Prehand Descriptions
Villain 1: regular, lots of history with hero, fairly passive, does not get paid off much, calls too much preflop but plays 100% fit or fold postflop, does not cbet, slightly scared money
Villain 2: regular, lots of history with hero, intelligent and understands basic poker strategy but spewy and loves to chase (justifies this by implied odds thinking he will get paid off every time), fairly loose preflop, calling station preflop, horrible spewy bluffer
Hero: tight-aggressive, occasionally bluffs and 3 barrels, but more or less usually bets for value, however more loose aggressive lately


$1/1 NL home game (5 handed)
UTG villain 2 ($300)
MP ($300)
Button hero ($120)
SB ($150)
BB villain 1 ($60)

Hero is dealt A5

UTG villain 2 limps, MP folds, button hero raises to $3, SB folds, BB villain 1 unhappily calls, UTG villain 2 casually shrugs and calls

Both villains are pretty easy to read, and it is clear that neither are slowplaying here. Villian 1's range is now is AQ-A8, small pocket pairs up to maybe 99, suited connectors, suited one gappers, and two high unsuited cards down to maybe T9. Villian 2's range is Ax suited, very small pocket pairs, suited connectors, one two, and maybe even 3 gappers, and unsuited mid connectors.

Flop ($10) T42
Villain 1 checks, Villain 2 checks, Hero bets $6, Villain 1 calls, Villain 2 casually shrugs and calls

I flop a gutshot, but the odds are so small that I would hardly consider this a semibluff. It's a simple cbet, and with 2 callers, I would usually give up. But here, the ranges are so narrow. Villain 1 calling narrows his range down to top pair mid-high kicker, pocket pair between 4 and T, or maybe flush draw and overcards, or maybe up and down straight with backdoor flush. Villain 2, based on his body language, clearly has either a flush or up and down straight draw. With such a read, I decide to fire another barrel if the turn misses straights and flushes.

Turn ($28) 9
Villain 1 checks, Villain 2 checks, Hero bets $12, Villain 1 complains and regretfully calls, Villain 2 casually shrugs and calls

At this point, it is very much clear that Villain 1 has top pair mid kicker, either JT, T8, or T7. A combo draw like QJ is also possible. Villain 2's range does not change. From past history, I know a river bet can easily push Villain 1 off his hand the majority of the time, assuming he has top pair.

River ($64) 4
Villain 1 checks, Villain 2 checks. Does Hero fire 3rd barrel here? If yes, how much does he bet? If no, why not?

Turn and river are not good cards to continue barreling. Your looking to barrel on scare cards, which is pretty much any non spade J-A, to push them off their marginal one pair hands. Once they both call flop, betting a 9 turn is spew.

fold pre

I'm fine with the C-bet but once both players call I think I give up. You still have some showdown value against a busted flush draw and if they have a 10 they are not folding. Something like 77 or 88 might but then you still have the other player to worry about.

bet larger on turn if youre going to double barrel, 15-20$

if they call the large turn barrel, just give up river, nothing on that board has changed, and if they liked what they have after the double barrel, theyre going to call off a river bet

Check the turn once two call you on the flop, you're not representing that the turn helped you in any way. I'm with fogo here.

If you do want to barrel, I agree with suqata, it has to be larger.

Given the calling ranges you assign to Vs, why are you raising with a hand that does worse against those ranges than virtually any other in the deck?

A5o plays terribly against A8-AQ and small/mid pockets. I know you can bluff sometimes, but we want to at least be able to think of reasonable situations where we can win a big hand postflop for value.

It's not going to change the post flop discussion too much I don't think but I think it's important to remember here that we are 5 handed to play this game.
I don't play a lot of 6 max (only when tables are filling up in the 10 seated tables at the casino) but I've got to feel that opening for A5 can't be all that bad, esp vs limpers.
On the flop, the cBet is fine. It's decent board texture. It would be better if it was 3 suits instead of 2, but it's still fine.
After that, we should be looking to quietly leave the party. Clearly they both have something decent, or at least a good draw. The only thing on the river that one of them should have is the busted flush draw. You have to have two things happen on the river. One villain has to fold top pair, and the other villain has to fold his flush draw. There are the times that one villain has 4Xss and he rivered trips, and you're never getting them to fold that.

Tl;dr, don't bet the turn. Don't bet the river.

IF, and it's a big if, if you are set on triple barreling, you are going to need to use your reads on villain to figure out the right size. I prefer just a little bit less than half the pot. The draws are folding for anything, and I think most people who fold top pair fold it either for any price or no price. No reason to risk too much.

You raised preflop so obviously the only hand in the universe you can have is AK.

So they are calling you down with any pair.

Also when villains are sighing and shrugging and calling you down they are usually strong.

So if you like lighting money on fire then bet river.

Otherwise, cut your losses and just surrender. They are never folding their bottom or mid pair garbage to you unless you seriously overbet pot and then they probably still call you. So fold.