Join Date: Aug 2013
A conversation about springs...(a long post)
Thought this may invoke some reaction and start some conversation...
This is edited from what I wrote for our newer armorers and range instructors when we approved the 1911 for duty to help diagnose issues that may arise and to understand the relationship between springs. I would interested to know of your opinions and experiences. Hopefully this formats okay since it is a cut and paste.
If you recall, prior to the “proofing” process on the range, we spoke of what may be called a “Triad”, ammunition, magazines and weapon. If the combination of these three has proved itself to be consistently reliable, but now problems are arising; have changes been made to the Triad since “proofing” or is the weapon and or magazines in need of repair? Of course there are “assumptions” made which will be listed and referred to below.
• Each shooter in the transition class arrived with a pistol with fresh or still serviceable springs of a known weight rating (every maker does not use the same).
o Recoil, main and magazine springs
• The weapon’s “hardware” (i.e. Ejector, extractor and other internal parts) components are still sized and fitted correctly; free of damage and both feed ramps and other “geometry” is within acceptable tolerances.
o Inspect for chipped or broken ejector and or extractor and its tension
• Shooter and weapon had no issues by end of class (after adapting to techniques required for 1911s)
• “Government Model”, 5 inch pistols
What has changed since the transition class?
What type of malfunction is occurring? Shoot it (with same ammunition when problem occurs), examine it and determine where in the eight steps of operation it occurs.
• Is the shooter encountering problems with the ammunitions used when the gun was “proofed”?
o If so, are all magazines the same as when proofed?
Is the problem with one mag or all
• If with one mag, discard and proof new one or;
o Diagnose components of mag
o Replace recoil spring with new one of same weight originally used
Careful of just selecting by weight
• Varying wire diameter can cause stacking
• Select for proper barrel length
o Can vary by maker on shorter guns
Some people are always seeking a way to get a .45 to recoil like a 9mm. There is only so much that can be done and there can be negative consequences in doing so. There are several factors involved in the felt recoil (the slide’s movement to the rear) and counter recoil (the slide’s movement forward) while maintaining reliable function. These are:
• Barrel lug impacting the frame (VIS)
• Impact points inside the front of slide impacting the guide rod (which is held in contact with frame via the recoil spring)
• Ammunition (“power factor”)
• Firing pin stop radius
• Magazine capacity and its required spring weight/strength and length
• Recoil spring
VIS and Impact Points
The first two are designed into the weapon and for most of us, beyond our ability to alter. Basically, these are designed as stopping points; the VIS to stop the barrels rearward motion and the other to stop the slide’s rearward motion. Though I am no “master pistol smith”, I would simply state that these engineered stopping points and other “geometry” of the pistol (feed ramps etc.) are the most difficult and complicated to alter; but critical to the weapon’s reliability. Corrections of these items usually require advanced knowledge, machinery and skill. If correct in the first place, there is rarely need of these two items for many tens of thousands of rounds.
When the gun fires, the other five items can have an effect on the slide’s speed fore and aft, distance traveled, felt or perceived recoil that can have an effect on the ability to feed, chamber and lock reliably. When referring to distance of slide travel, this is where we usually see or encounter the “limp wrist” issue. The intent is for the slide to come fully to the rear till it is mechanically stopped (VIS and slide to frame via the guide rod contact between the two) but a slightly larger “window” can be provided with a longer ejector as seen on most “modernized 1911s”. An example of this is when the pistol fires, extracts and ejects the last round but the slide does not lock open though the magazine follower and spring are serviceable. The slide came back far enough to complete the extraction and ejection functions; but not fully to the rear. This can also happen when using recoil buffers that may prevent the slide’s travel just enough to prevent the slide stop notch from proper alignment. An improperly selected recoil spring whose fully compressed length is too long (“stacking”) for that particular pistol, can also create this situation.
For the purposes of this discussion, ammunition is not a factor because it has not changed. More on changes in ammunition and its effects later.
