Fiftydriver
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It was calm early this morning so I decided to run up and test lil' Black Sunshine out at some decent range.
Set the 20" gong up and drove back as far as I could. I set the gong up next to an old fence post so I could use it to get a good reading off the wild range finder dialing it in for the measurement.
Took my range, came out to a hair shy of 2700 yards. I put my 3.5-15 NXS nightforce on the rifle which I had zeroed at 100 yards so I could dial up to any range out to around 2800 yards from what Exbal says.
Exbal reported I needed to crank 90 moa into the scope for a dead on hold. The wind was light, couple mph which will certainly make a difference but I wanted to check vertical first.
Let the first 300 gr SMK go and waited for the impact around the gong. To my suprise, the shot landed far down the hill and well short, very short in fact. This was out of a freshly cleaned and oily barrel so I shot another to make sure the drop was true. This shot landed within 3/4 moa of the first shot.
I cranked the scope up another 10 moa which topped it out so I dropped it down three moa just to keep the scope from being bottomed out in adjustment and keep it consistant. I also cranked in the windage for this shot as well. Shot another round. THis time the shot landed right where the bottom thick post begins on the MLR reticle when holding dead center on the gong with the main crosshair.
That made things simple. Used the bottom post for a reference hold and sent three down range. One hit about a foot or so to the right and even with the top edge of the plate. May be just inches above it. One was about a foot straight to the right of the gong and the third landed just a bit lower then that one. The second two would have easily hit the gong had they been over to the left a bit and the first shot was only inch above the gong.
In all, once I got the rifle dialed in for the range I sent 11 rounds toward the gong, no hits but 6 of those were within a foot of the gong so I was very happy.
What was a mystery to me was why I needed roughly 25 more moa to get the rifle grouping around the gong consistantly. I thought about this long and hard. Here are the knowns for what I Was dealing with.
The load had an average velocity of 3395 fps at 50 degrees F. Today the shooting temps were around 30 degrees. Certainly velocity averages would have been a bit lower but not much, may be 1 or at the most 2 moa, not 25!!!
Rifle was zeroed at 100 yards. Did it two days before I shot it this morning. Punched three cloverleafs at 100 yards that all measured under 3/8" and were right dead on point of aim at 100 yards.
Bullet BC is 0.780. THis is what I use for the 300 gr SMK. I have tested it from actual bullet drop ranging from 0.76 to 0.80 so I average those and just use this number.
This BC has worked for me for several rifles using this bullet with velocities from 2800 fps up to 3400 fps.
So why would Exbal tell me to use 90 moas of vertical and then find out I was a full 25 moa low still??
We saw this shooting at 2460 yards as well but I just chalked that up to me forgetting where my zero was on the scope.
That was not the case this time. The rifle was zereod, with a know velocity and a know bullet BC.
My conclusion, after looking at the extended range numbers from Exbal, 115 moa in vertical adjustment from a 100 yard zero should give a zero range of right at 2925 yards.
My theory is that my Wild range finder has been knocked out of adjustment and I thought I was shooting at 2700 yards when in fact it was more like 2925 or 2950 yards.
From actual bullet drop this makes perfect sense as I have never had a problem with this BC and this bullet.
Also, I have witnessed what the 300 gr SMK will do as it drops out of supersonic velocity out of the 338 Kahn. Consistany really goes to hell fast once it gets much past that 2000 yard mark where it approaches the transonic stage.
I was not seeing that with the 338 AM but at the altitude we are at it should be staying super sonic out close to these ranges.
Anyway, this is what I feel is the problem. I had to work this afternoon to make up for the morning shoot but will recheck the calibration of the Wild Range finder tomorrow and see where it is at and I suspect that will be the cause of this as I have never had Exbal be that far off in moa dial up prediction before. Couple moa, yes, 25, never.
Just curious if any of you have any ideas on what this could be other then the rangefinder not being calibrated properly, more then happy to hear what you have to say.
I was happy with the results. Until the wind came up I was easily holding moa accuracy at that range and even when the wind came up, vertical spreads were still holding moa or better but windage was opened up to as much as a couple moa. Hard to read the wind at this range when your only wind market is the impact dust cloud and how quickly it is blown away!! Unfortunatelly, it changes so much that is not real valuable either.
Thanks for your thoughts. One thing is clear. If my theory proves true and this was nearly 3000 yards this morning. I can say without a doubt that it is fully practical to make consistant 1 moa grouping at this range in ideal conditions. In breezy conditions, better hang it up for the day or move closer.
