Group question
- Thread starter HoustonPdLt
- Start date
If your parallax is set right, cheek position should not cause horizontal dispersion. At 615 yards, that looks like a decent group to me. You are well into the distance where down range wind could be causing that much variation.
I assume you have a 5rnd group and a 2 rnd group??
If this was all shot in the same string, then you missed a wind call.
If this is two different strings then no way to tell the issue because the numbers of shots are so few.
Shoot 2x 10 rnds groups at distance to get real data
If this was all shot in the same string, then you missed a wind call.
If this is two different strings then no way to tell the issue because the numbers of shots are so few.
Shoot 2x 10 rnds groups at distance to get real data
Assuming that is all one string of fire, depending on the caliber that horizontal spread can easily mean a missed wind shift.
A 155 grain .308 match bullet (mid .45 BC) @ 2950 - 3000 fps and a 175 gr .308 match bullet (mid .5's BC) @ 2600 fps will drift 0.8 mils in a 5 mph x-wind @ 600 yards. That's .8 mils x 3.6"/100 yd/mil x 600 yd = 17.28". Reversing the math, a 4.5" drift at 600 yds for that same .308 bullets will take only 1.3 mph of wind
Your target says no wind but at 600 yards there is always wind, guaranteed.
A 155 grain .308 match bullet (mid .45 BC) @ 2950 - 3000 fps and a 175 gr .308 match bullet (mid .5's BC) @ 2600 fps will drift 0.8 mils in a 5 mph x-wind @ 600 yards. That's .8 mils x 3.6"/100 yd/mil x 600 yd = 17.28". Reversing the math, a 4.5" drift at 600 yds for that same .308 bullets will take only 1.3 mph of wind
Your target says no wind but at 600 yards there is always wind, guaranteed.
First, that's a pretty nice group. If it's all one load, I'd say you are getting the velocities right down to the nubs, if not great harmonics as well.
So, what are you shooting? Speeds, SD's ED's if you've got them etc.?
Agree with those above, at that range, a small wind call miss seems big. And, as noted, parallax can get really tricky to nail right on at distances. It takes several checks to get it as close as you can. One thing I do to help mitigate that is practice lining up on the scope correctly (or the same at least) every time. Just in case my parallax is out just a tiny little bit. Get a sight pic and walk your head in until the sight picture meets the edges perfect every time. I practice that often. Just trying to shave tidbits off my mistakes.
So, what are you shooting? Speeds, SD's ED's if you've got them etc.?
Agree with those above, at that range, a small wind call miss seems big. And, as noted, parallax can get really tricky to nail right on at distances. It takes several checks to get it as close as you can. One thing I do to help mitigate that is practice lining up on the scope correctly (or the same at least) every time. Just in case my parallax is out just a tiny little bit. Get a sight pic and walk your head in until the sight picture meets the edges perfect every time. I practice that often. Just trying to shave tidbits off my mistakes.
So went back and tried again. Concentrated on consistent hold every time but now I have another question, that I have a guess of an answer for. Again no wind. The entire distance was over still water so I am certain of that. I was 3” left, clicked 1/2 MOA and was dead on a steel plate and then a paint can (which is great if we are ever invaded by paint cans!). Then with the same setting I was 1/2” right at 100. So is that me having the rifle canted?
Attachments
Canted is one answer and parallax being a tiny bit off can create that. Is there / was there any mirage issues when and where you are shooting? Sometimes you gotta wait for the boils to move off before you pull the trigger again.
I will say, you are doing an outstanding job shooting here. Not a lot of people can shoot 2/3 moa at 615 yds. If you have another area you can shoot, see what you do there as well.
I will say, you are doing an outstanding job shooting here. Not a lot of people can shoot 2/3 moa at 615 yds. If you have another area you can shoot, see what you do there as well.
Unless you were able to see mirage at different places along the way to the target there is no way you can be sure wind wasn't an effect. What the water surface looks like matters little since the bullet is quite a ways up from the surface where wind may or may not be present. Wind is not uniform in the vertical dimension any more than it is in the horizontal dimension. It takes less than 1 mph of wind to drift you 2.5" at 600 yds. And this isn't just book answer, but backed up by more than 10 yrs experience.
I've shot next to some really hardcore F class guys and the attention they pay to wind is beyond obsessive. Their matches are won on lost on X count and the size of the X ring at 600 yds is almost exactly 3" in diameter. They will favor into the slightest mirage they can detect on the spotting scope even if you can't see anything move or feel any wind on your skin.
Cant and parallax can definitely be issues, but you cannot ever ignore the wind if you're trying to do better than where you are now.
I've shot next to some really hardcore F class guys and the attention they pay to wind is beyond obsessive. Their matches are won on lost on X count and the size of the X ring at 600 yds is almost exactly 3" in diameter. They will favor into the slightest mirage they can detect on the spotting scope even if you can't see anything move or feel any wind on your skin.
Cant and parallax can definitely be issues, but you cannot ever ignore the wind if you're trying to do better than where you are now.
Last edited:
Seems to me you just don't want to believe what I'm telling you about the significance of breezes you can't feel and can only see through mirage. Horse, water, won't drink and all that. Good luck.
BTW I can already see two (possibly three) spots downrage where there is significant wind that will affect what you're trying to do.
Last edited:
Don’t think that. I do believe you about the wind, I know there is far more I don’t know, especially what’s going on way above the water. I do appreciate the advise. That pick was on another day, but I do agree there could have been winds where the bullet was traveling on the day I was shooting.
OK, sorry about misunderstanding your comments.
If you really want to learn how to manage the wind, put some NRA mid range and long range prone matches in your annual schedule.
Sling and F class shooters shoot the same match, just on different targets. If you shoot 308 or 223, you'll be in the F-TR class. If you shoot any other caliber, you'll be in F-Open. That's just so you tell the squadding guys in the morning.
NRA defines mid-range as any prone match at 300, 500, and/or 600 yds. And long range is any prone match at 800, 900, and/or 1000 yds.
Check these guys' schedule: https://bayourifles.org/index.php/competitions/high-power-rifle-division and show up. You don't need to be a club member to shoot an NRA match. Hell you don't even need to be an NRA member (but everyone should).
If you really want to learn how to manage the wind, put some NRA mid range and long range prone matches in your annual schedule.
Sling and F class shooters shoot the same match, just on different targets. If you shoot 308 or 223, you'll be in the F-TR class. If you shoot any other caliber, you'll be in F-Open. That's just so you tell the squadding guys in the morning.
NRA defines mid-range as any prone match at 300, 500, and/or 600 yds. And long range is any prone match at 800, 900, and/or 1000 yds.
Check these guys' schedule: https://bayourifles.org/index.php/competitions/high-power-rifle-division and show up. You don't need to be a club member to shoot an NRA match. Hell you don't even need to be an NRA member (but everyone should).
Hi,
Have you contacted the SOD of HCSO to see if one of their "shooters" could help you out in person?
Sincerely,
THEIS
Have you contacted the SOD of HCSO to see if one of their "shooters" could help you out in person?
Sincerely,
THEIS
I have not. But we have some good shooters in our SWAT team. Surely some of them are into long range shooting. Great idea!
Similar threads
