Hi. I shoot a surgeon 6.5 creedmoor. I shoot it at least 2 times a week. Ive noticed when shooting at 1k the dope ive written down from last week sometimes works..sometimes doesnt. Normally about .2 mils off. If my reloads are good..barometric pressure the same..temperature the same..h4350 powder..what could cause this? Do the pros experince this too?
Advanced Marksmanship Dope. how often does yours change?
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Living in Lubbock I would think the wind or slight change in breathing or moving rifle on your shoulder would be or could be an issue but slightest difference in powder charge could be an issue as well not to mention Coriolis and 14 other variables ? What kinda ballistic program ya running?
No joke on lunbock weather. Its been voted the worst nationally. . have a jallen stock that fits like a glove so I wouldnt think thats it..powder is done on a chargemaster. I like to think its accurate? Anyone think it the chargemaster could make .2 difference even if it says it weighs the same everytime?..i shoot north so coriolis shoudnt affect vertical i wouldnt think. Not sure though . Applied ballistics kestrel. I should mention the dope im talking about is vertical not horizontal.
What kind of bbl and how many rounds you have through it? is your MV accurate? i dont shoot 6.5 and have no idea what to expect as far as bbl life, but that would be my first thought if i were in your shoes.
Its a krieger. About 1500 rounds down it. Still groups great on paper. Should have 1500 more to go. I chroned and averaged 2810. I had to tell program 2750 to line up
if you had to cheat your ballistic program, i would guess thats the problem right there. Which one are you using?
Dope. how often does yours change?
What scope are you running? Also is your 100 yard zero floating at all or have you checked it when things don't match up from last week?
What scope are you running? Also is your 100 yard zero floating at all or have you checked it when things don't match up from last week?
zero stays pretty consistent. within .25 id say everytime I check it..
Applied ballistics. I don't see how that would be the problem. If I remember my old dope and write it down and I shoot the same target a week later and I'm .2 high or low then it wouldn't matter on ballistic program would it
vortex razor. It passed the box test
How was the wind? That can change it.
Under identical conditions, my zeros don't move at all.
Under identical conditions, my zeros don't move at all.
Parallax adjusted properly?
does going from sunny to cloudy make a difference? wind was in my face 10 mph
A head wind will make a small difference. Run the numbers through a calculator. Some say sun does, but I've only found that to be (somewhat) true with iron sights when shooting bullseyes, not with scopes. YMMV
it could. if it's not the wind then it very well be your parallax and mirage.
I would suspect vertical crosswind deflection. Assuming RH twist barrel, a left to right wind causes drop and a right to left causes a rise in POI. There is a thread on hear where dtubb addresses this.
Hope this helps. Also has some knowledge from LL in it. Enjoy
http://www.snipershide.com/shooting...tion-regarding-full-value-wind-elevation.html
http://www.snipershide.com/shooting...tion-regarding-full-value-wind-elevation.html
Here's your answer: Unpredictable recoil resistance. Unless the angle and arc created between line of bore at rest and line of bore at bullet exit is the same from shot to shot, bullet misplacement will be certain. To make the angle and arc consistent requires identical control over the rifle be applied from shot to shot to produce consistent recoil resistance. Usually, what makes shot misplacement apparent on different days, even though conditions are perceived as being similar, is the shooter's miniscule divergence in contact with the rifle and ground from one day to another. Of course, wind and weather will mask the sort of error that I am talking about.
I have a score book with most all my 1000 yard events at Ft. Knox. On days with what appeared to be virtually identical wind and weather conditions to earlier days, and even from the same target point, my beginning zeros have always had to be corrected, sometimes over an MOA.
I have a score book with most all my 1000 yard events at Ft. Knox. On days with what appeared to be virtually identical wind and weather conditions to earlier days, and even from the same target point, my beginning zeros have always had to be corrected, sometimes over an MOA.
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The program wouldnt be the probem, i was asking because i wanted to know if it had a truing function. To me, it sounds like your MV isnt what you think it is. But the rest of these guys have good thoughts as well.
I chronoed 2 different days with an oehler. Im not sure why applied ballistics isn't lining up perfect
Hmm interesting. I may need to test this
Thanks for the read but I had already know of this condition. whats weird is if anything the wind should of had me impacting high today. Instead I had to dial more.
I live 2 miles from my range so I think Im about to go OCD and shoot 5 rounds every morning before I go to work and see what I find
Could mirage have been part of the dope difference? This with a little parallax could get .2 @ 1k.
