It sometimes is kind of enraging to see that your newly bought Handuard doesn't fit the barrel you intened. That's why I made a simple, but kind of crowded table to see, wich combinations are possible.
M4:
HK416:
Similar is going to be done for other guns as well
Source: https://www.reddit.com/r/EscapefromTarkov/comments/ewq3ca/modding_table_m4_handguardsbarrelsblocks/