GURPS telescopic sights work fairly simply. Each doubling of magnification gives a +1 bonus if you aim for a number of seconds equal to that bonus. So the “valid” scopes are x2, x4, x8, x16, etc. If you have a x1.5 scope, like the minor magnification on the Steyr AUG, you get nothing (+0 to Acc). If you have a x3 magnifier stacked in front of a collimating sight and use it as a telescopic sight, you get +1.

Them’s the breaks of breakpoints. Sometimes something is sub-resolution.

I was pondering based on an appropriately named thread on the SJG forums if there is a slightly different way to handle such odd powers: simply rewrite the Size and Speed/Range Table for your scope’s magnification, which is another way of saying calculate range penalties based on the effective range after accounting for magnification.

Implementation could either be by making a custom Size and Speed/Range table for yourself, or simply dividing range by your scope’s magnification, which is math at the table. Personal preference would apply.

Does It Work?

Short answer: no.

Longer answer: not exactly; you have to make a modification based on the fact that you’re dealing with a scale that has its zero point at 2 yds instead of 1 yard, so you have to divide all the net modifiers by 2, rounding up.

Actual Range	Scope	RAW Bonus	Effective Range	Old Range Pen	New Range Pen	Wrong Bonus	Adjusted Bonus	Delta
270	15	3	18	-13	-6	7	4	1
500	1	0	500	-14	-14	0	0	0
500	2	1	250	-14	-12	2	1	0
500	4	2	125	-14	-11	4	2	0
500	8	3	63	-14	-9	5	3	0
500	16	4	31	-14	-7	7	4	0
500	32	5	16	-14	-5	9	5	0
500	64	6	8	-14	-3	11	6	0
580	1	0	580	-15	-15	0	0	0
650	20	4	33	-15	-7	8	4	0
820	3	1	273	-15	-13	3	2	1
1040	11	3	95	-16	-10	6	4	1
1220	15	3	81	-17	-9	7	4	1
2020	17	4	119	-18	-10	7	4	0
2460	3	1	820	-18	-15	3	2	1
3120	16	4	195	-19	-12	7	4	0
3180	15	3	212	-19	-12	7	4	1
4170	16	4	261	-20	-12	7	4	0

So, there are times when odd-power scopes actually make a difference, straddling range bands. The “divide by 2” thing is odd but that’s the way it goes.

Is math at the table worth it? Probably not. Strike that: certainly not. That’s a lot of fiddle to make a x1.5 or x3 magnifier work by division. First do the math, then more math, and most of the time it’s the same value as RAW.

What about the SSR?

There’s another way to do this, though, which is to leverage the power, as alway, of the size and speed range table. I’ve done this before (but can’t find it) in that I rescaled the RoF bonuses to be half the boost you get for the Size Modifier based on number of bullets fired. It works a bit better than the table in the Basic Set.

Looking at scopes, you see the same thing. You get +1 for each doubling of magnification; this is basically +1 for every (approximately) two steps up the Size and Speed Range table.

And yet the SSR has such NICE numbers. 1.5, 2, 3, 5, 7, 10, 15…

1.5x and 3x scopes are both found on real-world guns, and the 3x magnifier is standard issue for such things. One of the most common higher power scopes is the 10x.

So just use the numbers: each step up from a magnification of 1x gives you +0.5 bonus, and then round up.

Magnification	Raw Boost	Bonus
1	0	0
1.5	0.5	1
2	1	1
3	1.5	2
5	2	2
7	2.5	3
10	3	3
15	3.5	4
20	4	4
30	4.5	5
50	5	5
70	5.5	6

So the in-handle scope of the AUG gets you +1. 3x and 4x magnifiers get you +2, a satisfying improvement over a reflex sight and a reason to pair a magnifier with such a beast. Common ranges like 3-9x or 5.5-22x will all have a delta of about 2 points of Acc. A 10x is right there on the chart and gives you +3. Most spotting scopes are in the +5 zone, but I saw one monster with a 70x magnification and hey, that gets you +6.

Parting Shot

The simple doubling per +1 is exactly that, simple. And it does work. But a quick tweak as above gives more satisfying results (well, to me), and works better with my rate-of-fire fix that I implemented in my Alien Menace game (which I believe was the result of fiddling around with RoF for one of Mark Langsdorf’s games). It has the side-effect of explicitly addressing some common magnification ranges, too. It also doesn’t do funky math at the table.

It’s interesting that the “just divide range by magnification” doesn’t work, both because of “zero issues” that were discussed in my chat about scaling with EABA and GURPS, as well as just giving too big of a bonus, too fast (this issue also existed with high RoF, and had the same solution: halve it).

But I like it; in future games with guns, I’ll use it.