Frequently Asked Questions

  1. Is using the MBC™ (Modified Bolt Catch) make my AR legal in my State?
    Each State law differs from other States.  The commonality between most of the States restrictions on AR type platforms rest on the firearms “semiautomatic” mechanical operation.  The Bureau of Alcohol, Tobacco, Firearms & Explosives (ATF) and certain States define a “semiautomatic rifle” as any repeating rifle which utilizes a portion of the energy of a firing cartridge to extract the fired cartridge case and chamber the next round, and which requires a separate pull of the trigger to fire each case.  The International Firearm Specialist Academy (IFSA), which is staffed by former ATF agents and law enforcement officers that are experts in the field of firearms and ammunition, provides instructional training to law enforcement personnel and civilians to become Certified Firearms Specialist.  The IFSA states that any firearm that is not “self-loading” is Manually Loaded.  This means that after firing a shot, the shooter must manually operate something on the gun, in order to load the next cartridge into the chamber (

    The MBC™ (Modified Bolt Catch) is designed to eliminate the semiautomatic, auto-loading or self-loading function of the AR firearm making it a single shot/manually loaded firearm.  A firearm fitted with the MBC requires the shooter to manually operate the MBC after every shot in order to load the next round.  Whether the shooter manually presses and releases the MBC after every shot or manually holds it down, the shooter is still manually operating something on the gun in order to load the next cartridge into the chamber which is exactly what the definition is of a “Manually Loaded” firearm.

    The following links below are provided for informational purposes only.

    New York SAFE Act
    Law Center - New York
    New Jersey State Police
    Law Center - New Jersey
    Connecticut State Firearms Law
    Law Center - Connecticut
    California Department of Justice Bureau of Firearms
    Law Center - California

    Tier5 does not provide legal advice.  State laws are constantly changing, therefore does not serve as a guarantee that the inclusion of the MBC shall allow all ARs to be considered acceptable by law enforcement in all States and locations.  Refer to your local law enforcement agency for their definition of semiautomatic firearms.

  1. Can I install the MBC™ (Modified Bolt Catch) myself?
    The MBC is a Drop-In Modification with No Fitting Required.  However, any firearm repair or modification, no matter how simple should always be conducted by a knowledgeable and competent gunsmith.  Tier5 strongly recommends that the user of this product seek the assistance of a qualified gunsmith for installation and/or have the installation inspected by a qualified gunsmith before use.  Below is a link to an informational videos on the installation of the MBC.

    Installation Video

  2. Is there any fitting required to the AR-15 MBC™ (Modified Bolt Catch)?
    The MBC will fit all standard Mil-Spec AR-15 Platform.  NO MODIFICATION SHOULD BE DONE TO THE MBC.

  3. Will the MBC™ (Modified Bolt Catch) fit all brands of Lower Receivers?
    The MBC is manufactured to Mil-Spec measurements.  No alteration or modification is required to the AR-15 platform.  It will fit all Mil-Spec Lower Receivers if the current bolt catch being replaced is a Standard Mil-Spec Bolt Catch.

  4. Will the MBC™ (Modified Bolt Catch) fit lower receivers that incorporate ambidextrous bolt releases?
    The MBC will fit lower receivers that have ambidextrous bolt releases as long as the current bolt catch being replaced is a Standard Mil-Spec Bolt Catch similar to the MBC.  Fitting may be required regarding the use of the current bolt catch spring and plunger in conjunction with the MBC in order for the ambidextrous bolt release to function properly.  NO MODIFICATION SHOULD BE DONE TO THE MBC.  The original standard bolt catch spring usually requires shortening in order for both the MBC and ambidextrous bolt release to operate properly.  It is strongly recommended that a qualified gunsmith conduct this modification since it requires fitting.

  5. Can I use aftermarket accessories like the Magpul BAD Lever or other brand  products that allows ambidextrous operation?
    The MBC is manufactured to Mil-Spec measurements, therefore any aftermarket accessories made to fit standard mil-spec bolt catches will fit the MBC when used in forged Mil-Spec lower and upper receivers.  Some billet lower and upper receivers may not allow proper operation of the MBC in conjunction with the Magpul BAD Lever or other aftermarket ambidextrous release.