Terry
Gold $$ Contributor
Thank you for your comments.
I'm not saying anything bad about Hodgson products. I use them a lot.
I was surprised by the change. This is something I will retest.
H4895 Temp Changes
- Thread starter Terry
- Start date
Thank you for your comments.
I'm not saying anything bad about Hodgson products. I use them a lot.
I was surprised by the change. This is something I will retest.
I was testing and shot 5 four shot groups in a row to see if the they moved and group size would change. 31.0 was 2977 for 3 groups and it went up to 2982 in group 4 and 5. I would guess the lot # has a velocity change more than the heat form the barrel. This barrel took almost 150 rounds before the velocity was stable. ..... jim
I haven’t found a powder yet that was temp stable.
Bart
Bart
urbanrifleman
Site $$ Sponsor
Incorrect young Padawan Because how much the velocity changes varies greatly from powder to powder.It is a myth... Because the change in velocity is not coming from the powder.
Bart
urbanrifleman
Site $$ Sponsor
No, I meant the as the temp changes and goes up, with a given powder, the air density changes as there are less molecules of air in the air, and as a result less pressure is on the nose of the bullet, so the thinner the air gets the faster the bullet goes (and conversely the pressure increases at the case).
The bullet is a type of an airfoil. And somehow the entire shooting world has missed the concept that it behaves like every other airfoil.
Except me and you of course
Yep, just leave them in a hot barrel and see how much they move and see it on the Labradar.... jim
Please do it.
If there is any reloader who hasn't scratched their head at something, they haven't experimented much.
There are temperature variances for every powder if you look for them or ask manufacturers. Ballistics programs also have inputs for powder temp variances. Some powders have more temperature variance than other without any other weather related considerations.
Attachments
We'ell, YEAHH!??
As anyone who's actually CHECKED THIS finds out.......
test it people....
TEST IT!!
Thank You Terry...
That "fewer air molecules" idea perty much weirded me out this day......... WHAT kinda' silly is THIS???
Howsabout thems of us who shoot out of a building winter and summer from a hunnerd above to a hunnerd below..... and who FREEZE and COOK their powders thru a wide range of temperatures to TEST loads over a wide range of temps..... how come we ain't seem fewer molecules?
Are molecules so teeensy we CAIN'T SEE 'EM???
Or do I need to update my prescription?
Howsabout thems of us who shoot out of a building winter and summer from a hunnerd above to a hunnerd below..... and who FREEZE and COOK their powders thru a wide range of temperatures to TEST loads over a wide range of temps..... how come we ain't seem fewer molecules?
Are molecules so teeensy we CAIN'T SEE 'EM???
Or do I need to update my prescription?
Ned Ludd
Silver $$ Contributor
I HAVE tested it...over several years' time period, using hundreds of loaded rounds, and many different Lots of H4895 over at least a 40-50 degree temperature spread. I've never seen velocities jump like that, as I stated previously. So much for your testing theory. Why not the much simpler conclusion, that maybe, just maybe, something else besides a completely ridiculous and anomalous change in powder burn rate might be a significant contributing factor in this particular case? Given the sheer number of shooters that have tested and used H4895 over the years, I'd even say the odds that Terry might simply have gotten a bad Lot of powder are overwhelmingly more likely than a more general conclusion that H4895 has such a poor resistance to temperature-induced velocity variance.
Appreciate you posting your findings, interesting to see..Just curious what figures were you expecting?
Well THANK YOU for actually testing it
I apologize, in retrospect my (somewhat tongue in cheek) reaction is a little over the top. I messed up, tried to be funny. My apologies.
That said. I've never experienced what you're describing so I'm piqued.....
My testing has shown me that there's no such animal as "temperature stable powder" ie in controlled conditions where I load inside using different temperature stabilized powder loads I've found a direct correlation with temperature rise and pressure/velocity rise with all powders I've tested.... REGARDLESS of outside temp. Conversely I've kept powder in a cooler on hot days both at a 600yd match and in the varmint patch and while bullets definitely chart differently through range as temperatures and altitude change, the chronograph readings remain consistent to temp of powder.
I THINK Ned that what you're saying is that if I heat-soak my rounds at say 70 degrees, or in my case if I shoot out the window of my temperature controlled loading area, or better yet that I leave the rifle out on the outside bench (much more common in my case than shooting out the window) that the velocity will read substantially higher on hot days than on cold days....even though the rounds are heat-soaked at the same temp?
???
Because I load on my range, inside a room and mostly shoot outside and a lot over chronos and I have NOT ever noticed this effect, I'm confused.
BTST I load and develop loads for custom rifles and build temp/ballistic charts for them and if this effect is to be added to the mix I need to be aware of it. I send out my info based on "when your rounds are XX temperature expect such-and-such velocity."
Back to the testing board!
Ned Ludd
Silver $$ Contributor
Well THANK YOU for actually testing it
I apologize, in retrospect my (somewhat tongue in cheek) reaction is a little over the top. I messed up, tried to be funny. My apologies.
That said. I've never experienced what you're describing so I'm piqued.....
My testing has shown me that there's no such animal as "temperature stable powder" ie in controlled conditions where I load inside using different temperature stabilized powder loads I've found a direct correlation with temperature rise and pressure/velocity rise with all powders I've tested.... REGARDLESS of outside temp. Conversely I've kept powder in a cooler on hot days both at a 600yd match and in the varmint patch and while bullets definitely chart differently through range as temperatures and altitude change, the chronograph readings remain consistent to temp of powder.
