FWIW, I have two Arken scopes, an SH4J and an EP-5 . Both are on range guns, no problems. The SH4J is on a Tikka Super Varmint 6.5 CM. I took it deer hunting and like a dope, let it slip out of a 15 foot elevated stand. All the way to the ground, landed squarely on the elevation turret. Checked the reticle, zero and tracking. It was like nothing ever happened. I don’t know if Arken has addressed this, but a good practice after zeroing the scope is to back out the turret screws a few turns and add a drop of low strength Vibratite or Loctite. Easy peasy. They’ve really given me no reason not to recommend them.
Can’t speak directly to the EPL-4, however.