Your Density altitude alone could easily put you off by .5 mil. A chrony is usually +/-1%. There is your margin error. Your numbers ( fps, bc ) could be perfect, your can have 0temp variance and you could be off that much. Nothing replaces actually shooting at range and getting good DOPE.
Temp sensitive powder and fps ?
- Thread starter BrentM
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Your Density altitude alone could easily put you off by .5 mil. A chrony is usually +/-1%. There is your margin error. Your numbers ( fps, bc ) could be perfect, your can have 0temp variance and you could be off that much. Nothing replaces actually shooting at range and getting good DOPE.
BrentM
Well-Known Member
I believe I had the correct atmosphere conditions input and in order to be that far off it would have to be below sea level and -30 with powder temp turned on. According to the ballistics computer.
I will take the chrono out this weekend test some loads to see what number needs to be in the powder temp section. Based on Hogdon site it should be .36fps/degree. I will try and verify that. Temps here are 0-10F. I can stick some rounds next to my body and some outside and test the spread.
I think it is a combo of the temp sensitivity and lower BC. Berger and Nosler both have much lower BC numbers and both of those bullets are generally accepted to be of very good quality. In theory if I use .36 and a BC of .235 with 3800 FPS the elevation solution is very close. If my scope has some error I will try and rule that out as well.
Appreciate all the input and things to consider.
I will take the chrono out this weekend test some loads to see what number needs to be in the powder temp section. Based on Hogdon site it should be .36fps/degree. I will try and verify that. Temps here are 0-10F. I can stick some rounds next to my body and some outside and test the spread.
I think it is a combo of the temp sensitivity and lower BC. Berger and Nosler both have much lower BC numbers and both of those bullets are generally accepted to be of very good quality. In theory if I use .36 and a BC of .235 with 3800 FPS the elevation solution is very close. If my scope has some error I will try and rule that out as well.
Appreciate all the input and things to consider.
Kennibear
Well-Known Member
Scope, temp, BC, all these factors multiply.
In sighting in many (mine and friends) scopes I have never had exact movement of the group on target. As most people want their rigs sighted @ 200yds the movement should be two clicks per inch. I cannot recall that ever being the case. If memory serves the movements were always more, i.e. dial in adjustments, group moves too far, dial back to center up group. This is for typical hunting non - AO scopes. My ancient Weaver T16 is closest I remember but it was a smidgen off too. It didn't move enough as I recall. It's currently dialed in for a single load @ 100yds and I have't change it in years, probably frozen with rust at this point.
Don't know what turrets you have on the scope but I would check the screws just to be sure before I fired the next round. Probably do it at the bench just before shooting. I'm kinda annul that way. Found some loose scope ring screws time before last. It was actually a surprise as I Blue Locktite all my scope screws.
My vote is still BC = BS.
KB
In sighting in many (mine and friends) scopes I have never had exact movement of the group on target. As most people want their rigs sighted @ 200yds the movement should be two clicks per inch. I cannot recall that ever being the case. If memory serves the movements were always more, i.e. dial in adjustments, group moves too far, dial back to center up group. This is for typical hunting non - AO scopes. My ancient Weaver T16 is closest I remember but it was a smidgen off too. It didn't move enough as I recall. It's currently dialed in for a single load @ 100yds and I have't change it in years, probably frozen with rust at this point.
Don't know what turrets you have on the scope but I would check the screws just to be sure before I fired the next round. Probably do it at the bench just before shooting. I'm kinda annul that way. Found some loose scope ring screws time before last. It was actually a surprise as I Blue Locktite all my scope screws.
My vote is still BC = BS.
KB
Kennibear
Well-Known Member
P.S.
Am I the only one that thinks 0.36 fps/ degree is an incredibly good number???
KB
Am I the only one that thinks 0.36 fps/ degree is an incredibly good number???
KB
BrentM
Well-Known Member
I just got this scope back from Leupold who installed the m1's. My normal LR scope is Night Force, which tracks extremely well. However, that scope is on my 6.5-284 and I don't want to pull it off to conduct any testing.
