Amazing!!!!!!!!!!!!!

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Mass

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> Given identical guns within a group, one will almost always find that the engineering solution to controlling slide speed as bullet energy goes up is to increase slide mass. Colt chose not to do this with the Delta and ran into problems.<
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Colt dropped their candy with the Delta when they missed the opportunity to utilize more of the mainspring's effect by going with a 25-pound mainspring and getting back to the basics on the firing pin stop. Ted Yost and Ned Christiansen figured it out in about two shakes, and I understand that both of these world-class pistolsmiths use a very small radius on the firing pin stops in their Big 10 pistols...and they do it with less recoil spring than the factory standard of...IIRC...22 pounds.

Colt...All it woulda taken is a peek at the old blueprints and for somebody to notice and ask: "Why"
 
In the case of the Delta, springs where a bandaid when greater slide mass was clearly called for, and the results were never satisfactory.
 
Delta Woes

Quote:

>In the case of the Delta, springs where a bandaid when greater slide mass was clearly called for, and the results were never satisfactory.<
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No doubt that the slide could have used another ounce or two...but Ted and Ned seem to have gotten it sorted out in fine fashion...and they're dropping down to 18 or 20 pounds on the recoil spring as a matter of habit, so I hear.
Some of the guys who have tried the combination of small stop radius, 165 PF ammo, and a 23-pound mainspring are reporting short cycles with even 14-pound recoil springs...so the effect isn't imaginary.
 
165PF is slightly under par for .45 ACP, a full power 10mm is a completely different animal and should have been dealt with accordingly. The 10mm exists in a form close to .40 S&W and any Delta can handle that, but the original full power loading is beyond the normal 1911 capability without some serious mods if the life of the pistol is expected to remain long.
 
PF

>>165PF is slightly under par for .45 ACP, a full power 10mm is a completely different animal and should have been dealt with accordingly.<<
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I know that 165 PF is light. The reference was made to show that the stop radius does have an effect. Uhm...Maybe you should contact Ted Yost or Ned Christiansen for a full report on how their 10mm pistols do over the long haul. like I said...They seem to have gotten it all sorted out.
 
I think they would both agree that a 1911 will live a very long time with 165PF loads and a considerably shorter time with full power 10MM loads regardless of springing or FPS radius.
 
"P" Factors

As will anything that imparts higher energy and pressure against a breechblock. 38 Special vs .357 Magnum, etc.

What I'm curious about is how the thread went from discussing how using a small radius on the firing pin stop makes a .45 caliber 1911 sweeter to shoot, to how brutal the 10mm is on a standard 1911 frame and slide...about which I completely agree. The slide should have been beefed up.

Maybe you should invest 20 bucks in a stop and a new 23 pound mainspring and try it for yourself...
 
You know me Tuner, I'm just not very sensitive to the subtle changes some report with various modifications in spring weights. My first post outlined a simple way to quantify the change.
I guess you could say I don't see a problem to start with and remain somewhat skeptical of the actual effect this mod may have. Having seen different people report widely varying impressions of recoil with an identical pistol and ammunition, I am less inclined to trust impressions(my own included) and more inclined to trust hard data.
Lacking hard data in the form of high speed photography, the next best thing might be ejection distance with a pistol fitted with the two different stops firing identical ammo and fired from a Ransom rest to ensure identical hold. I don't argue that the mod doesn't change anything, I only question the amount of change.
I can of course alter ejection distance with recoil spring weight also, but that doesn't imply the pistol is running better or worse as long as function is not impaired. Only that slide speed at the end of the recoil stoke has been altered slightly.
There is also the question of ammunition tolerance, with a given slide weight the lighter spring will allow a wider tolerance of loads to be digested by the pistol.
 
Difference

Well...The difference isn't really that subtle. Most report a definite change in the recoil charactistics of the gun, while others report only a faster target reaquisition and split times...but sometimes even subtle changes are worthwhile. Every little bit helps...just like with the 10. it's not about making the gun indestructible. Can't do that unless the gun is never fired. It's about prolonging the useful life of the gun. That's why we change recoil springs and lube slide rails. As far as ammo sensitivity goes, I don't see it. My ammo ranges from 230/850 down to 200/750 fps with 16-pound recoil springs...but either will run all my guns with even an 18-pound recoil spring. Only yhe ejection distance changes. The 200/750/18 combo dribbles the brass out at my right foot...but I don't get short-stroke malfunctions. A different gun just might have a problem. Simple matter of dropping to a lighter recoil spring...which also helps tame the effects of (secondary) recoil
on the shooter.

