Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > GURPS

Reply
 
Thread Tools Display Modes
Old 01-07-2015, 07:17 PM   #11
hal
 
Join Date: Aug 2004
Location: Buffalo, New York
Default Re: [Tactical Shooting] Bullet Travel and MOA when Shooting Black Powder

Quote:
Originally Posted by Icelander View Post
Damn. Yeah, so it is.
Incoming. :)
hal is offline   Reply With Quote
Old 01-08-2015, 03:05 AM   #12
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: [Tactical Shooting] Bullet Travel and MOA when Shooting Black Powder

Quote:
Originally Posted by hal View Post
I wasn't going to dig up the book, but the title of a decent book to get would be:

THE GUNS THAT WON THE WEST
Firearms on the American Frontier, 1848-1898
by John Walter
Greenhill Books

I did a quick search on Amazon.com and a copy of the book can be had for 98 cents plus shipping and handling (which I would guess is a bit higher than $3.99 outside of the US, but still might be worth picking up used).

In all, I consider it a nice book to pick up, and when purchased used, a nice book at a nice price.
I'm very interested in the book, but being in Iceland, would have prefered digital format.

Since it's a third-party seller, I can't usefully combine the purchase with others that go in the same shipment. This means that handling and shipping will probably be more than the book costs new.

I will have the book at the end of February. That's nice, Amazon. I'll also get a book on British gunmakers in London at that distant point in time. At least Cartridges of the World was available in digital form, so I have that now.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 01-08-2015, 03:13 AM   #13
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Some places to look --

Quote:
Originally Posted by fredtheobviouspseudonym View Post
Some of the discussants have compared their accuracies with those attained by test shooters in the 1870s.

These latter documents would be what you're looking for -- I'd suggest searching US Army records on line for Bureau of Ordnance reports. Also IIRC there were congressional hearings early in the 1870s that reported on the testing of the new rifles for the US Army and, again IIRC, accuracies were reported to the US Congress.

IIRC modern shooters could get four minutes of arc with somewhat used weapons and careful handloading of black powder cartridges for an 1873. The careful handloading would not, of course, apply to 1870s shooters but then again their weapons would not be c. 140 years old.
I found that period tests showed the Martini-Henry grouping at around 27.5" at a range of around 1,200 yards. A modern shooter was able to get a 10" group at 900 yards*, but that would be Match Ammo in GURPS terms.

At 660 yards, the Remington Rolling Block chambering a 12.17mm round grouped just under 38". The Mauser IG71/84 grouped 31" at 660 yards. Most other service rifles of the day were making groups somewhere at the 31"-40" mark at 660 yards.

That's 4.7-6 MOA. In all cases except the modern shooter, this is using service ammunition and stock rifles.

The clear outlier is the Martini-Henry, with 2.3 MOA that persists even to extreme range using stock rifles and issue ammunition.

*No benchrest, he used a buffalo stick.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 01-08-2015, 09:04 AM   #14
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default The importance of knowing the exact range

Since black powder trajectories are significantly higher than typical smokeless powder weapons at any range which a human is likely to be able to see and engage a target, I thought I'd emphasise the importance of knowing the exact range in order to carry out long-range shooting with a black powder rifle.

Of course, in order to hit anything at all with any kind of ballistic weapon beyond point blank range, one must have a good idea about approximate range to the target.

I imagine that a trained shooter will usually estimate his range to within +/- 33% as part of what constitutes a Guns skill roll to hit the target in GURPS. If he keeps missing, it may be because his estimate is way off, and if he consistently hits, he evidently has a fair idea of how to compensate for bullet drop at the range with his weapon.

However, there is a difference between knowing the approximate distance, which can work when bullet drop is not a huge factor, and having sighted the weapon in to the correct distance.

Accordingly, I intend to give each weapon a maximum effective skill based on its MOA and the behaviour of its round at long range, but the practical maximum effective skill under combat conditions will be 3 points lower than this. However, the +3 for knowing the range exactly would apply both to the shooter's skill and the maximum effective skill for the weapon.

Taking 10 seconds to sight in, scanning the area for points of comparison and making a successful Precision Aiming check to estimate range more carefully would allow a shooter to know range within +/- 10% or so and adjust the sights or aim point to account for it. This would give +1 to the shooter's skill and weapon maximum effective skill.

