Temperature variation effect on 2209

[Tim N]

Hi All,
According to the previous thread RE17 is effected by temperature variation as reported by Mr Berry OCD extraordinaire.
Tony, or anyone else, do you have some data for 2209 and it's variation in different temps?
Hope to see you at the QLD queens/team shoot, any luck you could get second place.

[ecomeat]

Tim,
Unfortunately for US, it seems that you bloody New South Welshmen are relatively safe with 2209 when you head up here where the days warm up......... unless you are "right on" a nodal tune that in itself is very environmentally sensitive.
You have probably noted Williada talking about looking for good groups that are not right on the "peak", or in a "trough" of a harmonic wave. I put some groups from my 6 x 47 Lap on here (ozfclass) some months ago, that had two different nodes producing quite good groups. David commented that the faster one ..with the tighter group in the original testing....was right on such a "trough node" and very accurately predicted that it would be "environmentally sensitive". I posted the ET results a week or so after that where the whole day was bloody hot. I shot his recommended lighter load in the first string, and then the faster, tighter initial load that i liked best last, and the difference was a bit startling for me.
I will find the link shortly. It was called "Neutral Compensating 6 x 47 Broughton barrel".

Temperature and it's effects on pressure/velocity is one of the great things about QUICKLOAD that you can play with.
As an example :
A 284 Win with 51.02 gr of 2209 and 180 Hybrids at 28 C at a low 49443 psi and 2741 fps, changes just a bit if the Temp goes up to 36 C : 50,572 psi and 2756 fps

REL 17 : With 168 gr VLDs, a load at 21 C (hot day at Cessnock) that is safe (62088 psi in my cases) and right on an OBT node at 3019 fps , goes over Max pressure to 65,078 psi and 3040 fps if the temperature rises to 36 C.....yesterdays temp at Beaudesert.

[ecomeat]

Tim,
That thread is viewtopic.php?f=5&t=6334
Just go straight down to where Williada's comments start, bypassing the comments from Cam McEwan early in the thread , and have a look at the ET results .

[Tim N]

Hey Tony,
You must be thinking of the snowy mountains where 21deg is a hot day.
We often go over 40deg in summer.....
By your notes 2209 + 8 deg = 15 fps rise
RE17 + 15 deg = 21 fps rise

Can you check 09 with a + 15 deg
Seems like there's not much in it?

[AlanF]

Temperature and it's effects on pressure/velocity is one of the great things about QUICKLOAD that you can play with.
As an example :
A 284 Win with 51.02 gr of 2209 and 180 Hybrids at 28 C at a low 49443 psi and 2741 fps, changes just a bit if the Temp goes up to 36 C : 50,572 psi and 2756 fps

REL 17 : With 168 gr VLDs, a load at 21 C (hot day at Cessnock) that is safe (62088 psi in my cases) and right on an OBT node at 3019 fps , goes over Max pressure to 65,078 psi and 3040 fps if the temperature rises to 36 C.....yesterdays temp at Beaudesert.

Tony,

Looking at those figures 2209 goes up 15fps for an 8°C rise, and RL-17 goes up 21fps for a 15°C rise. So that says 2209 is MORE (1.9fps/°C) temperature sensitive than RL-17 (1.4fps/°C).

I don't know Quickload, but does it claim to know the temperature sensitivity of these powders or does it just build in a general figure?

Alan

[aaronraad]

I was under the impression that double base powders (e.g. RE17) were more temperature sensitive than single base powders (e.g. AR2209); and that triple base powders (mil-spec) were the most sensitive to temperature changes? Certainly from the same manufacturer when making their best attempts at temperature sensitivity across the range (e.g. Vihtavuori).

I can see the fps/°C figures quoted, but are we still talking apples with apples given that burn rates are significantly affected by pressure also?

The two loads quoted by Tony in the 2nd post are significantly different in terms of pressure and use 2 different projectiles -case volume change? I'm assuming primers were the same also?

The temperature ranges (28 - 36 °C & 21 - 36 °C) are also different and the relationship through this portion might not be linear (or linear enough), even if we roll back the scale to Kelvin instead of Celsius.