Really though...You should try it. Ya might find that ya like it a lot.
 
Stop

http://forum.m1911.org/showthread.php?t=13060

You can read some of the testimonials here. It started when John Caradimas...from Athens, Greece...was talking about a dilemma that he had.
Not being able to go out and buy a new pistol at a hat-drop, he was concerned about slide to frame battering in his two guns. Hard for him to order shock buffs without help on this side of the big pond...and having trouble with magazine timing with 18-pound recoil springs...he asked me what to do. I suggested one of EGW's stops with a small radius. I cut one for him, including a pre-fit to maximum print specs on the size...and mailed it. I mentioned that he would probably notice a slight reduction in felt recoil, due to the stop's braking effect...and within two days of installing the stop, he started this thread. It took off, and prompted a few others to try it...and they reported the same...which lit a wildfire. George Smith's firing pin stop sales have taken off, and everybody seems happy with the "modification" which is really nothing more than a return to basics. Ol' John Moses really did know what he was doin'. Yeppers, he did.
 
Not trying to rain on the parade, but it seems as if most of the anecdotes about this mod revolve around pistols that were not functioning well to begin with or needed a little tweaking to get them perking due to other factors.
I am interested in seeing more input from users who have substituted the FPS on 1911s that were running just fine prior to the substitution. I understand the mechanics and the forces involved, but I have trouble believing that a tenth of an inch difference(or less) on the position of hammer to FPS contact is going to make this much change.
I have the highest respect for Tuner and EGW and would like to see how the average shooter views the change. Sounds like we should have about 100 reports shortly. Thanks again for an enjoyable discussion.
 
I havee changed to the small radius stop on 2 pistols. One was a 10mm Delta Elite, which had some issues prior to the change. These have slowly been resolved.

The other was a 5" .45. There was absolutely nothing wrong with the way this pistol functioned. I ignored my father's advice, (if it ain't broke, don't fix it!), and changed the stop. There was only a slight improvement, barely noticeable. This was with a 19 pound mainspring. Going to a 23 pound mainspring made a great deal of difference. Ejected brass does not fly near as far. Firing 230/840 it is very well mannered.

Now that I look back at the experience, I was not actually going against my father's advice. The original firing pin stop was not broke, and they fixed it anyway. I am just correcting their fix.

I examined a Colt Pony .380 the other day, and noticed that its radius is pretty small. So somebody at Colt knows about this. It is a shame they weren't in charge of the Delta Elite production.
 
Interesting. Can't say I've seen a stock 1911 fling brass too far with standard loads, but on the other hand I don't want them dribbling out. I've also heard a lot of people using a 14lb recoil spring and 19lb hammer spring and proclaiming the pistol shot quite a bit softer. Subjective opinions seem to vary widely.
 
I am interested in seeing more input from users who have substituted the FPS on 1911s that were running just fine prior to the substitution.
Click to expand...
Tuner has installed dozens of them in pistols that were running just fine.
It was done to soften recoil.

I understand the mechanics and the forces involved,
Click to expand...
Obviously you don't.

...but I have trouble believing that a tenth of an inch difference(or less) on the position of hammer to FPS contact is going to make this much change.
Click to expand...
It's a matter of leverage NOT a matter of distance. :banghead:
Don't you find it easier to rack the slide of ANY 1911 Pattern pistol if the hammer is already cocked? Of course you do.
If you install a stock, unmodified EGW firing pin stop with the lower edge square just like they send it to you, it is dang near impossible to pull the slide back with the hammer down.
 
"It is a matter of leverage NOT distance."

