Reloading: changing powder - the same brand and number...

Reloading: changing powder - the same brand and number...

This is a discussion on Reloading: changing powder - the same brand and number... within the General Firearm Discussion forums, part of the Related Topics category; It didn't take me long to go through my 1 lb can of H4895 powder. Been doing a lot of playing with primers and cases ...

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Thread: Reloading: changing powder - the same brand and number...

  1. #1
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    Reloading: changing powder - the same brand and number...

    It didn't take me long to go through my 1 lb can of H4895 powder. Been doing a lot of playing with primers and cases to see what changes they might make. Just to answer that, I didn't see much advantage in anything. In primers I tried F205m, CCI BR-4, CCI 450, Winchester WSR, and tried the same primers in Lapua and Winchester cases. It just didn't make much difference in anything. I could say the BR-4s produced the lowest ES and SD, but not by much. And, all were 25 shot sets, so the results are pretty trustworthy.

    Having said that we can get on to the point of the thread. I've been shooting my BSF 12" carbon fiber a lot lately and I just about always chrono reloads. So I've been seeing velocities right around 2560 fps for a 75 gr Hornady BTHP-m with 23.6 gr of H4895. Yesterday shot the very same load and the velocity jumped to an average of 2603 fps and I was seeing some signs on the cases.

    It took me a minute to realize what was going on - I THINK, as in know more this afternoon. I had run out of the H4895 and bought 8 lbs of it. That was what I was shooting yesterday. If the new batch was a mere 2% hotter than the 1 lb can I had been shooting, that would account for the shift in velocity. So MAYBE, the puzzle is solved. I want to down load the charge by 0.4 gr and see what that produces this afternoon. I am expecting the average velocity to drop from 2603 to about 2558. Dropping the charge by 0.5 gr should give about 2546 fps average and that would be fine too. Hmmm, may try both.

    Anyway, this may be some definitive proof that powder "hotness" does change from lot to lot - as we've heard it does. I've heard it can vary as much as 5%. Just never seen the results before.
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    VIP Member Array tns0038's Avatar
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    I reload and or create new bullets for all my hunting rifles for over 40 years.

    I have used H4895 powder for years, and while the batch # may change the group impact location some, I have never seen it change that much. If your seeing signs on the primer and or casing, then your load pressure may be way to high.

    I found that cold weather, particularly when the rifle barrel is very cold will produce higher velocity. Also the barrel heating up from use, will change the group location and the velocity. Keep in mind I'm talking about 1/8 to 1/4 inch movement at 100 yards. But considering I've shot wild hogs and deer at over 500 yards, a 1/4 inch at 100 yards is a big thing.

    For that reason, I always had my rifle barrels floated, and plumbed to the action, and I make sure the bullet is just touching the lands of the riffling. But even with this when centering the scope, I shoot in 3 shoot groups, then waited 10 minutes. That way I knew when hunting, where the first bullet was going from a cold barrel.


    Let us know what you find out.
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    Quote Originally Posted by tns0038 View Post
    ...I have used [COLOR=#000000]H4895 powder for years, and while the batch # may change the group impact location some, I have never seen it change that much. If your seeing signs on the primer and or casing, then your load pressure may be way to high.
    What velocity variations have you been seeing from lot to lot?

    I went from no signs with the previous lot, to some signs with the new lot. Nothing else was changed - same cases, same primers, same bullets, essentially the same temperature.

    Quote Originally Posted by tns0038 View Post
    ...I found that cold weather, particularly when the rifle barrel is very cold will produce higher velocity. Also the barrel heating up from use, will change the group location and the velocity. Keep in mind I'm talking about 1/8 to 1/4 inch movement at 100 yards.
    Intriguing, since H4895 is reportedly very temperature stable. What kind of velocity changes do you see from cold to warm?

    Quote Originally Posted by tns0038 View Post
    ...But considering I've shot wild hogs and deer at over 500 yards, a 1/4 inch at 100 yards is a big thing.
    Amen brother! Been posting about the effects of velocity changes on POI for over a year now.

