Below insertion of deltoid (DC 5122)
This diagnostic code covers amputation or complete loss of use of your arm below where the deltoid muscle attaches (basically below your shoulder muscle). The VA doesn't assign variable percentage ratings for this condition - instead, you get a fixed rating based on exactly where the amputation occurred or where you lost function. You'll need to look at the specific amputation rating table in 38 CFR § 4.71a to find your exact percentage, which will be quite high since this affects most of your arm.
Disclaimer: This tool is for informational purposes only and is not legal or medical advice. Always consult with your VSO representative or a qualified veterans benefits attorney for guidance on your specific claim.