I THINK Ned that what you're saying is that if I heat-soak my rounds at say 70 degrees, or in my case if I shoot out the window of my temperature controlled loading area, or better yet that I leave the rifle out on the outside bench (much more common in my case than shooting out the window) that the velocity will read substantially higher on hot days than on cold days....even though the rounds are heat-soaked at the same temp?
???
Because I load on my range, inside a room and mostly shoot outside and a lot over chronos and I have NOT ever noticed this effect, I'm confused.
BTST I load and develop loads for custom rifles and build temp/ballistic charts for them and if this effect is to be added to the mix I need to be aware of it. I send out my info based on "when your rounds are XX temperature expect such-and-such velocity."
Back to the testing board!
That is not what I'm saying. I'm saying that I've shot somewhere in the neighborhood of at least 40-50 lbs of H4895, possibly more, in the last four years or so. A scientist by training, I am fanatical about load testing and I meticulously record temperature and all other pertinent data. I've never seen anything close to a 50 FPS velocity spread over a 20 degree temperature change with H4895. The sheer magnitude of that result alone tells you something else is going on. I would typically expect H4895 velocities to change somewhere in the 0.2 to 0.3 fps per degree F range. Varget and H4350 are just a tad better. No one is claiming that any powders are completely insensitive to the effect of temperature and, in fact, velocities do change as temperature changes. But not 50 fps over a 20 degree spread. That's a 2.5 fps per degree variance. I wouldn't even expect the most temperature-sensitive double based powder in the world to be that bad. Immediately making the assumption that H4895 is a bad powder with respect to its temperature-sensitivity is a mistake and will not allow Terry to find the real culprit.
Terry
Gold $$ Contributor
Thank you to all.
My report was just that, a report of my experience. I will be retesting. I hope to have similar conditions soon.
It is never my intention to get people upset or to cause division.
I have and use many Hodgson powders. I am not slamming them. Most of my experience is with Varget, 4831, 4350, and Benchmark. This is my first serious work with H4895. In the past I have found wider tune windows with Varget.
In my next test I will run two cronographs at the same time. Perhaps this will provide some insight.
Thanks again to all!
Terry
My report was just that, a report of my experience. I will be retesting. I hope to have similar conditions soon.
It is never my intention to get people upset or to cause division.
I have and use many Hodgson powders. I am not slamming them. Most of my experience is with Varget, 4831, 4350, and Benchmark. This is my first serious work with H4895. In the past I have found wider tune windows with Varget.
In my next test I will run two cronographs at the same time. Perhaps this will provide some insight.
Thanks again to all!
Terry
I'm not sure where the "assumption..bad powder" part comes from as #1, I don't "assume"
and #2, if I indicated "bad powder" I need to reword my post. NEVER was it my intent to malign any powder, my simple contention is that no powder is "temperature insensitive"
That said, I've never experienced powder shooting different velocities than predicted by it's stabilized temperature.
POWDER temperature, not air temperature. I can't even think like that cuz in my brain the climate inside a fired barrel in no way reflects "environmental conditions"
Ned Ludd
Silver $$ Contributor
I wasn't referring to you with regard to a making an assumption H4895 was a bad powder, rather it was the OP that seemed to have a bad opinion of H4895 using words like "touted" and "not what I expected". Had he not started the thread off that way, I probably wouldn't still posting in it.
It's really not that uncommon for shooters to be dissatisfied with vendors products from time to time, and I have no reason to doubt the OP observed the velocity variance that he stated he observed. Personally, I would have never worded it the way he did and my very first call would have been to Hodgdon rather than posting on the internet. Nonetheless, there are a pretty wide range of things that can cause velocity variance and the powder itself is only one of those variables. I've used a boatload of H4895 over the years, testing it rigorously and routinely and I've never observed anything like the temperature-sensitive velocity changes the OP experienced exactly as I stated. This powder has been widely-used for decades, a fact that would be very unlikely if it was as sensitive as the OP's results indicate. Then you come along and imply in your typical condescending manner that other people don't really ever test things or can't possibly know as much about it as you, while at the same time also claiming that H4895 is not temperature-stable. In a relative sense, that couldn't be further from the truth. No powder known to man is completely immune from the effects of temperature. But H4895 is right near the top of the list of those least affected by temperature.
If you want to believe you're the only one that knows anything about the topic, go right ahead. Clearly your not going to give me any credit for understanding how things like the temperature of the powder itself or the barrel might contribute to velocity excursions well above and beyond ambient temperature. Who would guess I might actually understand that a significant portion of the powder burn actually occurs outside the case, meaning that a hot barrel can have a much greater effect on velocity than the internal temperature of the powder in the case? Or understand the value of normalizing the temperatures of the barrel and loaded rounds? None of that really helps the OP toward understanding why he observed a 50 fps average velocity swing across a 20 degree temperature change. Blaming the powder is easy, and in all honesty, I can't rule out the possibility he got an aberrant lot of powder. But there's also a very good chance something else is going on and simply assuming the powder must be poor with respect to temperature sensitivity is a sure way NOT to find out what was really going on. But feel free to carry on, as clearly no else can possibly possess the level of understanding of physics and thermodynamics with which you have obviously been blessed. That's what this is really about isn't it?
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.