    Quote Originally Posted by tns0038 View Post
    ...Let us know what you find out.
    Will do!
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    This really maxed out my curiosity so I gave Hodgdon a call and explained what I had experienced. He said that is not surprising as powders can vary from lot to lot and it was not uncommon at all to see velocity variations from lot to lot. When I told him I saw about a 2% change in velocity from one lot to the next, he said that could very well be and there's nothing unusual about that at all.

    So, I guess there it is from the horse's mouth.
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    VIP Member Array dangerranger's Avatar
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    I don't remember where I read this But the makers of Unique kept a large quantity of the first batch of powder in a temp stable storage area to compare to modern samples to make sure they don't drift from the original. I don't know if its true or just a good story, But it seems as likely as KFC keeping their recipe in a vault! DR
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    Tangle, I love to see your posts. As careful as I am with my rifle loads, I get the same kind of swings with velocities. It really drives me crazy.

    Have you ever done much chrono work with factory loads? I chronoed (is that a word?) some factory loads for my buddy with a 300 Win Mag rifle and they were remarkably consistent. More consistent than anything I have managed to achieve. Makes one take pause....
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    Quote Originally Posted by Tangle View Post
    This really maxed out my curiosity so I gave Hodgdon a call and explained what I had experienced. He said that is not surprising as powders can vary from lot to lot and it was not uncommon at all to see velocity variations from lot to lot. When I told him I saw about a 2% change in velocity from one lot to the next, he said that could very well be and there's nothing unusual about that at all.

    So, I guess there it is from the horse's mouth.
    Did they by any chance tell you how much variation can be expected? Is the 2% that you are seeing a large variation between lots, or is that typical, or smaller than expected?

    I rarely push the upper limits of the published data, but this could make a big difference in how I approach the limits of any loads.
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    Quote Originally Posted by dangerranger View Post
    I don't remember where I read this But the makers of Unique kept a large quantity of the first batch of powder in a temp stable storage area to compare to modern samples to make sure they don't drift from the original. I don't know if its true or just a good story, But it seems as likely as KFC keeping their recipe in a vault! DR
    I heard some hamburger joint did the same thing with its grease.
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    Quote Originally Posted by BlackJack View Post
    Did they by any chance tell you how much variation can be expected? Is the 2% that you are seeing a large variation between lots, or is that typical, or smaller than expected?

    I rarely push the upper limits of the published data, but this could make a big difference in how I approach the limits of any loads.
    Yeah, I'm wondering the same thing and wondering why I didn't ask a few more questions.

    You make a good point about approaching limits - I'd like to know that too.

    To that end, I just got off the phone with them again. I asked the "how much" question but as I suspected, he would not/could not give a percentage. I did ask specifically about the 2% variation I saw and he said that was quite common.

    He also said when changing to a different lot, one should start low and come up.

    I pretty much push to the edge so I watch velocities and examine cases. When I saw the average velocity go up from 2550 to 2603 I terminated the test. I realize everything was the same except the powder.

    I loaded 25 rounds 0.4 gr lighter and shot them this afternoon. The average velocity was 2548 fps - that's pretty close to the 2550 fps I have been seeing. Unfortunately, the groups were larger than I like, so I will back off another 0.2 gr and give that a try.
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    The man who taught me about reloading always said if were in the upper range of a load always back off when adding a different component to the load. That includes even different lot numbers on any component. Humidity, altitude, cold barrel and hot barrel will change grouping of the same round. Crimp or no crimp will change velocity. Lots of things change velocity and groups.
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    Lot to lot variation can be minimal or considerable.

    In the early days of .38 Supers in IPSC Blue Dot was a common powder. The lot to lot variation was so much that it was common for competitors to find a lot that they could buy a bunch of and work up a load with it so they didn't have to work up another load for a long time. Buying multiple 8lb kegs was common with the guys who shot a lot. BTW shot to shot variation was considerable with Blue Dot too and folks tended to load heavy to be sure to make major.

    When I started shooting Super I settled on WW571. An ole buddy of mine clued me in to the fact WW571 and HS7 were the same powder sold under different names. I got to the point I would buy which ever of the two powders I could find or find the cheapest at the time and pour the new powder in on top of the old powder without ever a problem. Sure couldn't do that with Blue Dot.

    The only way to know what you can get away with is to chrono it and try things.
    Last edited by 1MoreFord; January 30th, 2020 at 05:57 PM.
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