phone: 888-310-0284

Glock® 21 Compatible RMR Cut Slide - .45 ACP

Usually ships the same day or the next business day!

Gen 3 compatible. RMR optic-cut. Ready for your PF45 build.

Completing a Polymer80 frame? Ready to upgrade your Gen 3 GLOCK® 21 and throw a red dot on it? This Glock® 21-Compatible, RMR-cut slide is the ticket. It's cut from 416R stainless, heat-treated and coated in a matte black powdercoat finish, and features front and rear serrations with dovetail iron sight and red dot cuts.

Pair with Holosun's popular 407 or 507 series, or any other RMR-compatible red dot.

Glock® 21 Compatible RMR Slide Specs

  • Forged from 416R stainless
  • Heat treated to RC 38-42
  • Internal dimensions meet Gen 3 OEM specs
  • Works with Glock®, Polymer80, and SS80 frames
  • Chambered for .45 ACP


DISCLAIMER: “GLOCK” is a federally registered trademark of GLOCK, Inc. and is one of many trademarks owned by GLOCK, Inc. and GLOCK Ges.m.b.H. Neither Gun Builders Depot, a/k/a nor this site are affiliated in any manner with, or otherwise endorsed by, GLOCK, Inc. or GLOCK Ges.m.b.H. The use of “GLOCK” on this page is merely to advertise the sale of GLOCK pistols, parts, or components. For additional genuine GLOCK, Inc. and GLOCK Ges.m.b.H products and parts visit

WARNING: Handling firearms parts and accessories can expose you to lead and other petroleum products known to the State of California to cause cancer and reproductive harm. For more information go to:

Shipping Restrictions

Shipping of various parts and/or accessories are prohibited to states and locales (ie New Jersey, California, New York, etc…) with restrictions against certain parts and/or accessories or "assault weapons" (i.e. states with high-capacity magazine restrictions, manufacturing of semi-automatic weapons, etc..). It is your responsibility to be aware of your local firearms laws before purchasing from our website or machining a firearm. We try our best to keep our shipping page current, but laws change daily. only ships within the United States. Federal legislation dictates we cannot ship our products internationally.


We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, Hawaii, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.