On hotter days isn't there more pressure in the case? Like if you make a maximum load in the winter, it could be dangerous in the summer? What do you do? Work up the max load in the summer and keep it in the fall?
Maxium load is seasonal?
- Thread starter goodgorilla
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M
milo 2.0
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The summer is definitely the optimum time for load development, if it works then, it'll work all year. But you can also skew your readings by taking the ammo out of an air conditioned truck and blast, you need to let the ammo get to ambient temps, or bake it in the sun for a true test. Unless you can control the atmosphere of your conditions at all times, and by atmosphere I don't mean temps, sunlight, etc.., I mean can you make sure the ammo doesn't exceed a certain temp.
Seasons can have an impact on your ammo. I've seen velocity rise by as much as 200 fps and more during our hot summers here in the south. Some powders such as those from Alliant are more sensitive than others such as Hodgdon. Back when I was using RE25 in competition, I would keep my ammo next to a cold pack in my backpack to keep pressures in check. Otherwise I would experience hard bolt lift and the occasional popped primer.
Speaking of max loads, I have heard that they might not yield the best accuracy. How often would you say that is true?
M
milo 2.0
Guest
Accuracy can come from anywhere in the spectrum, each rifle combo is different. A lot of rifle combo's, as long as they're chambered with the same reamer can run a reasonably similar load with success.
In manuals they will asterisk the most accurate load, disregard that horseshit, there's nothing about their rifle combo that matches yours, except maybe the brand of action.
I agree with above. Velocity is no guarantee of accuracy.
Conducting an OCW you will find various accuracy nodes from starting loads to maximum.
My goal is to find an accurate load that 1) maintains supersonic velocity for my max effective range 2) allows for a decent case life 3) cartridge will fit in my rifle mag well.
For most of my shooting, I have found a happy medium with the second to highest node. Higher pressure can take its toll on primer pockets, so to extend case life I choose a lower node.
In the end, you must choose a load based on your actual type of shooting. No need to burn up powder and brass if you will only shoot to 300Y. On the other hand, you may find a load that shoots cloverleafs at 100, yet it will go transonic at 600Y (you shoot to 800).
Conducting an OCW you will find various accuracy nodes from starting loads to maximum.
My goal is to find an accurate load that 1) maintains supersonic velocity for my max effective range 2) allows for a decent case life 3) cartridge will fit in my rifle mag well.
For most of my shooting, I have found a happy medium with the second to highest node. Higher pressure can take its toll on primer pockets, so to extend case life I choose a lower node.
In the end, you must choose a load based on your actual type of shooting. No need to burn up powder and brass if you will only shoot to 300Y. On the other hand, you may find a load that shoots cloverleafs at 100, yet it will go transonic at 600Y (you shoot to 800).
I will be shooting berger vld bullets when I get my rifle. It says in the berger manual that I should find the sweetspot on the coal before finding the optimum powder type and amount. I think in the OCW it says to find the powder first, I think that's the only deviation I am going to do to do OCW. Sad part is my barrel won't be done until January.
You must remember that the VLD has a secant ogive, many times the sweetspot is very close to the lands. This may restrict you to single loading your rifle.
That would suck, for I have a magazine setup. My best hope is that I will be using a 300 win mag magazine with my 7mm rem mag cartridges. The 300 win mag's look to be .05 inches longer than the 7 mags.
When you test rounds... measure your oal first with vlds and set them close to test with... like ten thousanths... off the lands.. then test powders with all bullets set there.... after you find the right load you can tweek seating depth again.... remember even temp stable powders are not perfect... they still vary with ambient temps... rl15 gives me 100 fps diff between 30 degrees at 110 degrees in a grendel i run..
Usually the most accurate load is not a max load... i feel pretty safe saying that... sometimes the most accurate is a over max load.. just be careful.. i run a over max load in my grendel... with re15 i crunch powder.... and ive yet to see published data for re15 in a grendel... but it works perfect for me.
lots of watching for bad signs... lots of testing...
ive yet to find a perfect round in under 200 or 300 test loads...
Usually the most accurate load is not a max load... i feel pretty safe saying that... sometimes the most accurate is a over max load.. just be careful.. i run a over max load in my grendel... with re15 i crunch powder.... and ive yet to see published data for re15 in a grendel... but it works perfect for me.
lots of watching for bad signs... lots of testing...
ive yet to find a perfect round in under 200 or 300 test loads...
Some powders are more temperature sensitive than others.
I think it's helpful to know how sensitive a powder is before I start developing a load.
In an ideal world I'd start with Hodgdon Extreme powders which all have very low temperature sensitivity, but Hodgdon Extreme powders like H4350 and Varget are the hardest to find these days, so I've had to find alternatives. I tried Accurate 4350 instead of H4350 in my .260 as a result of Hodgdon's published statistic of it being the least sensitive of the alternative powders to H4350, and the facts that it's available and performs like H4350 made me stick with it. My load was developed during the summer so I know it's not gonna blow my $hit up in the highest temperatures I'm going to experience. In the cold I know my hot weather load will be safe, and I can tweak it if need be.
I would not recommend developing a load in cold temps then shooting it during the summer without working up to it... not worth the risk IMO.
