Does temperature affect groups? What I mean is, am I waisting my time trying to find good groups when the temp is 100 and the same loads could be used hunting when the temp is closer to freezing. How does that kind of temperature change affect what I am truing to do? If I find a good load when it is hot outside, am I going to get that same good grouping when its cold?
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MarinePMI
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Nimrod,
Temperature does affect ammo....to an extent. Interestingly enough, it's not the outside temp, it's the temp of the powder that is important. I don't have the exact specs off the top of my head, but I know P.O. Ackley's "Handbook for Shooters and Reloaders" does. At matches (early spring, March/April) a lot of shooters kept their ammo in their left breast pocket so that it was consistently the same temp. In the desert/prairies I've seen some guys put their ammo in ice chests. How much is it really gonna affect your accuracy I guess depends on the load itself. I'll look those numbers up later, and post them here.
(Edited by MarinePMI at 12:48 pm on July 9, 2002)
Temperature does affect ammo....to an extent. Interestingly enough, it's not the outside temp, it's the temp of the powder that is important. I don't have the exact specs off the top of my head, but I know P.O. Ackley's "Handbook for Shooters and Reloaders" does. At matches (early spring, March/April) a lot of shooters kept their ammo in their left breast pocket so that it was consistently the same temp. In the desert/prairies I've seen some guys put their ammo in ice chests. How much is it really gonna affect your accuracy I guess depends on the load itself. I'll look those numbers up later, and post them here.
(Edited by MarinePMI at 12:48 pm on July 9, 2002)
Nimrod,
Temperature has an effect on your ammo, but I have found a high temp. effects your sighting more than your ammo. Once the barrel gets warm enough from being shot you start getting heat waves (mirage) and it's impossible to shoot as accurately as when it is cooler. This will also happen with a cool barrel if the outside temp. is hot enough, and it does not matter if your using a $50 or a $600 scope the heat waves will be there.
Temperature has an effect on your ammo, but I have found a high temp. effects your sighting more than your ammo. Once the barrel gets warm enough from being shot you start getting heat waves (mirage) and it's impossible to shoot as accurately as when it is cooler. This will also happen with a cool barrel if the outside temp. is hot enough, and it does not matter if your using a $50 or a $600 scope the heat waves will be there.
Hey,
I had an experience this past summer at a range in Pa.Three of us went to a public range.It had only six benches,and we had the place to ourselves.I only brought one gun with me,from SC.It's my 6mmBR.I had loaded up 50 rounds and had them in a plastic box.I set the ammo on the bench,along with my rifle.The first group was a ragged hole.I would then watch my buddies shoot their rifles,and watch the groups develope through a spotting scope.It was getting warmer and we were taking off our jackets.I shot my next group, and it open up slightly.About a 1/2 hour later my group went south.I told Dick,I can't believe my most reliable load went south.He said don't worry,I'll straighten it out for you.I didn't understand what he meant.He took my ammo box,and put it in the cooler,with his beverages.A 1/2 hour later it shot like the first group.
1geejay
www.shooting-hunting.
Nimrod,
Yes, temp does affect ignition pressure of all powders, ... thus it also affects velocity, barrel pressure, trajectory, and of course point of impact (accuracy). The warmer the temp of the POWDER, the higher the pressure and velocity, and vice versa. The US military insists that all their loads are stable, ignite well, and do not go outside pressure design specs at all conditions from -40 degrees F. to +125 degrees F. This is why they are now using R-22 and R-19 is many of their sniper loadings (30 cal.). I hope this helps.
Sgt.1000
Yes, temp does affect ignition pressure of all powders, ... thus it also affects velocity, barrel pressure, trajectory, and of course point of impact (accuracy). The warmer the temp of the POWDER, the higher the pressure and velocity, and vice versa. The US military insists that all their loads are stable, ignite well, and do not go outside pressure design specs at all conditions from -40 degrees F. to +125 degrees F. This is why they are now using R-22 and R-19 is many of their sniper loadings (30 cal.). I hope this helps.
