1. Ok, do this level of Keyholing us obviously bad, but what is it symptomatic of?

   1. The only time I had that bad keyholing was some bullets i cast that were too soft for the speed I was achieving in my 9mm. Once you go past 1,000 fps, you gonna leave lead in the barrel.
      And there are actually people casting .223 bullets. I did a search and cried.

   2. My guess would be that a .223 barrel blank received a 5.45×39 chamber.

2. I’ve seen that in a very, very old M16. Some gun left in the Guard that had seen continuous used since Viet Nam. Was essentially smooth bore 5.56. God knows how many rounds had been through it.

3. .223 fired through a. 300 barrel.

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   1. That’s what I’m thinking

4. Since it’s a “new” AR, for the sake of argument, we might exclude the barrel being shot out, although it might have actually not been rifled when manufactured (but that’s a small probability).

   More likely ->
   It’s symptomatic of 77gr Sierra HPBT or 70gr Barnes TSX ammo fired in a 1/9″ twist barrel (No, don’t ask how I know, but I will say it ‘twernt me)

   These bullets are too long to stabilize in anything slower than 1/8″ or Uncle’s 1/7″
   Even M855 ‘Green Tip’ fired in a 1/12″ twist barrel will still stabilize enough to not keyhole like that.

5. Someone posted recently having the same problems at 50 yds with a batch of Tula 55 gr out of a new decent name brand AR.

   Most of us speculated​ it was 5.45 bullets in .223 cases.

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6. My first AR-15 did that. Turned out that a 1-16″ 22 LR barrel had been chambered & marked 5.56 by mistake. The manufacturer replaced the barrel with the correct 1-9″ one and that rifle was great after that.

7. Those rounds would definitely mess you up if they could actually aim and hit you.
   .
   If you look at the 6 to 7 O’clock area of the 7, 8, and 9 rings? Were those the first, non-keyhole rounds before the barrel was fouled?

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