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tuning your pistol slide action

netfences

Plastic
Joined
Mar 5, 2017
The only thread I've seen on this topic is nearly ten years old so I thought it could stand a revisit. When we build our handguns, we consider the following:
1. load pressure range (initial rearward speed of slide)
2. spring tension(s) (forward speed of slide)
3. weight of slide (momentum, recoil and material durability)
Naturally these factors interrelate so what works the best for the greatest number of scenarios?

My aim here is to fully examine the pros and cons of each controllable parameter. The first and most important aspect of accurate shooting for me is recoil and torque yaw. Recoil is both front and back so as your load pressure increases on a gun with balanced action, the rear recoil will increase and the front recoil (barrel drop) will decrease. Many pro shooters lighten their springs in order to eliminate barrel drop, so as to keep their sight on the horizon line but this puts durability demands on the frame and increases back (felt) recoil. Let's discuss the pros and cons of lightening the slide.

Even though a lighter slide will increase the speed of the rearward recoil, the spring will now have less mass and momentum to act upon so the frame does NOT get hit harder by the slide. This is important to aluminum frame builders. Anyone who has seen an elongated plunger hole or other related frame deformity should understand exactly what I mean. Additionally, the lighter slide will reduce the front recoil and improve ejection but may introduce feeding problems. Does anyone here see it different?

Once we all accept this as a postulate we can move on to the reasons why a lighter slide might feel like it recoils more and we'll take a look at what happens to the feeding mechanism with the increased action speed of a lighter slide.
 
Okay, there are nearly 200 views at the time of this post without any challenges so we'll continue the first post topic. We broadly discussed the parameters and effects of changing them, now we'll get into a little more detail.
Perception: I lightened my slide and it feels like it kicks more, is it my imagination?
Explanation: No. It's a misinterpretation of what you're feeling. When you reduce the mass of the slide you are reducing its rearward force but you are also removing mass from the gun which
1. reduces the momentum that slows the reaction of that force and
2. the reduced mass of the gun makes you feel the action more.
Briefly, you are interpreting the increased rise and vibration of the gun after the shot as greater recoil. It isn't.
Perception: Why has the angle of my shell ejections become sharper?
Explanation: A lighter slide will accelerate and decelerate more quickly. This increases the ejection force and at a given point, will cause a failure to eject and also effect the chambering. These issues can be addressed by attending both the compression profile of the spring and the ejection port.
Perception: Why does my gun feel weird?
Explanation: More than likely, this is muscle memory telling you something has changed and you are noting the changes. The longer you have shot a gun with a particular weight and momentum profile, the longer it will take to become accustomed to the new feel but from a physics perspective, a lighter slide has greater potential for accuracy for the reasons discussed in the opening post.

If I haven't ruffled any feathers by now, I'm either talking too much sense for anybody to say otherwise or nobody is paying attention :)
 
Probably both. I don't see that many gunsmith related post but I am sure that many, if not most members here have interest in guns. Keep talking, I'm sure someone will pipe in, any excuse for an argument!
 
It's a shame. I think gun production will be a growing industry for the next score of this century so a practical machinist should get familiar with how the end product functions in order to better know how to make them. By the way, I can do the math and the motion dynamics analysis but I expect to learn a great deal from interacting here.

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I've read, but not really seen anything to comment on - I agree (at least in principle) with most of whats been said. I do think that the individual shooter really needs to tune the spring to themselves (they are part of the shooting system), but that matters little unless you're in a speed sport. As for lighter slides - my perception is _lower recoil_ as the sights certainly lift less for me. (Obviously the actual energy is the same no matter what you do with the gun.)

GsT
 
@GeneT

Agreed but the problem is usually determining what the shooter expects from the build. I think it helps to know ahead of time to zero in on the preferences and my submission helps to do that by explaining and identifying the dynamics. I've often thought about building a special purpose, long range, subsonic handgun with an aluminum slide. The 7075 aluminum slide could handle subsonic loads according to my calculations. To give you an idea of the result, a full frame 1911 would weigh less than 2 lbs. The gun could be used for a special accuracy competition division. The targets would be 100 meters hit with high b.c. rounds. In your opinion, what kind of interest would this spark?
 
The targets would be 100 meters hit with high b.c. rounds. In your opinion, what kind of interest would this spark?

I think it would not get many followers. If you look at the courses of fire that attract the most attention these days, speed is in and precision is out, mostly. An effect of the fictions of the entertainment industry in my opinion. And distances are short so scores can be high.
 
I agree with GGaskill that it would probably have low participation. Not because 'accuracy is out' - I disagree with that statement (precision rifle 'sniper' matches are getting very popular) - but because it's darn hard to hit a target at 100m with a pistol - very, very few can do it with any consistency at all. As such, I think the barrier to entry is too high. Lots of people would probably like to try to hit a target at 100m, but few are going to want to spend an entire day missing them...
 
The targets would be 100 meters hit with high b.c. rounds. In your opinion, what kind of interest would this spark?

Why? An extremely difficult bulls eye pistol event already exists, its called Free Pistol. Its a 50m .22lr event with very minimal rules as to the gun used.
 
