# More sensitive to temp. IMR7828 or H4831?



## beartooth (Feb 18, 2007)

Hey, which is more sensitive H4831 or IMR7828?? Need some help here, please!


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## Horsager (Aug 31, 2006)

There's very little difference between the two. A 200fps swing one way or the other means squat under 400-500yds anyway, +/- 200fps will change your POI very little. I looked at this a few weeks ago on another thread (something to do with loading for a 22-250 I think) and +/- 200fps still kept a 270 Win and a 300 Win inside a 6" kill zone out to 500 yds.

Something that is just as likely to cause +/- velocity is case prep and the amount of fouling in the barrel each time you shoot over the chronograph. Canting the chronograph a couple of degrees can easily add or subtract 50-80 FPS too.

The only reliable way to really know for sure would be to shoot targets at your intended ranges, measure the drop and back the numbers into a couple of ballistics programs. Or you could have a really good tripod and access to a range that's reletively non-busy allowing you the time to set up your chronograph exactly the same each time. Of course by the time you've shot targets out to 400 or 500 yds the actual velocity is a moot point because you already know what your corrections need to be.


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## beartooth (Feb 18, 2007)

Horsager said:


> There's very little difference between the two. A 200fps swing one way or the other means squat under 400-500yds anyway, +/- 200fps will change your POI very little. I looked at this a few weeks ago on another thread (something to do with loading for a 22-250 I think) and +/- 200fps still kept a 270 Win and a 300 Win inside a 6" kill zone out to 500 yds.
> 
> Something that is just as likely to cause +/- velocity is case prep and the amount of fouling in the barrel each time you shoot over the chronograph. Canting the chronograph a couple of degrees can easily add or subtract 50-80 FPS too.
> 
> The only reliable way to really know for sure would be to shoot targets at your intended ranges, measure the drop and back the numbers into a couple of ballistics programs. Or you could have a really good tripod and access to a range that's reletively non-busy allowing you the time to set up your chronograph exactly the same each time. Of course by the time you've shot targets out to 400 or 500 yds the actual velocity is a moot point because you already know what your corrections need to be.


Really interesting and gives much for thought. I would like I guess to just be in a ball park that is generally known and have accuracy at the same time. I really want a one two punch from my 300WBY and have settled out of experience on the 240gr for up close big game when I need quick expansion and shock effect along with good momentum. But also need a good load for far off big game as well as medium game so I am going with the 180gr TSX because of past performance of this bullet on game and retained energy and fair momentum out to the distant targets. I like the H4831, H1000 and Retumbo along with IMR7828 and also MagPro and RL-22. I have a friend who is using Quickload program which calculates the cartridge, case size, bullet construction and weight, barrel length along with other factors including OAL considerations and he has been surprised in that the program suggested powders he would have never thought about and ended up with not only better velocities but better accuracy to boot. I will let you know what he came up with when he sends it to me. you have some strong points on the Chrono so as I said in the beginning of this response I would like to know that I am in a general consensus of velocity range and I will work on accuracy factors by miner adjustments with case preparation, bullet seating, powder charge adjustments and so on. You have a great day and thank you for responding. :beer: :sniper:


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## beartooth (Feb 18, 2007)

Horsager, if you have any suggestions for load with the 180gr TSX in 300WBY mag or know someone who does, please share it with me for my comparison and consideration. thanks


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## Horsager (Aug 31, 2006)

Sorry I have no 1st hand knowledge loading for any of the Wby calibers.


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## 280IM (Mar 28, 2005)

I had a 300 Weby. about 15 years ago in a Ruger No.1. I can't remmber the loads but I do remmber the IMR 7828 preformed the best and the best wasn't very good. Tryed a load of different loads, had the forarm rebeded and still didn't shoot real well. I rebarred it to a Dakota 330 which shot really well. I belive you can make it shoot as the number of new bullets there are now should help. I know the one I had was real picky and shoot better when loaded to the max. You want to eat your wheaties if you are going to shoot it off the bench all afternoon.


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## mudstud (Nov 30, 2004)

Whether a +/- 200 fps variation is important depends on the individual shooter and his application. However, one point not yet mentioned, is that with temp sensitive powders, a load that works fine in moderate temperatures can be over-max in hot weather. I have some first-hand experience with this. A particular load I had worked up was a great load in cool weather, but generated the sticky bolt syndrome in warm weather. My solution was simply not to shoot that load in warm weather! This may not be the answer for everyone, but it worked for me! It does serve to illustrate, however, that there is more to temp senstiivity than merely a velocity change.


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## beartooth (Feb 18, 2007)

mudstud said:


> Whether a +/- 200 fps variation is important depends on the individual shooter and his application. However, one point not yet mentioned, is that with temp sensitive powders, a load that works fine in moderate temperatures can be over-max in hot weather. I have some first-hand experience with this. A particular load I had worked up was a great load in cool weather, but generated the sticky bolt syndrome in warm weather. My solution was simply not to shoot that load in warm weather! This may not be the answer for everyone, but it worked for me! It does serve to illustrate, however, that there is more to temp senstiivity than merely a velocity change.


Your point is well taken. Also there can be as much as a 10% difference in one lot of the same powder. For example, I am loading my 300WBY now with a Barnes TSX 180gr bullet and moving it on the average between 3260 and 3287fps using a load of RL-22. This load is almost 4grains over book max but no pressure signs in this hot weather where I live and the load is extremely accurate as you can see from the picture below. Now I worked up to this load a 1/2gr at a time when I went over max. Now this is what we call a cool lot of power. I will only use this pound for loading this load so I don't run out of it. When I do I will start 10% below max listed loads and work up again with this load because the next lot could be what we call a hot lot which would be as much as 10% hotter than the lot I am using.


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