Short answer: with the hammer cocked, slide the safety selector in from the left, drop the small detent into the hole in the grip area pointed end first so it rides on the selector, put the spring in the pistol grip's spring hole, and fit the grip so the spring goes into the receiver hole without binding. Tighten the grip screw snug, not hard, and check that the selector clicks between safe and fire. The pistol grip is what holds both parts in, so take the grip off over a tray.
The steps
- Cock the hammer (with a trigger installed) and slide the selector in from the left side of the lower.
- Drop in the detent. Turn the lower so the grip area faces up and drop the detent into the small hole behind the trigger guard, pointed end first, so the point rides in the selector's grooves.
- Spring in the grip. Put the selector spring in the grip's spring hole. Magpul's MOE-K2 instructions call it the right side top hole.
- Fit the grip. Line the grip up so the spring enters the receiver hole without binding, then thread the grip screw. Magpul says to hand tighten its supplied screw and not to reuse the original screw and lock washer.
- Test. With the rifle unloaded, the selector should click firmly into safe and fire, and on safe the trigger should not release the hammer. See the function check in our lower assembly guide.
How not to lose them
- Remove or install the grip inside a large clear bag or over a tray: the grip is the only thing holding the spring and detent in.
- When you swap grips, Magpul's instructions leave the detent in the receiver and move only the spring.
- Keep a spare. A detent costs a few dollars, and many lower pin and spring kits include both parts (see below).
If the selector binds or feels mushy
- Binds or won't turn: check that the detent's pointed end faces the selector and that the spring is seated straight, not kinked or caught on the edge of the hole.
- No click: the spring may be missing, short or still in the old grip.
- Ambidextrous selectors: use the detent and spring the maker supplies if they include them, as Radian does with its Talon, and follow their alignment notes; Geissele warns the detent and spring must line up. See ambidextrous controls.
Detents, springs and selectors, with today's prices
Lowest price across the stores we track:
Colt AR15A4 fire control selector detent
Pros
- Single replacement selector detent
Cons
- Detent only, no spring
Detent
CMMG AR-15 lower pin and spring kit
Pros
- 17 pins and springs
- Includes selector detent and selector spring
Cons
- No trigger or large parts
Spares kit
KAK Industry LPK pin and detent kit
Pros
- Pins and detents, including the selector detent
Cons
- Check springs separately
Pins and detents
CMMG AR-15 safety selector
Pros
- Standard replacement selector
Cons
- Left-side lever only
Selector
Radian Talon ambidextrous safety selector
Pros
- Ambidextrous
- Radian supplies its own detent and spring
Cons
- Follow Radian's install notes
Ambi selector
See the full lower parts kit guide, compare lower parts, or plan a build in the AR-15 builder.
Frequently asked questions
Which way does the AR-15 safety detent go?
Pointed end first into the hole, so the point rides on the selector. The flat end sits on the spring.
Where does the safety detent spring go?
In the pistol grip's spring hole; the grip pushes it up into the receiver against the detent.
Why won't my safety selector turn after installing the grip?
Usually the spring isn't seated straight or the detent is upside down. Remove the grip over a tray and reseat both.
Do I need to remove the detent to change grips?
No. Magpul's instructions leave the detent in the receiver and move only the spring.
Are AR-15 safety detents and springs universal?
Standard mil-spec parts are interchangeable, but some ambidextrous selectors ship with their own detent and spring; use the ones supplied.
