H4831 vs H4831SC "Carolina Load" 6.5CM

[yo-yo]

According to Jbm the sst bullet is slightly longer than the eld, only by .036

Wow! Interesting! I'll have to evaluate this a bit, but it does sound like my major issue was the powder. Do the bullet manufactures publish the various dimensions of each bullet? Like, for example, what the length of the boat tail is, the bearing surface, and the ogive? That would help me better compare bullets, rather than eye these with calipers.

 

[ma smith]

I just meant the purpose of choosing this recipe was to get a data point. There was no other starting point. There isn't *any* use of H4831 or H4831SC in any of the books for 6.5CM. Also, all the feedback I received about those powders was "they should burn very similarly", so I think the "data point" was a reasonable goal.

Here's a good example of mixing apples and oranges...

 

[ma smith]

Oh, and before you argue that I'm confusing H with IMR ...
ask yourself why these two powders have the same number?

 

[straightshooter1]

Thanks for the reply! I will digest this a little bit and do some vocabulary homework. Thank you!
I'm looking into some of the tools I can use to make these measurements, but I'm cringing looking at how accurate and repeatable these tools are. I'm an experienced engine builder, so I usually look for much better tool precision.
I'll study this a bit more!
Thanks!

I know what you mean about "better tool precision" as I worked as an aircraft mechanic and delt with parts for turbine engines and the tolerances involved. I think that's what turned me into bit of a perfectionist.

The kind of precision we're used to isn't really so necessary for reloading cartridges. Though some precision is certainly helpful toward the end game, where consistency/repeatability is what we want. Where precision really comes in for precision shooting is in the manufacturing of actions, bolts and barrels. . . and bullets too. If you go whole hog on building parts for this hobby and have a milling machine, then you'll need some good precision tools.

A good high end caliper is very useful, though still isn't a precision instrument. Only real precision instrument I have is a micrometer that I use to measuring neck thicknesses before and after I turn them. Also have some pin gauges that I use for more accurate neck tension measurements.

Interesting! I didn't realize there was a software program that cataloged this data. I'll look into those!
I understand that burn rates my vary with environmental conditions, but I assume since there is a table "from fastest to slowest" burns, there must be some documented burn rate for a given set of conditions (temp, humidity, atmos pressure, etc.). That's all I was looking for - for a base understanding of how the H4831 I have compared to other powders that were in the books I have. We have LOTS and LOTS of the H4831, so I wanted to use that, if it was similar to the H4831SC that was called for in the Carolina Load.

I do have a chronograph so I can fine tune into the power with that. Thank you for the suggestions!

I've not seen or heard of any of that kind of documentation that you're looking for. Those software apps are the best source known for what you want to do in comparing powders, since you can change variables that'll show you the result. The results are just a calculation that can be fine tuned by your input, but still only give you a ballpark idea of what to expect.

 

[6.5SH]

I just meant the purpose of choosing this recipe was to get a data point. There was no other starting point. There isn't *any* use of H4831 or H4831SC in any of the books for 6.5CM. Also, all the feedback I received about those powders was "they should burn very similarly", so I think the "data point" was a reasonable goal.

This is incorrect, it exists right on Hodgdon's site which I linked above. It is for a 140gr Swift A-Frame which is a flat bottom hunting bullet. Which gets right into the heart of the issue, the usable powder space. IF you mean you can't find "official" data for the ELD-M or SST you just answered your own question, it isn't an ideal combination.

Your question on powder "size"; the info does exist but not every vendor makes it easy to find, it is called "VMD"; volume measured density.

Your other post finally gets to the point; you have a bunch of H4831 and want to use it. Can you? Sure, it is going to require measuring YOUR components and YOUR chamber to figure out what you can safely get away with.

You seem to be all over the place on what you want to know as a first time reloader, immediately jumping into the unknowns then wanting info that a cartridge designer is going to use instead of starting at the basics first.

https://storage.googleapis.com/wzukusers/user-33607572/documents/560926619a0c4db184ef2af972d82744/Propellant%20%26%20Interior%20Ballistics.pdf

If you insist on this path, buy his book then contact him for an online or in person class to satisfy your curiosity:

https://bulletology.com/

https://www.amazon.com/Ammunition-Demystified-Bubbas-Guide-Really/dp/1662433328

IMO it isn't going to help you understand much where you are at now, you are trying to jump right to the end.

 

[straightshooter1]

Wow! Interesting! I'll have to evaluate this a bit, but it does sound like my major issue was the powder. Do the bullet manufactures publish the various dimensions of each bullet? Like, for example, what the length of the boat tail is, the bearing surface, and the ogive? That would help me better compare bullets, rather than eye these with calipers.

Other than taking measurement yourself, the QuickLoad app as this: