Slide Lightening: The truth about cutting your slide

Conventional wisdom on the internet says that lighter slides move faster, and return to target more quickly. How much more quickly, if at all, is a matter of considerable debate, which I hope to put to bed with the following experiment.

I began with a stock CZ Shadow 2 slide with a dovetail mounted optic, weighing in at 14.8 oz.

Next, I sent the slide to the excellent folks at Patriot Defense for a trio of cuts to eliminate as much weight as possible. This included direct milling for the optic, milling a hole in the the top of the slide, and milling out most of the dust cover.

The result was a new slide that weighed in at 12oz. flat.

I took measurements at the range both before and after the cuts, shooting the same batch of Freedom Munitions 147grain 9mm. 

Below are a set of measurements taken with a Mantis 10X on the same gun before and after having the slide lightened. From left to right, we have:

• Uncut slide, 11lb recoil spring
• Cut slide, 11lb recoil spring
• Cut slide 8lb recoil spring

Analysis: Now, at first glance, it would appear from the Mantis calculations that lightening the slide and spring actually increased the time it took to get back on target. However, I believe that's not entirely accurate for reasons I'll outline below. I think the most valuable takeaway from these measurements is looking at the character of the muzzle travel. With the 11lb spring measurements, we can see significant nose-diving in all shots taken, and a fairly wide muzzle swing laterally. But in the last set of measurements with the 8lb spring and the cut slide, the movement is far more constrained around the initial point of aim, showing a sharp rise after the trigger is pulled, and a fast return to center. This tracks with my subjective experience with the lighter slide; a sharp, fast dot bounce with a rapid return to point-of-aim. 

How much faster is this travel? Let's look below:

From the slowdown in the above GIF, by counting frames we can see that the cut slide returns to battery 27% faster than the uncut slide when using the same 11lb spring. There's no doubt that the lighter slide is objectively faster.

So, the slide is faster. So what? Will that translate to faster follow up shots? Possibly. But what a lighter slide and lighter spring definitely allow for is the use of my 129pf reloads with greater reliability. See the below GIF for a full demonstration:

As you can see, the lighter slide and lighter spring allow the light loaded ammunition to cycle the action faster than the higher powered ammunition did the uncut slide. So, we keep the advantage of a quick cycle, but also take note of the muzzle rise between the uncut slide with full power ammunition, and the cut slide with reloads and 8lb spring; the angle of rise is significantly lower. The dot bounce on the light slide with reloads is considerably constrained versus the stock. In fact, I was seeing some of my fastest splits I've ever shot during a doubles drill.

Also, take note of the timing between all 4 scenarios. The heavy slide and heavy spring snap back further, and the slide returns to battery before the muzzle dips, then settles back on target. With the light slide, light spring, and my reloads, the slide returns to battery exactly when the muzzle falls back on target. I pick the dot back up where I fired the previous shot.

Conclusion: Having my slide lightened has gone a long way towards tuning my firearms into a repeatable, predictable machine for competition. Because of the effects that lightening the slide, spring, and ammo in conjunction with each other have had, I have considerably more control over my gun. Lightening the slide wasn't the only factor in this change, but it absolutely made the most dramatic difference in terms of my gun's behavior during recoil.

Thanks again to the excellent people at Patriot Defense for their outstanding work milling my slide.