All auctions on GunBroker.com use the "15 Minute Rule" (which is similar the "going, going, gone" portion of in-person auctions) to ensure fair bidding for all users. If a user places a bid within 15 minutes of the scheduled end time, the auction automatically switches to a mode where the end time is extended until no bids have been placed for 15 minutes.
The 15 Minute Rule is intended to prevent sniping (where a bidder waits until the last possible moment to bid and win the auction) and offers all users an equal opportunity to place their best bid. When 15 minutes have passed with no bidding activity, the listing ends and the seller can be assured that they have received the maximum value for their item.
Note: while listing times appear in the format of Day(s), Hour(s), and Minute(s), actual listing times are programmed using Day(s), Hour(s), Minute(s), and Second(s). For this reason, we encourage users to place their highest bid amount when initially bidding to maximize their chance of winning.