The targets would be 100 meters hit with high b.c. rounds. In your opinion, what kind of interest would this spark?

I think it would not get many followers. If you look at the courses of fire that attract the most attention these days, speed is in and precision is out, mostly. An effect of the fictions of the entertainment industry in my opinion. And distances are short so scores can be high.

You can't shoot fast enough to hit. But people stop caring about splitting hairs with a pistol. That's not what pistols are for, outside of specialty guns like @GeneT references. So the slow fire bullseye pistol matches are a weird niche. USPSA and other sports more closely mimic the usage pistols are designed for. The accuracy is still within reasonable reality, and accuracy still counts way more than time does.

While I wouldn't mind seeing the A/B zones shrunk up a bit on the typical IPSC target, in the torso area, it ain't that bad right now.
 
Perception: I lightened my slide and it feels like it kicks more, is it my imagination?
Explanation: No. It's a misinterpretation of what you're feeling. When you reduce the mass of the slide you are reducing its rearward force but you are also removing mass from the gun which
1. reduces the momentum that slows the reaction of that force and
2. the reduced mass of the gun makes you feel the action more.
[/QUOTE]
OK, I am not a gunsmith, but some of what you are saying here sounds wrong from a physics stand-point. But first I will say that the perceived recoil is probably a complex subject, but to the pistol.
1. Reducing the weight of the slide allows for faster acceleration since force = mass * acceleration
2. When the return spring is fully compressed and stops the slide there will be greater force applied to the rest of the frame since energy = mass * velocity^2 (squared)
3. As you stated the lighter gun in total will accelerate more overall
So the impulse from the shot will be stronger but of shorter duration which would result in more recoil. This makes sense if you extrapolate this to lighter and lighter slide weight (theoretically of course since you can't make the slide and frame this light) to where the slide and frame approaches the weight of the bullet where the slide is moving really fast now and not providing any mass damping with all of the recoil energy imparted to the hand just over a larger area that the bullet will impact at the other end.

So it is not just a misinterpretation but an physically verifiable increase in recoil.
 
lanb said:
So it is not just a misinterpretation but an physically verifiable increase in recoil.
Thanks for the thoughtful reply but I think you're not taking sufficient account of the recoil spring. When the slide is lighter, the spring will be able to absorb a greater amount of the energy and it will do it more quickly because there is less mass moving rearward. Taking your example of an infinitely light slide, you should understand the spring tension is fully absorbing the energy and if matched to the load, prevents the slide from hitting the frame. Where the recoil is felt depends on the shooter. My hands are strong so I tend to feel the slide impact on the frame more than the initial burst but I can see how the perception could be reversed. From a physics standpoint, the energy recoil is the same as the load, the only difference is where and when it is absorbed. You have also neglected to account for the greater influence of friction on the lighter moving parts and the proportional increase in the mass of the spring.
 
@netfences,

I apologize if I added to a tangential topic earlier. I appreciate the information you're putting up regarding pistol tuning. I have done some myself, more often at the direction of another person requesting specific changes, than making my own decisions on it, but I haven't weighed in because I don't really consider myself "expert enough" to profess any manner of 'best practice'.

A big part of "felt recoil" actually has to do with acceleration. Not force. (as @netforces discusses) While @lanb is correct regarding the much greater impact of changing velocity compared to changing mass (linear vs exponential) in calculating force, it is only a small factor in felt recoil. Recoil is often 'felt' to be greater when it's sharper. You'll hear people reference the "slow, push" of some pistols versus the "quick, snappy" recoil of others. If you were to measure the actual force involved, I bet you wouldn't find it correlating directly with "felt" recoil. It's the acceleration of the slide pushing the gun back in your hand that does it, I believe (not exactly scientific)

Anyways... the most important thing is to not focus on what /word/ is used by someone, and think more about their intent. The use of the word 'force' is, imo, misapplied in the OP's posts a couple times, but I found it quite clear what was actually intended, and understood just fine.

Additionally, most shooters who are also lightening their slide for better "time back on target" (or eliminating time off target) are also downloading their ammo to the very point the bullet barely leaves the barrel, or the very point they ALMOST lose 'major power factor' in certain rulebooks.

So there are SEVERAL variables at play here, simultaneously.

All the "perceptions" and "explanations" given so far are in-line with my experience in competitive shooting and gunsmithing. It also agrees with the studying I've done on firearm actions and my general understanding of physics. I ain't no rocket surgeon, but I've laid out and solved my share of free body diagrams and designed my share of functioning dynamic mechanical systems.
 
@JNiemen
No apology required in my view. I'm trying to jibe the anecdotes of shooters to my calculations and if I'm wrong, I want to discover where I erred. Unlike others with my education, I don't consider myself infallible :)

I've heard the "slow push" description and completely understand how momentum (weight) adds to that perception and it does make sense that the reduced time lapse of the recoil on the lighter mass will make it feel "snappier" BUT as I stated above, your hand has less mass oscillation acting on it and very little, if any, slide stop jarring. These two factors should make the gun easier to manage and keep on target. I also believe it will be more comfortable to shoot. According to my calculations, the sweet spot seems to be about 230 grams for the slide (without barrel). What is the typical weight of a competition slide?
 








 
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