So with the Sharpshooter feat, you can take -5 to your to hit roll in order to gamble so that you get a +10 to your damage inflicted.

How do you normally decide whether to go for it on a given shot? What's your rule for "yeah, I'll risk it" or "nah, I'll play it safe"?

There's another feat that does similar for heavy weapons, Great Weapon Master, so feel free to discuss that as well/instead, since it's very similar in mechanics.

Typically, for features like this and similar ones, I'll usually go for it if: 

A. I have advantage. 

B. I have bardic inspiration, bless, luck points or other resources that could help bump up a miss or reroll a miss. 

C. The AC of the enemy seems to be on the lower end. 

D. I'm just feeling lucky. :D 

Things that will nudge me towards normal attacks: 

A. I have disadvantage. 

B. The enemey has a particularly high AC and I don't have anything extra active to bump up a roll or reroll a miss. 

C. I want to use a maneuver or arcane shot or something that requires me to hit first, and don't want to risk missing and being unable to do it. 

D. I feel unlucky in the moment for w/e reason. 

I don't really have an exact formula. 

The biggest question, for me, is 'do I remember I have this feat?' 99 times out of 100, I forget about that part and only remember the cover/long range parts. Can't remember the last time I used the -5/+10 part of the feat.

I would add:

E. If you think the monster has enough hit points where you're not wasting damage on a hit.  Like if you think that the monster maybe only has 5 hit points left, don't bother using Sharp Shooter.

I used this for my horizon walker ranger in a 1-5 campaign. There was never a time where it was not a good gamble. Down the adds with one shots and take chunks of hit points out of the boss monster. Even if a monster had high AC, which is not too frequent at low levels, the payoff for hitting was well worth it. My teammates were calling me the rail gun. 

Quote from Erik_Soong >>

I used this for my horizon walker ranger in a 1-5 campaign. There was never a time where it was not a good gamble. Down the adds with one shots and take chunks of hit points out of the boss monster. Even if a monster had high AC, which is not too frequent at low levels, the payoff for hitting was well worth it. My teammates were calling me the rail gun. 

 Yes, Sharpshooter and Great Weapon Master are amazing at Tier 1. That's why they're not 1st level feats in the One D&D playtest.

It's possible for your allies to boost you to the point where you can freely use it, and, at least early on, it's good enough to justify them doing that.

A good rule of thumb: if the monster is bigger than you and it's not a dragon, consider using the feat.

Quote from pocketmouse >>

The biggest question, for me, is 'do I remember I have this feat?' 99 times out of 100, I forget about that part and only remember the cover/long range parts. Can't remember the last time I used the -5/+10 part of the feat.

 
One thing that helps is I put a duplicate of my weapon on my character sheet and preset it to the -5/+10 so it displays directly below the normal weapon under Actions. That helps because I can just choose which one to use for each attack.

Oh, I absolutely have a duplicate version of both my bows with the sharpshooter feat pre-calculated. Still can't remember to use it.

Quote from pocketmouse >>

Oh, I absolutely have a duplicate version of both my bows with the sharpshooter feat pre-calculated. Still can't remember to use it.

 
😂

I mean that in a comradeship way.

If I think that with the -5 I'm going to be hitting on a roll of 12 I'll use it.  That's my general rule of thumb.  I've seen too many people play where they tried to use it on targets that they needed a 15+ to hit because "it'll pay off on average" only for them to whiff every attack they make the entire fight and consequently inflict no damage at all to be willing to use it on any riskier shots unless I really need a Hail Mary desperation move.

Quote from Beardsinger >>

Somebody somewhere once did the math and said that if the enemy AC is 18 or below then use it. That feels a little bit high for my taste. I would probably only go that high if I had advantage. 16/17 is probably my limit without

 
It depends on my attack bonus in relation to the target’s AC, not just the AC itself.

Quote from 6thLyranGuard >>

If I think that with the -5 I'm going to be hitting on a roll of 12 I'll use it.  That's my general rule of thumb.  I've seen too many people play where they tried to use it on targets that they needed a 15+ to hit because "it'll pay off on average" only for them to whiff every attack they make the entire fight and consequently inflict no damage at all to be willing to use it on any riskier shots unless I really need a Hail Mary desperation move.

 
Yeah, 12+ is my over/under too.

From a pure powergaming standpoint there is a formula involving your base damage and to hit bonus with wich you can get an AC up to which it would be better ON AVERAGE to use it.

16+TH-(D)/2>=AC

If you don't want to use such a formular, in most cases Sharpshooter is worth in most average cases and more so the better to hit and the lesser the enemy AC.

It partly depends on how high your damage (without the feat) would be. The higher your base damage, the more you're risking. If you have a +3 longbow with a +5 from Dexterity, then that's an average of 12.5 damage that you're gambling. That makes it more of a gamble than your L1 archer who has +3 Dex and a standard longbow who is only risking 7.5 average damage. 

It's obviously not the only consideration by any means, but I find it interesting that it hasn't really been discussed much so far.

I generally don’t bother with the feat’s -5/+10 but if I’m going to consider it I need to be able to eliminate all or most of the -5. If you are hitting AC 18  then the -5 means you need to get a 23 with all your bonuses.if you have a fifty-fifty shot of doing that then you are probably good to go but that means you need 13 points in bonuses.

I’m not sure that advantage is actually the equivalent of a +5 (maybe more like a +3.5 or 4), but yes that’s really my point - if you can’t get your attack down to at least a coin flip hit/miss chance you are better off NOT using that feature. If you can get better than coin flip odds of a hit you should be using the feature.

It may have just been because of the fact that the campaign was in Tiers 3 and 4, but I had two players with sharpshooter who applied it to their attacks 99% of the time. I think the only times they wouldnt apply it was if I put an enemy in front of them that was clear it had a substantial AC (like a Fire Giant Dreadnaught). One would say "I am applying Sharpshooter, obviously" which has honestly kinda turned me off from those types of feats as they are designed right now. I like what it sets out to do, take a penalty for a chance of doing more damage, but the fact that it feels like an "obvious" choice to take the penalty makes me feel like the penalty isnt as substantial as it should be. A risky shot should not be the obvious approach to the majority of your attacks. 

A Fire Giant Dreadnaught only has a 21 AC.  That's not really all that high at tiers where PCs can have +10-+14 to hit.