- 1 - M1A/M14 5/8-24 thread adapter Installation Instructions Table of contents Table of contents... 1 About the operators manual... 2 Adapter description... 3 Kit contents... 3 Technical specifications... 3 Barrel geometry considerations... 3 Installation on barrel... 4 Frequently asked questions... 6 Contact Information... 6
- 2 - About the operators manual This manual is organized into four main sections: 1. Description of the M1A muzzle thread adapter This section explains the function and features of the adapter. In addition, this section covers the proper use and maintenance of the adapter. 2. Installation and mounting This section covers the proper installation and mounting of the M1A adapter. In addition this section covers some of the variables that may be encountered with regards to the host barrel. 3. Accessory and sight mounting This section covers the proper usage of the M1A adapter to maximize the effectiveness and compatibility with sights and muzzle accessories. 4. Frequently asked questions This section engages many of the frequently asked questions posed by new users of the M1A adapter. Terms and conventions used in this manual: NOTE A note is used to provide additional information on the installation or use of the product. CAUTION A caution denotes an action that may pose a risk of, or result in, damage to equipment. WARNING A warning describes any action that may potentially result in serious injury or death.
- 3 - Adapter description The M1A adapter mounts directly to the muzzle of the M1A/M14 (and variants) in place of the mil-spec flash hider/bayonet lug or muzzle brake. The original equipment castle nut is used to secure the M1A adapter in the same manner as the original equipment flash hider or muzzle brake. The castle nut set screw (provided) is relocated while performing a similar function. NOTE This M1A/M14 adapter does not create a threaded muzzle. The muzzle must already be threaded to allow the adapter to be placed onto the host barrel. The M1A adapter provides industry standard 5/8-24 threads for the mounting of muzzle accessories with 5/8-24 TPI RH mounting threads. The M1A adapter provides tight critical geometry tolerances to minimize bore axis to accessory thread axis divergence and ensure shoulder perpendicularity. These tight tolerances minimize the risk of a projectile/accessory collision due to misalignment. Kit contents The M1A adapter kit contains the following: One M1A muzzle thread adapter One M1A adapter set screw One M1A adapter manual Technical specifications Material: Hardened stainless steel Thread specification: 5/8-24 UNEF Class 3A Weight: 45 grams (1.6 oz) Finish: Black oxide Barrel geometry considerations M1A/M14 components, including barrels, have been manufactured in many countries and to different manufacturers specifications. Given these varied sources, it is possible to see variation, especially in the width of the three longitudinal grooves near the muzzle. This adapter is designed to work with current mil-spec barrel geometry.
- 4 - Installation on barrel As with any firearm accessory, it is recommended that a certified armorer or gunsmith install this adapter. A certified gunsmith or armorer should inspect the existing muzzle threads and end face of the barrel to confirm thread concentricity and end face perpendicularity to the bore axis. Any accessory coupled with this adapter should be checked for proper bore alignment by a certified armorer or gunsmith prior to use. WARNING Before beginning installation, be sure to: Remove all live ammunition from the work area. Remove the magazine from the weapon. Lock the bolt in the open position. Visually and tactilely confirm the chamber is empty and that no ammunition remains in the action. Insert an empty chamber indicator in the chamber. 1. Remove existing flash hider or muzzle brake. Retain the castle nut for later use. 2. Inspect the muzzle threads, longitudinal grooves, and muzzle face for damage or irregularities. 3. Clean all traces of carbon and debris from the muzzle threads, grooves, and muzzle face. 4. Confirm that the set screw in the adapter is removed so that it does not protrude into the inside of the adapter. NOTE It is recommended to apply a small amount of high temperature anti seize paste to the threads of the adapter and to the longitudinal slots near the muzzle. 5. Position the castle nut in the opening of the adapter with the castle nut slots toward the adapter threads.
- 5-6. Slide the adapter over the muzzle of the barrel. a. Correctly rotate the adapter so that the sight base is in the proper orientation for use of the sights. b. Slide the adapter over the barrel until the castle nut threads can be engaged. 7. Tighten the castle nut. a. Use only a pair of castle nut pliers to tighten the castle nut. b. Turn the castle nut until the muzzle face fully seats against the adapter. c. Continue to tighten the castle nut so that the next wrench opening in the castle nut aligns with the tip of the set screw. 8. Install the set screw. a. Turn the set screw clockwise until the unthreaded portion of the set screw is inside of the castle nut wrench opening. b. The set screw should not be forced to bottom out on the barrel. Do not over-tighten the set screw. CAUTION
- 6-9. Install front sight (if desired). Frequently asked questions WARNING Always have any muzzle devices used with the adapter checked by a certified armorer or gunsmith before use to assure proper installation and alignment to the barrel bore. Q: I cannot remove my existing flash hider or muzzle brake or, it only removes after heating or driving off. A: The slots near the muzzle may be narrow. The flash hider or muzzle brake may have been driven or pressed on to allow for installation. We recommend taking the assembly to a qualified armorer or gunsmith for evaluation. Q: The adapter alignment pins fit tightly in the longitudinal slots in my barrel, what is wrong? A: The adapter is designed to fit to current military spec barrels. If the slots are less than 0.100 wide, the adapter may not fit or will require a press fit (depending on application). Q: I have a short barreled variant of the M1A/M14 with different barrel threads than the standard M1A/M14 barrel. Will the adapter fit my barrel? A: No. Q: Is the adapter offered in a bright or matte finish? A: The adapter is offered only in a matte black finish. Q: Do you sell front sights, castle nuts, or castle nut pliers? A: No. Q: I dropped the set screw during installation and it rolled under something too heavy to move. How can I obtain another set screw for my adapter? A: Send us an e-mail request containing your contact information. Contact Information Delta P Design Attn: Support PO Box 245 Walterville, OR 97489 (503)487-0007 (Monday through Thursday 08:00 17:00 PST) www.deltapdesign.com