Sniper shots

[kcdusk]

Fictional sniper. 10 strength and 10 rifle skill = 20 to hit.

M21 with bipod has range 75m + 15m = 90 for aimed shot with scope (short range), 180m Medium, 360m long, 720m extreme.


Using rules V2.2 our sniper shooting an aimed shot with sniper rifle, bipod and scope at an open target (i.e. no concealment or cover) 720m away would need to make a to hit roll of 5 or less (20 / 4 (aimed shot with rifle treated as formidable not impossible)).

So a 25% chance.

1. Do you think 25% is too high or low for this shot?

2. Its been reported that shots of 1,200 --> 1,600m have hit in real life. How do you allow or account for this in your game?

3. Do you allow any other positive modifiers in your games?

[rcaf_777]

Sounds right to me, try not real world this out, how this is calulated in the game to add to game play and give players with high weapon skills automatic hits ever time.

Remember snipers take a while to set up the shot, taking range and weather readings. I'm thinking that if the character been in place for awhile for this shot then you modify the number based the character "setting up the shot"

[leonpoi]

From memory the scope would also cause this to default to a long range hit chance if aimed = 50%

[kato13]

One of my favorite RPG source books was the "Compendium of Modern Firearms" written by one of the Morrow Project Authors Kevin Dockery.

It was particularly valuable for anything involving snipers as in addition to the normal stats for a weapon (weight, num of rounds, ammo type etc) it also presented the Dispersion Angle of the weapon.

No weapon fires perfectly straight. Sniper's rifles are much better than most but even a variation of 0.03 degrees will lead to a very large circle of potential deviation at 1200 meters range. This will mean luck is in the equation when you are dealing with extreme range limits of a weapon.



This graphic shows the effects of that Deviation when using a M-21 with match grade ammo. You can see that even when a rifle is bolted down and not effected by wind conditions there would only be a ~72% chance of hitting a body sized target at 1200 meters. When you add other variables like wind, human instability, and the over 40 foot drop the bullet would take over that distance the numbers seem right to me.

Other rifles are much better than the M21 in terms of deviation so those might be a better choice for a really long range shot.

[StainlessSteelCynic]

In addition to the info Kato supplied, it's worth remembering that many of the sniper shots taken at those longer distances were done with different ammunition to the M21.
Specifically, it was either .338 Lapua or .50BMG ammo, both offer a heavier projectile than the 7.62mmN round and an increase in propellant charge.
They're less affected by wind compared to the 7.62mmN and obviously have a longer trajectory (meaning bullet drop kicks in at it's worst, further down range than it does for the 7.62mmN).

For example (using Hornady's ballistics chart for their own ammo): -
At 300m, the projectile will take a trajectory that will place it x centimetres below the line of sight (to the target).
For .308 with 178grain projectile, trajectory is -47.1cm relative to line of sight
For .338 with 285grain projectile, trajectory is -38.5cm relative to line of sight
For .50 with 750grain projectile, trajectory is -33.9cm relative to line of sight

That is to say, at 300m all these projectiles will be travelling below the line of sight (LOS) but the .338 will be about 9cm closer to the LOS than the .308 and the .50 will be about 13cm closer to the LOS than the .308.
What does all that mean? As a gross simplification, if the shooter was aiming for a target at 300m, they will have to aim up (i.e. high) 47.1 cm to hit where they are looking at when using the .308 but only 33.9 cm high if they were using the .50BMG round.

Does that make sense? It's all clear in my head but I don't know if I explain it very well!


Notes:
1. Ballistics info for all rounds was taken from a 24 inch (60.9cm) barrel.
2. .308 is close enough for this purpose to 7.62mmN. I had to use .308 as the ballistics chart I was reading only had civilian ammo types!
3. I only selected the Match grade ammo types.

[swaghauler]

Originally Posted by kcdusk

Fictional sniper. 10 strength and 10 rifle skill = 20 to hit.

M21 with bipod has range 75m + 15m = 90 for aimed shot with scope (short range), 180m Medium, 360m long, 720m extreme.


