If you are looking for the full length handguard, you will need this.
https://www.eurooptic.com/DT-SRS-PK-027-SBK-A1-Desert-Tech-DT-SRS-Upgrade-KIT-from-Cov.aspx
You can contact a dealer to see if they can order one from Desert Tech but its expensive, probably discontinued, and wont match the patina you have on your gun already. You may want to ask if someone on the forum wants to swap you handguards, your Covert for their full size A1 handguard.
If the concern is about getting the rifle centered over the tripod, all you need is the RRS Desert Tech Plate. This is all I use and its perfect sitting on a tripod.
https://www.reallyrightstuff.com/BSRS-A1-Desert-Tech-Forearm-Mount
The center/balance point of the rifle is right about where your thumb is in the above picture, right in front of the trigger guard with a typical factory barrel.
Here’s mine:
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