A lot of terms are thrown around when it comes to the .308 world that you ordinarily wouldn’t come across when building a standard mil-spec AR-15. This short article should help you identify some of the characteristics of your .308 upper receiver so you can tell what accessories will be compatible.
Identifying whether your upper is high or low profile:
High profile uppers had a short run when they were in vogue, and now most manufacturers churn out uppers that are low profile by default with a few high profiles here and there. If you have an existing .308 rifle or upper then the following measurements should help. You’ll need a set of calipers, or a ruler.
- If the upper is installed on a rifle, remove the pivot and takedown pins and separate it from the lower receiver. Remove the charging handle and BCG.
- At the tang end of the upper, measure the height of the part that extends from the top rail and sits over the charging handle. In this case you are measuring from the top of the rain extension to the bottom edge that sits on top of the charging handle.
- For Low Profile Uppers this piece should measure 1/8 of an inch (0.150″)
- For High Profile Uppers this piece should measure 3/16 of an inch (0.210″)
Identifying whether you have a DPMS or Armalite patterned upper:
DPMS patterned uppers make up the lion share of what our customers run, but we have run into the occasional Armalite upper. We normally don’t carry parts for the Armalites and have found out that even the standard takedown pins on some models don’t fit. In cases like those, we’ve advised those customers to check their rifle/upper manufacturer for compatible parts and accessories.
Identifying what pattern your upper receiver is pretty straightforward with this one and doesn’t require any special tools or instruments.
- DPMS .308 patterned upper receivers have a rear rounded bottom edge
- Armalite AR-10 patterned uppers have an angled, rear bottom edge
Check our some of our .308 accessories, including DPMS low and high patterned handguards from the link below: