very best I have ever seen and his treatment of springs is more complete than most.

 

[1911Tuner]

re:

John...Read my last post.

Nobody said that the recoil spring could be completely disregarded. Nothing can be completely disregarded. Anything that CAN have an effect on the slide will do just that. Nothing means everything, but everything means something. The spring's effect on the TIME that it takes for the slide to move that first .100-.125 inch is so negligible that it almost can be disregarded though...at least in a recoil-operated pistol. "Time" and "Timing" are related, but they're not the same.

Straight blowback...Yes. Spring tension and slide mass are all that keep the breech from opening under pressure...and a 10% reduction in spring load can make a serious difference.

My stance is that the recoil spring's effect on unlock TIMING is a non-issue, because the unlock timing is a mechanical event. It will occur at the same point, regardless of how fast or slow the slide moves. All it has to do in this instance is NOT to reach it while the bullet is still present, and pressure is high.

Yes...Delaying or advancing the slide position in relation to the bullet's position can make the difference between safe function and unlocking while pressure is high...but the gun would have to be right on the peg, and if it did unlock under pressure, case bulging and/or gun damage would be the result.

 

[1911Tuner]

TiroFijo

That's the one! Thanks Jungle...

 

[JohnKSa]

The bullet leaves the barrel prior to unlock unless something is abnormal with the design.

Concur--but he also concludes (as I did based on the picture evidence) that the barrel definitely BEGINS unlocking before the bullet leaves the barrel. His numbers agree very well with what the picture shows. The bullet leaves the barrel pretty much in the middle of the unlocking process according to the picture and TiroFijo's calculations.

He does comment that the 9-10 lbs of force exerted by the recoil spring is not a major contributor but stops short of saying it is "negligible". His numbers put its effect somewhere around 10% of the equation, if I'm reading things right which agrees pretty well with my earlier WAG that the combined effect of the recoil spring & hammer cocking force were about 20% of the equation. I'll admit that it's not as much as I had expected, but I think that calling it negligible is a bit of an exaggeration.

I think what we've come down to is that if the gun has other problems such that it's on the hairy edge of being really messed up, you might be able to keep it on the safe side with recoil spring tension. However, if you're finding that the gun is showing alarming symptoms everytime the recoil spring gets weak, there are deeper problems that need to be addressed.