Using rules V2.2 our sniper shooting an aimed shot with sniper rifle, bipod and scope at an open target (i.e. no concealment or cover) 720m away would need to make a to hit roll of 5 or less (20 / 4 (aimed shot with rifle treated as formidable not impossible)).

So a 25% chance.

1. Do you think 25% is too high or low for this shot?



2. Its been reported that shots of 1,200 --> 1,600m have hit in real life. How do you allow or account for this in your game?

3. Do you allow any other positive modifiers in your games?

On an ordinary shot, 25% accuracy at Extreme Range would be about right. You can take into account the longer range shots that have been recorded by doing a couple of things. First, I add a FIFTH range band called Maximum Range. This is 2X Extreme Range (in following along with the basic rules). Maximum Range fire can only be conducted if:
- You have the weapon braced or bipod/tripod mounted.
- Your character has a To Hit Skill of at least 1 at Extreme Range.
- You have an optic on your weapon that will allow you to see the target.
- You use an "Aim" action (this does NOT increase your chance to hit above a snap shot chance).

The real problem is the generic way that Twilight2000 treats scopes. There are no rules regarding scope quality or magnification. I initially developed some basic rules for scopes until I could get better rules written. Here are my basic rules on Magnified Optics. Use what you will and ignore the rest.

Range Adds:

There are four levels of Scope Quality and these levels will vary how much the scope adds to your range. This range adds to the base range band for both snap shots and aimed shots. The four Quality Levels (and how to determine them) are:

Poor Quality: [Magnification X 1] is added to the weapon's base range.
A scope is of Poor quality if:
-It has no definite "click adjustment" for elevation & windage.
-It has distortion or is blurry at the edges of its lens.
-It is poorly sealed (fogs) and/or the lenses are not coated.
-There is no "repeatability" (doesn't return to where it was set) in elevation & windage adjustments.

Fair Quality: [Magnification X 1.5] is added to the weapon's base range.
A scope is of Fair quality if:
-It has a 1 MOA to 1/2 MOA "click adjustment" for elevation & windage.
-It has a small amount of lens parallax but no parallax adjustments.
-It has a sealed tube and coated optics.
-It has reasonable "repeatability" in its adjustments (off by a couple of clicks).

Good Quality: [Magnification X 2] is added to the weapon's base range.
A scope is of Good quality if:
-It has 1/2 MOA to 1/4 MOA "click adjustment" for elevation & windage.
-It has no obvious parallax and/or has parallax adjustments to account for it.
-It is sealed and has multi-coated lenses.
-It has good "repeatability" in its adjustments (off by a click).

Excellent Quality: [Magnification X 2.5] is added to the weapon's base range.
A scope is of Excellent quality if:
-It has 1/4 MOA or less "click adjustment" for elevation & windage.
-It has fully sealed,"optically ground," 1st focal plane reticle, multi-coated lenses.
-It has complete "repeatability" in its adjustments.

Gm's should round the Magnifications down or up based on the description of the scope's quality. This gives the GM one more tool to create truly diverse equipment for his game.

Variable Magnification Scopes: Use the highest magnification for the range adds and the lowest magnification for determining the Minimum Effective Range (see below). You can change the Magnification on a Variable Power Scope by a number of Magnification Power Levels equal to the user's AGL in a single 1 second Initiative Step (or Action).

Range Finders & Bullet Drop Compensation: Scopes which have EITHER of these features get to treat Extreme Range Aimed Shots as fired at Long Range. Scopes with BOTH of these features treat Maximum Range (see above) Shots as Extreme Range shots. Scopes without a Range Finder or Bullet Drop Compensation Do not receive the benefit of reducing the To Hit Difficulty Level at Extreme or Maximum Ranges.

