Summer vs winter hand loads

S

solano2482

Inactive
Hey guys, I currently reside in AZ where we get crazy fluctuating weather during the seasonal changes. I was wondering if anyone adjusts their favorite loads that they worked up in the warmers to accommodate the colder weather.

I can get half inch groups if I do my part during the warmer month. Now I'm not taking about shooting midday in 100+ degrees. I always went out at 7am when it was only just above 80 degrees. My powder of choice in most rifles is varget, which is suppose to be stable with temperature changes.

My best loads always came up somewhere jusy above the halfway mark between the starting load, and max load, so I'm pretty sure I'm not pushing max velocities, adding to the heating of the barrel.

I went shooting the other day at 9am, and it was 45 degrees in the morning with 4pmh wind. I noticed the same half inch groups were not doing as well as before. I'm just wondering if I should do another work up to see if there is a better combo in cold weather.

Thanks
 
Maybe, maybe not.

Quick answer. Maybe, maybe not. For a 270 for example I use H4831 or H4831sc. The same powder but one with a shorter cut. This is called an "extreme" powder, meaning it resists temperature fluctuations. One day I will shoot well. At times I wll shoot well 2 or 3 trips and then have one that I just can't seem to match the previous trips. The next time I will shoot well again. I have gone back to the bench and tried more loads and did ok but then back to the previous "good" load only to have it shine again. I wish I knew the answer. It could be the powder or the weather but I believe it is more likely me. Some days I am just not up to par as much as the gun or load. This may be a blessing because I end up shooting more often. I would much rather shoot in colder weather for the simple reason my barrel cools much quicker then. I get to shoot more. Again a blessing. I am pretty sure my answer didn't help much.
 
No worries. Any feedback is helpful. Maybe I was just underdressed, cold, and shooting poorly. I'm going to try it again, and see what happens.
 
"...we get crazy fluctuating weather during the seasonal changes..." No, you don't. Coming out of the house to 2 feet of snow(up to the top of the bumper of an F-150) that fell in 3 hours is crazy. Or 70F on Friday and less than your 45F on Monday is crazy fluctuating weather. snicker.
45 degrees F is not cold unless it's minus 45 degrees either. At that temperature, it doesn't matter which scale you use either. Minus 40 is friggin' cold. Anyway, the difference between 100F and 45F isn't enough to bother most powders. Between 100F and -45F is though.
Oh and I've been watching Phoenix' weather for years. Saw it was 20C(68F) the other day and thought ya'll would be freezing. It's about 2C(35F) here, today. snicker.
 
When we lived in the northern mid west, our club held matches all year around.
It could be as hot as the tropics in the summer and with snow and ice winters.
The loads could be very different with changes in the weather.
Sometimes the ammo would be chronographed for major and minor.
Loads from summer might very well fail to make the required power factor in winter.
 
I shot my best groups (as a session) this last week, it was 15 degrees to start with, a bit of wind (shooting shed has overhead heaters so big help)

One of the best groups was at the end, in the dim light, wind starting to blow targets over and got a 5 shot x 3/8

the pervious groups was abnormal, keeping in mind I am working with COAL

Conjecture is with all the layers on I got a better condition that is closer to free recoil, I have shot some better groups in the cold (and had some loads that shot well warm fall flat in the cold)

I can say that Varget while a great powder is a bit out of favor with the serious shooters as it has issues form lot to lot with consistency.

What it amounts to is there is no good answer.

The loads I was shooting were H4895 and H4831 that are extreme listed.

I did shoot a nice group of 1/2 inch at 105 with R17. Reports its not that good but they also seem to be pushing it past the limit when the did and got erratic results.

As noted, once you are under 3/4 MOA, all it takes is a very tiny change and things go off the rails.
 
With most powder a difference of 1-3 fps for each 1 degree of temperature change is normal. A load you develop at 40 degrees will be 60- 180 fps faster at 100 degrees. If the load developed at 40 degrees is pretty close to max, it may very well be over max at 100 degrees. And I'm sure you often see temps well over 100 there so it is something to consider.

Most people only think of this as being a problem developing loads at 70 degrees and hunting at -20. In that case the bullets will leave the muzzle 90-270 fps slower and long range ballistics will be off.

The powders that are less temp sensitive are still affected by temps, but only by about 1/2 fps for each 1 degree of temperature change. In the 1st case you'd only be about 30 fps faster in 100 degree heat, and in the extreme cold only about 45 fps slower.

All things being equal I'll pick a temp insensitive powder.
 
Agreed on the last.

More accurately, it shifts the sweet spot and even with extreme powders you may have to shift the load 1/2 to a grain if its range is wide enough.

I just ran some loads that did not seem to care, thought that was interesting, over 1.5 grains they were all doing good.

that said its more of a concern safety wise if you are cool and test and then shoot hot temps.

Not only more FPS, more kaboom and if at or somewhat over the edge it can put you further over.

I don't think too many shoot 500 yds at -20!
 
I spent several years developing a .270 Win load that would be consistent and stable across all anticipated shooting conditions, from 0 F to 100+ F.
I tested many powders, ranging from new 'extreme' powders to classic, conventional powders. In the end, I ended up with RL-19, predicted by "experts" to be the most temperature sensitive powder in my list; while most of the 'temperature insensitive' powders were only good through a narrow temperature range (a 20 to 30 degree range on the thermometer). :rolleyes:
It was expensive, time consuming, tedious, and took forever (had to wait on the seasons). But...

One load to rule them all!


On the flip side, I had a .458 SOCOM load that was very temperature sensitive. I never could get a happy middle-ground to work ideally. So, I went to a summer load, a hunting/winter load, and later also added a spring/fall load. The summer load powder charge was 0.5 gr lighter than the cold weather load; and the spring/fall powder charge was 0.2 gr lighter than the cold weather load.

