There's a few reasons you would want to modify your handgun, but ultimately they boil down to look and function.
There's an idea some buy into that modifying your firearm cosmetically will help protect you legally. Some say having your firearm personalized will aid in identifying both if it was stolen, or if you are being accused of brandishing your firearm. The other side of that, some CCW instructors will say, customizing your gun could work against you in the court of law. It could be argued that you had more intent to use it if it was all decked out. Again, these are just two sides of this argument I have personally heard, I don't necessarily believe in either.
Many firearm owners will have their guns cerakoted (It's a painting process), or plated. There's also more affordable options (or if you have commitment issues), such as wrap around grips, or "skins". A lot of California gun owners change out the load indicator on top of the slide, for no other reason than, it looks stupid and reminds them of tyranny.
Some other fun options for visual upgrades to your firearm include back plates, slide engraving, and grips.
Some of these cosmetic upgrades actually double into functional upgrades. Upgrading your grips for instance, you can change colors, which have no affect on functionality, but you can also change the texture. Changing the texture can greatly improve your grip, which ultimately improves your accuracy. You can change the width of the grips, which may be useful for those with grip issues or arthritis. You can get your gun hand or laser stippled with different textures, or even modify the frame of your gun to fit your hands better. It is important to note that many firearm manufacture's warranty's will be voided with and type of frame work. If you don't have the budget, or courage for permeant frame modifications, look into wrap around grips, slide on grips.
Changing the trigger can be either cosmetic or functional or both. Aftermarket triggers can come in all sorts of colors and patterns. Changing out the trigger, especially when working with Glocks (which have a pretty big space between the backstrap and trigger face), or full size firearms (I'm thinking of my TRP) will allow for an easier and more accurate trigger press. You can get a trigger that will sit further back, has a lighter pull (great for physical disabilities), or shaped different (curved, rounded, flat face, etc.). Modifying your trigger can help tremendously with your accuracy, remember that aim doesn't matter if you're not able to have a smooth, consistent trigger press.
Sights. So much can be said about modifying your sights, there's iron sights, fiber optic sights, night sights, red dot sights (RDS). Depending on your budget, there's lots of options out there. I think the most important thing to consider about modifying the sights on your firearm is this, if you can safely and accurately use iron sights, a RDS will not help you be a better gun fighter. I recommend to all my student to at least invest in night sights. These are more expensive than fiber optic sights, but less that RDS (depending on what you get of course). What are you primarily using your firearm for? This will help determine which type of sights you should invest in. Train, train, train with whatever sights you have, and if you decide to modify them.
Magazines, while technically not the firearm, I think many do not realize they can modify their magazines. Speaking to my CA friends, understand the law, understand that we are not allowed buy or sell magazines with more than 10 rounds, but it is perfectly legal to own and use them. That being said, many magazines are compatible with +2 or +5 base plates which will add to the round count you're carrying. You can also add weights, pinky grips, or extensions without extra rounds which will all be useful helping with reloads, clearing malfunctions and grip.
Slides and barrels, the industry is saturated in upgrades and modified slides and barrels. Whether for looks (um, hello oil slick slide and gold tin barrels!), or for function (cut out slides help reduce the overall weight of the firearm, bullnose barrels are arguably more accurate and durable), Depending on your budget and needs, there is most definitely something out there you'll find yourself needing, or wanting.
I get a lot of questions about what can be done to help make racking slides easier, and it is not as simple as just replacing springs. Please understand that firearms are precisely engineered tools, and replacing one spring will adjust the tension and pressure on the other springs in a way that could cause malfunctions or even catastrophic failure. That being said, certain firearms have more difficult to rack slides than others (I'm looking at you M&P Shield). There's a few options, train around it (learn how to rack the slide gripping it differently, work on your grip strength), or there's a nifty little grip you can add to the back of the slide for most makes and models.
For my lefty's, Glocks tend to be the firearm of choice, because of the ability to switch out parts making the mag catch on the right side and using an ambidextrous slide stop.
These are just some of the almost unlimited ways you can modify your gun. It is up to you to know and understand your local laws, and use your best judgement when modifying your firearm. It is easy to fall down the rabbit hole and dump a ton of money into "upgrades". I say always choose functionality over looks, never modify your firearm in a way that would make it unsafe or more difficult for you to use.
When you're using your gun, what do you wish was different, or easier? This industry has so many useful tools and gadgets, there's probably something out there that would help you. Always do your research, read real reviews (not paid), ask instructors and other shooters. I have boxes and boxes of stuff that I bought that I never use, or used a few times. I have stuff that was so expensive that I hated or didn't work for me and I have some cheap stuff that is holding up great after hundreds of thousands of rounds.
Finally, it's important to realize many issues are actually the shooter and not the gun (ouch, sorry not sorry). It's better to train out bad habits than to modify your firearm to accommodate them (you probably don't need a thumb rest, you need work on your grip....).
Have you modified any of your guns? Have you found any helpful upgrades that have improved your shooting? Let's hear about them in the comments!
Thanks for reading, until next time, train hard, stay safe!
Mama Bear Defense, Solano County, CA