Sgt.1000
so cal hunter
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All the answer's that are being put out there are all correct i did some research on temp. with load's and the outside temp varied from 40deg to +120 deg and the p.o.i. was only off by a very small amount but what really effect's the p.o.i. is powder temp, altitude, and air density out to 300 yds not much change but past that it really open's up. check out www.point blank.com and you can simulate different outside temp's altitudes and angle of fire and get a better understanding of what goes on. so cal hunter
Years ago when I used to shoot a lot more often than now, sometimes 3 times a week & often with a chronograph, I definitely noticed a performance difference in temperatures. That's why I take great effort in keeping my ammo in the shade & my barrel covered even to this day.
Like others already stated above, the biggest difference is point of impact change and is also why I try and avoid shooting when the weather is too hot or too cold. Group size also enlarges as temp increases.
Brand of powders where mentioned above and they do make a difference. My own experience has been the IMR & RL powders were least effected. H4831 was the most negatively effected by temp from the various powders I tried anyhow. Very good & accurate in my 270's & 7mags, however terribly erratic on the velocity & point of impact in regards to temperature changes.
Frank
Like others already stated above, the biggest difference is point of impact change and is also why I try and avoid shooting when the weather is too hot or too cold. Group size also enlarges as temp increases.
Brand of powders where mentioned above and they do make a difference. My own experience has been the IMR & RL powders were least effected. H4831 was the most negatively effected by temp from the various powders I tried anyhow. Very good & accurate in my 270's & 7mags, however terribly erratic on the velocity & point of impact in regards to temperature changes.
Frank
Handcannon
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nimrod,
Tho temperatures can and will affect load performance, I believe more of your concern is with the air density.Air changes quite a bit between the different seasons and speaking from experience(don't want to tell the story but still crying over it),it is best to do a final sight-in at least the week you will be hunting.Tho the temp might change the air density will be similar. Hope this helps ya.
Handcannon
Tho temperatures can and will affect load performance, I believe more of your concern is with the air density.Air changes quite a bit between the different seasons and speaking from experience(don't want to tell the story but still crying over it),it is best to do a final sight-in at least the week you will be hunting.Tho the temp might change the air density will be similar. Hope this helps ya.
Handcannon
I believe that the old standard which the marksmanship teams used was that for each 15-20 degrees of temperature increase, the elevation correction (down) should be one minute of angle at 600 yards. They used a canister grade version of IMR4895 in their 7.62Nato match ammo (M852).
This much I can tell you with assurity. When I shoot my Varget loads at 1000 yards, my elevation is more dictated by positional variances than temperature. If I nail the position solidly, the variations in elevation on the same shooting range do not vary from temperatures of 55-95 degrees.
When I first played with Varget in spring of 95, I would test a ten-shot string from the bench at 600 yards and across the chronograph. After cooking an 11th round in the hot chamber for 60 seconds. This 11th shot would go into the same group and would fall within the extreme spread of the prior 10 shots. The same result was seen using a .223 with 80 grain bullets. My reasoning for so testing this powder was for team shooting where one would have to lay on the gun for long periods without having to open the bolt on a hot round during a long string of shots.
Although I have shot quite a bit of H4350 and H4831SC, I never tested them for thermal stability. Supposedly, all of the Hodgdon powders that are extruded stick powders have this same capabilty like Varget.
FYI...
This much I can tell you with assurity. When I shoot my Varget loads at 1000 yards, my elevation is more dictated by positional variances than temperature. If I nail the position solidly, the variations in elevation on the same shooting range do not vary from temperatures of 55-95 degrees.
When I first played with Varget in spring of 95, I would test a ten-shot string from the bench at 600 yards and across the chronograph. After cooking an 11th round in the hot chamber for 60 seconds. This 11th shot would go into the same group and would fall within the extreme spread of the prior 10 shots. The same result was seen using a .223 with 80 grain bullets. My reasoning for so testing this powder was for team shooting where one would have to lay on the gun for long periods without having to open the bolt on a hot round during a long string of shots.
Although I have shot quite a bit of H4350 and H4831SC, I never tested them for thermal stability. Supposedly, all of the Hodgdon powders that are extruded stick powders have this same capabilty like Varget.
FYI...
19TH_SFGA_18D
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Its laymans terms, yes temp will affect your groups. air temp wise the hotter it is the higher your group will rise. The colder lower. when your barrel warms up it will it will tend to open up your groups. basically if you cannot rest your hand comfortaby on your barrel you are cranking them off to fast. well thats if you have a heavy barrel.
