Hi Guys,

I recently responded to a posting on another site that I thinks merits posting on this much finer site. Here you go.

The use of GPS for precision point location is not all that new outside of the military. Civilian surveyors have precision point GPS that can locate a point on the earth to less than 10 centimeter. The handheld civilian units are not capable of this level of accuracy.

Civilian units are more capable than they used to be becuase of the decryption of the GPS satellite system that was recently placed in effect. There used to be an encryption system on the GPS constellation that limited non-military uses to 100 meters of accuracy.

With the advent of GPS guidance for the landing of civil aircraft for ILS landings, there was some pressure from the civilian side to do away with the encryption that limited the precision capability of the GPS constellation. So, with that said, YES, GPS "could" be used to index reference points in a sniper "****" zone so to speak.

Old SF guys, Rangers, and any other infantry type would tell you that you NEVER, EVER enter your own **** zone prior to putting on the ambush. Esentially, that is what a sniper attack is, an ambush. So the act of going into your target area to "grid it out" and get precise ranges to reference points violates a couple of operational principles. All of those priniciples are well proven over many years and wars.

With that said, I am not an advocate of laser range finders. They are still NOT accurate enough, especially under adverse conditions. Good tactical sense would state that you would want know distances to reference points on the ground long prior to the target entering the area. I imagine that is why you asked about GPS for getting a good range to a target reference point.

Now, this is something of a sore subject. I am not a fan of mil relation for ranging targets. I won't get into why because of the heat it caused on this site some time ago. I'd be happy to discuss it with you on the email net or over the phone. Allow me to present another method.

My humble apologies for raising the fur of anyone who disagrees with this method. You don't have to use it, like it or approve of it. It simply works.

Theodolites are very accurate for gridding out a **** zone long before a target enters the area. Indeed, with some time and small effort, you can get multiple ranges to multiple objects in a **** zone to within an accuracy level of 1.4 meters at 1600 meters. It takes a 1" theodolite to do this, which is extreme, but it can be done. A 6" theodolite will do as good as you need to do.

Theodolites take multiple angle readings and take known sizes of objects (kind of the same that mil relation does), but can use much smaller objects. There is another method that doesn't require a known size at all, you simply have to aim the theodolite at the same point on the ground every time. It is simple surveying.

Now, it takes way more time and space that I can put on this website to publish the method. Anyone interested, please contact me on the email net. Be glad to help out.

Take care all...

Here's some follow up on the previous posting.

Good comments across the board. I'm in total agreement with you. Here's another way to look at the theodolite.

1. Replace your spotting scope with it. This is for extreme range shooting. Tailor the gear for the mission. Toss the regular spotting scope. The theodolite does a very good job of reading trace.

2. Many teams carry lasers now. By replacing the laser and the spotting scope, you have probably saved some weight. Baseplates for the theodolite can be made from carbon fiber for weight. All you need are legs about 6" long. Have made them before, not a big deal.

Range determination is a necessary animal becuase of Danger Space. The danger space dimension is the distance that drives the level of accuracy needed when determining a range to a target.

For example, a 1000 yard shot on a human target requires about 2 minutes of angle of accuracy from the gun/shooter to hit that target. The level of accuracy needed to get a shot into that 2 minute of angle circle is only an allowable error of 22 meters. That's 11 meters in front of the target and 11 meters behind the target. Misdetermine the range by 15 meters long and you'll shoot over that target.

Just for comparison the same 2 MOA target has a danger space of 46 yards for the 338 Lapua and a 120 meter allowable error using a .50 caliber rifle against a 1 METER target. Cartidge/load is a major factor here.

Here's an analysis of the errors that are encountered when using mil relation for LONG RANGE interdiction. For most combat shooting, the mil relation is okay as long as the target agrees to stand still long enough to be engaged.

EXAMPLE RANGING PROBLEM / EFFECT OF MIL INTERPOLATION ERROR USING ALLOWABLE ½ MIL ERROR IN TC 31-20-4

MIL Reading @ 3.5 Mils = 5 meters X 1000 = 5000 divide by 3.5 MILS = 1429 Meters
MIL Reading @ 3.0 Mils = 5 meters X 1000 = 5000 divide by 3.0 MILS = 1667 Meters

ERROR = 238 Meters split in half for a center aim (119 meters in front of and behind the target). This is outside the parameters for an 5 meter target (125 meter DS, split in half = 62.5 meters in front and behind the target). This is a miss on the overall target. The key number is the split. If the range error split is larger than the DS split, a can will occur, long or short.

ERROR OF ONLY ¼ MIL INTERPOLATION

MIL Reading @ 3.0 Mils =5 meters X 1000 = 5000 divide by 3.0 MILS = 1667 Meters
MIL Reading @ 3.25 Mils =5 meters X 1000 = 5000 divide by 3.25 MILS = 1538 Meters

ERROR = 129 Meters split in half for a center aim (64.5 meters in front of and behind the target). This is outside the parameters for a 5 meter target (125 meter DS, split in half = 62.5 meters in front and behind the target). A miss can occur with only a ¼ Mil error.

ERROR OF ONLY 1/10th MIL INTERPOLATION

MIL Reading @ 3.0 Mils =5 meters X 1000 = 5000 divide by 3.0 MILS = 1667 Meters
MIL Reading @ 3.1 Mils =5 meters X 1000 = 5000 divide by 3.25 MILS = 1613 Meters

ERROR = 54 Meters split in half for a center aim (27 meters in front of and behind the target). This is within parameters for an 5 meter target (125 meter DS, split in half = 62.5 meters in front and behind the target). This small error is okay to hit a target 5 meters high.

I have carried the theodolite as have other operators. Yep, it's a pain, but damn, it is accurate. Jacob Bynum at SNIPER'S PARADISE is on board with this method and he swears by it. It's accurate, dead on. For "passive" range finding systems, it is unbeatable. Again, my humble opinion.


[This message has been edited by SP Webmaster (edited 12-07-2000).]