Sunday, February 3, 2013

Validating GURPS's ranged model : a GM on the range.

I often wondered what is my skill level in archery. I've been shooting for two years and have seen striking improvements between what the club beginners can do and how I shoot today. Let's crunch the numbers and figure out what is my skill level, and whether this is consistent with GURPS mechanics. I want to specify that I didn't try to make it fit as well as it did: I just threw in values that seemed reasonable from a GM's perspective. This post was inspired by a recent post by +Douglas Cole that can be found here. i once tried the same exercise with AD&D, and it didn't made a lot of sense.

Let's assume that I have a DX 10, which is reasonable and a good assumption in absence of other supporting evidence. I have a good quality, mid-level recurve bow (+0 quality), with a sight and a stabilizer (+2 for both as my dispersion goes from 3" to 8" if I take them off and keep everything else unchanged). I assume that the bow has an intrinsic Accuracy of 3 ( as per basic rules), although it isn't a "longbow". It is, after all, a target shooting/tuned bow. We'll assume that the bonus to be "on the range" is +7.  At 15 yds (-5), I shoot about 50% of my arrows within 3" (-8) of the bull's eye (I eyeball this, my average is around 26/30).

In summary, my modifier for any given shot is: Range (-5), Size (-8), Aiming (+5), Sight/Stabilizer (+2), Quality (+0), "On the range" (+7) = +1 . This means that to have a 50% chance of hitting such target with a +1 modifier, my net skill must be 9. This means DX-1 (or one rank for a DX/A skill), which implies one character point into bow for me. I've been shooting for about 80 hours total, unsupervised by a teacher (not enough to put a second point into it). This makes perfect sense, assuming that the "On the range" bonus is reasonable.

Now, let's consider the newcomers at the club. There are a lot of them since the "Hunger Games", and "Brave", and some other TV series that I don't know much about. A newcomer essentially will be putting 50% of their arrows within 2ft (-4) at 10 yd (-4). Club bows are not as finely tuned, so let's downgrade their Accuracy to 2, but of a normal quality.  In summary: Range (-4), size (-4), Aiming (+4), "On the range" (+7) = +3. The net skill has to be about 7 to get a 50% chance of success, or DX-3. This kind of makes sense because the default for bow is DX-5, and that this levels really applies only for the first few arrows. The world seems to make sense, if anything, the default DX-5 may be a little stiff.

Ma' Girl, shooting a high-density foam wolf.
Let's see if this makes sense. Here is a picture of a 3D tournament. For the non-archer in the audience, a 3d shoot involves 20 targets at undisclosed ranges, of various shapes and sizes. The mean target size is 3ft, so let's call it 1 yd (-2), with the "vitals" being size 1ft (-5), and the heart 3" (-8). The ranges in the recurve category are between 15 yd to 30yd (-5 to -7). As I'm not outfitted as a hunter, my sights has only one setting. I think that this degrades the "On the range" setting to +5.

My probabilities of hitting "things" are thus as follow: range (-6), Aiming ( +5 ), Equipment (+2), "On the range" (+5) = +6 without range penalties.

  • Animal (-2) : +4 [+9=13], or 83%, 13 arrows * 5pt = 65 
  • Vitals (-5) : +1 [+9=10], or 50%, 14 arrows * 8pt = 112
  • Heart (-8) : -2 [+9=7], or 16%, 6 arrows * 10 pt = 60

If I tally all of these scores, this gives me a tournament final score of 237. Which is, shockingly, just about what I scored last December (Can't remember the precise score, I think that it was maybe 225 or so)!

In conclusion, I ascribe that in most cases, people's shooting tend to get better largely because equipment upgrading (hunting sights, side-stabilizers, clickers, quality +1 equipment) rather than a progression in character points. I also think that anyone who makes it to DX +1 or above would tend to lose their edge very fast if they stop shooting.


  1. Dabbler perk, gives people who dabble in things like that improved defaults.

    p.16, GURPS Power-Ups 2: Perks

    1. I can see people trying archery as more likely to be dabblers. This makes sense.

  2. Would you believe that I have been waiting since Oct to go to the CFB Halifax range!

    I am on a waiting list for Noobs. All Noobs must qualify on newbie night before they can shoot on the other 2 nights.

    From where I sit on this list, it appears that very few people in front of me are qualifying.

  3. Because of the precarious building, or over cautious building code, the range has been closed since December. You have not missed anything, unfortunately.