The bore of the SGB is machined to closely fit around .750" diameter mounting bosses found on most M4 Carbines and AR-15 rifles.#html-body [data-pb-style="62DF828752827"]{justify-content: flex-start; display: flex; flex-direction: column; background-position: left top; background-size: cover; background-repeat: no-repeat; background-attachment: scroll; border-style: none; border-width: 1px; border-radius: 0px; margin: 0px 0px 10px; padding: 10px;}#html-body [data-pb-style="62DF828752834"]{border-style: none; border-width: 1px; border-radius: 0px; margin: 0px; padding: 0px;}