This is a discussion on Ballistic Coefficient within the Rifles forums, part of the Sniping Related category; Hi all,
I am looking for some assistance with factory ammunition. I have a new rifle (.308 Tikka T3x Tac A1) that I have mounted ...
Post By Martino1
I am looking for some assistance with factory ammunition. I have a new rifle (.308 Tikka T3x Tac A1) that I have mounted with a Swarovski DS 5-25x52p digital scope. I have not started reloading yet and my issue is that the ammunition manufacturers BC1 values for the ammo seems to be quite variable and in many cases quite far from the actual to calculate a center hit at longer +300m distances. I know that Kestrel and Applied Ballistics have their own tests and list of BC for their trajectory computing but I am wondering if anyone has a link to a similar list of factory ammunition BC tests or if my best bet is just to buy a Kestrel or continue to do my own calculations and corrections. Don't mind buying a great peace of kit like the Kestrel to gain access to their and AB hard work but have an old windspeed meter and currently don't need a new one aside from gaining access to the BC tests. Would also be happy if anyone has a recent list that they would be willing to share of the factory ammunition that Kestrel and AB have done BC tests on even without the BC results in case the solution is to go with purchasing a Kestrel just to make sure my favorites are on there.
For BT bullets, the G7 tables are a bit more accurate (especially when they go transonic) but yes, the posted BC numbers are not always completely accurate. Sierra tends to be pretty close, hornady is getting better and Berger seems fairly accurate as well. Typically, even with the fancy ballistics software, I confirm the data with good old fashioned shooting.
One point I like to emphasize to marksman is to not get too caught up with BC numbers. Its much more important that you find a load and bullet that is consistent and accurate in your rifle. If it drops a bit more than a different bullet, it doesn't matter if you are shooting groups half the size. Don't get too caught up in hype and chasing the latest fad (like super high BCs). Just my opinion.
Try reading these: https://www.midwayusa.com/s?targetLo...ItemsPerPage=0
Doppler verified BC values...written by a rocket scientist in a format we all can understand. By the way, Bryan, is the lead guy for Berger bullet design.
Newer Hornady bullets are Doppler verified as well.
Between the accurate G7 BC’s and Chronoing your rounds out of your rifle with whatever brake or can you’re going to use in the field is how you get key data for your bal. app. Measure the environmentals when you chrono your rounds at least temp humidity and altitude. Kestrel does this for me through interface with my ballistics ap. Once you’ve got a decent Extreme Spread and Standard dev, and average speed then you pop in that chrono data into the ballistics app.
In most apps you setup the weapons and the bullets. You put in the brand, model, weight, G7 BC. Then you put in the speed and environmentals when you zeroed and Chronoed. Then you update the environmentals for current conditions and generate your range card. Then you test the card under those environmentals and that bullet and weapon. If you’re getting impacts with your elevation then your only wildcard is wind which for me in flat country is left or right correction.
I get my BC info from the Applied Ballistics ref book I got from Litz’s seminar. It actually has BCs for different bullet speeds for the same projectiles. Once you put all that bullet info in you are done for that weapon and that bullet.
Last edited by Martino1; 07-14-2019 at 02:25 AM.