Minimum Effective Range: All scopes have a minimum effective range which increases with the scope's Magnification. If a weapon with a scope is fired at a target below this range; The chance to hit becomes ONE LEVEL more difficult (ie an AVE roll becomes DIF) due to the narrower field of view and "zoom" of the scope's magnification. A scope's Minimum Effective range is determined by multiplying its Magnification by 5 [Mag X 5]. If the combat range drops to the scope's Magnification in meters; The difficulty increases by TWO LEVELS (ie AVE becomes FRM). Variable power scopes use the lowest power setting to determine Minimum Effective Range.

I also include some other scope features that you may find useful in game.

Light Transmission: A scope's light transmission is determined by the scope's "Exit Pupil." To determine a scope's "Exit Pupil," divide the scope's Objective (in mm) by its Magnification (use the lowest one on variable power scopes). The three transmission ratings are:

Poor: Exit Pupil of Less than 4. Scopes with poor light transmission are one level more difficult to shoot in reduced light settings.

Normal: Exit Pupil of 4 to 7. Scopes with standard light transmission give the shooter no penalty or advantage in reduced light situations.

Good: Exit Pupil of more than 7. Scopes with good light transmission are as easy to shoot in light level 2 (as per Twilight2000) conditions as in direct sunlight.

Weapon Speed: Scopes with a fixed magnification of less than X10 add 1 to the weapon's bulk for determining who shoots first. Scopes with a magnification of X10+ OR a variable power magnification, add 2 to the weapon's bulk for weapon speed.

Field of View: This is important when a character is "on his scope" and needs to spot a target. Field of view in degrees can be converted to ft at 1000 yards by using this formula [Degrees X 52.5 = feet]. You can then convert to meters. Scopes can be used just like binoculars to reduce the Range of Observation (see my post in Spotting and Observation for more about this) for spotting a potential target. The spotting range reduction bonus is 1/2 the Scope's Magnification.

Durability: This is a trait that I use to determine damage to Optics, Electronics, Power Tools and other delicate items. It is a rating from 1 to 10 and measures a device's "resistance" to impacts or abuse. Whenever an item is dropped or subject to concussion or hard impact (say being run over by a car) it is subject to a durability check. If the distance dropped in meters or blast damage in dice is less than the object's durability; NO DAMAGE IS TAKEN. If the force it is higher than the object's durability; INCREASE THE OBJECT'S WEAR VALUE BY THE REMAINING AMOUNT. Gm's may want to have players roll OVER the NEW WEAR VALUE to avoid damage that must be fixed. Durability falls into three distinct categories:

"Poor Durability"......... is from 1 to 2
"Normal Durability"..... is from 3 to 5
"Rugged Durability" .... is from 6 to 8
"Milspec Durability" ..... is from 9 to 10

The Gm should set the item's durability based on its real world description.

Other Equipment of The Sniper:

Bipods: I have three distinct types of bipod in my game.

Light Bipods: Light bipods represent the very thin bolt on or "clip on" (via a scissors-type clamp) after market bipod. These bipods only add 5 meters to a rifle's range and are more suited to Assault Rifles than DMRs or Sniper Rifles. The bipod on the FAMAS is of this type. These Bipods add 1 to the weapon's bulk when attached UNLESS THE BIPOD IS INTEGRATED INTO THE WEAPON (like the FAMAS).

Medium Bipods: These represent the heavier but still limited in adjustment bipods. The typical example of this type are the bipods on the RPK, RPK-74, and the BAR. These are not as "flimsy" as Light Bipods, and add 10 meters to the weapon's base range when used. Medium Bipods NOT INTEGRATED INTO THE WEAPON'S DESIGN add 1 to the weapon's bulk.

Heavy Bipods: These are the robust but limited adjustability bipods of GP Machineguns or the slightly smaller (but equally heavy) fully adjustable bipods often put on Target and Sniper rifles. The Harris Bipod would be a good example if this. These bipods add 20 meters to the weapon's base range and add 2 to the bulk of any weapon not designed with one on it.

Target slings: These represent a specialized sling like the "Ching Sling." You adjust the sling to "tie yourself into the weapon," and help reduce recoil by 1 point. The downside is that this type of sling will increase your weapon's "bulk" for determining weapon speed by 1 point as well. The shooter may choose not to use it at any time; "picking speed versus control" in his shooting. Ching Slings run about $100 use standard swivels and are (c/c).

