Gunner Wade on Boresighting an RCO with issued collimator

    We previously covered 2nd Mar Div’s Combat Camera productions involving Gunner Wade and suppressor Fact or Fiction series, but the 2nd Marine Division Gunner is back at it again, this time he is covering how to properly boresight a service rifle and RCO using an issued collimator (although he is using his personal rifle in the video). The process is extremely simple, but if done incorrectly, can result in a very long day of zeroing. After inserting the device in the muzzle of an M16A4, M4, or M27, essentially there is that little diagram inside the collimator, that lines up within the RCO or SDO, and Marines have to match up the 100 meter marker that is the tip of the red chevron (“tip of the d**k” as we say in the Infantry) to the proper diagram within the collimator. However, the video is somewhat misconstrued because this is truly only half the process of zero. The other half involves actually shooting 10 rounds (2 groups of 3, then 1 group of 4 to confirm) at 25 meters to get the RCO or SDO zeroed properly, then another group at 100 meters to get the 100-meter confirmation.

    I do like how the video so casually makes a note that spotting scopes and collimators can be requested at Division armories as if any Marine stationed at Camp Lejeune can simply send an e-mail and have a collimator ready at weeks notice or so.

    The video is extremely well produced using animation to properly illustrate what the camera cannot capture. Overall, I’m somewhat jealous that these videos are out now, as they could have been extremely useful to Marines of previous generations.

    Before this collimator was issued, the Marine Corps used a laser bore sight unit, which used to be an absolute hassle to put together because it tended to be so intricate.


    Infantry Marine, based in the Midwest. Specifically interested in small arms history, development, and usage within the MENA region and Central Asia. To that end, I run Silah Report, a website dedicated to analyzing small arms history and news out of MENA and Central Asia.

    Please feel free to get in touch with me about something I can add to a post, an error I’ve made, or if you just want to talk guns. I can be reached at [email protected]