A tailcap works. A remote switch earns its place when it keeps your grip, frees the light to move, or
runs more than one accessory. Here is how to decide.
Where you put a light on your rifle comes down to three things: where your support hand naturally sits, where the light itself provides maximum performance, and whether you can reach the switch without changing your grip. Get those three right and the light disappears into how you already run the gun. Modlite's modular bodies, heads, tailcaps, and switches let you set that up the same way on every rifle you own.
Jump to a section in the video: 0:16 What ergonomics means · 0:36 Why modularity matters · 1:23 Principle 1: support hand · 1:47 Principle 2: light placement · 2:28 Principle 3: activation · 3:33 Build 1: subgun · 4:40 Build 2: HOG on a short rifle · 5:34 Build 3: 16 inch rifle · 6:43 Things to remember
Why does ergonomics matter for a rifle light?
Ergonomics is the study of how efficiently people work in their environment. On a rifle, that translates to comfort. When holding and running the gun is comfortable, your attention goes to the skill you are practicing. When something is in the wrong spot, your attention goes to the thing in the wrong spot. A light you have to hunt for with your thumb is a light you will not be able to use efficiently under stress.
That is where modularity earns its keep. Because every Modlite® light is built from separate bodies, heads, tailcaps, mounts, and switches, you can put each piece exactly where your hand wants it, then repeat that setup on the next rifle so nothing has to be relearned. The video puts it plainly:
"With Modlite, you can completely tailor accessories to fit your preference and comfort level on any rifle."
Principle 1: start with your support hand
Before you mount anything, find where your support hand naturally lands. That spot moves from gun to gun: a short handguard on a subgun puts your hand in a different place than a 15-inch rail on a 16-inch rifle, and caliber and recoil change how hard you drive the gun. Once you know the spot, everything else gets placed to support it, not to fight it.
The test is simple. Mount the light, take your normal grip, and check whether you had to move your hand to make room. If the light changed your grip, the light is in the wrong place, no matter how good it looks.
Principle 2: put the light where it works for you
There is no single correct position. Different people prioritize different things, and the video lays out the two most common trade-offs. Some users push the light as far forward as the rail allows to reduce suppressor shadow, the dark wedge a suppressor throws into the beam when the light sits behind it. Others pull the light back, tight against the handguard and any laser, to cut down on snag hazards around gear, slings, and vehicle doors.
One consideration that rarely comes up: which side. The video describes a benefit of mounting on the left side of the rifle. During the shooter's transition to a pistol or when slinging the gun after a string of fire, the suppressor is hot, and a left-side light puts a buffer between that suppressor and his body. Not a rule, but worth knowing.
Principle 3: make the switch easy to reach and easy to use
Whether you run a tailcap, a remote switch like the ModButton™ Lite, or both, the activation method has to live where your thumb already is. If you shoot with your thumb over the top of the handguard, the switch belongs on top of the handguard. The video shows a compact rifle with a tailcap and a laser remote sitting side by side right under the thumb, so both are reachable day or night without shifting the grip.
Then decide what kind of activation you need. Momentary for quick checks, constant-on for working a position where your support hand may have to leave the gun, or both. Simplicity and weight savings are valid priorities too. A tailcap alone is the lightest, simplest setup; a remote switch adds reach; running both gives you redundancy.
Three real builds, one set of principles
The video walks through three personal rifles set up with the same logic. The details differ because the guns differ; the principles do not.
| Rifle | Light | Placement | Switching | Why |
|---|---|---|---|---|
| Subgun (matches, plinking) | Standard head, OKW | Left side, pushed forward | ModButton Lite on top plus GASCAP tailcap as backup | No suppressor shadow; redundant switching for barricades and prone |
| Short-barrel rifle | HOG on a 21700 body | Forward | ModButton Lite plus GASCAP | 169,000 candela for 150 to 200 yard targets at night; 21700 battery life in the cold |
| 16-inch rifle (tripod, bag, prone) | HOG | Mounted far back | Unity Axon SL (momentary and constant) | Switch reachable from any supported position; 169,000 candela makes shadow irrelevant |
Build 1: the subgun
Light on the left of the handguard and kicked forward. A ModButton Lite sits on top of the rail on a Driven Arms Co. Angler so the thumb pushes forward instead of straight down. A Unity® GASCAP™ tailcap is the fail safe: if the remote goes down, the big GASCAP™ button still gives momentary and constant activation. Constant-on matters when the support hand has to leave the gun to brace on a barricade or in prone, or if you might need to hold down the activation for an extended period of time. The video makes the case for forward placement in one line:
"I have this light that's capable of 69,000 candela and I'd rather have all of that going down range than some of it or a lot of it in some cases be blocked by my suppressor."
