As today community update in COD Mobile reddit, there's a new info about the free version HBRa3 that will come out in next month.
If you read the community update until you reach the HBRa3 Availability, you will see the dev letter regarding the HBRa3.
According to the dev letter, we will be able to get the HBRa3 in next month which is the next season 7, there are no info on how you can get it yet.
Our speculation is that the HBRa3 will availble for you to get by some type of grind, like how you grind for the Cordite smg. or by purchasing in the credit store.
Update: The HBRa3 maybe availble in the form of seasonal event rewards, rank mode reward, or general reward in the next season, officially confirmed by Latest COD Mobile Reddit community update.
HBRa3 Skin version: Dragon Dance Skin
If you don't know, the HBRa3 is the most fan requested gun since season 4 currently there is only the skin version and the free one finally come out.
HBRa3 Free version: (Edited)
The HBRa3 is one of the best gun to use in current season with high damage, fast fire rate, and low recoil, which is really good to use in any range.
As current season 6, we've get 4 free version guns such as:
Thanks to the Call of Duty Mobile Devs Team that provide the fun grind for us during these tough times.
Conclusion
In Short, The HBRa3 is officially confirmed that the gun will come out in next month which is when the season 7 coming out as well.