I'm sure this has been asked before, but i'm wondering why the change in action details for Semi-auto and Full-auto fire in this game vs Dark Heresy, Rogue Trader and Deathwatch?

from my memory, in DH, RT and DW its as follows:

Semi-Auto Fire:  Full Action, +10 to BS, every 2 margins = extra hit.

Full-Auto Fire:  Full Action, +20 to BS, every margin = extra hit.

Single shot:  Half Action, no bonus to BS.

In the Only War Beta, its different.

Semi-Auto Fire:  Half-action, no bonus to BS, every 2 margins = extra hit.

Full-Auto Fire:  Half-Action, -10 to BS, every margin = extra hit

Single Shot:  Half Action, +10 to BS.  

Why the change?  Did I miss something perhaps??

I could guess that the change perhaps reflects the Guard's instruction to fire single, aimed shots with lasguns and learning to fire automatic weapons comes secondary?  just seemed odd they would change it from all previous games.  I dont own Black Crusade, so I cant say what its like.

The old way was so that firing on full auto was ALWAYS the best option making all weapons without accurate or full auto very useless.

 I agree, and in many cases a real munchkin player could spend a round aiming, then go full auto and get a total of +40 BS.  So why not FAQ the older games to the Only War method?  

I'm just curious as to why they stuck with one method for so long, at least 3 games over a few years….then suddenly change it.  was it based on feedback?  playtesting?  

vyrago said:

The change was made with Black Crusade actually (or maybe DW but I don't own that).
Not sure why they don't errata it, probably because the errata is there to fix mistakes and having the bonuses and actions like that isn't a mistake, it's just bad design.

Bad design also being the keyword to describing Dark Hersesy when compared to more modern version of it (see OW).
I don't dislike DH but the skill system is bloated, Psychic Powers are very weird to roll since its the only part of the system that uses a dicepool and the combat is wonky.

you're right about Black Crusade, I asked a friend who owns the book to look it up for me.  I own Dark Heresy, Rogue Trader and Deathwatch and they all share the 'old' rules about single, semi and auto-fire.  I'll try them out a bit more in Only War and likely adopt them for my other games, since they do make a bit of sense.  I particularly like that they are all Half-Actions now, which allows either for aiming or moving to cover…etc.  I'm glad that Suppressive Fire is basically unchanged across all games.

I like the rules as they were changed to in BC. It makes other options than Full Auto viable, and makes Semi-Auto a good choice for people without extremely high BS.

The only criticism is that it it now sometimes too easy to hit things, and with many DoS. This boosts Accurate weapons, and there have been plenty of "are accurate weapons too good?" threads (no they aren't).

They simultaneously changed the melee options too, to work similarly to the ranged. So Single/Swift/Lightning works just the same as Single/Semi/FullAuto.

Goodie :)

Now taking your time to line a single shot is actually more accurate than unloading your gun in full auto with reckless abandon.

I like the change. So far it has been working well in my games.

 I always thought that full auto should have had a progessivly worsening bonus. Short range plus 20, mid-range plus 10, long-range 0, and for every 10m after that a stacking -10. Or something along those lines to reprozent the progessivly smaller target and the recoil of full auto fire. Sorry for any misspeld words or gramarical errors im doing this for a PS3.

 I quite like the change. Question: did the Overwatch action always exist? It's wonderfully flavorful and very handy. I wish the groups I've been with over the years had made use of things like cover and Pinning and all that. I guess having armor goes to their heads.

Plushy said:

This change would be near-pointless in Deathwatch because, post-errata, almost no Astartes weapons fire full auto.

In any of the game systems, single shot had the advantage of letting you be able to shoot and then move into cover.