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Old 05-11-2016, 12:55 AM   #11
Polydamas
 
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Default Re: Handling Long-Range Musketry

Quote:
Originally Posted by Varyon View Post
I don't know how far back it goes, but GURPS Acc actually has a close relationship to the weapon's MoA - you can see this in Tactical Shooting, where Acc serves to allow you to calculate maximum effective skill (which is a function of MoA).
Minutes of Arc are a measurement of a model which was designed to be simple and describe late 20th century firearms, and safisher reminds us that assigning weapons an Acc score in GURPS is a matter of judgement and looking at the stats of similar weapons, not a matter of measuring something. If you check the FAQ, they explain the process- and the kind of testing from a clamped rest which some firearms manufacturers use to measure accuracy in minutes of art would not work for lariats, javelins, and other things with an Acc score in GURPS

Its possible that TS uses Acc to calculate maximum possible Aim bonus and skill because its the most appropriate game stat, not because if Hans were building a model from scratch, he would use one number to represent pointability, accuracy from the shoulder over iron sights at medium range, and accuracy prone from a rest at extreme range.
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Last edited by Polydamas; 05-11-2016 at 01:25 AM. Reason: Added link to FAQ
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Old 05-11-2016, 01:58 AM   #12
Tomsdad
 
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Default Re: Handling Long-Range Musketry

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Originally Posted by Varyon View Post
This is a spin-off from the What kinds of firearms would people start making [After the End]? thread, wherein there was some debate over how accurate smoothbore muzzleloaders should be, with a nod toward their strange exterior ballistics (namely, that they have a bad habit of deviating from their aimpoint more rapidly than standard GURPS Range rules suggest - this is due to a combination of factors, from not being a perfectly-smooth sphere to changes in trajectory due to spin).

Based on the numbers from a Master's thesis linked in that thread, I think I have an idea of how to handle this in GURPS. In that, at some point between 50 yards (-8 to hit) and 80 yards (-10 to hit), the projectiles picked up somewhere between -3 and +2 to skill, with an average of -0.111 (I approximated this using 1d-4). Beyond this, there was something like a further -1 to hit at each -1 from Range, for a total of -2 per point of Range. The shots only went out to about 170 yards, however.

Still, from this, a bit of a pattern emerges. A low resolution solution is to double all Range penalties beyond 70 yards, so that a musket sees range penalties as (...-7, -8, -9, -11, -13, -15, -17...). A bit higher resolution option would be to replace the first -1 with 1d-4, and you could possibly push the range back a step, with (1d/2)-2 beyond 50 yards, rounding normally (so you'd be between -1 and +1 to hit). A much higher resolution option would be to do something like (1d/2)-2, 1d-4, 1d-5, 1d-6, 2d-10, 2d-11, 2d-12, 3d-16, and so forth (although I'd replace each nd with 1dxn, so that you don't get a tighter spread with each added die).

The range at which this starts to come into play is going to vary. The above is perhaps appropriate for an Acc 2 weapon (not certain how good the weapon used in the testing was). Each +1 to Acc from being Fine (Accurate), opting for Careful Loading, and so forth, is +1 SSR to the range beyond which the above effect comes into play. Higher-quality ammunition may also be available - while typically below GURPS resolution, such ammunition is double cost but is +2 SSR to the above range (and this does stack with Accuracy modifiers). Each -1 to Acc from being Cheap, black powder fouling, and so forth, is -1 SSR to the above range. Using field-expedient projectiles drops the range due to Acc penalties and gives a further -2 SSR to the range.

Do keep in mind that, with the sorts of penalties the character is already going to be suffering for Range (by default, the above rules kick in at 100 yards, or 70 if using (1d/2)-2, which correspond to penalties of -10 and -9, respectively; a base Acc 1 pistol firing field-expedient projectiles is about the worst situation possible, and even it doesn't see an effect until it's at -7 or -6 from Range), the above typically isn't going to make much difference, and can probably be safely ignored in most campaigns. If a musketeer sniper harms your Sense of Disbelief, however, the above is a way to handle that. If using Tactical Shooting, note that the above modifiers come into play after the MoA-based skill cap.
Would you do be doing this is addition the the flight time mods from TS?

