I recently busted out the chronograph to test my standard 5.56 AR load and a few of it’s variants to see how it measured out of different length barrels as well as compare it to a new TAC load that is supposed to be all the rage in the forums. My standard load consists of 25.5 grains of Accurate Arms 2230 behind a Montan Gold 55 grain bullet topped off with a CCI #41 primer. For years I had used the same load but with only 24.5 grains of AA2230 but increased it by a grain to gain a little more velocity out of the rifle for improved long range target engagements as well as adding a little more reliability to the AR’s gas system. With the added pressure I needed to get some new measurements to add to my ballistic apps, so off to the range, chrono in hand.

For testing the following rifles were used to see how different barrel lengths would affect the velocity of the bullet:

  • 18″ DPMS 3G1
  • 14.5 BCM BFH
  • 10.5 LMT MK18

Now before I present the chronograph results I’d like to mention that if I were to go on feel, how much felt recoil I had gotten from the rifles, I would be mistaken. The AA2230 felt dramatically lighter than the TAC  so it is pretty amazing how much the velocities didn’t align with how much “kick” the rifles had. I really was surprised that the soft shooting AA2230 had a much faster velocity out of all the rifles than the hard hitting TAC. I think this little experiment really underscores the need for experimentation with proper instrumentation.

On to the data. Here is an overview of the data collected listed by rifle/load. I also added a factory PMC 223 to the matrix for reference. I’ve truncated the data below to show the complete results for the 14.5″ BCM, but added a little for the 10.5″ LMT and the 18″ DPMS.

Load Data – Click for larger view

 

For my purposes the Accurate Arms 2230 is the clear winner since it sends the pills downrange faster (meaning less drop and affected less by the wind) and has much less felt recoil than the Ramshot TAC. Also note that the Standard Deviation of the 25.5 AA2230 load is much lower than the other combinations. Again, you really have to use a chronograph to when comparing loads to truly see what the loads are doing out of your rifle.

Why You Have To Use A Chronograph – AA2230 vs. TAC
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