18 Str 4 AP 0 shots

12 Str 4 AP-1 Shots

9 Str 4 AP-2 Shots

4.5 Str 4 AP-2 2Dam Shots

3.6 Str 4 AP-3 2Dam Shots

(1/18) * 3 per gun = 0.17 for the Auto Bolt Rifle

(1/12) * 2 per gun = 0.17 for Bolt Rifle

(1/12) * 3 per gun = 0.25 for the Auto Bolt Rifle

(1/9) * 2 per gun = 0.22 for the Bolt Rifle

3.6 Str 4 AP 0 Shots

3 Str 4 AP-1 Shots

3 Str 4 AP-2 Shots

(10/36) * 3 per gun = 0.83 for the Auto Bolt Rifle

(10/36) * 3 per gun = 0.83 for the Auto Bolt Rifle (1/3) * 2 per gun = 0.66 for the Bolt Rifle

(1/3) * 3 per gun = 1.0 for the Auto Bolt Rifle

(1/3) * 2 per gun = 0.66 for the Bolt Rifle

3.375 Str 4 AP0 shots to cause 1 wound (27/8)

2.7 Str 4 AP-1 shots to cause 1 wound (54/20)

2.25 Str 4 AP-2 shots to cause 1 wound (9/4)

(8/27) * 3 shots per gun = 0.89 for the Auto Bolt Rifle

(20/54) * 2 shots per gun = 0.74 for the Bolt Rifle

(20/54) * 3 shots per gun = 1.11 for the Auto Bolt Rifle

(4/9) * 2 shots per fun = 0.89 for the Bolt Rifle

There is a threshhold for AP where the returns on improving AP diminish. This point entirely depends on the armor save of the target, with armies like Daemons who only have a 5++ to speak of shrugging off better AP values.Then other armies like Orks only suffer AP up through AP-1; for most of their army any AP past that is pointless as they have 6+ saves. So the discussion here is about Assault 3 VS Rapid Fire 1 and lets talk a bit about the Stalker as well.For all of this, imagine you have 5 Intercessors. That means, 15 Auto Bolt Rifle shots, 10 Bolt Rifle shots, and 5 Stalker Bolt Rifle shots. Assume no rerolls so we can get some raw looks at the difference in AP and Volume of Fire.To kill 1 Primaris MarineThe Stalker Bolt Rifle is a High Quality, Low Output weapon and really belongs to a different role. I'm not going to talk about it too much, because it does not have overlapping purposes in the same manner the Auto Bolt Rifle and Bolt Rifle do.So what we can do with these numbers is assign a score of "killed Primaris per shot" times the number of shots, which we can rank. Again, just Auto VS Regular.Let's look at Ork Boyz next. They have a 6+ Armor Save so improving the Bolt Rifle is not valuable.The surprising thing to me is thatAgainst Cultists who also have a 6+, the Str VS Toughness doesn't change that the Auto Bolt Rifle will outproduce the Bolt Rifle. The difference would remain but effectively be amplified by 33%.Now for the GEQ, really a study on 5+ armor saves.There are many things to consider. The Rapid Fire Stratagem will double the production of the Bolt Rifle -- but do consider that the Auto Bolt Rifle is similar to having that Stratagem at 50% always on.The Auto Bolt Rifle in Devastator Doctrine is better VS Salamander type Defenses (ignores AP-1) because of Volume of Fire, but in Tactical Doctrine where a Bolt Rifle is AP-2, the Bolt Rifle leaps ahead. And consider that the 30" range of Bolt Rifles is very good, VS the 24" range of the Auto Bolt Rifle.The best take away from this is that any Intercessor blob should take a long and serious look at the Auto Bolt Rifle. It is very productive in a wide range of scenarios and addresses one of the most difficult problems in the Marine arsenal: Volume of Fire.