Because my first thought would be to adjust that mod for certain weapons

(To be honest I would tend to adjust that mod for changes in circumstantial factors anyway)
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Old 05-11-2016, 02:19 AM   #13
Tomsdad
 
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Default Re: Handling Long-Range Musketry

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Originally Posted by Polydamas View Post

I would be surprised if those other systems are any more accurate than GURPS if you look closely at the numbers and compare experimental data.
I haven't done a side by side test for different systems (which would be dependent on a lot more factors than just this one anyway). I just generally like the idea that certain set ups favour certain ranges bands, and that would seem to match reality. It was more an observation anyway.


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Originally Posted by Polydamas View Post
And can you imagine how much work it would be to get performance at different ranges under combat conditions for every weapon in High Tech?
I don't think it would have to be that specific. If nothing else just as there are a lot of Acc 4 rifles, I'm guessing there would be a lot for ballistic performances that were pretty much the same at the level of granularity we're dealing with. (I actually think tying it to different projectiles would be a more appropriate way to go in some instances)

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Originally Posted by Polydamas View Post
I have never had a game session be less fun because a weapon performed slightly differently than it probably would in the real world, if the real world had magic, demons, and Gunslinger. Sometimes we shrugged and said "that is not not we think it works, but changing the rules would be too much work and might not be any better, so lets do what they say and get on with the adventure."
Well In general I agree, but what's generally true for us isn't necessarily true for the everyone one on this website (or come to that every type of game I might conceivably want to run)

Last edited by Tomsdad; 05-11-2016 at 05:55 AM.
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Old 05-11-2016, 02:25 AM   #14
swordtart
 
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Default Re: Handling Long-Range Musketry

I think this is a specific muzzleloader issue and possibly only muzzle-loaders firing round ball(rather than say Minnie Ball).

As such I don't think a whole scale revision of every gun in the game is required. The games has exception conditions all though it (one of the reasons we like it is that whilst the stat lines are fairly constant there are sidebar comments that allow additional complication if you want to do the extra work).

With modern guns, you can probably plug in some fairly consistent formula and get a number that is close enough to the real life performance (given the granularity of the stat lines). Modern snipers have tables to allow for wind and gravity. This suggests that modern guns are fairly precise and fairly predictable and thus can be modelled (so you can get good groupings, even if they all hit a foot below and 6 inches left of your point of aim).

With smoothbores firing round ball the arc gets increasingly erratic and not just in the vertical. You can easily add a cumulative penalty, but I think the key point is that this penalty should not be offset by greater skill (or skill enhancing modifiers - like better sights and aiming). With a predictable change you can compensate (aim higher for longer range, ain off to allow for wind etc.) and this is a function of skill. No amount of skill can compensate for the projectile having an unpredictable flight path.

You could simply apply a flat rule that says at x range the maximum chance to hit including all modifiers is Y. Y decreases by 1 per additional z range interval.

It should also be fairly simple to model the historical test results. We know the target size in GURPS terms. We know the percentage hits. The only thing we need to do is decide the skill level of the shooter and any situational modifiers and work out what the GURPS chance to hit is and work out the required modifier to bring it down to the test chance. For simplicity you could just average the results rather than try to do this per specific gun (as better performance in a particular test could be from better training, better equipment, favourable conditions on the day or any number of unrecorded variations.

Arguably the MSc trial shows the effect of maximum skill. The gun was braced in a fixed mount and laser sighted. It wasn't testing if the ball could hit a specific target just the grouping from a consistent aim point. You could allow that a skilled musketeer might be able to improve on the results a little if he had the foresight before the battle to select the roundest most consistent ball, carefully measure his powder and load carefully to avoid any distortion of the ball and reduce windage.
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Old 05-11-2016, 03:05 AM   #15
Tomsdad
 
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Default Re: Handling Long-Range Musketry

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Originally Posted by swordtart View Post
...

