Firstly i'm afraid this will be a lengthy post but hopefully it will be interesting. I have recently tentatively settled on a load for my .20 TAC.
The load is a 39gn sierra blitz king
25.1 grains of N133
CCI 450 primer
.20 TAC Dakota cases.
This gives an average velocity of 3775fps
±±±±±This load is safe in my rifle±±±±±±±
I worked up slowly and am getting no pressure signs although i suspect quickload will scream.
If I concentrate this will produce very tiny groups. The es is too high at the moment but I have only measured one 10 shot string so will see how it looks with a few more rounds tested.
Anyway, headed out yesterday after a few crows and the only 2 I had a shot at I missed. Now they were 300 yards away and there was some significant wind. This led me to realise I had no experience or skill at judging wind. In the light of this I headed out today to do some practicing.
The wind was similar today as it was yesterday. So I settled at 200 yards. As an aside, as I approached the field I kept myself behind the hedge in case there was a crow etc in the field. Sure enough there were 2, one at 180 yards and one at 135 yards. I selected the one at 135yards, waited till it moved to a safe place and crowned it with a well placed blitzking. No problem at this range.
Anyways, I digress.
I use the "Shooter" app and have found it very good. So I plugged in all the details.
Now according to a zero height of half an inch, shooter says I should be 0.4 inches low at 200. I am inclined to believe this as when i missed the crows yesterday I saw the strike (about 8 inches down wind! )
Anyway, the target below shows the actual (5 shot) group. Now I know its not a fantastic group but i haven't done much practice recently and I forgot my rear bag! (excuses over!) The rough drop is 1.4 inches. About an inch more than predicted. Now i know it could be simply that the computer is a bit out but i wouldnt expect this round to drop that much, with this zero height.
View attachment 33345
(for some reason the image is rotated 90 degrees left and i cant change it!)
The main question is could the wind have caused the additional inch of depression. now i only consider this as the field is quite steeply sloped from left to right and as such the wind blows over the top and down, over the line of sight. See picture below. (there is a safe backstop, there is a bank of earth behind the target)
This topography means that the wind was coming from roughly the 10 to 11 oclock position from the line of the shot but also from the top of the hill to the left and down onto the line of sight. Now because i have little experience of shooting in the wind at extended ranges I was hoping to get some opinion of other people who may have greater experience.
anyone any thoughts?
As an aside, the .20 TAC is a joy to shoot and devastating when the driver is on song!
Thanks very much for listening to the ramblings, there isnt really an issue in real world terms as this would still be acceptable on quarry under these circumstances but i like to know exactly why things happen!
p.s i dont know what is happening with the picture of the target it has decided it likes it at the bottom!
The load is a 39gn sierra blitz king
25.1 grains of N133
CCI 450 primer
.20 TAC Dakota cases.
This gives an average velocity of 3775fps
±±±±±This load is safe in my rifle±±±±±±±
I worked up slowly and am getting no pressure signs although i suspect quickload will scream.
If I concentrate this will produce very tiny groups. The es is too high at the moment but I have only measured one 10 shot string so will see how it looks with a few more rounds tested.
Anyway, headed out yesterday after a few crows and the only 2 I had a shot at I missed. Now they were 300 yards away and there was some significant wind. This led me to realise I had no experience or skill at judging wind. In the light of this I headed out today to do some practicing.
The wind was similar today as it was yesterday. So I settled at 200 yards. As an aside, as I approached the field I kept myself behind the hedge in case there was a crow etc in the field. Sure enough there were 2, one at 180 yards and one at 135 yards. I selected the one at 135yards, waited till it moved to a safe place and crowned it with a well placed blitzking. No problem at this range.
Anyways, I digress.
I use the "Shooter" app and have found it very good. So I plugged in all the details.
Now according to a zero height of half an inch, shooter says I should be 0.4 inches low at 200. I am inclined to believe this as when i missed the crows yesterday I saw the strike (about 8 inches down wind! )
Anyway, the target below shows the actual (5 shot) group. Now I know its not a fantastic group but i haven't done much practice recently and I forgot my rear bag! (excuses over!) The rough drop is 1.4 inches. About an inch more than predicted. Now i know it could be simply that the computer is a bit out but i wouldnt expect this round to drop that much, with this zero height.
View attachment 33345
(for some reason the image is rotated 90 degrees left and i cant change it!)
The main question is could the wind have caused the additional inch of depression. now i only consider this as the field is quite steeply sloped from left to right and as such the wind blows over the top and down, over the line of sight. See picture below. (there is a safe backstop, there is a bank of earth behind the target)
This topography means that the wind was coming from roughly the 10 to 11 oclock position from the line of the shot but also from the top of the hill to the left and down onto the line of sight. Now because i have little experience of shooting in the wind at extended ranges I was hoping to get some opinion of other people who may have greater experience.
anyone any thoughts?
As an aside, the .20 TAC is a joy to shoot and devastating when the driver is on song!
Thanks very much for listening to the ramblings, there isnt really an issue in real world terms as this would still be acceptable on quarry under these circumstances but i like to know exactly why things happen!
p.s i dont know what is happening with the picture of the target it has decided it likes it at the bottom!
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