Firing Pin Stop Radius
The question of the radius on the firing pin stop and its effect on recoil has come up. The firing pin stop engages low on the hammer (below the face that strikes the primer) during recoil and is responsible for cocking the hammer and in turn compressing the mainspring. Obviously, the smaller the radius, the lower it strikes the hammer which means less leverage, and more initial force is required and a slowing of the slide occurs. According to experts, the smaller radius increases lock time and “can” add to the accuracy of the pistol. It is commonly done in bullseye competition pistols.
The downside is that it makes the gun harder to manually cycle with the hammer down; and in some cases, requires the hammer to be thumbed back prior to working the slide. This may be fine in some arenas of competition but, for most, it may not be recommended on a duty weapon that may need to be manually cycled one handed (example: hooking the rear sight on my belt). I have experimented with a small radius firing pin stop and find some advantage after settling on different spring rates through experimentation and lots of shooting.
In addition to this I have inquired with several well-known pistol smiths, and been advised that there is no fear of stress to other components when using the smaller radius (i.e. Hammer, hammer pin, hammer pin hole in a quality steel frame), though common sense would tell me to not do this in an alloy framed gun for fear of “egging” the hammer pin hole.
Just remember that changing the radius of the firing pin stop will likely cause a need to change one or all three of the springs later discussed. That and more range time changing these combinations to determine what set up work reliably with a given ammunition.
This leaves us with three springs: recoil, main and magazine. Realize that all three work in relationship to one another with regards to recoil. Recoil (the rearward travel of the slide) is when several things must occur: extraction, ejection and cocking the hammer. Simply changing one spring, can have an effect on the reliable function of the pistol; and or cause damage over time. The changing of the weight of one spring may result in the need of changing one or both of the others due the speed of the slide’s rearward motion changing.
The magazine spring is pushing the top round into the bottom of the loading lug (the “rib” in the center of the slide behind the breech face) when in battery. This pressure is at its greatest with a fully loaded magazine seated. The greater the mag capacity, the greater the pressure since a longer and stronger spring is required to ensure the last round will feed. This pressure does for a short time create drag on the loading lug during recoil until the slide retracts far enough that the lug is no longer in contact with the top round in the magazine. Again on the slide’s trip forward, the top cartridge is being forced upward against the feed lips of the magazine and this pressure must be defeated by the slide’s loading lug until the round being stripped from the magazine clears the feed lips. Though as each round is stripped from the magazine; incrementally, this pressure will be reduced with each round fired until the magazine is empty and slide (hopefully) locks back, provided there is enough spring pressure remaining to push the follower up with sufficient pressure to engage the lobe of the slide stop into the slide stop notch. And remember that each round must be pressed firmly against the feed lips of the magazine prior to the loading lug passing the rear of the magazine on its travel forward.
This is also why that magazine that works fine in a Government Model (5” gun) may cause issues in a pistol with a shorter slide/barrel since the slide of the short gun is traveling forward faster due to lighter mass and a greater weight recoil spring. In the short guns, the rounds have to travel upward in the magazine body quick enough to keep up with the slide speed.
So what is the purpose of the recoil spring? It is to slow the slide so as to reduce the force exerted on the impact surfaces/points of the frame and slide, but not to totally prevent these points from impacting against each side of the guide rod. Or at least getting very, very close so that complete function occurs-that “window” mentioned earlier. I do not want the gun to be so dependent on perfection that it fails to function when shot with less than perfect support or a mild variance in the ammunition’s power factor.
The military ammo used in WWII 1911A1s was 230 grain ball travelling 800-825 fps or a USPSA “power factor” of about 189. Our Gold Dot is also 230 grain at 890 fps or a power factor of 204. This small increase in velocity creates an obvious felt recoil difference. The original Browning design specified the spring design and material but not compression weight. Most research will show that the recoil spring weight on the WWII contract guns was 14-15# and 16# ultimately became the standard for 5” barreled pistols. Some modern maker s of custom and semi-custom 5” 1911s install 17-18.5# recoil springs.
