Description
This is the finishing touch a lot of AR builds are missing. The Yankee Hill Machine 7/8" Forearm End Cap threads right into the front of a compatible YHM free float handguard, closing off that open gap around the barrel so debris, dust, and range grit stay out of your rail. It's machined from aluminum with a black finish that blends in with your existing YHM setup, and at just over a half ounce it won't add any noticeable weight up front.
The cap is sized with a 15/16" (0.925") inside diameter, which means it's built for standard-profile barrels. If you're running a heavier 0.936" barrel, that's a different model, so it's worth double-checking your barrel before ordering. It also does not fit YHM's S.L.R. series of handguards, so this one is meant for the traditional YHM free float tubes and quad rails.
Why the YHM Forearm End Cap Earns Its Spot
Beyond looks, there's a real function here. The end cap is drilled to allow proper heat venting, so it caps off the handguard without trapping heat around the barrel, and it's designed so it does not interfere with the free-floating of your barrel. Folks who've run these say it dresses up the front end nicely and gives an open-ended rail that clean, professional finished appearance.
Installing Your YHM 7/8" End Cap
This is a screw-in design that goes on during handguard installation, and it comes with blue-grade thread locker to keep it seated. One thing worth knowing up front: the retaining plug screws that lock the cap in place are sold separately, so grab a set of YHM end cap screws if your handguard needs them. Once it's on, it stays put and rounds out the whole build.
Key Specifications
- Manufacturer: Yankee Hill Machine
- Manufacturer Part Number: YHM-9484-A
- UPC: 816701013030
- Material: Aluminum
- Color: Black
- Inside Diameter: 15/16" (0.925")
- Barrel Fit: Standard .925" barrels
- Weight: 0.608 oz
- Length: 4.35"
- Installation: Screw-in, includes blue-grade thread locker
- Compatibility: YHM free float handguards; does not fit S.L.R. series
What’s Included
- Yankee Hill Machine 7/8" forearm end cap (aluminum, black)
- Blue-grade thread locker
Frequently Asked Questions
What barrel size does the YHM 7/8" forearm end cap fit?
This end cap has a 15/16" (0.925") inside diameter, so it's made for standard-profile barrels. If you're running a heavier 0.936" barrel, you'll want the 9484-B model instead. Measure your barrel at the point where the cap sits before ordering to be sure.
Does the forearm end cap fit all YHM handguards?
It fits YHM's standard free float tubes and quad rails that are designed to accept their end caps. It does not fit the S.L.R. series of handguards. If you're not sure which rail you have, check your model number against YHM's listings before buying.
Does the end cap come with the screws to lock it in place?
The cap threads in and includes blue-grade thread locker, but the retaining plug screws that fully secure it are sold separately. A lot of builders pick up a set of YHM end cap screws alongside the cap so they have everything for the install. It's a small part but worth grabbing at the same time.
Will the end cap affect my free-floated barrel?
No. The cap is designed so it does not touch or interfere with the free-floating of your barrel. It's also drilled for heat venting, so it caps off the handguard cleanly without trapping heat up front.




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