H-1000 velocity variation/air temp value??

[BrentM]

I'm just trying to replicate factory loads, MV with COAL. We are not going to get into all this ( how far off the lands and groves is the ojive of the projectile ) All my stuff need to fit into the magazine of an AR10 and when it comes to my 300 WIN MAG, well, I have to be able to hit what I need to at any range using off the shelf Hornady 200GR ELD-X.

OK, to be clear, you are shooting an AR 10 and running 2.80 COAL max and want factory velocity right? What isn't stated in the charts is what cartridges are being tested. The chart is just a guide. You will have to field trial on your own, especially a gas gun. imr 4064 is listed as .53. So if you shoot 2800 at 50F, then you'll see 2790-2810. That is a 40 degree change and .53 fps/degree, 20 fps. That is 6" at 1000 yards, or .6 moa roughly. That is using a 308 with 155 berger.

What I do believe, through my own testing, is that temp stabile powders work well in wide temp swing around the temp the load was developed in. Temp sensitive powders usually shoot very well in the specific temp they are developed in but tend to go wonky when outside plus or minus 20. Velocity is just 1 component of the equation and it can usually be accounted for within reason. The other part is if the velocity changes too much you can easily be out of barrel time node and the round is now inaccurate or changes its release at the muzzle and your load is no good. For example it may be an inch high and left if it is 50 fps slower or faster.

It's just something to think about. I'd dial the load in, low sd/es, and accurate in your current environment. I'd take 10, 2 groups of 5, and put 5 in the freezer over night, and keep them on ice. I'd take 5 and put them in the house. When going to the range I'd zip lock them and put the rounds next to your body, like your chest(core). Chrono the loads and test your zero. If all is within reasonable expectations, you are good to go.

Like mentioned earlier I run RL26. I developed a load in the spring in temps 50-70. I've shot that load from -10 to 90 and never had issues hitting my targets. Velocity has changed very little. I tested it again last week at 30F and it was 3fps different over a 5 shot average. I hunt predators all winter and I've been hammering yotes from 500-1125 and don't use this feature.

 

[Deleted member 112929]

OK, to be clear, you are shooting an AR 10 and running 2.80 COAL max and want factory velocity right? What isn't stated in the charts is what cartridges are being tested. The chart is just a guide. You will have to field trial on your own, especially a gas gun. imr 4064 is listed as .53. So if you shoot 2800 at 50F, then you'll see 2790-2810. That is a 40 degree change and .53 fps/degree, 20 fps. That is 6" at 1000 yards, or .6 moa roughly. That is using a 308 with 155 berger.

What I do believe, through my own testing, is that temp stabile powders work well in wide temp swing around the temp the load was developed in. Temp sensitive powders usually shoot very well in the specific temp they are developed in but tend to go wonky when outside plus or minus 20. Velocity is just 1 component of the equation and it can usually be accounted for within reason. The other part is if the velocity changes too much you can easily be out of barrel time node and the round is now inaccurate or changes its release at the muzzle and your load is no good. For example it may be an inch high and left if it is 50 fps slower or faster.

It's just something to think about. I'd dial the load in, low sd/es, and accurate in your current environment. I'd take 10, 2 groups of 5, and put 5 in the freezer over night, and keep them on ice. I'd take 5 and put them in the house. When going to the range I'd zip lock them and put the rounds next to your body, like your chest(core). Chrono the loads and test your zero. If all is within reasonable expectations, you are good to go.

Like mentioned earlier I run RL26. I developed a load in the spring in temps 50-70. I've shot that load from -10 to 90 and never had issues hitting my targets. Velocity has changed very little. I tested it again last week at 30F and it was 3fps different over a 5 shot average. I hunt predators all winter and I've been hammering yotes from 500-1125 and don't use this feature.

Thank you for the information. I would venture to say 99% of all the hunters going for big game at long distance have not considered any of the parameters and then wonder why even in their rifle was in a lead sled and the target was still they missed. As I get more and more into this subject matter I find it interesting and intriguing. I'm now 67 and have been shooting for a while but only recently have I wanted to go out further just to see if I can hit a 10" plate out at 1000 yards and what it take to do so with my hand load and factory guns. I just want to be better than average with bolt action and SA rifles and pistols. Thanks again. Oh, I forgot to mention I've pretty much only shoot three weights of bullets. 168 GR HPBTMK, 178GR ELD-X and 200GR ELD-X 99% is 168 gr and soon to switch over to the 178 ELD-X if it proves to be more accurate than the 168 GR. From all that I have read if I am to believe the factory the BC on the 178 gr ELD-X / 200 gr ELD-X exceed the 175gr HPBKMK used by the military.

 

[BrentM]

Thank you for the information. I would venture to say 99% of all the hunters going for big game at long distance have not considered any of the parameters and then wonder why even in their rifle was in a lead sled and the target was still they missed. As I get more and more into this subject matter I find it interesting and intriguing. I'm now 67 and have been shooting for a while but only recently have I wanted to go out further just to see if I can hit a 10" plate out at 1000 yards and what it take to do so with my hand load and factory guns. I just want to be better than average with bolt action and SA rifles and pistols. Thanks again. Oh, I forgot to mention I've pretty much only shoot three weights of bullets. 168 GR HPBTMK, 178GR ELD-X and 200GR ELD-X 99% is 168 gr and soon to switch over to the 178 ELD-X if it proves to be more accurate than the 168 GR. From all that I have read if I am to believe the factory the BC on the 178 gr ELD-X / 200 gr ELD-X exceed the 175gr HPBKMK used by the military.

Its a complex rabbit hole but generally once a person understands the variables it comes together enough to not be a big concern. I agree with you on the premise and especially running factory ammo, not knowing if it stabile or not. If you haven't done so look up the WEZ, weapon employment zone, by Brian Litz. It is basically a discussion covering percentage of hit factor for ammo, rifle, and shooter capabilities. IMHO What most people don't spend enough time on is wind. Wind is the freaking devil and destroys long range accuracy and hunting. Yesterday I had a pack of wolves in the drainage across from me. 1000-1200 yards and it was blowing 14 mph. What I noticed was 3 wind direction and velocity changes. Even if I could have gotten a clear shot it would have been luck to hit one. I need 6 moa for full value, likely 1.5 moa for vertical for updraft at the shooter, and then I needed to figure out those changes. Shooter wind was 30% value, Mid point likely closer to 7-10mph but full value, and at the last half to target the wind was likely 3-5. I wanted to pull over and shoot a rock inside the drainage next to them to test my theory of dropping 1 moa and running 3.5-4 left. However, it was a high probability the wolves would have left and ruined any chance. Normally, I would take the shot and test myself. Mountain terrain shooting is humbling.