Admin server dupe timing!

I own my own server and I am wondering if anyone has a firm grasp on how long I must wait before tossing my items into a tent, barrel, car, etc before resrarting.

Some say a 13 second window, others say 30 seconds???

I'm doing the old glitch where you hold your items on our person for a min or two and then toss them in the tent and quickly restart.

My question is, how long should I be waiting to restart my server?
I used to have it working like a charm but now it seems the timing is off and I am losing UMP Magizines like mad!

Any insight on timing would be a huge help!

Thanks guys