In this case leverage would be calculated by the distance from the hammer pivot point and the intersection of the FPS and hammer. So the difference between the standard FPS and the modified FPS is the difference in distance from the hammer pivot point to FPS at hammer intercept. That is leverage. Can you calculate a numerical difference?
I can't break out the calipers right now, but my rough guess is about one additional pound of spring force.
Please correct this if you think I'm wrong with your figures.
 
re:

Jungle, mah fren...The only suggestion that I have is that ya get one and see for y'self. I'd say that a .060 radius...a fresh 23# mainspring...and a fresh 16# recoil spring would do it.

Bear is correct. Try though I might, I can't seem to keep an EGW stop on hand here. Every time I show it to somebody on the range, the reaction is invariably: "I want one!"

All my instincts are tellin' me that this resurrected thread probably needs to go to bed...:scrutiny: but I'll try this instead:

The increased leverage probably doesn't add much more than an extra pound or two of resistance...that's a fact...but it's not the amount of extra force applied so much as WHEN and WHERE it's applied. In this case, it's at the inception of recoil, when the impulse is highest. As you are doubtless aware, about 90% of the energy imparted to the slide is at the instant of firing. It's right there that the hammer offers resistance, since the recoil spring's resistance at that stage of compression is relatively small.

Go back to the drag race mentioned earlier. Would a one-second brake application have more influence on slowing the car at the very beginning of the race, when the car has just started to accelerate...or near the end of the race, when the car is moving at a hundred miles per hour?
 
I think it's one small modification worth trying...cheap too!

If there are any left, ;) , I'm going to order one. The worst that can happen is you can't feel the difference and you end up with a spare FP stop...that "ain't bad".
 
Stop

45Auto said:

>The worst that can happen is you can't feel the difference and you end up with a spare FP stop...that "ain't bad".<
***************

That's the spirit, lad! It's a system, so be sure to start with fresh springs.
23# on the mainspring...16 for the recoil spring.:cool:
 
Tuner,

I use a 19.5 lb mainspring now, but I'll try the 23lb also.

Since I shoot "moderate" loads, maybe 170 PF, I do use the 14lb recoil spring which I find "sweet" in overall operation. I'm looking for the FP stop to "hedge" some recoil to the frame, among other things, while using lighter recoil springs.

What do you think?

Thanks
 
Sorry it took a while to get back, but I did get a few measurements and did a few simple calculations to illustrate the effect of this modification.

First, a few basics. The 1911 will fire and eject just fine with no recoil spring. The force applied at firing is a momentary impulse of about 1300 lbs. To find this take the area of the cartridge base and multiply by the pressure. This is difficult for most any spring to resist at least for the initial travel-slide mass controls slide speed during the initial stages of recoil. The bullet moving at 830 FPS causes an equal and opposite recoil of the slide and barrel at about 24 FPS, with the slide mass being decelerated by the recoil spring at the end of it's stroke.

Now, what part does the hammer play in all of this? The hammer acts as a lever against slide movement through the force of the hammer spring. And how much force is applied? We will measure in inch pounds. The distance between the hammer pivot point and contact with a standard slidestop is about .540 inches. The 23 LB hammer spring is at about 60% of it's rated weight with the hammer at rest. So, 13.8/.540=25.55 inch pounds.
The small radius stop is contacting the hammer at about .532 inches from the hammer pivot point. So, 13.8/.532=25.94 inch pounds.

The difference is .39 inch pounds. About the same force it takes to flip open the cap on a tube of toothpaste.

Maybe old JMB knew something when he approved the "new fangled" FPS.

High speed film shows the slide's movement will slap the hammer out of contact with the slide on firing. When you hand rack the slide the hammer will maintain contact with decreasing force as the FPS rides up the hammer.

I hope you enjoyed this quantification of the matter being discussed.

Any comments? How about you BluesBear? Would you like to demonstrate your understanding?
 
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Any comments?
Click to expand...
I am reminded that some mathematician is supposed to have proved, through careful calculations, that it was impossible for bumble bees to fly … :eek:

Once upon at time gunsmiths building target pistols on the 1911 platform would cut a radius in the bottom of the hammer face, so the only part left was that which impacted the firing pin. They would also radius the firing pin stop more, even to the point of making it a bevel rather then a radius. The purpose of this was to eliminate the buffering effect of the hammer so that the pistol, firing powder-puff target loads, would cycle easier. The modification was particularly popular on .38 Special and .22 R.F. conversions.

