Quickload and ADI / Hodgdon powders. Why are their Quickload properties different?

[David_S]

I am new to Quickload but am finding it very educational. Just playing with different variables - powder, COL, case capacity etc - gives valuable insights about their relative importance.

One thing is puzzling me though. ADI of Australia make most of the popular Hodgdon powders. Varget is ADI AR2208, H4350 is AR2209, H4831SC is AR2213SC for example.

I would expect then that the properties Quickload gives for the equivalent powders would be the same. This is in fact true for some such as Varget/AR2208 but not for others such as H4831/AR2213, H4350/AR2209 and H4895/AR2206H.

Does anyone know why this is so? Does Quickload use old ADI data for instance? I use ADI powders as they are readily available here in New Zealand but have found that Quickload will often predict velocities more accurately with the Hodgdon powder than the ADI powder.

Any ideas anyone?

David

[Brian Pfleuger]

QuickLoad's powder data is based either on information supplied directly from the manufacturer or from "bomb tests" if the manufacturer will not supply the information.

I would suppose that perhaps the ADI data comes from older info from the manufacturer and the Hodgdon data comes from actual testing, making it more accurate.

Just a guess.

[GJSchulze]

In another post someone told me that QL did not accurately calculate 9mm pressures correctly. Is this true and is there any documentation on it?

[Brian Pfleuger]

It's not 9mm in particular, it's straight-walled (or nearly so) cartridges.

It's not necessarily incorrect, just less reliable and consistent, takes some extra tweaking to get good conformity with reality.

[FrankenMauser]

A lot of data used to create the formulas for QL calculations was acquired through actual testing in loaned rifles or barrels, with donated components.
So, the data is frequently based on information from a specific group of lot numbers tested in a limited number of rifles/barrels, rather than the manufacturer's "enclosed bomb" performance target.

QL is a guide. It isn't perfect.

[David_S]

I think you are probably right, Brian. I doubt ADI powders are readily available in Germany, or Europe generally, so the data on them is likely to be less reliable or up-to-date than the Hodgdon version.

Incidentally, which is the key powder characteristic(s) to tweak to align predicted velocities with measured velocities. I have been experimenting with the "Burning rate factor" Ba with reasonable results.

Also does anyone know if there is a forum specialising in Quickload or reloading software? TFL seems more directed to the practicalities of reloading.

David

PS Frankenmauser. I take your point but this would indicate a significant variation from batch to batch of ADI production as the Hodgdon/ADI powders are supposedly identical. I think there was a post here some time ago with a letter from ADI to that effect.

[Brian Pfleuger]

Here's a pretty good rundown:

http://www.6mmbr.com/quickload.html

Weighting factor is a big variable.

It's based on the cartridges "over-bore" status to an extent, which is problematic in that there is no actual definition of "overbore" but it also seems to be backwards to a certain degree. It says "overbore" cartridges should be down around 0.33 while straight-wall are higher, as much as 0.75.

Trouble is, if you enter the cartridge design data, QuickLoad gives you a default number for the weighting factor and the more "overbore" the cartridge is, the HIGHER the number it seems to give you.

The default numbers don't make much sense either. IIRC, .243Win is set at 0.50 while the AI version is 0.65. I'll have to check later to see if that's the one I'm remembering.

If you read on it a bit, the weighting factor actually seems more related to the expansion ratio or bore capacity. It's essentially a measure (percentage) of how much of the charge and gases actually follow the bullet down the bore. A weighting factor of 0.50 means that 50% of the charge is chasing the bullet, basically.

The interesting thing with the weighting factor is that lowering the number decreases predicted PSI but increases predicted velocity. That can get you in trouble if you're velocity chasing and start lowering the weighting factor to match your higher velocity when what you really have is a higher pressure causing your higher velocity, which is the opposite of what you'll get changing the weighting factor.

[David_S]

Brian, thanks for that link. A lot of good reading there including a comment on ADI AR2208 and Hodgdon Varget differences, so I am not the only one noticing that. Interestingly the author found better results with ADI than Hodgdon whereas I found it was the other way round.

David

[FrankenMauser]

PS Frankenmauser. I take your point but this would indicate a significant variation from batch to batch of ADI production as the Hodgdon/ADI powders are supposedly identical. I think there was a post here some time ago with a letter from ADI to that effect.

All it might indicate, is that the range of ADI lot numbers tested showed different aggregate performance than the aggregate of Hodgdon lot numbers tested.
Some powder companies have openly admitted that they have powders in their lines that are allowed to vary as much as 10% lot-to-lot.

Or... perhaps the powders sold under the ADI name were not held to standards as tight as those sold under the Hodgdon/IMR names in the Litigious States of America.

[David_S]

Or... perhaps the powders sold under the ADI name were not held to standards as tight as those sold under the Hodgdon/IMR names in the Litigious States of America.

Now that is an interesting possibility that I hadn't thought of. You don't think they might send the lower standard powders to their mates across the Tasman? Nah, the Aussies wouldn't do that!??? ......Ummm! Perhaps I should try some Hodgdon equivalents as a test.