---
title: CMMG Mk4 platform specifications
description: "Receiver Materials: Upper – Billet 6061-T6 Aluminum Lower – Forged 7075-T6 Aluminum Buffer Tube Material – 7075 Alum. (During high demand we do supplement with 6061 Alum.) Buffer Weight(s): A1 – 5.2oz"
---

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# CMMG Mk4 platform specifications

**Receiver Materials:**

Upper – Billet 6061-T6 Aluminum

Lower – Forged 7075-T6 Aluminum

Buffer Tube Material – 7075 Alum. (During high demand we do supplement with 6061 Alum.)

**Buffer Weight(s):**

A1 – 5.2oz

Carbine – 2.952oz

H – 3.784oz

H2 – 4.6oz

H3 – 5.4oz

**Bolt Carrier Group Materials:**

Bolt – Steel, 9310

Carrier – Steel, 8620

Extractor – Steel, 4140 or 4340

Ejector – Steel, S-7

**Currently available in the following calibers:**

22LR

5.56x45mm (.223)

300 BLK

350 Legend

4.6x30mm

5.7x28mm

6.5 Grendel

6mm ARC

9mm

Virtual Patent Information can be found [here](https://cmmg.com/patents).

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