If you’re a regular reader on AccuracyTech you know I’ve been looking into the new 115gr DTAC bullets sold by David Tubb. I’ve been working on a ballistic performance evaluation of the new rebated boat tail DTACs for a few reasons. For starters, I have had excellent results and performance with the 105gr Berger Hybrid bullets. So why switch you might ask? The answer lies with the ballistic coefficient of the new DTACs. It’s been advertised as having a G1 value of 0.620! That puts it on par with the 6.5mm Berger 140gr Hybrid which has a G1 value of 0.624. So we’re talking about the same wind fighting ability as a 140gr bullet packed into a 115gr package. That’s pretty attractive! This article series is going to go into some of the evaluation work done before I made a decision on whether the switch would be worthwhile!
Ballistic Performance Evaluation
The first step I usually take when undertaking something like this is some theoretical or “on paper” numbers that I run to get an idea of what the performance differences are going to look like. On paper values don’t always translate to real world performance but it’s nice to have an idea where to start. I will plug in some values in my Applied Ballistics Mobile App and run the numbers at around 750 yards or so. In these examples I’ve run them at 1040 yards because I have some video and photos to go with that distance coming up. However, I think 750 yards is a realistic range to run your comparisons because that is a good benchmark range.
You can run all your ballistics numbers at 1000 yards. Do you do the bulk of your shooting at that distance in matches? Change the scenario to fit your rifle’s purpose. If you’re a hunter do you do the bulk of your shooting at 1000 yards? Run the comparisons where you expect to use the rifle the most. The farther the distance, the greater any differences between the ballistic performance of two bullets there will be. That’s the other reason I did some of this work at 1040 yards. To help illustrate the differences. I also have photos and data at 640 yards and 840 yards to go along with it.
I’ll take these numbers and take note of the drop in inches and drift in inches. In the case of the 105gr Berger Hybrid moving at 3123fps out of my 6x47L rifle you can see what we get. Rounded numbers of 251″ of drop and 62″ of drift in a 10mph Full Value crosswind. That’s pretty good performance. I’ve had great results but the G1 ballistic coefficient of the 105gr Berger Hybrid is 0.547. That’s what I ran the ballistic performance evaluation with. However, Bryan Litz has recently revised the G1 BC of these bullets down to 0.536. So let’s run that ballistics simulation again.
Still really good performance from a 6mm bullet. Just slightly less attractive (all of 3″ difference at extreme range) at 1040 yards with the lower G1 BC. Now we’re looking at around 254″ of drop and 64″ of drift in the standard 10mph Full Value Wind. I’m not knocking Berger, at all. That’s great performance and these are awesome bullets. They’re jump insensitive and extremely consistent. The question then becomes, is there a better mousetrap? What does performance of these new DTACs look like and how does it stack up against the Bergers? Lets find out!
So on paper what are we dealing with? The new DTACs give up about 5″ of drop to the 105gr Berger Hybrids. That’s at 1000+ yards too! So the closer we get, the less difference in the trajectory we will see. The DTAC is 10gr heavier and moving over 100fps slower, so 5″ isn’t much of a trajectory difference. It’s still shooting really flat. The big difference comes with the wind drift! The new DTACs drift a full 14″ less at 1040 yards in a 10mph Full Value Wind. More than a foot less wind drift is significant. Most of our misses at distance are due to errors with reading and compensating for the effects of the wind.
In part two of this series on ballistic performance evaluations I’m going to show you guys how I went about testing the performance of the new DTACs with live fire. We’ve already established a pretty compelling reason to explore them beyond the theoretical. I’m willing to give up 5 inches of trajectory in order to gain 14 inches less drift in the wind. The question then becomes do the new bullets group well? Are they as jump insensitive as the Berger Hybrids? How do they really perform at distance? Most importantly, how accurate is the G1 ballistic coefficient of 0.620? These are all things I’m going to explore with you all in this series of articles. Remember, to each his own! A hunter might have different ballistic requirements than a competitive shooter, or a Military Sniper. In this case, I’m looking for performance in tactical rifle competitions. So as we move forward, that’s the goal I’ve got in mind! If you have questions or anything to add, drop it below in the comments!