R
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Chrono could be off. True your data via some longer range targets and then see if it is holding true over the course of several outings. Like so many people are using now, believe the bullet. The chrono will give you a good baseline, but it's far from being final. If your dope starts making large changes, you know your barrel is going to shit, which can happen on a 6.5 even at 1500 rounds depending on the load/conditions of use.
Are you taking in consideration the change in Density Altitude, this can change in the course of day let alone from one week to the next.
Next would be the ability to have a consistent shooter platform from one day to the next.
cheers
Next would be the ability to have a consistent shooter platform from one day to the next.
cheers
This is what I was getting at. Start with your measured MV, then put in your data in the truing function and that will give you your actual MV. Use that actual MV and I'm betting you will be back in business.
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Can u give an example of dope making large changes? Also what If barrel still shoots .3s at 100?
All of a sudden your dope is a half mil off and then you go check the MV and it's down...sign you've shot your barrel out. That doesn't sound like the case here. To me it sounds like you need to true your dope as it's probably close, but not quite dialed in or you're not taking some sort of environmental factor into consideration. I'm betting if you use a truing feature for your data that you're going to come up with some better numbers.
You don't need to test at 1000. You can test at 100 to see the effect of unpredictable recoil resistance. You must however be able to recognize when you have a consistent position to understand the effect of a less than consistent position.
But, let's say you can build a consistent position, as appraised by your ability to shoot very small groups, then, the only thing you need to do to see effect of unpredictable recoil resistance is get out of position and move to another firing point with some divergence from the ground previously shot from. You can also change your clothing or virtually any other aspect of your position to see shot misplacement from unpredictable recoil resistance.
The bottom line is that any change in your relationship between gun and ground will cause a misplaced shot due to recoil resistance becoming unpredictable; and, if the change itself becomes consistent, then misplacement will form a group, indicating the need to re-zero.
Thing is, most of us cannot get exacting consistency between shots much less relays so we are not able to realize the literal definition of a zero: where the bullet path and line of sight intersect and their resulting value in any form of measurement is zero. Instead we triangulate a zero from the groups we shoot, essentially a bunch of misplaced shots caused by a multitude of errors. This may make isolation of error due to changing recoil resistance hard to discern for the average shooter. In fact, since a zero created from any grouping is one which has accounted for a multitude of errors any specific source of error may not be discernable. This is why instead of focusing on the error as seen on the target we should focus attention on what needs to be properly accomplished at the gun, i.e. properly pointing the rifle with consistent sight alignment and pulling the trigger without moving the rifle utilizing smooth trigger control.
In addition to shooter inconsistency, changing wind and weather, and less than perfect ammunition will also preclude the maintenance of a zero. All of these things being likely, making zero corrections will be a reality for the best results.
Think of it this way, anything that is different will produce a different result. When something different becomes consistent it will produce a consistent different result. Since this is expected, instead of being stuck on a zero, just concentrate on the fundementals and if shots are off call adjust your sight and move on.
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Maybe direct sunlight on ammo increased older temp a degree or two enough to change the mv?
Actually, a 20 degree temperature increase or decrease can change the muzzle velocity about 50 fps. This has a 1 minute value. So, this and a multitude of other problems/errors could be causing the inconsistent results. If the OP recorded his shots and conditions in a Data Book he would not need to speculate. One more thing, setting a target higher or lower than where the sight was initially zeroed can produce error since the shooter's relationship with the line of bore will be altered to accommodate the higher or lower placed target.
OP,
Get a data book to record shots and conditions they were fired under. The purpose is to confirm zeros and note trends that will increase accuracy and confidence.
yea op said the temp was the same (im assuming it was ambient air temp and not ammo temp) which is why i asked if it was direct sunlight one time and in the shade another.
+1 on the data book every range day im taking my shooting log and chrono. timing is good as the temps are starting to climb i should be able to get from 60-100 degree vel and impact changes.
Do you clean between range sessions? I don't recall reading anything of that nature.
For example, after a range session, I run a dry bore snake through the bore once. Next time I shoot, the follow up shots to the cold bore shot all go in the same hole - no change in point of impact.
If you're cleaning and not getting all the solvent out, or you're removing the copper and it's being laid back down into the bore, you will likely see some vertical stringing of your shots.
Sorry if these questions are silly, but I don't know the op or his habits.
For example, after a range session, I run a dry bore snake through the bore once. Next time I shoot, the follow up shots to the cold bore shot all go in the same hole - no change in point of impact.
If you're cleaning and not getting all the solvent out, or you're removing the copper and it's being laid back down into the bore, you will likely see some vertical stringing of your shots.
Sorry if these questions are silly, but I don't know the op or his habits.
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