---
title: "Get a caliber ballistic profile"
method: GET
path: "/v1/calibers/ballistics"
tags: ["Calibers"]
---

# Get a caliber ballistic profile

`GET /v1/calibers/ballistics`

## Request

- Base URL: `https://api.gunspec.io`
- URL: `https://api.gunspec.io/v1/calibers/ballistics`
- Auth: one of:
  - API key in header `X-API-Key`
  - HTTP bearer

Returns the ballistic profile for a cartridge out to a chosen distance, using its typical load.

**Requires Builder tier or higher.**

## Query parameters

- `id` string, required
- `distance` integer

## Headers

- `If-None-Match` string

## Response `200`

Get a caliber ballistic profile

- object
  - `success` boolean, required: Always true on a successful response. Every error carries `false` and an `error` object instead.
  - `data` object, required: The response payload.
    - `caliber` object: The cartridge the profile was computed for.
      - `id` string: Slug of the cartridge.
      - `name` string: Display name, as the maker writes it.
    - `distanceM` integer: The distance the figures below are quoted at, echoing the `distance` parameter.
    - `muzzleVelocityMps` number, nullable: Muzzle velocity in metres per second, for the default load.
    - `muzzleEnergyJ` number, nullable: Muzzle energy in joules, for the default load.
    - `velocityAtDistanceMps` number, nullable: Remaining velocity at `distanceM`, in metres per second.
    - `energyAtDistanceJ` number, nullable: Remaining energy at `distanceM`, in joules.
    - `timeOfFlightS` number, nullable: Time of flight to `distanceM`, in seconds.
    - `bulletDropCm` number, nullable: Bullet drop below the line of sight at `distanceM`, in centimetres.

## Other responses

- `304`: Your copy is current. No body is sent, and this response does not count toward the daily request allowance.
- `400`: Validation error
- `401`: Missing or invalid API key
- `403`: The credential is valid and the caller is not permitted. Three causes, none of which reissuing a key changes: the plan is below the endpoint's tier, the account is suspended, or the key is not attached to the thing being acted on, meaning a user account for `/v1/me` or a shop for `/v1/vendor`. Distinct from 401, which means the credential is missing, malformed or expired and a new one can work.
- `404`: Resource not found
- `429`: A limit was reached. `RATE_LIMITED` is the per-minute limit: wait `Retry-After` seconds (a minute) and retry. `DAILY_CAP_EXCEEDED` is the plan's daily limit, per key: nothing will be served until the counters return to zero at midnight UTC. `MONTHLY_CAP_EXCEEDED` is the plan's monthly allowance, for the whole account: nothing will be served until midnight UTC on the first of next month, or until the plan changes. For both, `Retry-After` is the seconds until then and `error.resetsAt` says when as an instant. Calls made after a refusal are refused too and do not spend the month, and a free key that keeps calling is paused, so stop at the first one and resume at the reset.
- `500`: Internal server error

---

[API](https://skmtc.dev/gunspec/apis/gunspec-io-api.md) · [All operations](https://skmtc.dev/gunspec/apis/gunspec-io-api/llms.txt) · [OpenAPI document](https://skmtc.dev/gunspec/apis/gunspec-io-api/revisions/f2e974d8b05c?raw)