Interesting Keyhole Target From AR-15

[OK Corgi Rancher]

So I put together a gun today using an old Colt A1 upper. It functions perfectly and the sights were pretty much dead on when fired at 25 yds. I did notice on the 25 yd target a minor oblong shape to the 3 shots I fired to verify zero.

I moved closer, to about 10 yds, and WOW! The picture below shows the results. The barrel looks fine...no bulges and good rifling, etc. It's not marked for twist but I'm guessing it's a 1/12 twist. Does that sound right for an old A1 Carbine upper?

I was firing General Dynamics SS109 62gr stuff. I wanted to try some 55gr stuff but apparently I don't have any in my stash or, if I do, it's on stripper clips in bandoleers and isn't readily apparent what it is (except for green tip stuff).

Would this be normal for a 1/12 barrel to keyhole like this with 62gr bullets? I've never had this happen before so it's pretty new to me.

 

[Snattlerake]

no pix.

 

[OK Corgi Rancher]

I posted the picture...it shows on my end. I'll try again.

 

[PanhandleGlocker]

1:12 should stabilize 62gr bullets.

 

[rockchalk06]

Well, that's not something you see every day!

1:12 should I would think.

 

[adamsredlines]

With a pattern like that you should go dove hunting

 

[bigred1]

Dang, if there's such a thing looks like that would hurt worse.

 

[Firpo]

I’d measure the twist rate with a cleaning rod to confirm. Only time I ever saw anything like that and it was with a T-38 Arisaka. The person had reloaded way to light a bullet, I believe it was around 85 grains and the bullets tumbled like that. I loaded some with 140 grain bullets which it was designed for and it’s amazingly accurate now.

 

[PanhandleGlocker]

I’d measure the twist rate with a cleaning rod to confirm. Only time I ever saw anything like that and it was with a T-38 Arisaka. The person had reloaded way to light a bullet, I believe it was around 85 grains and the bullets tumbled like that. I loaded some with 140 grain bullets which it was designed for and it’s amazingly accurate now.

IIRC the Polish Tantal 5.45x39 we’re infamous for keyholing. Had a chance to get one one time and did my homework luckily.

Hope it’s just an ammo issue, OP.

 

[Snattlerake]

Damn! Are you shooting those rounds or throwing them?