You could allow that a skilled musketeer might be able to improve on the results a little if he had the foresight before the battle to select the roundest most consistent ball, carefully measure his powder and load carefully to avoid any distortion of the ball and reduce windage.
Just to say there are rules for this in LT, if you double your loading time (doing all that) you get +1 bonus.
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Old 05-11-2016, 06:46 AM   #16
swordtart
 
Join Date: Jun 2008
Default Re: Handling Long-Range Musketry

Indeed, I was suggesting that this might be the only action that might allow you to improve the precision of the musket.

If you apply a skill cap, this could improve it by one. If you choose a maximum chance to hit this could increase it by one.

I also think that it is something that needs to be prepared for in advance by aquiring the equivalent of Match grade ammunition (probably casting it yourself with a custom mould and fettling it). With an imperfect ball, loading carefully won't help. Loading fast with a perfect ball may turn it into an imperfect ball.

From experience, a perfect ball also needs to be protected. Musket balls rattling around in a pouch quickly aquire flat spots (though interestingly it also knocks off the mould lines and sprue stubs). Cartridges provide adequate protection and allow you to carefully measure the powder in advance. They can also be weather protected more easily than loose powder.

Loading with a cartridge (with a correct size ball - undersized balls were used to speed up loading) can take longer than with a collar of bottles and loose ball so this may fit well the rule cited by Tomsdad.

You will also need to load your own in advance. Ordinarily cartidges are mass produced in factories and so are not tailored to a particular gun. This is ideal for regimented armies using a similar bore who want to fire quickly and cheaply, but not so useful for the targeteer who wants to maximise his chance of hitting.

Loading a mass produced cartridge forgoes the benefit of loading carefully as you have no control over the size of the ball, whether it was well formed, or the quantity and quality of the powder (which could vary significantly between cartridges of different batches and storage times). You also need to be wary of the manufacturer who may have cut corners to increase their profits (replacing a portion of the powder with soot or sawdust for example), especially as you can't really check a cartridge without opening it.
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Old 05-11-2016, 08:31 AM   #17
Varyon
 
Join Date: Jun 2013
Default Re: Handling Long-Range Musketry

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Originally Posted by Ulzgoroth View Post
There's a very interesting, though possibly problematic, box on page 41 of Tactical Shooting relating to this. It includes halving Acc for a gun with misaligned sights and reducing it to 0 if the sights are destroyed.

The problem with this, of course, is that there are lots of weapons with no sights and non-zero Acc values throughout the books...
In the hands of a modern shooter, giving a weapon without sights Acc 0 may well be appropriate, as they'd be so used to having sights that they would have issues Aiming without them. GURPS characters, as well as shooters at lower TL's, on the other hand, should probably be expected to know how to use the barrel itself for Aiming (much like an archer can Aim down the shaft of an arrow; failing that, I came across one account of a person using the bayonet lug for primitive sighting), although I don't think this should allow for more than Acc 1 or 2.

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Originally Posted by johndallman View Post
It appeared in After the End 1, p32, after having been on PK;s MyGURPS site for several years.
Alright, then - that -1 Acc reduces the Range at which scatter comes into play.

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Originally Posted by Polydamas View Post
Minutes of Arc are a measurement of a model which was designed to be simple and describe late 20th century firearms, and safisher reminds us that assigning weapons an Acc score in GURPS is a matter of judgement and looking at the stats of similar weapons, not a matter of measuring something. If you check the FAQ, they explain the process- and the kind of testing from a clamped rest which some firearms manufacturers use to measure accuracy in minutes of art would not work for lariats, javelins, and other things with an Acc score in GURPS
Fair enough.

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Originally Posted by Tomsdad View Post
Would you do be doing this is addition the the flight time mods from TS?
In addition. Granted, the majority of the shots I'm basing it on had velocities over 400 yards per second (a couple were instead in the mid-300's), and you're looking at 1d-5 at around 200 yards. So, this spreads things out more rapidly. You could probably be forgiven for only using one or the other, however.