As cautioned in the transition class, I mentioned that some shooters with “full power” duty type ammunition, like the feel of running an 18# spring. However, this requires more physical effort supporting the gun to prevent “limp wristing” in order to ensure reliable function. This becomes even more critical when shooting one handed.
With so many makers producing pistols based on the Browning design, each has made their own changes to accomplish their individual goals. With regards to mainsprings there is no longer a standard. The primary purpose of the mainspring is supply enough energy to the strut to drive hammer with enough force that the firing pin is struck sufficiently for ignition of the primer to occur. Due to deviations from maker to maker, as to sear angles, hammer hook depth, hammer weights, firing pin weights, tip diameters, hardness of primers and mainspring housing locks; mainspring weights can range from 17-28 pounds. But the weight of the mainspring can also have an effect on the felt recoil and the slide’s rearward speed during recoil since the firing pin stop (part of the slide assembly) engages the hammer upon recoil.
So with that said, the questions arise as to what effect does the recoil spring have on “counter recoil” (the slide forward motion) and the mainspring’s effect on trigger pull.
Provided the slide reliably travels to the rear far enough for extraction, ejection, cocking and feeding (within the “window” of operation); it only requires sufficient energy to be driven forward with enough force to accomplish its task. That task is to strip the top round from the magazine and feed, chamber and lock back into battery. So how much energy is that? It depends. How much force is being applied to the underside of the slide by the magazine spring when the magazine is at full capacity? It has to overcome the disconnector protruding from the frame. Then still have enough energy to overcome the round’s contact with the feed ramps, chamber, breech face and extractor while camming the barrel upward to lock back into battery.
With all these factors at play during counter recoil, the fitment of parts and correct angles come into play. A heavy recoil spring can overcome some issues of poor fitment and geometry because it stores enough energy to “force” the round through the process. That is provided the power factor of the ammunition was sufficient to drive the slide fully to the rear in the first place. This is why some pistols will run fine with stout ammunition and a heavy recoil spring but not be reliable with softer shooting or lower power factor ammunition.
The heavier spring can also help overcome the carbon build up, lack of lubrication and dirt of a heavily used pistol between cleanings.
Cycling the action quickly through an entire magazine with action proving dummy rounds and a 12# recoil spring can help determine where issues requiring attention may lie.
So what weight recoil spring should “you” use? For most, if everything in the “Triad” worked during the proofing process, leave it alone and replace springs with the same weight and total compressed length as you started with when needed. Most people do not shoot enough, often enough to either see and feel the advantages of changes; or ever create damage to the weapon.
For those that do, use the heaviest spring that will reliably function the pistol under all conditions that it will be used. That means, strong hand only, support hand only, multiple positions, a week or two since last lubrication was applied (depending on maintenance schedule) , dirt conditions and number of rounds you expect to be fired in a given session.
The mainspring’s effect on trigger depends on the depth of hammer hook and the primary and release angles of the sear. This can vary from gun to gun and maker to maker. Depending how close the trigger pull weight is to the minimum acceptable/approved standard; changing the mainspring could result in a trigger pull below that allowed by department policy. A change of the mainspring could have an effect on safe operation (too light) or cause early wear to ignition parts (too heavy)
Remember that changing the recoil spring, mainspring or firing pin stop radius (though not recommended for most); either singularly or any combination thereof; will have an effect of the slide’s speed. These changes can result in changes to reliability or wear. Changing the magazine spring’s pressure can effect slide speed (though slight) and reliable feeding.
Caution with regards to 10 round magazines in single stack 1911s. Though there is a division in USPSA competition called Limited 10 in which thousands are successfully used. I have also seen many 1911s choke with 10 rounds mags. Stoppages created in the first couple rounds due to excess mag spring pressure or malfunctions in the last couple rounds due to lack of spring pressure. Obviously this can be corrected with experimentation of spring combinations and tuning but I personally prefer to leave that for those pistols used in competition and not for defense purposes.
Last edited by Mike240; 08-28-2013 at 05:13 AM.