With a Precision Aiming roll, 1 minute of time and ranging shots, I imagine that most shooters could establish very good idea of the range and sight their gun in for it. I would require a minimum of 2 ranging shots and give a bonus according to the RoF table for more than this, up to a maximum of (time spent in seconds / [bullet flight time to target in seconds + 3) shots within the time taken. For having done this, I would give +2 to shooter skill for knowing the range and to maximum effective skill.

The Time Use rules apply to both methods and Deadeye has its usual time-reducing effects. A critical success or success by 10+ on the Precision Aiming roll increases the bonus for knowing the range by +1, up to the maximum of +3.

The Eye for Distance Perk becomes very important, because it allows a character with it to guess range to within +/- 5% with a simple IQ check. Accordingly, a trained shooter with a familiar weapon could sight in his weapon in 1 second of estimating with a Concentrate and 1 Ready maneuver to adjust his sights. This would give him +1 to skill and to weapon maximum skill.

Success with 5+ would give +2 to skill and weapon maximum skill and a critical success or success with 10+ would give the maximum +3 bonus for knowing the range exactly. Starting from a base of 2 seconds, the character can use the Time Spent rules for a further bonus and while he does not require ranging shots if using a familiar weapon, he can get a +1 bonus for 2 and a further bonus according to the RoF table, as per the rules for normal shooters.

Regardless of whether a character has Deadeye or Eye for Distance, remembered landmarks at known distances, pre-marked range indicators or a well-lit shooting range with marked ranges give a bonus to the Precision Aiming roll ranging from +1 to +10, with bonuses above +5 never applying under combat conditions. This can be abstracted away for plinking on a gun range at known distances, with the Precision Aiming roll assumed to be an automatic success and the +3 bonus for known range always applying.

Having with these rules in play, having done some ranging, marking of indicators and sighting in before combat starts would thus become critical for effective long-ranged fire. In my view, that is realistic, especially with the parabolic trajectories common to black powder rounds.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Old 01-13-2015, 04:25 AM   #15
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Maximum Effective Skill

I think the effect I want is achieved at around Maximum Effective Skil 24 (plus up to +3 for knowing the exact range) for ordinary military rifles shooting service ammunition for around MOA 5.

The Martini-Henry would then be M(aximum) E(ffective) S(kill) 25. Or would it have MES 26 and more-accurate-than-normal rifle that still didn't approach it would have MES 25?

Inaccurate service rifles would have MES 23.

How does this sound, as far as realism goes?

I'm going by Douglas Cole's work in this post for how to correlate MOA to MES, but I'm requiring shooters to know the exact range to qualify for the best MES that the mechanical accuracy of the weapon can give. Also, I'm a bit less optimistic about maximum accuracy in combat.
__________________
Za uspiekh nashevo beznadiozhnovo diela!

Last edited by Icelander; 01-13-2015 at 04:33 AM.
Icelander is offline   Reply With Quote
Old 01-13-2015, 05:14 AM   #16
hal
 
Join Date: Aug 2004
Location: Buffalo, New York
Default Re: [Tactical Shooting] Bullet Travel and MOA when Shooting Black Powder

This is just a guess on my part, but I suspect that the only weapons that should get best possible accuracy should be those that are finely made as opposed to run of the mill weapons. Seeing just how much a bullet could miss by with a cross wind (that book I mentioned earlier shows this for a few of the weapons) would also indicate that the accuracy you mentioned would likely require near perfect shooting conditions - which most long ranged shots aren't likely to have.

Again, that's just a guess on my part.
hal is offline   Reply With Quote
Old 01-13-2015, 07:21 AM   #17
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: [Tactical Shooting] Bullet Travel and MOA when Shooting Black Powder

Quote:
Originally Posted by hal View Post
This is just a guess on my part, but I suspect that the only weapons that should get best possible accuracy should be those that are finely made as opposed to run of the mill weapons.
I'll figure out the MOA and consequent Maximum Effective Skill for typical military weapons first and then fiddle with how Fine or Very Fine (Accurate) weapons and Match and Hand-Matched to Gun loads affect this.

Note that around 5 MOA was derived from the groups shot at 660 yards with several stock service rifles using normal service ammunition. MOA 2.8 for the Martini-Henry was derived from grouping at 1200 yards with a stock rifle and service ammunition.

An unmodified 100+ year old Martini-Henry can deliver just under 1 MOA. This can be achieved at 900 yards, without a benchrest, in the hands of a real-world shooter using hand-matched ammunition.