Kirby Allen(50)
Set the 20" gong up and drove back as far as I could. I set the gong up next to an old fence post so I could use it to get a good reading off the wild range finder dialing it in for the measurement.
Took my range, came out to a hair shy of 2700 yards. I put my 3.5-15 NXS nightforce on the rifle which I had zeroed at 100 yards so I could dial up to any range out to around 2800 yards from what Exbal says.
Exbal reported I needed to crank 90 moa into the scope for a dead on hold. The wind was light, couple mph which will certainly make a difference but I wanted to check vertical first.
Let the first 300 gr SMK go and waited for the impact around the gong. To my suprise, the shot landed far down the hill and well short, very short in fact. This was out of a freshly cleaned and oily barrel so I shot another to make sure the drop was true. This shot landed within 3/4 moa of the first shot.
I cranked the scope up another 10 moa which topped it out so I dropped it down three moa just to keep the scope from being bottomed out in adjustment and keep it consistant. I also cranked in the windage for this shot as well. Shot another round. THis time the shot landed right where the bottom thick post begins on the MLR reticle when holding dead center on the gong with the main crosshair.
That made things simple. Used the bottom post for a reference hold and sent three down range. One hit about a foot or so to the right and even with the top edge of the plate. May be just inches above it. One was about a foot straight to the right of the gong and the third landed just a bit lower then that one. The second two would have easily hit the gong had they been over to the left a bit and the first shot was only inch above the gong.
In all, once I got the rifle dialed in for the range I sent 11 rounds toward the gong, no hits but 6 of those were within a foot of the gong so I was very happy.
What was a mystery to me was why I needed roughly 25 more moa to get the rifle grouping around the gong consistantly. I thought about this long and hard. Here are the knowns for what I Was dealing with.
The load had an average velocity of 3395 fps at 50 degrees F. Today the shooting temps were around 30 degrees. Certainly velocity averages would have been a bit lower but not much, may be 1 or at the most 2 moa, not 25!!!
Rifle was zeroed at 100 yards. Did it two days before I shot it this morning. Punched three cloverleafs at 100 yards that all measured under 3/8" and were right dead on point of aim at 100 yards.
Bullet BC is 0.780. THis is what I use for the 300 gr SMK. I have tested it from actual bullet drop ranging from 0.76 to 0.80 so I average those and just use this number.
This BC has worked for me for several rifles using this bullet with velocities from 2800 fps up to 3400 fps.
So why would Exbal tell me to use 90 moas of vertical and then find out I was a full 25 moa low still??
We saw this shooting at 2460 yards as well but I just chalked that up to me forgetting where my zero was on the scope.
That was not the case this time. The rifle was zereod, with a know velocity and a know bullet BC.
My conclusion, after looking at the extended range numbers from Exbal, 115 moa in vertical adjustment from a 100 yard zero should give a zero range of right at 2925 yards.
My theory is that my Wild range finder has been knocked out of adjustment and I thought I was shooting at 2700 yards when in fact it was more like 2925 or 2950 yards.
From actual bullet drop this makes perfect sense as I have never had a problem with this BC and this bullet.
Also, I have witnessed what the 300 gr SMK will do as it drops out of supersonic velocity out of the 338 Kahn. Consistany really goes to hell fast once it gets much past that 2000 yard mark where it approaches the transonic stage.
I was not seeing that with the 338 AM but at the altitude we are at it should be staying super sonic out close to these ranges.
Anyway, this is what I feel is the problem. I had to work this afternoon to make up for the morning shoot but will recheck the calibration of the Wild Range finder tomorrow and see where it is at and I suspect that will be the cause of this as I have never had Exbal be that far off in moa dial up prediction before. Couple moa, yes, 25, never.
Just curious if any of you have any ideas on what this could be other then the rangefinder not being calibrated properly, more then happy to hear what you have to say.
I was happy with the results. Until the wind came up I was easily holding moa accuracy at that range and even when the wind came up, vertical spreads were still holding moa or better but windage was opened up to as much as a couple moa. Hard to read the wind at this range when your only wind market is the impact dust cloud and how quickly it is blown away!! Unfortunatelly, it changes so much that is not real valuable either.
Thanks for your thoughts. One thing is clear. If my theory proves true and this was nearly 3000 yards this morning. I can say without a doubt that it is fully practical to make consistant 1 moa grouping at this range in ideal conditions. In breezy conditions, better hang it up for the day or move closer.
Kirby Allen(50)