Wind Meters/Barometers: These are used to identify atmospheric conditions, which are then used to make scope corrections (known as "doping the scope"). This will give the shooter a bonus of 1 to his To Hit Roll if he spends 2 combat rounds computing the wind and "doping his scope." These are also valuable tools for Artillery Fire Direction. Wind meters, like the commonly used Kestral Brand, cost $150 (S/S) have a Durability of 6, a Bulk of 0.1 (in my system) , and a Weight of 0.1kg.

Ballistic Computers: This is either a Black Berry looking device or as an APP for 21st Century Smart Phones. The external device costs $500 ($100 for the APP) (R/R), has a Durability of 4, a Bulk of 0.25, and a weight of 0.2kg. It does calculations for bullet drop, spin drift, wind effects, altitude, and barometric pressure. It takes 3 combat rounds to enter the data and "dope your rifle," but these computers make your hit probability ONE LEVEL BETTER (ie AVE becomes EASY) than the base shot would have been.

Surefire"KillFlash" Lens Covers: This lens cover goes over the front of your scope and reduces "lens flash" that might reveal the shooter's position when using a scope without an "anti-flash" coating on it. The item costs $100 (S/S) and has negligible weight and bulk.


I hope this helps you bring more depth to your DMRs and Sniper Rifles in game.

Swag.

[swaghauler]

I made some changes to my scope posting to update it.

[James Langham2]

I may sound cynical but I regard it as way too high UNLESS the firer is shooting a cardboard target on a known distance range. For a distance shot in combat without wind flags etc the chance should be next to zero (a recommended read for this is Shadow Over Babylon by David Mason - excellent on technical details).

[swaghauler]

Originally Posted by James Langham2

I may sound cynical but I regard it as way too high UNLESS the firer is shooting a cardboard target on a known distance range. For a distance shot in combat without wind flags etc the chance should be next to zero (a recommended read for this is Shadow Over Babylon by David Mason - excellent on technical details).

I'd have to ask a question about the shooting scenario above. Are we talking about an ordinary "grunt" who just happens to have a scoped rifle, or are we talking about a trained "Designated Marksman" or a trained/experienced "Sniper" taking the shot? If it's just a "grunt," I would say James is probably right. I would say that a trained sniper/designated marksman would be able to make such a shot. Why? Training.

First. Most trained shooters can use "mirage" or vegetation moving to determine wind speed. Every long range shooter KNOWS that 6kph of Wind Speed equals 1 MOA (or 3 Mils) of "hold off" on a target. The common US sniper scope usually has 5 Mils of lateral holdoff. This means the shooter can fire WITHOUT scope adjustments (using "favors" and "holds") in a 10 to 12 kph lateral wind.

Second. The above scenario is an Aimed shot on a stationary target (a sentry perhaps?). If you have time to Aim, you probably have time to range the target. There are 3 Mils or 1 MOA in 1000 yards. Knowing this, it is easy to determine a target's range. Range determination is fairly easy using a MilDot Ranging Reticle at ranges up to 800 meters (beyond this, visual acuity can affect range estimation). Each dot in the reticle is 0.2 Mils and the distance between the INSIDE OF THOSE DOTS is 0.8 Mils (equaling 1 Mil when combined). You can use these to measure the target in order to determine its size. Once you know the target's approximate size (you can also compare the target to an object of "known size" using the reticle), you can determine its Range in meters. You can determine the target size (in meters) by using the following two formulas.

1. Object Size (in inches) / (39 X 1000) / Mils Read on Scope = Target Size in Meters.
2. Object Size (in inches) X 25.4 / Mils Read on Scope = Target Size in Meters.

You then "plug in" the target size (in meters) into the following formula to determine the target's actual real world range:

Target Size (meters) X 1000/ Mills Read on Scope = Range to Target in Meters.

