RL17 temp sensitive
- Thread starter craig6547
- Start date
Larryh128
Silver $$ Contributor
I don't use N150 but I buy RL-17 in the big jugs and use it in quite a few calibers. I haven't seen RL-17 be
super temp sensitive yet. It probably changes a little but not enough that I can see any noticeable pressure differences like some of the single based powders that I've used before. A few are max loads and there has been no issue shooting in hot conditions.
super temp sensitive yet. It probably changes a little but not enough that I can see any noticeable pressure differences like some of the single based powders that I've used before. A few are max loads and there has been no issue shooting in hot conditions.
Jay Christopherson
Not An Admin
dmoran said:
+1 I shoot all my practice rounds over a chronograph, in varying conditions, year round. I keep a record of velocity vs. temperature and adjust accordingly. Some powders are much more sensitive than others, but I have yet to find any powder that does not react in some way to external temps.
swed6.5
X1ON
I have been using RL 17 for a few years, and have pretty good results, once last fall on a cool morning i got some verticle at 600 i found the next day that once adding .2ths more my tune was good. I did find that my hotter bench rest loads were getten hotter at a F class match on a dirty barrel with over 180 fired, but thats the difference between diff techniques of shooting,At this time with hard to find components dont bake your round in a hot chamber and work harder on finding better seating depths and a good velocity spread, get to know how the rifle and load will react to changes . Im very pleased with RL 17.
You don't need to wait for the ambient temperature to change in order to evaluate the temperature sensitivity of a powder. That isn't really a controlled way of doing it anyway. The problem is that you don't really know that the internal temperature of the round has reached equilibrium with the outside temperature. If the ammo has been stored in a plastic box, or in your pocket, the temperature of the powder inside it is probably not the same as the ambient temperature.
Try running a controlled test, over a chronograph. It isn't difficult and only requires 15 rounds of ammo. The way the tests works is that you soak 3 batches of ammo at hot, cold and ambient temperature for at least two hours (5 rounds of each). I use a cooler with a heating pad for hot, the freezer in the clubhouse for cold (an icebox works too), and just sit the rounds out in the open for ambient. Temperature is measured with thermocouples and/or mercury thermometers. Then, you fire them one round at a time in a round robin sequence (ambient, hot, cold, ambient, hot, cold...). You let the barrel cool in between each shot. When you fire each round, you just transfer that round from the hot/room/cold storage to the chamber and fire it through the chrono as quickly as possible. You don't want to give the rounds any time to change temperature internally due to contact with the chamber. I set the scope on the lowest magnification and just make sure I'm sending the round through the sweet spot of the chrono (no groups). You basically want to be the Jerry Miculek of loading a boltgun and firing it through a chrono. This is best done on a short pistol range, close to the berm. Record the velocities and temperatures and plot them to a line chart. From this you can derive the change in fps per degree easily and compare different loads.
I start soaking the ammo when I arrive at the range, then run the test before I leave, after doing all of my other shooting. Whole thing takes maybe 20-25 min. (including setup). It isn't complicated and it gives you a good indication of the temperature stability of a load in one range session.
Try running a controlled test, over a chronograph. It isn't difficult and only requires 15 rounds of ammo. The way the tests works is that you soak 3 batches of ammo at hot, cold and ambient temperature for at least two hours (5 rounds of each). I use a cooler with a heating pad for hot, the freezer in the clubhouse for cold (an icebox works too), and just sit the rounds out in the open for ambient. Temperature is measured with thermocouples and/or mercury thermometers. Then, you fire them one round at a time in a round robin sequence (ambient, hot, cold, ambient, hot, cold...). You let the barrel cool in between each shot. When you fire each round, you just transfer that round from the hot/room/cold storage to the chamber and fire it through the chrono as quickly as possible. You don't want to give the rounds any time to change temperature internally due to contact with the chamber. I set the scope on the lowest magnification and just make sure I'm sending the round through the sweet spot of the chrono (no groups). You basically want to be the Jerry Miculek of loading a boltgun and firing it through a chrono. This is best done on a short pistol range, close to the berm. Record the velocities and temperatures and plot them to a line chart. From this you can derive the change in fps per degree easily and compare different loads.
I start soaking the ammo when I arrive at the range, then run the test before I leave, after doing all of my other shooting. Whole thing takes maybe 20-25 min. (including setup). It isn't complicated and it gives you a good indication of the temperature stability of a load in one range session.
Jay Christopherson
Not An Admin
It's not controlled, but there is a definite correlation, which is much easier to make. Shooting matches and soaking your ammo to a specific temp via heating pad or cooler is not really practical or applicable since your ambient conditions will never be that controlled.
You're not trying to establish the specific sensitivity of a powder by correlating to external temperature - you are trying to find a correlation between the ambient temperature and the effect it has on your loaded ammo, with regards to staying within a node.
If I were trying to establish a constant for *powder* temperature variation, then you're method would be a much better way to go about it. But, I don't care about that - I care about what my loaded ammunition will be doing when I'm shooting at match at 42º - 52º ambient temp. And again later in the summer at 69º - 83º ambient temp over the course of a match that starts in the morning and ends in mid-afternoon.
You're not trying to establish the specific sensitivity of a powder by correlating to external temperature - you are trying to find a correlation between the ambient temperature and the effect it has on your loaded ammo, with regards to staying within a node.
If I were trying to establish a constant for *powder* temperature variation, then you're method would be a much better way to go about it. But, I don't care about that - I care about what my loaded ammunition will be doing when I'm shooting at match at 42º - 52º ambient temp. And again later in the summer at 69º - 83º ambient temp over the course of a match that starts in the morning and ends in mid-afternoon.
