External ballistic knowledge and range preperation

[bsouthernau]

This link is to an article about Density Altitude and its effect on bullet drift , on the Llilja Barrels website
It might be of interest to some, and is in laymans language.
http://www.riflebarrels.com/articles/50 ... ensity.htm

Thanks Tony. I have to say that his statement that clouds float and steam rises because water vapour is less dense than the main atmospheric gasses is complete and utter bullshit. I'll also note that his assertion that it's the near wind that has the greatest effect is far from universally accepted. There's a discussion on this in Litz's book. Apart from that his main point that the effects of the wind on bullet and flag will maintain their proportion sounds pretty plausible.

Barry

[RDavies]

I find all this stuff very interesting but let's not lose sight (pun intended) of what we're talking about which is coming up with some sort of guess regarding the initial sight setting. Once you're on the mound all you've got to work with are the flags, the bullet holes and your head. I own and use some of the gear we've been talking about but all you really NEED is a book where you record your sight settings each time.

Barry

I enjoy learning about all the technical stuff Barry, but I may not be pedantic enough to be currently making good practical use of it. Hence why I ask what other people do with it. I'd still love to hear from Dave Mc, Cam Mc, Rod, and many others on their own practical use of the info, if they have time.

I guess a racing car driver doesn't need to be a mechanic or an engineer, he just needs to know how to get 100% out of the car, if the cars doing what he wants it to and if its not he only needs the ability to describe the problem to his crew. We may not have a pit crew, but Ozzy shooters have Wiliada!!!

Unfortunately I cant be of much help as I don't really know a huge amount about ballistics and not all that interested in the theoretical technical mumbo jumbo. As it is I wouldn't know a corialis if I walked past one in the street and wouldn't have a clue what different humidity does. (whenever I have a ballistics question, I ask Dave Mac) Reading through these posts it seems that these two don't have a huge effect, so I have probably been wise to concentrate my limited mental capacity to things which have more effect on hitting a known distance target somewhere close to the middle. Then again, I don't use many sighters, but more often than not the 5s will either be up or down, so maybe I could pay closer attention to ballistics and likely will in the future.
As far as temperature, yes if it is a hot day I will adjust my elevation slightly lower at longer ranges to allow for less dense air, and screw on a bit more if it is cold. I am running about 12 different barrels at the moment and each only has sight settings listed on one small page in a Sinclairs zero book so I don't think it takes much paperwork. My usual shooting temperature is around 24 degrees and I would say most of my sight settings are done somewhere close to this temperature. If it is much hotter or colder, I will allow for it at long ranges. Looking at my zero note book I have written some different settings at the same distance for some of my barrels depending on temperature. For example, with my current 284 I have the following scrawled in.
Malaba 800M 18.25 12 degrees
Canberra 800M 17.5 34 degrees
I haven't written anything extra in my short range settings but will fudge a click or two if I think the temperature is a long way from the usual. I don't have a ballistics computer and don't have any way of reading air pressure, humidity, density or altitude so I cant write any of this in.
If the wind is from the right say around 2 moa, I will give it a click or two down and of course if it is say 2 moa wind from the left I will give it a click or two up. I also allow for this effect (not sure what it is called) when I write my scope settings down so that the elevation setting I write down is closer to zero wind elevation setting.
I do take spin drift into account. One of my guns is mainly used at 300-600 so its spin drift wind zero is set for somewhere around 300-500yds. (Luckily all my main competition barrels for this gun have identical wind zeros). My other gun is used with 6.5 and 7mm barrels at 700-1000yds mainly and the wind setting is set for around 800-900 yds (once again, luckily my main competition barrels have the same wind setting). I have only ever once used this gun at 300yds (my most recent shoot) and I kept reminding myself that it will hit more to the left at short range and had to concentrate on this when shooting in direction changes.
This is about as far as I get into it, but I think that when I have the time I will likely look a bit more into ballistics in the future.

[DenisA]

G'day Rod, thanks for your insight. There are a couple of main ideas I get from your post. I guess it demonstrates that through experience you have developed a natural talent to judge conditions. From what you've said, you still see the differences and make educated tweaks to compensate for the important ones, but you seem extremely relaxed and comfortable and don't feel like you have to put a name to them.
Maybe that's a key trait to successful shooting. Not just being comfortable on the mound but being completely mentally relaxed while still being focused during the whole event including preperation. My minds always racing, "have I done this, have I done that, what's happening now, am I missing something", etc. once I'm on the mound and the first sighters away, I'm fine.

Thanks for commenting Rod, your insights refreshing to hear and puts another approach to it all.

Maybe reading into all the ballistic mumbo jumbo, as interesting as it is, clouds the mind of the basic and important parts to shooting and wind reading. Maybe the right place for all the extra info is at home. Keep it off the range. Let it naturally seep into practical improvement over time.