19TH SF,
Some of the people I deal with put ammo in a small igloo cooler when training on hot days, instead of just keeping their ammo in the shade or covered. How do you feel about doing this?
I have also noticed that some shooters, even though they placed their ammo in an igloo or kept them covered, will place their cool ammo in a previously fired hot chamber and close the bolt. After closing the bolt they will allow the round to sit in the chamber for an extended period of time. This does not seem to make any sense to me. Why should they even bother placing their ammo in an igloo if they are just going to allow the ammo to be heated by the chamber?
Some of the people I deal with put ammo in a small igloo cooler when training on hot days, instead of just keeping their ammo in the shade or covered. How do you feel about doing this?
I have also noticed that some shooters, even though they placed their ammo in an igloo or kept them covered, will place their cool ammo in a previously fired hot chamber and close the bolt. After closing the bolt they will allow the round to sit in the chamber for an extended period of time. This does not seem to make any sense to me. Why should they even bother placing their ammo in an igloo if they are just going to allow the ammo to be heated by the chamber?
19TH_SFGA_18D
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Datum,
I guess that these guys do alot of match "palma" type shooting which I do not have alot of experiance in. As you know my experiance has been pretty much military orientated which would apply to hunters. I think that too many hunters have tried to confuse "palma" type shooting with "field" shooting which is what they should be concerned with. For hunters I would suggest the following.
1. Make yourself a Log Book. In it you should record the following:
Round count (to include Date, Lot number, Rounds fired)
2. copies of your 100yd zero targets. On these you should have Date, time,
temperature, ground elevation and any misc. info.
As far as zeroing goes you should re-zero whenever you change ground elevation, air temperature or ammo lots.
In regards to ammo lots if you reload make sure you track how many rounds have been through your brass. I suggest that you start with brand new brass and call that your "lot" your lots will change when you go through primers and powder. Both these items have there own lot numbers on them and you should be aware of this as it will affect you zero. the projectiles you use should also have there own lot numbers.
so in laymen terms make sure your lots all have corresponding numbers in regards to projectiles, brass, powder and primers.
I do agree that you should not "cool" your rounds in an igloo then leave them in a hot chamber it seems kind of usless like "masterbation without the payoff" so to speak.
I guess that these guys do alot of match "palma" type shooting which I do not have alot of experiance in. As you know my experiance has been pretty much military orientated which would apply to hunters. I think that too many hunters have tried to confuse "palma" type shooting with "field" shooting which is what they should be concerned with. For hunters I would suggest the following.
1. Make yourself a Log Book. In it you should record the following:
Round count (to include Date, Lot number, Rounds fired)
2. copies of your 100yd zero targets. On these you should have Date, time,
temperature, ground elevation and any misc. info.
As far as zeroing goes you should re-zero whenever you change ground elevation, air temperature or ammo lots.
In regards to ammo lots if you reload make sure you track how many rounds have been through your brass. I suggest that you start with brand new brass and call that your "lot" your lots will change when you go through primers and powder. Both these items have there own lot numbers on them and you should be aware of this as it will affect you zero. the projectiles you use should also have there own lot numbers.
so in laymen terms make sure your lots all have corresponding numbers in regards to projectiles, brass, powder and primers.
I do agree that you should not "cool" your rounds in an igloo then leave them in a hot chamber it seems kind of usless like "masterbation without the payoff" so to speak.
nimrod
I thought I would add a couple of things to this thread:
1) Colder air is more dense than warmer air so the BC of the bullet design assists in the bullets ability to pierce the atmospheric conditions is important. As to altitude of course the air density is thinner the higher you climb, when you encounter thinner air (Warmer conditions/Higher Altitude) you of course have less drag on the bullet so your POI will climb....
2) Powder/ Primer Combinations
In warm conditions you will experience hotter ignitions of your components if you reload I would *strongly suggest* you develop and test loads in the conditions that you will most likely deploy with this ammo....
