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Smokeless Powder Burn Rate Chart

Burn rate charts are handy but they aren't gospel. Several factors affect actual burn rates. One example in the first chart linked of such a case is h4198 is shown to be just a tick faster than n120. I've never seen that to be true in anything I've loaded both in. The n120 has always proven to be about 1.5gr faster than h4198. Some people are running near 36.0gr of h4198 in 30br's. I'd be pretty nervous about that much n120 under the same bullet. Actually, more than a little.
Use charts as a general approximation but don't bet your eyeballs on burn rate charts.
 
jackieschmidt said:
Good question.
in many cases, a powder that gives as close to a 100% fill while achieving the desired velocity will also often be the most accurate load.
A good example that I have found is with my custom 30/06. Shooting the 178 grn AMax. I can get my desired velocity with powders as fast as 4895 all the way to as slow as H4831SC.
however, the load with the 4831SC , which is 61.3 grns, is actually a compressed load. It is also the most accurate.

In my 6PPC competition rifles, the go to powder is N133. By all accounts, it is actually on the slow side for a 68 grn. The loads many of us shoot can only be used when we use a long small hole drop tube to get it all in there and still have room for the bullet.
I have found that this “compressed” load is by far the best combination for optimum Agging capability.

The same can be said for my 30BR. The load of either H4198 or LT-30 can also be classed as a 100%density load.

Of curse, there are multitudes of combinations where this simply is not true. Every bullet/power/barrel combo is different.

As for listed burn rate, myself and two friends found a stark discrepancy in the latest chart. That being, H1000 and N170.

We we’re working with the 7mm Geramo, which is a 6.5x55 necked up to 7mm and then Ackley Improved.

We found H1000 to be very accurate with 162 grn ELD’s. We wanted to try something just a little faster because the H1000 was a compressed load.

Ed got some N170. We dropped the load a couple of grns, but to our surprise, the velocity was wwwaaayyy down. We finally ended up with just about a full case, and the velocity was still an average 200 fps slower than the H1000.
TIf you look at that chart, you will see it listed before H1000.
By weight and volume in a given case, that simply is not true. By a long shot, (pun intended).
Click to expand...
just because the powders are close on the chart doesn't mean they have the same pressure curve, I spent alot of Money on a small VERY RARE book by W.L. Godfrey on The .30-06 he tests 70 different powders and bullets from 60 to 155, absolute pressure, MV, FPS this guy was a mad scientist of ballistics.
 
Some of the questions asked by some posters, makes me wonder. do they ever look at and read a reloading manual ? , or even own one. Most explain powder burn rate, to some degree and even have charts in the front of the manuals for reading, to learn and for safety reasons in reloading your own ammunition.
 
CJ6 said:
I wish it was more up to date. It's a 2013 list.
Click to expand...

There are more up to date [LHS] versions. Unfortunately, being produced for European handloaders, the later versions omit all REACH non-compliant grades. ie most Hodgdon and Winchester powders, plus all IMR grades now that the 'Endurons' have been discontinued.

Mentioning IMR 'Enduron', 4166 is a good example of the potential weakness of burn rate charts. Hodgdon's chart lists it as slower burning than either 4895 version and faster than VarGet (which itself has moved several steps 'slower' than shown in other charts/tables.) On the basis therefore of 'comparable' powders, 4166 should be ideal for 223 and 77s/80s given that all the powders 'around it' are well suited to the application. Looking for loads a year or two ago, nobody listed it in 223 Rem loads bar Hodgdon itself in its 'Annual Manual', and that at a mere 22.0gn 4166 with the 77gn SMK compared to 22.6gn H4895 and 23.0gn IMR-4895, both weight limited by being compressed loads, VarGet shown as 23.7gn max, also compressed. (QuickLOAD with its default settings based on the factory data that no doubt also gives the powder its burn chart position calculates considerably higher safe maximum loads at pressures and MVs comparable to the other three grades.)

On the range and working up loads in very small increments, 4166 pressured out at below H4895's, never mind VarGet's usable charges and MVs, and also underperformed apparently much faster burners such as AR-Comp.

IME, many Vihtavuori powders are shown as over-'slow', and Lovex (Shooters World) as over-'fast' in charts in real-life use. It can be very poor practice indeed to use these charts in order to determine anything beyond identifying a grade as a possible alternative to any other and therefore as worth undertaking further research into published loads for it in the application.
 
It is my understanding that burn rate charts do not utilize a standard test method, and that the various manufacturers simply rate powders compared to others that they produce. It does not incorporate the amount of energy produced.
 
CharlieNC said:
It is my understanding that burn rate charts do not utilize a standard test method, and that the various manufacturers simply rate powders compared to others that they produce. It does not incorporate the amount of energy produced.
Click to expand...

That's also my understanding.

For a different approach have a look at the Norma table which is based on 308 Win actual pressures / MVs using a common case, bullet, and single charge weight then indexed against IMR-4350's results:

https://www.norma-ammunition.com/en-gb/reloading-data

Unfortunately, it's a very old chart now and omits many powders (including H. VarGet) introduced over the last 25 years or so. (The 'Accurate' grades are also the pre-Western ones and are today's 'Lovex' or where appropriate Shooters World products.) The only recent additions are a couple of Norma's own grades including URP.

Using the indexed pressure values, Viht N150/550 are considerably 'faster' than IMR-4350 and even more so H4350, and even N160 is shown as a bit 'faster' than this pair, never mind being anywhere close to IMR-4831 as shown in most other charts. (The Hodgdon list has N160 between the two 4831s, ie 'slower' than the IMR version and 'faster' than the Hodgdon. I don't know how often I've seen or heard British shooters say words to the effect that N160 is 'the same as 4831' so far as loads go, solely based on inaccurate burn rate charts!)

HOWEVER ............ if you really want to lose ALL trust in these charts, have a look at this view:

https://www.chuckhawks.com/powder_burn_rate.htm

Here's another Chuck Hawks article of interest too explaining some of the complexity / confusion

https://www.chuckhawks.com/powder_relative_burn_rate.htm
 
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