Opinions vary on how much if at all you should modify your carry gun. The modifications fall into a couple of different categories.
First, cosmetic/esthetic modifications. Think of taking that boring, black, utilitarian, pistol, and customizing it with a Cerekote paint job, or color-filled slide. Or perhaps you just want to change out the color on your grip panels? These are not truly modifications in the sense that they do not modify how the gun functions or is used. They do not offer any sort of advantage, other than changing how the gun looks.
Certain cosmetic modifications could have a potential downside. Decking your every day carry (EDC) gun out with grim reaper imaging, vulgar slogans, or the like is completely legal. However, if there is any doubt as to your motivation leading up to a self-defense use of force, death imagery is not a good look. To be clear, your justified use of force is not likely to turn into a conviction based solely on punisher skull handgrips, but it is better not to have to address them in the first place.
The second modifications are those that modify or replace a component(s) of the gun for some perceived tangible benefit. These modifications are typically the subject of debate amongst self-defense gun carriers. Should you or should you mess with the manufacturer's secret sauce? The debate revolves around questions like:
-do modifications void a warranty
-expose me to potential legal issues
-does this modification help
These are all considerations you should weigh before modifying a gun you are going to carry for self-defense. Not all modifications are created equal though.
Some mods may give you an advantage, but along with it a big downside. A modification that comes to mind is greatly reducing the trigger’s pull weight. Super light trigger mods typically are not recommended for defensive use for a couple of reasons. Arguably Uber-light triggers have the potential for unintended shots to be fired. Equally concerning are the reliability issues that can develop if it is not done right.
That is not to say working the internals so that the trigger travels smoothly and breaks crisply is a bad idea. Often time this can be done without any major modifications and without reducing the trigger pull. Before jumping into trigger modifications, it is best to do research. It does not take much for your basement trigger job to make your gun unsafe.
If you are on a budget, it is prudent to look at the return on investment that said modification may provide. In the above example, you may be able to make the trigger feel and perform better for 20 or thirty dollars, which seems reasonable. But if you are a new shooter, before you drop $250 into all new internals and a trigged upgrade, spend the money on ammunition and a good training class. Better you learn how to be a good shooter with a stock gun and trigger than a sloppy shooter with a tricked-out gun.
And since you stuck around, here is the best modification you can make. It comes with nearly all upside and no drawbacks. Other than the fact you must spend some money.
For your EDC, you need good defensive gun sights. Guns like the Springfield Hellcat, the Sig P365, and Glock 43X all are coming with decent sights straight from the factory. Even Glock, who had notoriously lousy stock sights, are stepping up their game. So, what makes a good self-defense sight? Glad you asked.
You can look for different attributes in various sights on the market based on what your eyes respond best to. The number one key component would be a high contrast front sight. Something bright, be it fiber optic, tritium infused, or just brightly colored allows you to use a flash sight picture as well as pick up the front sight when more precision is necessary. I prefer a subdued or blacked-out rear sight without any dots or lines. For most applications, markings on the rear sight are unnecessary and can compete with the front sight for your eyes' attention.
A good set of self-defense sights like those from companies like Night Fission, XS Sights, TruGlo, etc. will round around a hundred bucks but are so with it.
While we are talking about the benefits of self-defense sights, a rear sight that has a flat face is ideal. This makes one-handed slide manipulation easier than one with a sloping face.
As a bonus, if you have not yet purchased your everyday carry gun, look for one that comes factory cut for an optic. Even if you have not jumped on the EDC 'carry optic' train, it’s the way of the future for defensive guns. Especially for aging eyes, the benefits of red-dot sights are becoming harder to ignore.