Using the cold weather load in the summer did not push pressures beyond safe limits. So there was no danger in making a mistake when selecting ammunition. But it was a little harder on the brass, due to action timing being a bit different.


Sometimes you eat the bear.
Sometimes the bear eats you. (Or you're too lazy to try any more powders -- which is where I was at with the SOCOM. ;))
 
Sometimes there is a difference

I always check how a load shoots in hot and cold temp.
( the extremes )
if the load falls apart in one I will rework it
if it is merely a point of impact change I will make a note
of that and continue with that load

Most of the time just a minor adjustment of powder charge
cures the problem

You say the load is with Varget, it's not as temp. sensitive as others
but it still is affected by temp.
Try tweaking the load on another cool day
Also keeping in mind it could be you ( we all have off days )
 
I don't

I live in the Sacramento central valley where the winter is fairly mild.

I don't feel it gets cold enough to adjust my loads from summer (when I do most my load work ups).

Further, I don't load to the top of the pressure scale, so I have quite a bit of wiggle room either way with just about all my set load recipes.

I did test my IDPA and ICORE power factor ammo on a cold winter day - just to make sure they made the cut when the temp is low. They did.
 
Been there, done that. It is why I don't use alliant powders or win powders anymore. I made a .300 win mag load in March with reloader 22..... sticky bolts in the desert in the summer. Made a load for my .338 LM with reloader 33, stuck cases in the summer. But with H1000, velocity varied only 23 fps from 90 degrees to 30 degrees. Similar story with powders listed below.

Imr 4166, Hodgdon Benchmark, Varget, H1000, Retumbo, H4831 & 4831sc are all fairly temp stable.

Now, I realize this narrows your powder choices, if you don't use them, you will need a warm and cold weather load. Simply using a light load might mean no hot weather pressure issues, but the load might still move off your accuracy node. For instance, if you find an accuracy node at 95% of max in the summer and say "ok this is safe year round"....well you are probably right, but in the winter that could be 91% of max pressure moving you off your accuracy node.

So, I only use extreme powders for that reason, especially hunting loads, though I do have a few IMR hot and cold reloads.
 
I do realize that AZ doesn't get into the - temps very often. A 50 degree high in the winter, compared to 117 in the summer is drastic. We may not get snow in the Phoenix area, but that 67 degree difference is a big swing. I'll be shooting up north in Flagstaff next weekend in an area where I can go out past 500 yards. The low will be in the 20's, with the high in the 40's. I'll just have to report my findings when I get back.
 
I have friends that fish and hunt, when fishing there is no way to describe their intensity. You will not believe this but I was fishing with one of them one day and by mid after noon we had caught nothing. It was about that time he handed me his tackle box and instructed me to dump the lures into the water but not before he stuck his head under water. I explained to him I needed an explanation because if he did not want to lures I would like to have them.

He explained in desperate time he gets desperate; he wanted me to dump the lures into the lake to determine what the fish would go for. When it comes to shooting in hot and cold weather nothing changes; I suggested if he was going to develop loads in the summer TEXAS heat for hunts in the winter in Colorado and Wyoming store his loaded ammo in the freezer and carry it to the range in a cooler. If the refrigerator has an ice machine on the freezer side the temperature has to be close to -5°

F. Guffey
 
solano2482, I'm from Co and I've been down to a roping @ Westworld, Scottsdale few times and we had frost AM in Feb. We use to go to Hollbrook then down to Payson to Scottsdale instead of going to Flagstaff and down as that road freeze. I got so I'd take some of my winter cloths down there. Forget just getting old but I've shot at Ben Avery few times.
 
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Truth is there is nothing like trying things out to be sure.

I've worked up most of my best loads in a roughly 70'ish degree temp range. Truth is that I have had to adjust some down due to summer heat. We not only have swinging temps where it might be 25 in the morning and 75-80 by evening but also usually have 60% plus humidity and are hardly ever much more than a few hundred feet over sea level. All of that plays into your load.

You can also take rounds to the range in a cooler but it does nothing for your rifle. It will all have be out in either hot or cold to be completely accurate.

I've had a similar experience as mentioned above using both RL-19, & 22, but only in a couple of loads. I have however had a much wider experience hitting a stable load using the medium to slower powders in the Extreme Hodgdon line over anything else. I haven't decided to try any of the newer powders which are subscribed to be temp insensitive powders brought out in the past year or so.

Usually I try to work up early in the year to a top end or max load, around the end of February or March so I get in some of the middle temps and some cool to cold mixed in. Then I'll drop the load about a grain, adjust seating depth from there for accuracy, and shoot it as the temp climbs through the summer. If things hold together I use it right on through hunting season. I do also try to get out and at least shoot some more rounds on the colder days.

So far over the past 25+ years this has usually worked out for me, but I have had some combinations just completely go to pieces for one or more reasons. Usually though those show up early as the temps are climbing.
 
Close but not exactly. Colder air and drier air are more dense than warm or moist air. This does not appreciably affect your muzzle velocity, but the more dense air will slow the bullet down more quickly after it leaves because drag is proportional to air density.

The other thing that happens is that when air is more dense and drag is greater, bullets have a higher minimum rate of spin required to remain stable in flight. I don't know your velocities or bullet lengths or your barrel's rate of twist, so I can't guess whether this may be a factor in your case or not.

Denton Bramwell demonstrated pretty conclusively that barrel temperature has more effect on the powder than ambient temperature does, except when your barrel is cold (of course). Cold air will cool your barrel more rapidly between shots. For hunting in cold weather, I always recommend letting the barrel get cold between shots, and even cleaning it between shots, if that's the condition it will be in when you get game in your sights.
 
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