Certainly would be interesting to better understand which formula the internal ballistic software programs utilise for powder temperature sensitivity...starts making external ballistics look simple

[williada]

There is no doubt temperature effects velocity and that it is the major factor in the environment that causes velocity change. There are two fast ways to measure it using an infra red temperature sensing gun and a chronograph; and it means work, if you don’t have Quickload which is not absolute for all gear but an approximation. Or you could take a long time over a season and measure the velocity with given temperatures.

Firstly, if it’s going to be a hot day start early and take velocity readings at 10 degree F increments of case temperature where the ammunition is left in the shade with the rifle and note the velocity spreads. I use imperial measurements because that is a sign of age. The other way, which is much quicker, and used by extreme distance shooters, and it is to use plastic ice packs covered by a towel with ammunition placed on them until the ammunition cools to a desired temperature in a container. The ice packs are then removed. Same deal, as the ammunition warms, or is induced to warm with a hairdryer etc. at 10 degree F intervals on the case, take velocity readings.

Take the readings and graph them in Excel as velocity V temperature for the powder used. The aim of the game is to maintain the desired velocity to maintain the desired tune. That means you take powder out of the case the hotter it gets. This means more tests and repeating the former with rounds loaded with varying charges in order to work out a set velocity at a given temperature. You just might observe, like a carby tune, the air fuel mixture changes because you could change the air gap significantly. So the powder changes ain’t necessarily linear.

There is no hard and fast rule because each barrel is different. Like I believe, there is no general accuracy node that so many quote, at a given speed for a given calibre. It all depends.

[Steve N]

Dave if an accurate load is on the higher side of the given charge weight approaching the maximum pressure is it right to presume that higher than normal temperature could push it over the edge to peak and then become an inaccurate load? If so is it wiser to load at the minimum charge of that node for general use or at least for when you are expecting higher ambient temperatures for more stability. I have had a very accurate load with my 6.5x47L that I suspect was much less accurate on hot days. Reducing the charge slightly has not seemed to affect the good accuracy so I am hoping that now the problem has gone.....
Then again may have been mirage or something completely unrelated.
Any opinions or suggestion s great fully appreciated.
Steve

[williada]

Steve the short answer is yes. If you are a nodal tuner, the lower charge in the nodal range is good insurance.

A nodal tune has a built in velocity tolerance where many sine waves from various vibrations interact to form a tight spot, usually on a peak or trough. But sometimes its hard to spot a peak or a trough in a heavy barrel as Tony can attest to. So for the purpose of discussion lets call a node a tight spot. Sometimes this nodal tolerance can be short and sometimes it can be longer depending on how many harmonic frequencies are interacting.

So yes, a lesser charge can keep the velocity in the nodal range on a hot day. Yes, your normal load can push you past the node if velocity is increased outside the nodal range by the heat of the day. The rifle tuned in such a way may well be set up with an environmentally tight window. That is, that tight spot is surrounded by poor groups. As soon as the pressure changes, so do the interaction of many frequencies of vibration which we see expressed on the target as hollow groups, arching groups, vertically strung groups, diagonal groups etc.; and yes throw mirage into the mix to confuse you.

Consider tuning before a peak on a tight spot, it allows slower shots to be tossed up and so this is in reality a slight positive compensation tune with colder morning conditions. As the day warms and within reason you pop up to the full nodal tune with increased velocities.

Be aware there are other tuning methods such as Optimal Charge Weight method which are environmentally more forgiving and mimic a neutral compensation tune. But they can drop out at long range with 6 o'clock shots if loading preparation and group management are not good.

If you are getting troughs and peaks with hollow patterns, and are forced to reduce your load to get acceptable groups but you really feel you are under gunned, then the first port of call is the common seating depth test. It takes time. You need to test an upper load, a middle load and a lower load at different seating depths going from the jam in .010”, then .005” out, .010” and so on in .005” increments until say .025” out. Common environmental adjustments can be in the order of .3 grn to .6 grn so your loads should represent this spread at a minimum. Make up 3 rounds each of the same charge and seating depth to fire as a group at each aiming mark. Prepare a short range target, 100 yards to 140 yards whatever your poison, with three aiming marks across and enough down to accommodate the seating depth differences. So, on the top three aiming marks you shoot the different charges with the .010” jam, the next target with the .005” free flight and so on down the rows of three aiming marks. A reasonable free flight is where you find the tighter groups of the three different loads with the same free flight impacting on a similar elevation. David.