The current OKW™v2 head puts 95,000 candela on a standard body, so the same argument holds with more light behind it.
Build 2: a HOG on a small rifle
A big light on a short gun looks odd until you hear the reason: output. The HOG delivers 169,000 candela and runs on a 21700 battery, which means more runtime, especially in cold weather where cells sag. For night matches with targets at 150 to 200 yards, that combination is the difference between seeing the target and guessing. Same forward placement, same redundant switching: ModButton™ Lite and Angler on top, GASCAP™ for constant-on when prone.
Build 3: the 16-inch rifle
This one is built for positions other than standing: tripod, bag, support, prone. The HOG is there to push 5.56 out to 600 yards day or night through the optic. The switch is a Unity® Axon™ SL for both momentary and constant activation, and it is mounted well back on the rail so the thumb can reach it from any supported position without climbing over the gun. Suppressor shadow drops down the priority list here because at 169,000 candela in the center of the beam, the shadow is not visible at any distance this rifle would be used at night.
How to test your setup without going to the range
The video's closing advice is the part most people skip. Mount the light, then experiment: different positions on the rail, different sides, tailcap versus remote. You do not need a range, and you do not need darkness. Dry fire at home, take your grip, hit the switch, change positions, hit it again. If you have to think about where the switch is, move it. Once it is right, copy the layout to your other rifles; the modular system is what makes that possible.
Key takeaways
- Find your natural support hand position first, then place the light so it does not change that grip.
- Push the light forward to reduce suppressor shadow, or pull it back to reduce snags. Both are valid; pick the one that matches how you use the rifle.
- The switch, tailcap or remote, goes where your thumb already is. Running both gives redundancy.
- Bigger heads earn their place through output: the HOG delivers 169,000 candela on a 21700 body, which is why it shows up on short rifles too.
- Test in dry fire at home. If you have to think about the switch, move it.
Frequently asked questions
Should a rifle light go on the left or right side?
Either works. The video notes one benefit of the left side: during a pistol transition or when slinging the rifle after firing, a left-side light keeps a buffer between a hot suppressor and your body. Put it on whichever side keeps your support hand grip unchanged.
Should I mount the light forward or back on the handguard?
Forward reduces suppressor shadow and puts the most light downrange. Back reduces snag hazards and can bring the switch closer to your hand in supported positions. On a very high-candela head like the HOG, shadow matters less, so placement can follow reach instead.
Tailcap or remote switch?
A clicky tailcap is the simplest and lightest option. A remote switch like the ModButton Lite puts activation wherever your thumb sits. Running both, as in the builds in the video, means a backup if one fails and a constant-on option when your hand has to leave the gun.
What is suppressor shadow?
The dark wedge a suppressor throws into the beam when the light sits behind it. Pushing the light forward on the rail reduces it. Heads with very high candela, like the 169,000 candela HOG, overpower it at practical distances.
Why put a HOG on a short rifle?
Output and runtime. The HOG produces 169,000 candela and runs on a 21700 battery, so it reaches targets at 150 to 200 yards at night and holds up in cold weather. The size is the price of that performance.
Start with the switch
If your rifle light is not getting used, the switch is usually the reason. A ModButton Lite on top of the handguard, right where your thumb lives, fixes that on most rifles for the price of a mount. Pair it with a mount that lets you slide the light forward or back until the grip feels untouched.
Source video published by Modlite Systems, April 2025. Last updated October 1, 2026. The video shows the previous-generation OKW head at 69,000 candela; the current OKWv2 produces 95,000 candela on standard heads. HOG specs are unchanged.