Boker Applegate Knife
https://www.bokerusa.com/applegate-fairbairn-desert-120543des

DeSantis Slim Tuk MC1sc
https://amzn.to/32GIgBo

WY Trader's Vest
https://amzn.to/2mY3WXz

Burris FastFire III
https://amzn.to/399t2VY

KelTec RDB
https://www.youtube.com/playlist?list=PLVlCoEE1rzM60wsyiKI5X6CuBlRYCRSkI
https://www.keltecweapons.com/firearms/rifles/rdb/

Mossberg MC1sc
https://www.youtube.com/playlist?list=PLVlCoEE1rzM7gh64vJIPmatTzMDVFj0XX
https://www.mossberg.com/category/series/mc1sc/

Start Close behind cover, then one yard, then two, then three, then four, then No obstruction between you and the target
Establish sight picture then without transitioning
Mentally change focus from sighting eye to non-sighting eye then back to sighting eye.
Left and Right
Get inside the sights then switch to the other eye and notice the side of your rifle and your surroundings, then back to the sights.