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Originally Posted by swordtart View Post
I think this is a specific muzzleloader issue and possibly only muzzle-loaders firing round ball(rather than say Minnie Ball).
Yeah, Minie Ball is going to greatly reduce this problem. Lack of spin is going to be a bit problematic, but that's handled well enough by the lower Acc the weapon has for not using a rifled barrel.

Quote:
Originally Posted by swordtart View Post
No amount of skill can compensate for the projectile having an unpredictable flight path.

You could simply apply a flat rule that says at x range the maximum chance to hit including all modifiers is Y. Y decreases by 1 per additional z range interval.
My suggestion actually does this, when combined with the Minute of Arc rule from Tactical Shooting. A skill cap of, say, 26* means that, at 70 yards, you cannot have effective skill higher than 17, or a 98% chance (although with Malf. 14, that drops to an 84% chance). Using just the MoA rule, that means at 200 yards you cannot have effective skill higher than 14, or a 91% chance. Adding in my suggestion, the low-resolution version means at 200 yards you cannot have effective skill higher than 11 (62% chance). Higher resolutions make this variable, but still average out around 11.

Of course, you don't have to be a master shooter (Skill 20, Braced, Aiming for 3+ seconds, and using an All Out Attack to reach 26) for the ball's scatter to mess you up, which is why I have it as a penalty, rather than just a cap.

*It's hard to find decent data on musket MoA using a few quick Google searches, but from what I can tell they typically have higher MoA than the 5 implied by a skill cap of 26. If we assume MoA 36 is typical of a smoothbore musket (as I saw claimed in several of my results), that's a skill cap of either 20 or 21 (the musket from the thesis, based on performance at 50 yards, appeared to have a skill cap somewhere in the vicinity of 23 or 24). Note this markedly changes to above probabilities - assuming a cap of 21, 70 yards means maximum skill of 12 - 75% - and 200 yards means a maximum skill of 9 - 37% - and my suggested rule drops the 200 yard shot to 6 - 9%. It also means we only need skill 15 - an expert shooter - to be able to hit our cap. As period rifles apparently had MoA's somewhere around half those of muskets (at the worst), that's a cap of at least 23, and helps explain why you'd want a rifle for distance shots.

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Originally Posted by swordtart View Post
I also think that it is something that needs to be prepared for in advance by aquiring the equivalent of Match grade ammunition (probably casting it yourself with a custom mould and fettling it). With an imperfect ball, loading carefully won't help. Loading fast with a perfect ball may turn it into an imperfect ball.
Simply properly measuring out the powder (already done for any paper cartridge made by a competent shooter) and having a smooth loading should be enough to see a boost in Acc. Using a perfect ball is below normal GURPS resolution - most balls are good enough for GURPS Acc granularity - but as I noted in my post, it should be an option that increases the range at which you start taking penalties for scattering.

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Originally Posted by swordtart View Post
You will also need to load your own in advance. Ordinarily cartidges are mass produced in factories and so are not tailored to a particular gun. This is ideal for regimented armies using a similar bore who want to fire quickly and cheaply, but not so useful for the targeteer who wants to maximise his chance of hitting.
From my reading, GURPS automatically assumes the characters are loading their own cartridges and making their own bullets. High Tech notes that troops typically spent the night before a battle making their own cartridges, while Low Tech states that armies typically just carried around lead ingots, and the troops used these to cast their own bullets (using molding gear specific to their weapons). Using standardized bullets with muskets that aren't standardized strikes me as a losing proposition.

Last edited by Varyon; 05-11-2016 at 08:36 AM.
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Old 05-11-2016, 09:48 AM   #18
Polydamas
 
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Default Re: Handling Long-Range Musketry

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Originally Posted by Tomsdad View Post
Well In general I agree, but what's generally true for us isn't necessarily true for the everyone one on this website (or come to that every type of game I might conceivably want to run)
Absolutely ... but until we can find one person who is actually playing GURPS and finds that the rules for long-range musketry make their games less fun, its probably not a good idea to worry too much. Playing around with ways to represent things in the real world can be fun, but in my experience it does not have much impact on play unless all the work can be front-loaded. Even then, it may be more a GM's worry than a player's worry, like setting design.

