6 C-SRM4 if you can. Way better grouping and better dps if you can handle it. Fire in 2 salvo if you worry about ghostheat.
What enileph said. You also get the advantage of using less crit slots despite having the same tonnage and Alpha. Even if you compare 4 C-SRM6+A vs base 6 C-SRM4 the 4s still have better grouping and cycle faster. And heat per second is still the same barring ghost heat! The math is similar for LRMs. My rule of thumb is that if you can achieve the same number of tubes using smaller launchers on a chassis, it's a good idea to do so.
I absolutely hate when people open a thread with half a line and a "discuss". It's not even acceptable from the worst lazy-ass teacher. eni, Karl, it depends on what you want to do and on what mech you are working. On a Jenner-IIC, sure, 6 SRM4s. But if I have the tonnage I'd go for 4 SRM6s with Artemis: slower rate of fire, but tight grouping and much more heat efficient. But again, it depends on the mech, and if you have other weapons. Also, multiple small launchers instead of few heavy launchers might look good on paper because of the high theoretical DPS, but it leads to damage dispersion and/or ghost heat. => my rule of thumb is 4 launchers, and alpha strike.
Indeed, my assumption is w/o +A upgrade. In that case it is hardly a choice. The spread of vanilla SRM6 is huge and defeats the purpose of an alpha strike.
SRM spread is a non issue after this latest srm buff. 5 srm6 stalker is a great example. I used to run Artemis because it was essential to killing blows. But now I can swap back to no Artemis because the spread is better, and instead of smaller engine and less ammo I have bigger engine and more ammo. If given the opportunity I would run 6-8 srm6 in the place of 4-5 srm6. The main reasoning for running 4 srm6 would be limited number of hardpoints. Otherwise more srm4s are always better than less srm6s.
SRM6s are still terrible without artemis. Sure, you will probably get good damage numbers or do alright just from said overwhelming damage, but in terms of effective damage I'd put my money on SRM4 every time if there is no artemis. With artemis is a more interesting conversation and is extremely mech/role dependent. There isn't a huge amount of mechs that can field 6 C-SRM4, especially with artemis. For clans, I stand by always taking artemis and sticking with SRM6 as much as possible. IMO you get the best return for your tonnage with C-SRM6+A. aside from straight damage output and effective damage spread, 4x SRM6 has the added benefit of being min/max for face time to alpha vs. defense time. You can fire a volley and immediately twist to defend. You also have a longer cooldown to utilize for twisting. It's very ideal. Here are some general number comparisons assuming a cooldown module and fast fire. Also, 6x cSRM4+A is 2 tons heavier than 4x cSRM6+A. So I used that tonnage for 2 addition cDHS for the comparison, assuming both builds would have ~same amount of ammo. That tonnage could be used for many things. Biggest note is that both systems deal the same amount of damage. However the 4x SRM4 will be dealt over 2 1/2 second shots versus just 1 alpha. Which can be a pretty big deal for effective damage. Both have their advantages however.
Well, it would be more interesting to compare 4xSRM6+A, vs vanilla 6xSRM4. In which case the spread is closer. Obviously it is easier to find a mech with 4 Missile hardpoint than 6, and hardpoints maybe more over the place with 6 of them, which means more spread out shots, or parts that could otherwise be stripped as a shield arm. I would say do the 6xSRM4 if you can afford the luxary, but 4xSRM6+A is a good alternative for bigger mech.
If a Mech has 6 M-HPs (and that's really rare), you can simply try out loading the mech with both option and see where you get at. I'd say if the Mech has more than 3 M-HPs always go boating SRM4 over SRM6+A just to keep the used tonnage low for other needed things like Ammo, Speed, Armor, secondary weapons etc. Also don't forget CDT 3secs vs 4secs! IS: 6SRM4 = 12 Tons 4SRM6 = 12 Tons 4SRM6+A = 16 Tons !! Clan: 6SRM4 = 6 Tons 4SRM6 = 6 Tons 4SRM6+A = 10 Tons!
personally 6x csrms4 for me the loading/cooldown time for srms6 is just killing me when im zipping tru the fine line of death within the ball of red death.