Right now I'm developing a .308 load with IMR4064 which I understand to have a fair amount of temp sensitivity, so it's likely I will have to re-develop in the winter for that one (if I shoot it that much).
The .260 has proved to be pretty forgiving at low temps so I did not tweak it.
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The berger manual said to find the vld sweet spot prior to changing powders because the vld is more sensitive to seating depth than powder types. Here is what the berger manual says to do to find the sweet spot:
Load 24 rounds at the following COAL if you are a target competition shooter who does not worry about jamming a bullet:
.010 into (touching) the lands (jam) 6 rounds
.040 off the lands (jump) 6 rounds
.080 off the lands (jump) 6 rounds
.120 off the lands (jump) 6 rounds
Load 24 rounds at the following COAL if you are a hunter (pulling a bullet out of the case with your rifling while in the field can be a hunt ending event which must be avoided) or a competition shooter who worries about pulling a bullet during a match:
.010 off the lands (jump) 6 rounds
.050 off the lands (jump) 6 rounds
.090 off the lands (jump) 6 rounds
.130 off the lands (jump) 6 rounds
Most likely I will be restricted by my magazine length, and will do something like the above. I am a little confused you just say .010 off the lands then go for the powder.
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GG,
A node is a certain range of velocity that your barrel has the least oscillation at the muzzle.
That's the problem with temp sensitive powders. To keep the velocity in the node you have to adjust the powder charge according to temperature to keep the FPS in that nodes velocity range. Also why I avoid them except for plinking ammo on IPSC targets at close range with the 223.
I think it's a big disservice in this day and age that we even have to deal with temp sensitive powders personally. One of those stupid things in life which shouldn't be but is anyway!
If you were working up a load in the summer you could pick the lower node then add more powder later on in the year to keep the FPS constant.
A node is a certain range of velocity that your barrel has the least oscillation at the muzzle.
That's the problem with temp sensitive powders. To keep the velocity in the node you have to adjust the powder charge according to temperature to keep the FPS in that nodes velocity range. Also why I avoid them except for plinking ammo on IPSC targets at close range with the 223.
I think it's a big disservice in this day and age that we even have to deal with temp sensitive powders personally. One of those stupid things in life which shouldn't be but is anyway!
If you were working up a load in the summer you could pick the lower node then add more powder later on in the year to keep the FPS constant.
I know what a node is, but I did not guess that the seasons would change the velocity enough to throw me out of a node. damn. I guess sacrificing performance for less temperature sensitive is good. Anyhow, all of this has proven to me how awesome a hobby this is.
edit: here was an interesting post as to what brands and types of powders are sensitive to temperature:
http://www.longrangehunting.com/forums/f28/powder-temperature-sensitivity-31096/
I doubt I will be using the 4350 that I have. Based on what I have read, for the 7mm berger 168 hunting vld, I should be experimenting with H4831 SC or h1000
edit: here was an interesting post as to what brands and types of powders are sensitive to temperature:
http://www.longrangehunting.com/forums/f28/powder-temperature-sensitivity-31096/
I doubt I will be using the 4350 that I have. Based on what I have read, for the 7mm berger 168 hunting vld, I should be experimenting with H4831 SC or h1000
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Can be seasonal. Identical load in my 44 mag.
warm weather 1473 FPS
cool weather 1260 FPS
Don't remember so many years ago if it was group size or POI change that made me chrono the load in warmer weather.
warm weather 1473 FPS
cool weather 1260 FPS
Don't remember so many years ago if it was group size or POI change that made me chrono the load in warmer weather.
Seems every where I look, about half of people say IMR4064 is temp sensitive and half say it is not. What gives? Hodgdon's own website says that from 0ºF - 125ºF there is only 46 fps difference. I would qualify that as pretty damn good.
I was thinking more about the sensitivity of loads for heat and developing a resilient load. Initially I thought developing a load during the hot summer, but after reading that any spectrum could throw your load off, I'm guessing I should do the OCW method when it's neither hot or cold outside. Seems like this thread is going from max load to most resilient loads.
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Already mentioned, but go with a temp insensitive powder like IMR 4064, IMR8208XBR or Varget and be done with it. As long as you're not loading at sub zero temps or over 100 degrees you should be good to go throughout the spectrum. I'd imagine if you work up a load and it's in the middle of the temp extremes you'll be good to go.
In addition to some powsers are more sensitive than others;
As a reload ages waiting to be fired there is corrosional welding that goes on between the brass of the case and the guilding coating on the bullet.
Fresh off the reload stand it may take only 50 pounds of force to slip a bullet out,
After a year of sitting around in air it may take 100 pounds.
After a decade of sitting around in air it may take 200 pounds.
While this effect is generally a lot smaller than powder pressure variations over temperature,
given a few years of sitting around, it can be the straw that broke the camels back.
Fresh ammo works better.
As a reload ages waiting to be fired there is corrosional welding that goes on between the brass of the case and the guilding coating on the bullet.
Fresh off the reload stand it may take only 50 pounds of force to slip a bullet out,
After a year of sitting around in air it may take 100 pounds.
After a decade of sitting around in air it may take 200 pounds.
While this effect is generally a lot smaller than powder pressure variations over temperature,
given a few years of sitting around, it can be the straw that broke the camels back.
Fresh ammo works better.