When zeroing the Leupold it was quite responsive and I shot multiple .25 to .38 groups at 100. My last adjustment was .5 high and .25 right. 2 clicks down and 1 left put me on the black .5 square for 2, 3 round zeroing groups.
Not sure about .36 being good or not. I use retumbo in my 6.5-284 and my solutions on elevation have extremely good from 0 to 90, 2500 to 10200 ft, and out 1660 yards. This temp thing is a new issue for me. I figured I would have some issues with it and IMR powders, just was not sure how sensitive it might be. Kind of a fun learning opportunity.
When zeroing the Leupold it was quite responsive and I shot multiple .25 to .38 groups at 100. My last adjustment was .5 high and .25 right. 2 clicks down and 1 left put me on the black .5 square for 2, 3 round zeroing groups.
Not sure about .36 being good or not. I use retumbo in my 6.5-284 and my solutions on elevation have extremely good from 0 to 90, 2500 to 10200 ft, and out 1660 yards. This temp thing is a new issue for me. I figured I would have some issues with it and IMR powders, just was not sure how sensitive it might be. Kind of a fun learning opportunity.
Kennibear
Well-Known Member
BrentM
All those powders, Hodgdon's Retumbo, H1000 etc. and the IMR series are manufactured by ADI in Australia for Hodgdon who now own the rights to DuPont's powder line. Hodgdon claimed to have applied the "Extreme" powder technology across their line after so much success with, I believe, "Varget" their first such powder.
Hard for me to believe that cold weather slows the powder at all this day in age....
But BC's haven't escaped the Ad department yet.....
KB
All those powders, Hodgdon's Retumbo, H1000 etc. and the IMR series are manufactured by ADI in Australia for Hodgdon who now own the rights to DuPont's powder line. Hodgdon claimed to have applied the "Extreme" powder technology across their line after so much success with, I believe, "Varget" their first such powder.
Hard for me to believe that cold weather slows the powder at all this day in age....
But BC's haven't escaped the Ad department yet.....
KB
BrentM
Well-Known Member
Understood. I think you are correct about the BC thing. This is not the first time I have heard or read about it. Looking at Litz info I can see the differences from claimed to actual pretty well. If I had been shooting a claimed temp stable powder my little brain might have gone straight to BC, but I blocked that out.
I appreciate all the input and variables everyone has discussed. I will test this weekend and finish dialing in the rifle. My kid and wife will use it for wolf hunting along with my 6.5 so I want it tuned up perfectly so they have confidence in it.
BrentM
Well-Known Member
MOA on the brain. My new turrets are IPHY not MOA and I didn't switch it. Doh.
While out wolf hunting yesterday I tested the 204. My chrono was showing an average of 3780 and I used to the factory BC. Out to 450 the solution with IPHY and bullet strikes were lining up very well. For giggles I took a shot at 880. The bullet was low 2 feet and left 10". I am still testing loads and playing with some extreme powders for temp stability but next time out I will take some more ammo and test from 500 to 800 and see how it goes.
While out wolf hunting yesterday I tested the 204. My chrono was showing an average of 3780 and I used to the factory BC. Out to 450 the solution with IPHY and bullet strikes were lining up very well. For giggles I took a shot at 880. The bullet was low 2 feet and left 10". I am still testing loads and playing with some extreme powders for temp stability but next time out I will take some more ammo and test from 500 to 800 and see how it goes.
Kennibear
Well-Known Member
BrentM
IPHY does not compute. Explain to the slow guy please!
KB
IPHY does not compute. Explain to the slow guy please!
KB
Michael Eichele
Well-Known Member
IMHO that is very acceptable. Not all loads will work well with extreme powders. Not all load dynamics will show the same results as what you see on Hodgdon's website either. I use RL powders often with great results and minimal extreme temp spreads.
BrentM
Well-Known Member
My computer was set to moa but the turrets are 1/4 inch not .25 moa.
I think I am close now. Fine tune and shoot. : )
I think I am close now. Fine tune and shoot. : )
BrentM
Well-Known Member
Played with benchmark and h4198. Got best results with 4198. 3780 with less than 10 ES. Accuracy was good at .25 @ 100.
