Laser Sight Zero Range - PBR - XDTalk Forums - Your HS2000/SA-XD Information Source!

Learjet Jockey · 04-03-2007, 10:26 PM

I have read several posts on this and other forums about sighting in a laser sight mounted below the bore C/L. With the laser mounted below the bore, the bullet only crosses the laser beam at one point (as opposed to two points for a sight above the bore). I was unable to input a negative sight height into several ballistic programs in order to get the bullet trajectory from a laser sight mounted below the bore. I spent some time reviewing my geometry and created an Excel spreadsheet that can calculate the bullet path in relation to a laser beam zeroed at a given distance. The input required is bullet drop for a given load combination (bullet wieght, ballistic coefficient, & velocity), laser sight distance from the bore center line, zero range for laser, the vital zone (+/- inches from laser beam) to calculate the point blank range.

I am willing to share this with anyone trying to figure out what distance to sight the laser in for or where the bullet is relative to the laser beam at any given distance for a defined load. You can PM me for the spreadsheet or give me your load specifics and I'll run the ballistic path for you as well. I need the laser height from bore and vital zone parameters to calculate the point blank range.

Learjet Jockey · 04-04-2007, 01:07 AM

XD Springer,
Yes, if the iron sights are POA/POI at 25 yards (typical for XD-45 factory sights) and the laser is also zeroed at 25 yards, the bullet impact, line of sight (iron sights), and laser dot all coincide at 25 yards. At distances less than 25 yards, the bullet is always above the laser, but may be above or below the LOS depending on the yardage. At distances beyond 25 yards, the bullet is always below the laser and LOS. The bullet is much lower from the laser than LOS. Since lasers are usually used in home defense, the laser is usually sighted in for the farthest distance a BG will be in the house. The question is if the laser is sighted in for 17 yards, at what distances will the bullet hit +/- 2" from the laser. If the laser is 2.6 inches below the bore C/L like a TLR-2 on the XD-45, then the bullet will be +/- 2" from the laser from 5 yards to 25 yards for a 230 gr JHP traveling at 717 FPS. Meaning: 2" high at 5 yards, 2 inches low at 25 yards, and dead on at 17 yards. At the muzzle the bullet is 2.6" high.

Some lasers are not adjustable so they cannot be zeroed at a specific distance to coincide with the iron sights.

The same bullet will be +/- 2" from LOS of the iron sights from 0 to about 41 yards, assuming the iron sights are .5" above the bore C/L and zeroed at 25 yards.

bham shooter · 04-05-2007, 09:23 AM

I've got the X2L on my XD40 Service. I did have to sight it in. First time out I shot a few rounds, and they were pretty low. I was shooting at about 10 yards. I tried it from a rest, and they were all hitting 6-8 inches low. With several people getting the same results. I didn't have my hex with me, but when I got home, I taped the target we were shooting at to the door, got out the rest, and turned the laser on. I slowly dialed it up 6 inches, and the next time out at the range I tested it. At 10 yards, it was within 2 inches of where I was aiming at consistently. Roughly the same at 20 yards. That's close enough for its intended use as my nightstand gun. I could probably tweak it a bit more and get it to hit right on target at 15 yards, but I really don't see the need.

04-03-2007, 10:26 PM	#1
Learjet Jockey XDTalk Member Join Date: Feb 2006 Location: PA (Central) Posts: 78	Laser Sight Zero Range - PBR I have read several posts on this and other forums about sighting in a laser sight mounted below the bore C/L. With the laser mounted below the bore, the bullet only crosses the laser beam at one point (as opposed to two points for a sight above the bore). I was unable to input a negative sight height into several ballistic programs in order to get the bullet trajectory from a laser sight mounted below the bore. I spent some time reviewing my geometry and created an Excel spreadsheet that can calculate the bullet path in relation to a laser beam zeroed at a given distance. The input required is bullet drop for a given load combination (bullet wieght, ballistic coefficient, & velocity), laser sight distance from the bore center line, zero range for laser, the vital zone (+/- inches from laser beam) to calculate the point blank range. I am willing to share this with anyone trying to figure out what distance to sight the laser in for or where the bullet is relative to the laser beam at any given distance for a defined load. You can PM me for the spreadsheet or give me your load specifics and I'll run the ballistic path for you as well. I need the laser height from bore and vital zone parameters to calculate the point blank range. __________________ XD-45 ACP; Night Sights, TLR-2 & Springer Trigger Sigma 9MM Blackhawk 45 Colt S&W 642 - 38 Spec. Ruger Mark III SS Competition

04-04-2007, 01:07 AM	#2
Learjet Jockey XDTalk Member Join Date: Feb 2006 Location: PA (Central) Posts: 78	XD Springer, Yes, if the iron sights are POA/POI at 25 yards (typical for XD-45 factory sights) and the laser is also zeroed at 25 yards, the bullet impact, line of sight (iron sights), and laser dot all coincide at 25 yards. At distances less than 25 yards, the bullet is always above the laser, but may be above or below the LOS depending on the yardage. At distances beyond 25 yards, the bullet is always below the laser and LOS. The bullet is much lower from the laser than LOS. Since lasers are usually used in home defense, the laser is usually sighted in for the farthest distance a BG will be in the house. The question is if the laser is sighted in for 17 yards, at what distances will the bullet hit +/- 2" from the laser. If the laser is 2.6 inches below the bore C/L like a TLR-2 on the XD-45, then the bullet will be +/- 2" from the laser from 5 yards to 25 yards for a 230 gr JHP traveling at 717 FPS. Meaning: 2" high at 5 yards, 2 inches low at 25 yards, and dead on at 17 yards. At the muzzle the bullet is 2.6" high. Some lasers are not adjustable so they cannot be zeroed at a specific distance to coincide with the iron sights. The same bullet will be +/- 2" from LOS of the iron sights from 0 to about 41 yards, assuming the iron sights are .5" above the bore C/L and zeroed at 25 yards. __________________ XD-45 ACP; Night Sights, TLR-2 & Springer Trigger Sigma 9MM Blackhawk 45 Colt S&W 642 - 38 Spec. Ruger Mark III SS Competition

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04-05-2007, 09:23 AM	#3
bham shooter XDTalk 500 Member Join Date: Feb 2006 Location: Birmingham, AL Posts: 567	I've got the X2L on my XD40 Service. I did have to sight it in. First time out I shot a few rounds, and they were pretty low. I was shooting at about 10 yards. I tried it from a rest, and they were all hitting 6-8 inches low. With several people getting the same results. I didn't have my hex with me, but when I got home, I taped the target we were shooting at to the door, got out the rest, and turned the laser on. I slowly dialed it up 6 inches, and the next time out at the range I tested it. At 10 yards, it was within 2 inches of where I was aiming at consistently. Roughly the same at 20 yards. That's close enough for its intended use as my nightstand gun. I could probably tweak it a bit more and get it to hit right on target at 15 yards, but I really don't see the need.