Grenade Parts Guide (Full)

This guide covers all grenade parts in-depth, and assumes you have read the base guide here, as well as the general formulas guide here.
Firstly, let's re-define the values from the base guide, properly sorting them into their exact bonus type, and note down extra unique parts not mentioned in the base guide.

Material

As mentioned in the basic guide, the only materials with stat bonuses are the Torgue ones, which provide +2 child count grades.
The Anemone DLC added exact copies of all base materials, with the exact same stat bonuses.

Blast Radius

The blast radius parts have grades ranging from -1 to +2.
The base blast radius is 580, and each grade adds a further 120.
The Anemone DLC added exact copies of all blast radius parts, with the exact same stat bonuses.

Child Count

The child count parts' grades corrolate directly to the amount of extra child grenades. The parts have grades ranging from 0 to +6, and add from 0 to 6 extra child grenades.
The base child grenade count is 0, and each grade adds +1.
The Anemone DLC added exact copies of all child count parts, with the exact same stat bonuses.

Delivery

Ignoring how the grenade is actually thrown, standard deliveries only affect the fuse time's grade and scale. Unique deliveries mostly only affect damage and blast radius.
A full list of deliveries and their stats is available here.

Trigger

The trigger parts have grades ranging from -1 to +4.
The base fuse time is 0.6s, and each grade increases it by 0.6.
The Anemone DLC added exact copies of all trigger parts, with the exact same stat bonuses.


None of the following parts have models, and thus can only be told apart by calculation or checking in a save editor.

Accessory

The accessories define both the element of the grenade and the (unlisted) status chance modifier. This chance is per hit, so grenades that hit multiple times like teslas are much more likly to apply a DoT.
Each element has five accessories at different grades, and there's also an additional accessory for explosive.
The Anemone DLC added exact copies of all accessories, with the exact same stat bonuses.
The Monster Trap has the only other unique accessory. It provides no stat bonuses, and is actually non-elemental, depite being displayed as explosive on the card.
The first grade of an accessory just enables that element, all others provide the following Status Chance Modifier bonuses:
FireShock CorrosiveSlagCryo
+13% +13% +11.5% +15% +10%
As there are no explosive DoTs, there is only one grade of explosive accessory, which has no bonus status chance modifier.
Both the Status Chance Base and the Status Chance Modifier are 1 by default.

Damage

There are eight possible damage parts, with grades from 0 to +7. These parts add +0.03 bonus damage.
The seraph grenades all use their own damage parts. These parts have the exact same stats as standard ones of the same grade, they just don't overwrite the rarity.
Similarly, the Anemone DLC also added exact copies of all damage parts, with the exact same stat bonuses.
The base damage, before any bonuses are added, is equal to exactly 100×β.

Payload

The payload controls what exactly happens when the grenade explodes. It also provides some stat bonuses.
There are six standard payloads:
Area Effect, Bouncing Betty, MIRV, Singularity, Standard, and Transfusion
In the Pre Sequel there is an additional version of each of these payloads that can shatter air masks, but otherwise share all the same stats as their base versions. There are also several unique payloads in both games.
Payloads are also what's used to enable child grenades, even with several bonuses no child grenades will spawn if the payload is incorrect. All payloads with a child grenade count value enable them, even if that value is 0.
A full list of payloads and their stats is available here

Status Effect Damage

There are six possible status effect damage parts, with grades from 0 to +5. These parts affect all elements except slag and explosive.
The base status effect damage is always equal to exactly 200×β.
Each grade adds a set percentage of the base status effect damage, based on element:
FireShock CorrosiveCryo
+5% +7% +6% +5%
The Anemone DLC added exact copies of all status effect damage parts, with the exact same stat bonuses.

Grenade Definition

Also known as "Type" in gibbed.
The grenade definition can be thought of as a prototype for each grenade. It not only defines the parts each grenade can use, but also the base stats, and how different grades affect them.
So far everything on this page has come from the "Standard" definiton, which all non-unique grenades use. Generally a lot of the stats are the same across definitions, so these numbers are usually correct, but some are overwritten in unique definition.
A full list of definitions and their stats is available here