If you are part of a Sniper Team, the Spotter will be doing these calculations as the Sniper "Dopes his scope" (makes the adjustments for Windage & Elevation). Fun Fact- The primary Spotter (sniper teams frequently switch roles) is normally the MORE EXPERIENCED SHOOTER.

I have personally seen shooters ranging and shooting at "UNKOWN DISTANCE TARGETS" at the Sniper Walk competitions being held in PA and OH on a regular basis (some of the ones in Arizona & Colorado feature navigational exercises as well). Based on these experiences, I see no reason why making shots out to Extreme Range by an experienced Sniper or Designated Marksmen should be a problem during the game.

[ArmySGT.]

Thing it doesn't reflect is engaging a target under 100 meters. A fleeting glimpse at a fast moving target that really, really doesn't want to get shot.

Apply a strong negative to that ..... -50% for variable power scopes and -75% for fixed power scopes.

[James Langham2]

Originally Posted by swaghauler

I'd have to ask a question about the shooting scenario above. Are we talking about an ordinary "grunt" who just happens to have a scoped rifle, or are we talking about a trained "Designated Marksman" or a trained/experienced "Sniper" taking the shot? If it's just a "grunt," I would say James is probably right. I would say that a trained sniper/designated marksman would be able to make such a shot. Why? Training.

First. Most trained shooters can use "mirage" or vegetation moving to determine wind speed. Every long range shooter KNOWS that 6kph of Wind Speed equals 1 MOA (or 3 Mils) of "hold off" on a target. The common US sniper scope usually has 5 Mils of lateral holdoff. This means the shooter can fire WITHOUT scope adjustments (using "favors" and "holds") in a 10 to 12 kph lateral wind.

Second. The above scenario is an Aimed shot on a stationary target (a sentry perhaps?). If you have time to Aim, you probably have time to range the target. There are 3 Mils or 1 MOA in 1000 yards. Knowing this, it is easy to determine a target's range. Range determination is fairly easy using a MilDot Ranging Reticle at ranges up to 800 meters (beyond this, visual acuity can affect range estimation). Each dot in the reticle is 0.2 Mils and the distance between the INSIDE OF THOSE DOTS is 0.8 Mils (equaling 1 Mil when combined). You can use these to measure the target in order to determine its size. Once you know the target's approximate size (you can also compare the target to an object of "known size" using the reticle), you can determine its Range in meters. You can determine the target size (in meters) by using the following two formulas.

1. Object Size (in inches) / (39 X 1000) / Mils Read on Scope = Target Size in Meters.
2. Object Size (in inches) X 25.4 / Mils Read on Scope = Target Size in Meters.

You then "plug in" the target size (in meters) into the following formula to determine the target's actual real world range:

Target Size (meters) X 1000/ Mills Read on Scope = Range to Target in Meters.

If you are part of a Sniper Team, the Spotter will be doing these calculations as the Sniper "Dopes his scope" (makes the adjustments for Windage & Elevation). Fun Fact- The primary Spotter (sniper teams frequently switch roles) is normally the MORE EXPERIENCED SHOOTER.

I have personally seen shooters ranging and shooting at "UNKOWN DISTANCE TARGETS" at the Sniper Walk competitions being held in PA and OH on a regular basis (some of the ones in Arizona & Colorado feature navigational exercises as well). Based on these experiences, I see no reason why making shots out to Extreme Range by an experienced Sniper or Designated Marksmen should be a problem during the game.

I agree that in ideal conditions this is achievable. However in a COMBAT situation this is less easy.

I also remember coaching once at Bisley and looking at the wind flags to see each was blowing in a different direction... decision - take the shot and adjust!

[copeab]

Originally Posted by swaghauler

I'd have to ask a question about the shooting scenario above. Are we talking about an ordinary "grunt" who just happens to have a scoped rifle, or are we talking about a trained "Designated Marksman" or a trained/experienced "Sniper" taking the shot? If it's just a "grunt," I would say James is probably right. I would say that a trained sniper/designated marksman would be able to make such a shot. Why? Training.

I really doubt an ordinary grunt would have rifle skill 10.