what's the difference

[MagnumManiac]

Burn rates may vary a bit from lot to lot, but you cannot compare or make a judgement on the "burn rate" of a powder in a particular cartridge. Published burn rates are obtained in a laboratory under extremely controlled conditions. How any particular powder behaves with your case, primer, bullet, rifle, temperature, etc., combination compared to another is conjecture at best, especially considering all the variables.

Please provide your proof of the STANDARD that these powder burn rate charts are compared to. There isn't one in existence…
I worked for ADI, they make ALL of Hodgdons Extreme line, amongst others, and EACH manufacturer has its OWN powder that it bases all other RQ numbers against. Not ONE powder made by X company is compared in a lab against Y company.
A list of RQ numbers is published, this MAY or MAY NOT coincide with the RQ number provided by another company, and actually it rarely is even close. RQ is the Relative Quickness number.
ADI bases an RQ Number of 100 to 2206H (Hodgdon call this H4895) then every other powder is given it's own RQ number, a higher number than 100 is faster than 2206H, a smaller number is slower.
Again, I will repeat this, burn rates are NOT CONSTANT. Period.

Cheers.

 

[sturner]

Sounds like a rabbit hole

 

[Stokesrjsr]

Please provide your proof of the STANDARD that these powder burn rate charts are compared to. There isn't one in existence…
I worked for ADI, they make ALL of Hodgdons Extreme line, amongst others, and EACH manufacturer has its OWN powder that it bases all other RQ numbers against. Not ONE powder made by X company is compared in a lab against Y company.
A list of RQ numbers is published, this MAY or MAY NOT coincide with the RQ number provided by another company, and actually it rarely is even close. RQ is the Relative Quickness number.
ADI bases an RQ Number of 100 to 2206H (Hodgdon call this H4895) then every other powder is given it's own RQ number, a higher number than 100 is faster than 2206H, a smaller number is slower.
Again, I will repeat this, burn rates are NOT CONSTANT. Period.

Cheers.

I understand what you are saying and agree in principle. However some companies do compare their own and other companies powders in a closed bomb test under laboratory conditions. I am a member of the SAAMI technical committee and a member of the NAMMO small caliber R&D team. NAMMO owns Vihtavuori and many other companies. Vihtavuori does conduct burn rate tests of competitors powders to generate their burn rate comparison charts. But in the end they don't test all lots of any powder and I'm looking at the certificate of compliance for two lots of H4350 from ADI right now, and these two lots would give different answers in those rankings.
So in the end, burn rate charts are only generally accurate.

 

[Litrfoot]

Yup, I've seen the burn rate flip flop a bit over the years.
It also seems some powders are happier in some cartridges than others. I run rl19 in my 338win with 225's but in my 300win I run rl22 with 165.180 grain bullets. My 7stw is happier with rl25 with 140's. I've tried test loads with rl19 in the 300win and 7stw and it wasn't as happy. My 25wssm loves h4895 with 100's; it hates 4064. My 30-06 and 405 win like 4064. My 405win doesn't run h4895 very well.

Thisthe standard variance is +\- 5% burn rate, that means in the extreme, the difference could be 10%, how, if your published base line is X, the published chart, this means the burn rate could be 5% low for one lot and another lot could be 5% high for a total difference of 10%. Where this matter is for loaders loading max loads. That's why it is important to always test when cracking open a new lot. Just because you bake a cake with the same recipe doesn't mean it's going to taste the same ever time.

 

[judgebill]

What does the "average" guy do when trying to develop/work-up a load for his new rifle? Well, begin with the manuals and select a combination of bullet and powder that promises a "reasonable" [i.e., not the "max", just "reasonable...hich can be found in many manuals that list "most accurate", a choice usually less than max] performance. If a careful shooter, one who measures and weighs everything, and is cautious (not beginning with the max load) and testing for ACCURACY rather than max velocity, you should have a good load for your gun with your powder choice and your bullet choice. By "testing" I mean doing a ladder test and exploring variations. Reading most literature we discover recommended bullet weights and styles that work for whatever game you plan on shooting. Ranges...that's up to what you determine is your comfortable range.

 

[Rocketeer77]

All tests done on the same day with the same equipment. Regardless, burn rates are not constant…and your statement is incorrect.

Cheers.

Burn rates are usually constant when you're working under identical conditions, change brass, projectile weight, primer type/brand, ambient temperature etc then the identical powder won't be consistent in that calibre. That's a known for most handloaders and why we're very careful. My two cents worth

 

[MagnumManiac]

Thisthe standard variance is +\- 5% burn rate, that means in the extreme, the difference could be 10%, how, if your published base line is X, the published chart, this means the burn rate could be 5% low for one lot and another lot could be 5% high for a total difference of 10%. Where this matter is for loaders loading max loads. That's why it is important to always test when cracking open a new lot. Just because you bake a cake with the same recipe doesn't mean it's going to taste the same ever time.

Again more misinformation…
For a CANISTER powder to called such, it HAS to be within 3% TOTAL of the original parameters of the first ever powder named so. This is 1.5% +/-, not +/- 3%.

This is why I struggle talking about technical facts here, everyone, educated or not, has their own opinion…

 

[MagnumManiac]

However some companies do compare their own and other companies powders in a closed bomb test under laboratory conditions

Where are these calorimeter bomb test results published? If they're not published, then it is meaningless information.

I could post ANY RQ number as a guess, it means nothing and neither do burn rate charts.

Cheers.

 

[RichCoyle]

Barrel length can make a big difference on what works in your rifle compared to published load data. The faster powders can work better in short barrels if they allow for complete powder burn. An incomplete burn may have a detrimental effect on your accuracy even though you get similar or better velocity.

This has been proven incorrect in scientific studies. The powder producing the fastest result and long barrel produces the fastest result in a short barrel.