Ditch the Toothbrush: CAT M4 Tool Scrapes Carbon in Seconds
Ditch the Toothbrush: CAT M4 Tool Scrapes Carbon in Seconds
The Aero Precision M4E1 Upper Receiver has cult-like status among AR builders for good reason. Here’s our hands-on review — what it nails, where it cuts corners, and whether it’s worth the price.
Every AR build starts with the lower. These are the billet, forged, and polymer strippeds worth starting a build on — plus the ones we’d avoid even at their discount price.
From 5.56 general-purpose builds to .300 Blackout CQB and 9mm PCC uppers, a quality complete upper is the fastest way to add a new caliber or build a second rifle. Here are the nine we trust.
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