Double-Barrelling (also known as 'firing the second bullet') refers to the situation where a poker player places a continuation bet on the turn after having already done it on the flop. The term continuation bet indicates that the both the flop and the turn bets are being placed without a made hand.
Depending on the exact situation you're facing, this strategy can be either very rewarding or completely foolish. Below, I will go over the main aspects that you should consider before deciding to reach out to your stack and throw in that second bet.
The number of opponents you’re facing
One of the biggest mistakes beginners make when bluffing is not noticing how many players they are against. This is a very important thing to take note of. Generally, bluffing is only effective if there’s only one or two opponents in the pot. If there’s more then you have to have a very solid read on most of them in order to go through with your bluff.
When double-barrelling, your one and only objective is to get your opponents to fold their hands. In case you have four or five players against you it is very likely that at least one of them is either on a draw or has even hit something and slowplays you. Remember, your strategy will fail even if just one player out of those five decides to make the call. For your double-barrel to work, you must get rid of EVERYONE in the pot.
The texture of the board
This is definitely something that’s not to be overlooked when making a decision to double-barrel. You need to take into consideration the likelihood of some of your opponents being happy with the board – I’ll give you two examples:
2s 9d Jh 5c – on a board like this, it is very likely that none of your opponents have hit anything. You raised pre-flop, indicating a strong hand, fired another bet on the flop, saying you either have a set, an overpair, or a jack with a good kicker and you’re showing off further confidence on the turn. This way, pretty much the only hands that can call you are a high jack and a slowplayed set – even a weak top pair may get easily folded here.
8d 9d Ks Ac – this texture, on the other hand, suggests you to get out of the action as cheaply as you can! Compared to example #1, this board has countless of possibilities for hands your opponent might have to justify their call. They may be on either a flush draw or a straight draw, they might slowplay you with any two pairs (AK, A9, A8), they might even have a weak ace that they can’t force themselves to throw away!
It’s always a good idea to go through those possibilities in detail before making the decision to double-barrel. Bear in mind that the second barrel is generally a lot more expensive than the first one! Which brings us to ...
The size of your bet compared to what’s already in
It’s very important to size your continuation bets properly. You need to take into consideration both the size of the pot and how many chips your opponent is left with. If there’s 1000 chips in the middle and your bet is only 150, you will most certainly get a call from any half-good drawing hand, forcing you to either make another bluff on the river or losing you the hand in case your opponent hits their draw or even if they don’t hit but are ahead of you with a high card or a small pair! In order to get rid of such players, your second bet needs to be at least half the size of the pot.
Another thing to notice is how many chips your opponent has in their stack. If there’s 800 chips in the pot already and you make a well-sized continuation bet of 600 chips, but one of your two opponents has only 200 left in their stack then the size of your bet quickly becomes totally irrelevant. One of the two might indeed fold, but more often than not you will get the call from the short stack and lose 200 chips more than you would have by just checking it down. It’s almost never a good idea to make continuation bets against short stacked players, unless you’re on a draw yourself.