If a general rule of muzzle velocity is 1% every 20 degree variance from your sight in temp… is it a similar effect on your point of impact. Most my guns poi is 250 yards… most my truing is in wintertime.. so 20-30 degrees here in Missouri….. Any advice appreciated ..
- Thread starter Mskeets
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Two separate issues.
First is powder temperature sensitivity. Some powders will burn faster and more aggressively in higher temperatures giving you a higher muzzle velocity. Other powders are less sensitive and will be close to the same speed in a variety of weather conditions.
Second issue is external ballistics. Cold air is dense air which slows down the bullet and will affect your shots at distance. Warm air is less dense, so the bullet flies flatter longer. A ballistic solver on a phone app or a kestrel will take care of all these calculations for you.
First is powder temperature sensitivity. Some powders will burn faster and more aggressively in higher temperatures giving you a higher muzzle velocity. Other powders are less sensitive and will be close to the same speed in a variety of weather conditions.
Second issue is external ballistics. Cold air is dense air which slows down the bullet and will affect your shots at distance. Warm air is less dense, so the bullet flies flatter longer. A ballistic solver on a phone app or a kestrel will take care of all these calculations for you.
Yes sir… understood… my question is… there is plenty of info on temperature and powder and muzzle velocity… but i can’t find anything on ….the effect the muzzle velocity does to poi… If my gun is sighted in at 250 yards and my muzzle velocity is 3,000 fps… and it is 30 degrees… move to June. And temperature is 80 degrees… my muzzle velocity will increase app 2.5% let’s say. Or 75 fps…. So my muzzle velocity is now 3075 ish….What does that 75 fps do to my point of impact… can I assume similar … add 2.5%…. app 6.5 yards I think…to my point of impact… is there kind of a rule here… I know my math is approximate on all of these…. Thanks.
A change of 75 fps could easily result in a change in your rifle's zero, even ignoring the ballistic effects of bullet drop. Different harmonics, barrel movement on recoil, etc can all have an effect.
A change of 75fps and a change in the air density from summer to winter will have all sorts of effects on shooting at distance, even 250 yards but especially farther out. My suggestion would be to move to a 100 yard zero and read up on ballistics and start using a ballistic calculator to solve for shooting at distance.
A change of 75fps and a change in the air density from summer to winter will have all sorts of effects on shooting at distance, even 250 yards but especially farther out. My suggestion would be to move to a 100 yard zero and read up on ballistics and start using a ballistic calculator to solve for shooting at distance.
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