Scopes.

[jes722]

Why does a scope do +3 to an existing ACC?
The iron sights and a scope is two difrent things!

[clu2415]

The ACC stat is based on things like mechanical accuracy of the weapon, muzzle velocity, and probably some other things that contribute to make it easier to hit what you’re aiming at. You could think of the iron sights as a “scope” with +0 ACC.

[Icelander]

Existing Acc is meant to reflect a combination of inherent mechanical accuracy of the weapon and ammunition, the ergonomics of the weapon and the ballistic properties of the typical ammunition. E.g. rifles chambered in .50 BMG will often receive equal or higher Acc than rifles firing .308, despite the specific .308 rifles being capable of greater inherent precision than a typical M82/M107 rifle, which is done to reflect in some way the much better external ballistics at long range and less windage for the heavier .50 BMG round.

There exist a few instances where poor, small or almost non-existent iron sights of specific weapons give a penalty to Acc, but the iron sights are usually in no way a major component of the factors that go into determining what Acc to give a weapon in GURPS. For example, .50 BMG rifles that come without any iron sights at all have Acc 6 in GURPS.

Now that military weapons are usually equipped with some form of combat optic, it might make sense to make an explicit note for weapons which have their Acc altered because of short sight radius, poor sights or similar factors, noting that this did not apply when using mounted optics. It is something to consider for a hypothetical GURPS 5e, far in the future.

[jes722]

A few... I could come up with MANY rifles that have no sights if you dont mount a scope!
But why dint they just give a scope a ACC and the weapon it self! And then swap scope in if you use it and/or give weapon a max acc even with a scope because of the weapons own statistics!

[JMason]

Weapon Acc and Scope Acc work very differently. A weapon gets its full Acc with one second of aiming. This is to account for how accurate the weapon is based on the factors others have listed above. Scope Acc on the other hand is more like an additional aim bonus, that builds up one second at a time. It has more to do with magnification, crosshairs, and other things that assist in the actual prolonged aim. This way the same scope can be added to two very different weapons, and grants the same level of additional benefit, but the basic weapon level Acc is still fixed based on the weapon.

[Icelander]

Originally Posted by jes722

A few... I could come up with MANY rifles that have no sights if you dont mount a scope!
But why dint they just give a scope a ACC and the weapon it self! And then swap scope in if you use it and/or give weapon a max acc even with a scope because of the weapons own statistics!

They do.

Literally all of what you describe exist as rules in GURPS, either in the GURPS Basic Set, GURPS High-Tech or GURPS Tactical Shooting.

The +3 Acc you mentioned are the stats for a fairly standard 10x fixed scope, popular for medium to long range shooting at TL7, but at TL8 usually replaced by a variable power scope of some sort.

[Kelly Pedersen]

Originally Posted by jes722

\
But why dint they just give a scope a ACC and the weapon it self! And then swap scope in if you use it and/or give weapon a max acc even with a scope because of the weapons own statistics!

Both of those things are already how it works. If you see a weapon with an Acc given as "X+Y", the "Y" value is the Acc from the scope, and it will change if you put a different scope on it. And the bonus to Acc from a scope or other targeting aids can't exceed the weapon's base Acc.

[jes722]

I totaly missread that sorry!
Then its all good :)

[Rupert]

Originally Posted by Icelander

The +3 Acc you mentioned are the stats for a fairly standard 10x fixed scope, popular for medium to long range shooting at TL7, but at TL8 usually replaced by a variable power scope of some sort.

Actually, it's probably a x3-x9 variable power scope at late-TL7, or something fixed in power of anywhere from x8 to x12 from mid-TL7 onwards. Note that the latter is usually a target scope (where allowed) or varmint scope. For early-mid TL7 if you used a scope for medium or large game shooting it was most likely a fixed x4 or x6 power scope (4x32mm, 4x40mm, and 6x40mm were all standard scope powers in the late 80s and early 90s). From mid TL7 x2-x5 vari-power scopes were also popular for brush/bush hunting.

You occasionally found x16 power scope (target/varminting), and x6 to x10 scopes with huge objective lenses for night shooting.

It wasn't until a decade into TL8 that mid-range vari-power scopes weren't viewed by many shooters (with some justification) as being more delicate than fixed power scopes and more likely to 'leak' allowing moisture in and thus fogging up and becoming less than useful.

x3-x9 or x4-x16 with 40mm or 50mm objectives still seems pretty standard for normal hunting use, which doesn't surprise me - without stabilisation or a fixed mount more than x8-x9 magnification is quite hard to use. For hunting deer and the like I'd be quite happy with a x3-x9x50mm scope - plenty of power and an objective big enough to not lose brightness up to about x7 magnification. However, for many sporting rifles a scope bigger than about 40mm requires higher than normal mounts, which can affect comfort and accuracy due to a poor cheek weld and general posture.