When I wrote a review of the then newly reintroduced Ramshot rifle powders into the UK some years ago, I spent a lot of time trying to get an answer to this question online ......... and failed pretty comprehensively. Here are a couple of pieces from Western Powders / Accurate on this issue from the company's website at different times.
First, current (from the site's FAQ section):
7. What is the real story behind temperature stability?
Most of our powders are not insensitive, and will show some effect at hot and cold temperatures.
However, we test at -40F and +125F and the deviation in most cases are ca 3% to 5% at these extreme levels. Therefore most shooters do not notice much difference under normal practical hunting conditions.
More elaboration on the subject:
Complete temperature stability can only be achieved with tubular extruded powders designs, either with double base (NG) and/or with other coating technologies.
Because the ballistic performance at extreme temperature is completely dependant on the specific combination, it is very difficult to quantify and qualify.
Our standard powders perform very well at extreme temperatures, and usually pass the strict military requirements by a large margin.
This is a subject that often fraught with misconceptions and inaccuracies.
The term is used loosely by manufacturers without qualifying the subject, and is obviously exploited for marketing purposes and perceptions.
The facts are:
- Although powders can be improved, it’s really only possible with advanced coating procedures and additives which increase the cost.
- A particular powder can be improved re temperature stability for certain combinations, within a certain envelope which is specific to the following three main parameters/aspects
- The caliber.
- The weight of the projectile/bullet.
- The performance level.
If any of these parameters/aspects go beyond or outside the intended ratio/s, the results will change and the performance will sometimes be different.
It is also very important that when a comparison is made, that all conditions re weapon i.e. components primer, case, bullet and the velocity are equal, and preferably done at the same time on the same day."
Second from the Accurate powders website maybe 10 years ago:
".................. Here’s what Keith Anderson of Western Powders’ ballistics lab said in a forum post last year:
“All of the powders sold under the Ramshot or Accurate brands meet or exceed the military specification [presumably NATO?, author]
for hot and cold stability. As with anything, some powders are better than others. Single base powders such as Varget can be made to be more temperature stable than double based powders such as Accurate 2520 although there are trade offs to anything. While the nitroglycerin in a double based powder makes it less temperature stable it is the component that makes double based powders cleaner burning and allows them to attain higher velocities and their single based cousins.
“In both the single base and double base lines of powders some powders have better temperature stability than others, Ramshot ‘TAC’ is one of the most temperature stable double based powders available. It is this very reason that so much of it is being used for military applications in both Iraq and Afghanistan. Even under extreme temperatures Ramshot ‘TAC’ will vary less than half what the military will allow.”
IMHO, there is a large element of
Give a dog a bad name .......... on this issue. A lot of double-based and ball powders' alleged issues probably were true at one time, but technology has moved on a long way in 100 plus years. (The original British Cordite propellant used in late 19th / early 20th century 0.303 ball cartridges had a make-up of 57% nitroglycerin, 38% nitrocellulose, 5% mineral jelly - it wore barrels out in around 1,000 rounds; by the time of the 303 Mk VII ball cartridge's introduction in 1910 the nitroglycerin and nitrocellulose proportions were pretty well reversed and barrel life improved accordingly.)
What you do find on the issue online is a huge amount of opinion and anecdote, but few facts from professionals. Yes, sure some individual products no doubt correctly have reputations - good or bad - which are deserved. H4350 is undoubtedly very temperature stable even by the standards of other ADI / Hodgdon 'Extreme' extruded grades, but some older single-based tubular extruded types are reckoned to be very temperature affected and I'd imagine many modern 'ball' grades are considerably less so. What cannot be done - but regularly is on forums - is to say type A is invariably good and type B is invariably bad.
) as to whether any precision shooter would come up with a ball type application that really works in the more demanding disciplines. So far, silence!
