Hunting in the rain.
 

I’ve been a member here for several years. Granted I don’t stop in very often. If this has been covered I apologize for repeating it.

I’ve hunted for many years like everyone else in the rain at times. I’m fairly new to hunting where it snows. I’m an old Florida boy. How much affect does a rain drop or say snow have on the travel of the projectile? We all know wind can and will drift it off. Hitting a small twig. I just wonder how much a rain drop does or snow for that matter. I’ve killed several deer in the rain usually at a short distance. I missed a fairly long shot once in heavy rain. The scope was wet and I put the blame there. I’m sure the heavier the projectile the less it’s affected. I know there isn’t anything we can do about Mother Nature just go with the flow. I just wonder what everybody’s experience is hunting in the rain.

If it makes a difference, I haven't shot far enough in the snow to see it happen. Not something I worry about.

I love hunting in a light rain.. keeps away my scent and they never hear me coming

Usually, all I do for rainy days is factor in the relative humidity and temperature effects, plus the wind dope, then add in some "fudge factor, and pray for luck.

We know the bullet will be less stable, and will slow down faster (drop more) than it would on a clear day, so I plan my shots accordingly.

But hey, let's run with it for a second...

From a physical standpoint, the estimation of the effect of a given rain storm or snowstorm is exhaustive beyond what we're capable of doing "off the cuff" in the field.

Obviously, a raindrop doesn't have the "resistance" that a twig has, nor would a snowflake, so I don't expect my bullet to be "deflected" by raindrops, otherwise it'd be DANGEROUS to fire a gun in the rain (picture a bullet pinballing back and forth between raindrops).

But what you CAN account for is that the air around you is more dense, so your bullet will be slowed down. Based on my experience with fluid mechanics and flight (professional engineer with a private pilot's license), the level of error we'd incur if we made enough assumptions to estimate the effect will negate the level of improvement we'd make over typical "guesstimation". We'd need to make some assumptions about the relative density of the air/rain mix, and then further make assumptions about the viscosity of the mix as well. We might be able to get fairly close for density, based on rainfall rate, but ultimately, the size of the drops will have a HUGE effect on the overall dynamics of the system.

Then, even if we make accurate estimations for the fluid viscosity and density, we still have to account for the relative frequency and direction of impact, which we'll have no way of knowing HOW that frequency effects the projectile flight without FURTHER making assumptions about the projectile and the rain. If a bullet has a right hand twist (top rolling to the right as viewed from behind) a large drop striking 50% contact at the middle of the bullet on the LEFT side TOP will slow the twist of the bullet. The same impact on the RIGHT side TOP will increase the spin. HOWEVER, both drops will have a greater viscosity than the air around the bullet, so BOTH would SLOW the spin of the bullet. And BOTH drops would instantaneously partially adhere to the bullet, increasing it's mass on one side or the other, slowing the spin of the bullet, and creating a destabilizing imbalance.

Then consider that the projectile will develop an "air dam" in front of the tip, making the functional SIZE of the tip larger than the physical dimension. The boundary layer of air moving across the bullet will also thicken as it approaches the rear of the bullet, making the tip more sensitive to impact than the tail. HOWEVER, the tail is LARGER DIAMETER (for spitzer type bullets), so the likelihood for TOP impact in the TAIL is much greater than for the tip, so even though the tail is less sensitive, it'll experience more frequent impacts.

Then consider if the bullet "glances" a droplet. As mentioned above, impacts on either side will slow the spin of the bullet. However, when we consider "glancing" droplets, you must consider 1) the tip bullet tip can be deflected slightly AWAY from the droplet, and 2) the side of the bullet passing through the droplet will actually slow, causing the tip to trend towards that side (think of steering brakes on tractors), so the tip will actually be pulled TOWARDS the droplet. Which of these effects gets the net "win" might be different for every drop, depending on any number of factors. At best, we could consider that the tip is slowed proportionately to its deflection, so its course is unchanged, but then the stabilization is diminished greatly.

So now we have to make estimations for how much ALL of those components (and probably a dozen others I neglected) will effect the bullet's flight, and make some predictions for where the bullet will strike accordingly. If we're off by 10% in all of those estimations, then the collective estimation will be CONSIDERABLY off the mark.

Again, the easy answer is the bullet will slow down faster, and be much less stable, so plan your shots accordingly. Make your estimations for relative humidity and temp, and then add some fudge factor, and plan on MUCH lower accuracy than you're used to.

Relatively speaking, I expect that RAIN would be much more of a problem than snow. Using the addage that "a foot of snow is about equivalent to an inch of rain", we'd estimate that snowflakes are no more than 1/12th the density of rain, so when a bullet hits a snowflake, it'll have MUCH less effect than if it would hit a raindrop of the same physical size. The adhesion of liquid water to the bullet should also be slightly less, since the air dam in front of the bullet, and the boundary layer surrounding it will more successfully divert more of the less dense snowflakes than it could raindrops (unless you're talking about drizzle).

Nomercy, I appreciate your thoughts and comments. Very detailed.

Haha, I guess the important take away from all that is that being there and pulling the trigger (or deciding NOT to pull the trigger) is way more important than any estimation we could make based on the rain or snow.

Sometimes the bad part of being an engineer (with a bad case of OCD according to my wife :hit:) is that when you know how to run calculations like this, unfortunately sometimes you TRY to make the calcs, rather than just realizing that 10min at the range can tell you as much as 2hrs of calculations... I'm always trying to keep myself in check and not get so dug into the details that I forget that "empirical experimentation", aka just shooting the dang thing, will usually give more precise results!

I do not think that for common hunting purposes it matters. Possibly in very heavy rain it could. But, in rain that heavy, you can't see far enough for it to matter anyway. I've shot deer in both snow and rain. OUt to 150 yards. Never had any issue. You could hit the range and see what kind of results you get maybe.
In my opinion, for common hunting purposes at common ranges, it doesn't matter too much. Ridge Runner and some of these other LR guys may have better input for the longer shots.
-Jake

Just because I like to smile everynow and then, I have read where a little rain increases accuracy. But say a bullet going 2800 fps it's splitting the air and is it possible that it's pushing the air in front of it (say .00001") and creating a sort of air sheild from the rain, ah come on guys smile with me

rjhans53 go read Nomercy448's thread to have your question about the air shield answered.