Semi-Auto / AR-15 grouping question
I was shooting some different loads today in my AR-15 and got some interesting results. With the same load I was seeing two distinct groups form. I believe that this is due to variations in chamber-time, or the time the round sits in the chamber warming up before firing. Is this a common thing to happen with semi-auto fire?
Elevation was pretty much the same but the two groups are about 1.5" apart. Taken by themselves, the 3 shot group is around .5" and the two shots grouped to the right are .375".
These 5 rounds were all loaded the same:
75 grain Hornady A-Max
2.260" Cartridge OAL
Thanks in advance