In this kind of application the modification worked well. However if you took and fired regular .45 ball ammunition in such a pistol, slide/frame battering would soon appear at the rear of the recoil spring tunnel, and if one kept it up the usual result was a frame cracked through the rail at the slide stop cut-out. Consequently these pistolsmiths did not make this change on pistols intended to shoot full loads. They may not have been math whizzes but they knew what worked, and what didn’t from experience.

While the slide may (or may not) kick the hammer back, contact with the firing pin stop will remain the most at the lowest point. As Tuner has pointed out, the “firing pin stop effect,” to the degree that there is one, happens as the slide is starting to move. It is at this point that the recoil spring – regardless of its weight – has the least effect.

Obviously this modification isn’t for everyone. Neither is any other of the sundry modifications inflicted on this pistol. But many who have tried it have found it to be beneficial, particularly when the platform is pushed to its limits – as in those chambered to use the 10mm cartridge in its heavier loadings, and heavier recoil springs are not the answer.

One of the advantages of this experiment is that it is relatively inexpensive, and the part itself is of excellent quality. Since there is no radius to start with, one can use whatever kind they like. I would note that the radius specified by Tuner comes close to the one originally used by Browning. Once up on a time someone introduced JMB to an Army officer, who called him an “engineer.” Browning then pointedly commented that, “no he wasn’t an engineer, he was a mechanic.”

I don’t think Tuner is an engineer either … :cool:
 
Being the excellent historian you are Old Fuff, I am sure you can tell us that JMB approved the modification that changed the parameters of the original FPS.

Exploring the measurable mechanical effect of a modification seems to work better than vauge and unreliable feelings or subjective impressions. I am neither for or against, just wanted to show the actual net effect. Have you any actual measurement you wish to share?
 
Understanding

Maybe old JMB knew something when he approved the "new fangled" FPS.
Click to expand...
You are misunderstanding. Browning designed and built the 1911 under contract and in cooperation with the Colt's Patent Firearms Manufacturing Company. Once it was accepted by the US Army Browning was out of it. It was Colt's who respecified the firing pin stop at the insistence of the US Army.
The Army said it was too difficult for a big strapping calvaryman to hand cycle the slide with the hammer down. So Colt made it easier.

Now forget about math for a minute. If that simple change made it easier for a human to cycle the slide with the hammer down just think how much easier it then became for the cartridge to do the very same thing.

Jungle has a predispoded opinion and is trying to use Algebra to prove himself right.
Classic misdirection.
What you need is Geometry and Physics.


And common sense.





Go ahead try it. Buy a $15 EGW slide stop and try it. If then you don't agree with us, I'll personally buy it from you for twice what you paid for it.

Go ahead, put your money where your mouth is. Change the stop and then try and tell us that it doesn't require more energy/force to retract the slide with the hammer down. You don't even have to fire a shot.
Until you experience the physical results anything else is just an unproven theory anyway. You want proof so prove it.

Jungle all you have is a theory (and a strong prejudice).
The rest of us have physical experience.

WE understand.
 
Perhaps your "understanding" is based on your own unproven feelings.

Let's take the example of a Baer 1911, which many observe to be very tightly fitted in lockup, and very difficult to rack by hand. Yet, wonder of wonders, it functions perfectly. Hand racking and how the pistol behaves under the dynamic conditions of actual firing are two entirely different things. The actual forces generated by firing a live round are stronger than many are aware of, and it boils down to momentum to control this force.

Like I said, I'm neutral on this, and if you can demonstrate that less recoil is generated through some simple practical experiment I am all ears. Even though dynamic forces are different than hand racking, you could rig a trigger pull type measurment of manual racking force and actually demonstrate that difference. How much exactly would that be? And how much effect would that have against an initial 1300+LB momentary impulse?

I have no prejudice, indeed I would like to see this work, my only question is how does it do so.

Show me how .39 inch pounds is going to make a measurable difference.


Just one more thing, can you point me to the documentation that shows Colt modified the design without any input from JMB?
 
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