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Crossbow nock types explained: half-moon, flat, capture, Omni and Alpha

The nock is the safety-critical end of a crossbow bolt, and fitting the wrong type is one of the most common causes of a dry-fire.

Half-moon and flat nocks

A half-moon nock has a grooved, curved base that cradles the string, and it has to be indexed so the groove lines up with the string for each shot. A flat nock has a flat base and simply sits against the string.

These two are not swaps for each other. Excalibur crossbows are recurve bows and use a flat nock, so on those you use flat. On a bow designed for a half-moon, fitting a flat nock can let the string ride over the bolt, and on a half-moon bow you must index the nock correctly every time.

Capture and brand-specific nocks

A capture nock, used by Barnett among others, wraps around the string so it holds position without the shooter having to index a groove. It is designed for the way those bows load and fire.

TenPoint uses the Omni-Nock, which has multiple grooves so it can be loaded in more orientations, and the Alpha-Nock on many current models. Ravin uses its own clip-on nock that snaps onto the string for its cam system. Each of these is matched to its bow and is not a generic part.

Why interchangeability is a safety issue

The nock controls whether the string stays behind the bolt and drives it forward. If the wrong nock lets the string slip past or off the bolt, the bow releases its full energy with nothing to push, which is a dry-fire.

A dry-fire can crack limbs, break the string and cams, and injure the shooter. That is why nock type is not a matter of preference: it has to match what the crossbow was designed to use.

Matching the nock to your bow

Start from the crossbow maker's spec, which names the nock type for your model. If you are replacing bolts, buy ones that already carry the correct nock, or the correct replacement nocks for your existing shafts.

Micro-diameter systems from Ravin and TenPoint use their own nocks on their own shafts, so on those bows you cannot fit a standard half-moon or flat nock at all. Follow the maker's arrow and nock list for the model.

Related

Sources: TenPoint · Barnett · Excalibur