2 3 3r 4

I've been swimming in this water for 40 years and no longer see it.  Some of this will be clear as mud to some people.

Gun stats changed a lot between GURPS 2e and 3e.

In 2e there are two kinds of ranged attack.  Snap and aimed.  If you don't aim, you get a -4 penalty.  If you take an action aiming, no penalty.  If you aim for up to three more turns you get a +1 for each turn of additional aiming!

In 2e an Assault Rifle (I think it's supposed to be an AK-47) was TL7, did 2+3 dice of crushing damage, had a point blank range (P-B) of 3, an increment (Inc.) of 10, 1/2D range of 75, Max range of 1,500, cost $800 and weight 12 lb. with a minimum ST of 8.

P-B range is the range, or less, that you get +4 to hit and +1 damage for a missile weapon.

Inc is the step, in yards where you take a -1 to your chance to hit.  For the example assault rifle, -1 at 10 yards, -2 at 20 yards, etc.  This seems fine until you start using more than one weapon and totally lose track of where you are.

You are -1 to skill for each point below minimum ST.

Notice a lack of ammunition and rate of fire in 2nd edition?  There's, literally, no rules for anything that can fire more than one shot a turn!  They admit that details like that would be coming in later supplements.  Autoduel, for example, has the rules for multiple shots and firing bursts.

3e has rules for multiple shots and bursts built right in.  You roll separately for each shot in semi-auto and for each burst in automatic fire.  Bursts are 4 shot unless your RoF isn't divisible by 4, then the last burst is 1-3 rounds.  There's a table for seeing how many rounds in a burst of a given size hit depending on how well you make the to-hit roll.

In the 3e (and 3eR) Basic Set an AK-47, 7.62mm R, SU does 5d+1 of crushing damage, with a Snap Shot (SS) of 12, Accuracy (Acc) of 7, 1/2D range of 400, Max range of 3,011, Weight of 10.5 lb., RoF of 10*, Shots of 30, minimum ST (ST) 10, Recoil (Rcl) -1, Cost $290 and is TL7.

The SS penalty is a -4 to hit if your skill, without aiming, is lower than the SS number.

Accuracy is a bonus you get if you aim for a full turn, you still get that +1 per turn of additional aiming.  The rules assume you're at a nice, safe, range by default.  Bullet shyness (up to -10 depending on the volume of incoming fire), buck fever (-1 to -10) and flinch (applies the Rcl penalty before firing) are added for combat situations.

The RoF is shots per turn (second) the asterisk means it's select-fire.

Rcl is the penalty of each burst of up to 4 shots, fired per turn.  -1 for the first 4 rounds, -2 for the second, -3 for the third... etc. until you spend a turn recovering from recoil.  If your skill is below 12, double the recoil penalty.  If your ST is below the minimum for the weapon, double the recoil penalty.  If both, quadruple the penalty!

If your ST is below the minimum, take two turns to recover from recoil instead of one.

Range penalties are now on the speed/range table.

High Tech 1e to 3e amends these numbers slightly with the AK-47, 7.62x39mm, Guns(LtAuto), adding the full name of the chambering and what skill you needed to run it, rounding Max down to 3,000, the Weight to 10 lb.; adding an Ammunition Weight (AWt.) stat of 1.8 lb., Shots are changed to 30+1.

There's rules in High Tech distinguishing bullet damage from crushing damage that becomes piercing damage in 4e. 

Rcl is changed slightly, adding the recoil penalty to the second and third shots fired semi-automatically as well as for bursts.  -0 for the first shot, -1 for the second, -2 for the third and keep going until the shooter takes a 1 turn pause in firing to recover from recoil.

Just more detail from the Basic Set, really.

4e rolls to hit once per turn, regardless of the number of rounds fired.  You get a bonus to hit for firing a lot of bullets, but after that it's effective skill and multiples of the Rcl number from there.

This is unpopular with a lot of players and many kept on with the 3e rules because of it.

In the 4e Basic Set, we're back to generic guns, but the AK looking one is the Assault Rifle, 7.62mS, TL is still 7, Damage is still 5d+1, but now we have piercing to replace crushing.  Accuracy is lower at 4, 1/2D and Max ranges are consolidated into Range 400/3,000, as is the Wt and AWt into Weight 10.5/1.8, RoF 10, Shots is 30+1(3), ST 10†, Bulk -4, Rcl 2, Cost $300, LC 2.  With a note about how a semi-automatic version differs from the real thing.

The lower accuracy is because several penalties have been built into the combat rules that were tabulated separately.  However the term "aiming" changed a bit and there's no longer a snap-shot penalty for a low skill.

There's now a bonus to hit depending on the number of rounds fired, this comes up with the new recoil numbers.

Shots now includes, in parenthesis, the time it takes to reload the gun using the generic rules.  More detailed rules come later.

4e reverts back to -1 to skill for every point below the minimum ST your character has.  The † next to the ST means you need to use two hands or take a penalty in firing it.

Bulk, essentially, replaces the Holdout penalty and is a modifier to using the move and attack maneuver.

Recoil is completely changed.  This is the number you must "make it by" to get a second or subsequent hit on a target.  Thus, if your effective skill was 14, you need to roll a 12 to get two hits, 10 to get three, and so on.

High Tech 4e, again, makes minor changes to the stats but it's Izhmash AK-47, 7.62x39mm, now.  Range changes to 400/3,100, Weight to 11.3/1.8, ST to 9†, Bulk -5 Cost to $450/$30.  Shots are shown as 30(3), but I think that's an (unaddressed) errata and should stay 30+1(3).

Cost now incorporates the price of a magazine after the slash.

The number of hit points the average person has did not change at all between all the editions.  4e gets it from ST, all others from HT.

The 2e Assault rifle's 2+3 dice does 5-15 points of damage, averaging 10.

The 5d+1 (pi or cr) does 6-31 points of damage, averaging 18.5.

Guns are a lot more deadly in 3e and beyond.