Developing reloads for colder conditions then placing them in a cooler and then again placing them in a hot chamber for a period of time should be considered dangerous, you have no way to determine pressures in your chamber and barrel till after the fact (How Hot *IS* too Hot) diminishing the reloaders ability to watch for the first signs of higher pressure (Hard Bolt Lift and Extraction of the Fired Case) and if you were to over load the charge for hot conditions, have you ever examined a catastrophic failure at the worst, blown primer/case head separation at best, however both should be considered dangerous.
Reloaders tend to play with bullet jump to tune the harmonics of their barrel to establish their accurate load, when moving the bullet closer to the lands you must reduce the charge first to ensure reliable pressure signs first, then rebuild the load....
Lastly on this issue, does it make sense to you to test your loads for accuracy on a *hot day* by placing your cases in a cooler, I would presume to test them for consistency in hunting conditions which is usually cooler...
It baffles me why people do this and I see it all the time at the range, I see people there and they say something like "it was perfectly sighted in before hunting season" (when the temps were warm to moderate) and then they could not hit the broad side of a barn when it counted....
Why?
Because the stock, action, barrel and especially bedding of all the before mentioned under go changes when it is cold! ;o)
They did not perform a proper test of components and equipment under the conditions that they would deploy with....
Lastly:
Varget Powder is temp stable and was specifically designed that way for a specific purpose, I dont know if any other powder could be considered to be like Varget in that regard although I am not some kind of authority on the subject and there may well be other powders like Varget....
I have a friend who extensively tested the Varget powder by placing his reloads in the freezer and fired them across a Chrony and then went on to the other extreme and put the same lot in a oven (At low temp of course) to determine velocities under both extreme conditions, the Varget performed relatively consistently under the extreme conditions tested, he determined the lot of reloads were safe....
I will close for today, before I end up writing a book ;o) Like I always end up doing but this might add some food for thought...
Boy its GREAT to be back at Jesse's!!
Regards, Augustis ><>
I thought I would add a couple of things to this thread:
1) Colder air is more dense than warmer air so the BC of the bullet design assists in the bullets ability to pierce the atmospheric conditions is important. As to altitude of course the air density is thinner the higher you climb, when you encounter thinner air (Warmer conditions/Higher Altitude) you of course have less drag on the bullet so your POI will climb....
2) Powder/ Primer Combinations
In warm conditions you will experience hotter ignitions of your components if you reload I would *strongly suggest* you develop and test loads in the conditions that you will most likely deploy with this ammo....
Developing reloads for colder conditions then placing them in a cooler and then again placing them in a hot chamber for a period of time should be considered dangerous, you have no way to determine pressures in your chamber and barrel till after the fact (How Hot *IS* too Hot) diminishing the reloaders ability to watch for the first signs of higher pressure (Hard Bolt Lift and Extraction of the Fired Case) and if you were to over load the charge for hot conditions, have you ever examined a catastrophic failure at the worst, blown primer/case head separation at best, however both should be considered dangerous.
Reloaders tend to play with bullet jump to tune the harmonics of their barrel to establish their accurate load, when moving the bullet closer to the lands you must reduce the charge first to ensure reliable pressure signs first, then rebuild the load....
Lastly on this issue, does it make sense to you to test your loads for accuracy on a *hot day* by placing your cases in a cooler, I would presume to test them for consistency in hunting conditions which is usually cooler...
It baffles me why people do this and I see it all the time at the range, I see people there and they say something like "it was perfectly sighted in before hunting season" (when the temps were warm to moderate) and then they could not hit the broad side of a barn when it counted....
Why?
Because the stock, action, barrel and especially bedding of all the before mentioned under go changes when it is cold! ;o)
They did not perform a proper test of components and equipment under the conditions that they would deploy with....
Lastly:
Varget Powder is temp stable and was specifically designed that way for a specific purpose, I dont know if any other powder could be considered to be like Varget in that regard although I am not some kind of authority on the subject and there may well be other powders like Varget....
I have a friend who extensively tested the Varget powder by placing his reloads in the freezer and fired them across a Chrony and then went on to the other extreme and put the same lot in a oven (At low temp of course) to determine velocities under both extreme conditions, the Varget performed relatively consistently under the extreme conditions tested, he determined the lot of reloads were safe....
I will close for today, before I end up writing a book ;o) Like I always end up doing but this might add some food for thought...
Boy its GREAT to be back at Jesse's!!
Regards, Augustis ><>