[Steve N]

Thanks for the detailed answer Dave. We may have gone off the original topic a bit but I am sure this information will be very valuable to anyone trying to get a good consistently accurate load.
Steve.

[ecomeat]

Steve,
I shot at Goondiwindi OPM a couple of years ago with a MagnetoSpeed chrony on, testing Primers in a fairly warm environment. In my 284 Win, it turned out that PMC primers gave me virtually identical ES and SD as the Fed 210GM's , but were 20 fps lower average speed.
CCIBR2's didn't work for me, with almost double the ES of the other two.
Since then, I have loaded accordingly, with PMC's used for "after lunch" in warmer weather.
It's a pretty simple way for me to attempt to deal with temperature induced velocity changes, where I am expecting a much hotter afternoon.
It obviously didn't work well enough at Crows Nest OPM when you beat me home by an "X"

[Steve N]

Tony interesting observation about the velocity difference with different primers. My Chrony is nowhere near accurate enough to show those slight differences so I prefer to keep away from loads they might be temperature sus. Whatever the load you used on the Saturday at Crows Nest to take out the Sweepstakes worked damn well!
Steve

[ecomeat]

By your notes 2209 + 8 deg = 15 fps rise
RE17 + 15 deg = 21 fps rise

Can you check 09 with a + 15 deg
Seems like there's not much in it?

Tim,
If I drop the Temp to 21 C (70 F...coz QL is only fahrenheit) that same 180gr Hybrid load shows 48174 psi and 2723 fps.
If I lift the Temp to your very real 40 C, it lifts to 51201 psi and 2764 fps.
Remember that this is specifically for MY load, in MY cases......and this #2 Bartlein likes jumping Hybrids a rather large 0.080", so pressures will be way lower than any sort of jammed load.
Also, I don't shoot 2209 in any current 284 barrel, as I have a quantity of 2213sc I am working my way through.
One load I had played with on paper with a Maddco barrel was 168 gr VLDs with 56.38 gr of 2209 showed an OBT at 63827 psi......getting up there......and 3002 fps.
If I lift that to a balmy Cessnock summer day of 40C, it goes well over pressure to 65369 psi and 3026 fps. So an extra 24 fps in velocity, and an extra 1542 psi in chamber pressure.
In my 284 Win with 2213sc i get 6fps - 8 fps for every extra 0.1 gr of powder, so that equates to approx 0.3 gr powder increase. If someone happily heads off to a Queens with loads varying by 0.3 gr and not worry about it, then I guess they wouldn't need to consider temperature induced variations.
Will 20 fps tip you off a node ? If you have an OCD like many,it sure is fun finding out

[ecomeat]

Looking at those figures 2209 goes up 15fps for an 8°C rise, and RL-17 goes up 21fps for a 15°C rise. So that says 2209 is MORE (1.9fps/°C) temperature sensitive than RL-17 (1.4fps/°C).

I don't know Quickload, but does it claim to know the temperature sensitivity of these powders or does it just build in a general figure?

Alan

Alan,
I have to admit that I can't swear to any of that. I simply don't know the answer to your question....but I don't think that QL makes any attempt to allow for specific temperature sensitivities. I think that your suggestion of them building in a general figure is probably correct.
I googled everything I could find on QLoad when I was thinking about getting it, and a new user is basically warned that whilst all powders have been tested if they are in the data base, it's really only a single Lot tested for "Burning Rate". You are specifically advised that your current powder Lot may differ markedly from the Lot tested by QuickLoad etc etc.
Burning Rate is the factor you are advised to manipulate first to "calibrate" against real world, believable chronograph figures that you have compiled.
Tony

[KHGS]

[quote="aaronraad"]I was under the impression that double base powders (e.g. RE17) were more temperature sensitive than single base powders (e.g. AR2209); and that triple base powders (mil-spec) were the most sensitive to temperature changes? Certainly from the same manufacturer when making their best attempts at temperature sensitivity across the range (e.g. Vihtavuori).

Correct! I do not see 2209 as any marked difference to 2208 or 2206 or 2206H. I do & have burnt lots of these powders. Any of the double based powders will be generally more temperature sensitive than any single based powder. The ADI powders are less sensitive than most other single based powders that I know of. Double based powders are generally harder on throats as well.
Keith H.