If the velocity of the ammo is changing, so is pressure and so is the time the bullet spends in the barrel. These things changing are what un-tune your ammo, and take it off the node. A change in velocity and pressure due to a change in temperature has the same effect as a change in velocity and pressure due to a change in powder charge at a fixed temperature. The more temperature stable the powder, the wider the temperature range the ammo will stay on the node.
The point isn't to try and control the temperature of your ammo, it's to chose a load that is less affected by temperature change without having to invest the time and expense of firing that load over a long period of time in order to determine it.
The point isn't to try and control the temperature of your ammo, it's to chose a load that is less affected by temperature change without having to invest the time and expense of firing that load over a long period of time in order to determine it.
dmoran said:
I've never seen a spread that large for Varget, but I've only ever ran it in the 53-62kpsi range (measure with a pressure trace system). There have been some variation in the results with different loads and different lots of powder, but I've never seen a change of over 30 fps. The results have been relatively consistent whether the load was tuned or not. For there to be a change in velocity, there has be a proportional change in pressure. I can't imagine how having the load tuned vs. un-tuned would cause that to happen if the powder charges were close to each other in weight and nothing else was different (i.e seating depth, neck thickness, etc...).
It makes sense that things would be different for different cartridges, that have a different case volumes and operating at a different pressures. You're dealing with a gas. How it behaves depends on pressure, volume, temperature and the amount of compound being burned to create it. But, I struggle to understand the mechanism in physics or chemistry that would cause a huge difference in the results when all of these are nearly the same.
Have you tried repeating the experiment more than once, under the same conditions with the same lot of components? If an experiment is not repeatable under the same conditions, that generally points to problems with the experimental method itself.
Have you tried repeating the experiment more than once, under the same conditions with the same lot of components? If an experiment is not repeatable under the same conditions, that generally points to problems with the experimental method itself.
jonbearman
I live in new york state,how unfortunate !
How do you heat it up to a stable temp to test the powder.Are you using a pyrometer or infared?
I was asking w.r.t. the one that was different (125 fps vs. 36-44 fps.). If I was getting results that were consistently between 36-44 fps. then all of the sudden got one that was 125 fps., that is definitely something I would want to try to re-produce and understand the cause of if it was repeatable.
very interesting posts so far on this. Something that ive never really thought about is the temperture.
Anybody used or heard of anyone using N150 with 140's in the 6.5 x 47 ?
I was out on sunday to test seating depths. All was going good with development and managed 3 groups measuring between .274-.330 " with 3 shot groups with speeds averaging 2750 fps. On sunday it was 8 degrees warmer than my previous test days and it gave me an extra 100 fps with slight pressure signs on the head stamp and groups opened up. I dont want to be chasing loads for winter and summer so not sure i want to continue to use this powder now.
Someone said it coudlnt have been the temp that done that to my rounds as it was to much for little change of degrees. Said it must have been something to dow ith my cases but they were made very consistently and cant seehow it could be them to fault.
Other powder i was going to try was N150. Similar burn rate to H4350 and RL17. I can get 3 tubs of this if it would be a good candidate and good chance of it working without too much temp sensitive problems ?
Craig
Anybody used or heard of anyone using N150 with 140's in the 6.5 x 47 ?
I was out on sunday to test seating depths. All was going good with development and managed 3 groups measuring between .274-.330 " with 3 shot groups with speeds averaging 2750 fps. On sunday it was 8 degrees warmer than my previous test days and it gave me an extra 100 fps with slight pressure signs on the head stamp and groups opened up. I dont want to be chasing loads for winter and summer so not sure i want to continue to use this powder now.
Someone said it coudlnt have been the temp that done that to my rounds as it was to much for little change of degrees. Said it must have been something to dow ith my cases but they were made very consistently and cant seehow it could be them to fault.
Other powder i was going to try was N150. Similar burn rate to H4350 and RL17. I can get 3 tubs of this if it would be a good candidate and good chance of it working without too much temp sensitive problems ?
Craig
I agree with you and say to agree on the ballistic test.
I've reduced my load tests to 39.0 - 40.8 and see if I can find a good accuracy node in that range.
If that doesn't work then I'll try Viht N150 and see how that goes. I've just started reading about double based and single based powders , the later being better on barrel life so I may just try the N150 anyway and if it gives good results then ill stick with it's I can get this stuff very easily in the UK
I've reduced my load tests to 39.0 - 40.8 and see if I can find a good accuracy node in that range.
If that doesn't work then I'll try Viht N150 and see how that goes. I've just started reading about double based and single based powders , the later being better on barrel life so I may just try the N150 anyway and if it gives good results then ill stick with it's I can get this stuff very easily in the UK
VV N150 with BR$/Feds Match is my go-to powder for 6.5X47L... I use 120 grs bullets, but work very well with 140s also. I tried Norma 203B, Reloader 15, Varget, N550, N140, H4350 but N150 gave me best accuracy w. lowest ES/SD numbers. It is also very easy on throats.
I think 8 degrees more is for sure not the reason for extra 100 fps... I use same same powder charge in summer/winter with very little difference. Probably chrono error, lightening, barrel went faster, scale error...?
Try N150, you wont regret it !!!
I think 8 degrees more is for sure not the reason for extra 100 fps... I use same same powder charge in summer/winter with very little difference. Probably chrono error, lightening, barrel went faster, scale error...?
Try N150, you wont regret it !!!
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