That falls between MES 30-31. If we assume that range was known exactly, the rifle would have a normal MES of 27-28. Using service ammunition, it would thus have somewhere around 25-26, since Match rounds give +1 and Hand-matched rounds to a given gun give +2.

Hence me assigning the Martini-Henry either MES 25 or 26.

Quote:
Originally Posted by hal View Post
Seeing just how much a bullet could miss by with a cross wind (that book I mentioned earlier shows this for a few of the weapons) would also indicate that the accuracy you mentioned would likely require near perfect shooting conditions - which most long ranged shots aren't likely to have.

Again, that's just a guess on my part.
Cross-winds actually matter less for heavy, but relatively stubby, .45-inch or greater bullets common to black powder weapons than it does for extremely streamlined lighter bullets common to modern weapons.

In any case, wind and weather conditions impose a penalty to long-range shooting, which the appropriate gear and Precision Aiming technique can reduce or eliminate. It doesn't really affect Maximum Effective Accuracy, as theoretically, a good enough shooter could compensate perfectly for it.

Of course, unknown or erratic windspeed would be impossible to compensate for fully and would affect both shooter skill and maximum effective skill.

I'm also toying with noting that beyond certain ranges, round X or Y will have lost enough velocity to be less predictable in flight, causing a penalty to skill and MES. Some rounds are very accurate at ranges up to 150 yards, 200 yards, 300 yards or even 600 yards, but at one (or more) breakpoints they lose much more accuracy than the normal GURPS ranges modifiers assume.

This applies to many heeled bullets, particularly in pistols. It's also true for many faster, lighter express bullets, that are flat-shooting and accurate to the limits of their intended range, but exhibit unpredictable and erratic characteristics once their velocity falls further than that.

I want to be able to distinguish between a round that is ideal for hitting small targets at under 300 yards and one that is worse at that role, but better at hitting man-shaped targets at 800+ yards.
__________________
Za uspiekh nashevo beznadiozhnovo diela!

Last edited by Icelander; 01-13-2015 at 08:02 AM.
Icelander is offline   Reply With Quote
Old 01-13-2015, 03:40 PM   #18
fredtheobviouspseudonym
 
Join Date: May 2007
Default Range assessment

Quote:
Since black powder trajectories are significantly higher than typical smokeless powder weapons at any range which a human is likely to be able to see and engage a target, I thought I'd emphasise the importance of knowing the exact range in order to carry out long-range shooting with a black powder rifle.
There was a small book I read some years ago which described a gadget to estimate range. This was popular in the US Army c. 1880.

Essentially it was a milliradian gauge. There were markings on it for the height of the "average man" (then assumed c. 5'9") correlated to the range. The user held one end of a measured string in his teeth and extended the gauge to the end of the string to give a specific sight-radius for the gadget. He then placed the gauge so that a one mark was at the foot of the target man and another at his head; the second mark would give the range. I believe that some had similar markings for the "average horse."

While seeming very crude apparently an experienced user could get fair approximations of range. This assumed that the enemy would oblige you by standing straight up on the battlefield and that his person would be of 5'9" in height.
fredtheobviouspseudonym is offline   Reply With Quote
Old 01-14-2015, 06:17 AM   #19
Icelander
 
Icelander's Avatar
 
Join Date: Mar 2006
Location: Iceland*
Default Re: Range assessment

Quote:
Originally Posted by fredtheobviouspseudonym View Post
There was a small book I read some years ago which described a gadget to estimate range. This was popular in the US Army c. 1880.

Essentially it was a milliradian gauge. There were markings on it for the height of the "average man" (then assumed c. 5'9") correlated to the range. The user held one end of a measured string in his teeth and extended the gauge to the end of the string to give a specific sight-radius for the gadget. He then placed the gauge so that a one mark was at the foot of the target man and another at his head; the second mark would give the range. I believe that some had similar markings for the "average horse."

While seeming very crude apparently an experienced user could get fair approximations of range. This assumed that the enemy would oblige you by standing straight up on the battlefield and that his person would be of 5'9" in height.
I suppose this would count as equipment to get a bonus to the rolls above. I guess +2 or so would be fair.
__________________
Za uspiekh nashevo beznadiozhnovo diela!
Icelander is offline   Reply With Quote
Reply

Tags
adventure guns, bullet travel, harsh realism, high-tech, tactical shooting, victorian

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 02:03 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.