shooting in the heat

[jraney]

a while back i loaded some 22-250 rounds shot some and they were great.
i wanted to try some cold bore shots to see where i was hitting this past weekend. so i took my gun and shells to my parents i got there about noon
left everything in my truck the temp outside was near 90 i later went to shoot
and all my shots were hitting almost 1.5-2" high @ 100yds. the first time i shot this load it was cooler, will the heat affect shots that much @100yds?
the shots were still grouping but everything was high, plus i only shot 2 clean cold bore shots the following shots were hitting where the cold bore shots did.does this sound normal?

 

[MildBill]

good chance the heat is having some influence, give us more details, type of gun, stock, bedded or not, and details on the load itself.

 

[jraney]

the gun is a savage mod10 predator no bedding just the cheap factory stock, and i am sure this will get some folks blood boilling but as far as the load all i can really say is it is a mild load with re15 and a 52gr sierra bthp. the gun is all factory 14 twist 24"barrel nothin fancy. i do have an extremely sturdy bench and vise type rest. the only thing i could think of was the heat by the time i went to shoot it was very hot inside my truck even with the windows down all day. hope this helps. i did not record the load, for reason i do not understand. i plan on pulling a few bullets to confirm the load though. the 1st time i shot this load i shot the smallest group i have ever shot, that is the main reason i think it was something other than the load itself. i thought
i had read on here or somewhere that the extreme heat or cold could effect P.O.I. .

 

[necchi]

Some powders are very sensitive to temp swings,,
Some powders are more tolerant of temp swings,,
Almost every load will act differently when they've been baked in a hot truck!! Or have ole
Mr. Sunshine beating down on'm on a 90 degree or hotter day.
Could the heat affect on the ammo and gun cause a 1.5-2" rise at 100?
Yeah Man.

I try to stay with Hodgons "Extreme" powders because of that very reason.
I live in MN, we can have 101 or -30, I try to do most load development in spring and fall around the 40-50 degree range and have found they still work well in colder weather, but the heat changes the game.

 

[joed49]

Well, at least you're not using H380. I tried that as my first powder last summer and watched the POI change every month as the temps changed. Switched to Varget after the POI changed by 3".

It could also be your rifle as wood stocks swell with humidity. I'm a big fan of synthetic anymore and all my rifles are free floated.

 

[Shynloco]

Some powders are very sensitive to temp swings,,
Some powders are more tolerant of temp swings,,
Almost every load will act differently when they've been baked in a hot truck!! Or have ole
Mr. Sunshine beating down on'm on a 90 degree or hotter day.
Could the heat affect on the ammo and gun cause a 1.5-2" rise at 100?
Yeah Man.

I try to stay with Hodgons "Extreme" powders because of that very reason.
I live in MN, we can have 101 or -30, I try to do most load development in spring and fall around the 40-50 degree range and have found they still work well in colder weather, but the heat changes the game.

He nailed it! But I never shoot in temps below 45 or above 95. I've found I'm just wasting my hand loads, especially for testing purposes.

 

[jraney]

well i suppose i will try to keep the heat regulated somehow. here in oklahoma it is hardly ever perfect shooting conditions it is either to hot or to cold, and my itchy finger does not descriminate. thanks for the replies.

 

[bheadboy]

I got to say it, did you consider the mirage, i often get 1-2" at 100yd in a 90 degree day with little wind.

9o is not a real bad temp for many powders but will give a real rise to point of impact. Shooting pd in wy at 100 the rise can be even more,so dont be too quick to change loads etc. just check the mirage effects by shooting late evening at same temp afterf the sun is off the range

Bob

 

[jraney]

well i did not know that the mirage could affect p.o.i. that close. can someone educate me on this or tell me where i can find more about the mirage effect. i just naturally figured that since everything had been in the truck allday it was much hotter than the 90 of the outside temp. that is very interesting. oh ya don't worry about me changing this load to much on a normalday with not much heat or mirage it shoots extremely well. i will take the mirage into consideration though. i also have now got a notebook to keep records in of my reloads so this should be fun. thanks for the replies

 

[bheadboy]

jraney,
mirage is a variable, which many wiser than me have written about, however from my experience, 65 years -
mirage is the effect of rising air distorting the light waves causing image to appear at a location other than reality
mirageis worse at higher temp
mirage is worse with high humidity or moisture on the ground/grass
mirage moves the impact up, more or less depending on the combination temp and humidity
mirage will in conjunction with the wind move the bullet up and left with a 4-5oclock wind
mirage will in conjunction with the wind move the bullet up and right with a 7-8 oclock wind
mirage will in conjunction with the wind move the bullet down and left with a 1-2 oclock wind
mirage will in conjunction with the wind move the bullet down and right with a 10-11 olcock wind

mirage is almost never constant as wind, light, clouds, all alter its effect
bbl heat waves can alter the point of impact upwards

hope this helps - suggeston, at the range on a hot day purposely shoot when you see the target ripples different and watch the effect.

Bob

 

[jraney]

not saying you or anybody else does not know what they are talkin about but if the mirage is the case then WOW, no wonder i can hardly ever hit my targets. most of the time i get to shoot it is real hot so now i can compensate for this. i suppose the mirage could be fairly bad over water too. i will keep an eye or 2 on this from now on and i am sure things will change.

 

[Minesweeper3433]

tag

tag is where you add a tag to the forum discusion for later reference it makes it very easy to pull the discusion up from my profile page.

 

[bheadboy]

what is ment by
"tag"
take a guess?
Bob

 

[potatoe]

jraney: I was almost in the same boat as you just yesterday. I was missing ground hogs like crazy @ 200 yards. I went to the range to verify my zero and it was perfect, but then back to the field and I was still having the same problem of hitting high.

This evening my pops and I went out and shot at 200 and 300 and my rifle was shooting great, not high at all, if anything I was a touch low at 300. This didn't really tell me much, other than I was the culprit or the temp. effected something with the gun/ammo. I would say to try the same thing I did,shooting it again on a nicer day but when your gun/ammo hasn't been beatin up by the sun but try to leave everything zeroed the way you had it before you started hitting high.

This is only a baby step for me so far, if it happens again I'll obviously start digging deeper looking into the ammo first then seeing if the gun is the one being effected by the heat.

 

[bheadboy]

Potato, dont mess with the ammo and gun, check out the mirage, go on the internet and read some of the articles, what you and jraney are seeing is nothing more than heated air rising from the ground distroting the light waves and causing you to "SEE" the target higher than it is

Bob

 

[K22]

I've noticed a fairly consistant change in impact with my varmint rifles from early spring to mid summer when the tempertures climb into the high 80's low 90's despite using the Hogdon Extreme Extuded Powers (Varget, Benchmark, and H4350). The change is not drastic, but noticable usually about 1/2 to 1 inch vertical at 100 yards.