It would have been better if they had clarified how cheap firearms work in HT, but GURPS is very complex, and because citing sources is against house style, books which are compiled from earlier GURPS products or contain a lot of technical details are hard to write and edit.
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Old 05-11-2016, 12:28 PM   #19
Anthony
 
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Default Re: Handling Long-Range Musketry

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Originally Posted by Tomsdad View Post
If reality is that accuracy in general is maintained for longer but then drops faster past a certain point, that to me that sounds like the underlying issue is how range table spaces the range penalties by distance.
It's not really.

For pretty much any modern weapon, hit probability for a correctly aimed shot at 100 meters will be 100%. In the real world, shots at 100 meters do not hit anywhere near 100% of the time. This tells us that most shots are not in fact correctly aimed -- i.e. the issue is shooter error, not anything about the gun. GURPS skill is mostly about error rates.

A more realistic version of accuracy than what GURPS does would be an aim bonus that is completely determined by the ergonomics of the weapon, and then a maximum skill that is determined by the intrinsic accuracy of the gun.
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Old 05-11-2016, 12:31 PM   #20
Varyon
 
Join Date: Jun 2013
Default Re: Handling Long-Range Musketry

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Originally Posted by Polydamas View Post
Absolutely ... but until we can find one person who is actually playing GURPS and finds that the rules for long-range musketry make their games less fun, its probably not a good idea to worry too much. Playing around with ways to represent things in the real world can be fun, but in my experience it does not have much impact on play unless all the work can be front-loaded. Even then, it may be more a GM's worry than a player's worry, like setting design.
My suggestion isn't much more of a hassle to use than the Time of Flight rules, and if opting for the low-resolution version is fairly easy to frontload - all smoothbores would have an additional Range value, call it Effective Range or whatever, which would designate the point after which it suffers a -2 per Range increment, rather than a -1. You could add it in parentheses after the weapon's Range. So, you might have a weapon that is Range 120/1200 (70), which means for a 200 yard shot you're at the normal -12 for Range, then another -3 (for being 3 steps beyond 70) for drift. I think a more important factor, however, might be adjustments for proper MoA - if smoothbores do indeed hover around MoA 36, that's a maximum effective skill of 21*, which is reachable without having a cinematic character (unlike effective skill of 26).

That said, the above is likely more useful to answer the question of "Why bother with rifles when muskets are only marginally less accurate and can be loaded more quickly?" which is, as you noted, more a GM/setting question than a player question (where "+1 Acc on a weapon I can only use once per combat anyway? Yes, please" is the answer).

*Assuming I'm figuring out maximum skill correctly, anyway. I figured out how it goes a while back and am basing my current numbers off of old posts, as I don't remember exactly how it's meant to be calculated. MoA 36 is a grouping of around 1 yard at 100 yards, meaning you can just barely hit a circular target with a 1 yard diameter, which would be right around SM 0, at 100 yards (-10 to hit). A roll of 10.5 implies normal conditions; a higher or lower roll means luck was (perhaps slightly) for (lower roll) or against (higher roll) you. Round this up to 11 (implying luck being slightly against you), or use the optional "Taking 11" rule, and that means effective skill of 21.
(EDIT: Looks like MoA actually refers to a 69% hit rate, which is more like a roll of 11.5 or 12. That would mean effective skill of 21.5 or 22)

Quote:
Originally Posted by Anthony View Post
A more realistic version of accuracy than what GURPS does would be an aim bonus that is completely determined by the ergonomics of the weapon, and then a maximum skill that is determined by the intrinsic accuracy of the gun.
Yes, please.

Last edited by Varyon; 05-11-2016 at 12:54 PM.
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