.223 Keyhole / Tumbling

[howabouttheiris]

Thought I would post this photo from my range session yesterday. Here are some of the details.

1. Shot with my Stag Arms Model 3G AR15 in .223, a generally ~MOA setup. 1-8 twist barrel is usually really good to stabilize 69gn match ammo (which I have shot to over 600yds)

2. Distance is ~40 yards.

3. Ammo is 55gn .223 Monarch (Academy) steel case lacquered

4. Gun cycled reliably and no difference in feel was noticed.

5. Gun returned to a tight group (or as tight as I shoot, as I was shooting standing tripod) with an ammo change to a better 55gn round.


This is super cheap Russian ammo. Unsure that I can believe that tumble would happen due to a few percent lower velocity, as the 55gn should stabilize without issue.

My only guess is undersized bullets not touching the rifling at all.

Anyone with an alternate theory?



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[Tony Pic]

Were you holding the gun straight?
They were all hits and the grouping for the keyholes was tight.
All seriousness...I'd say cheap undersized poor quality ammo...No doubt. 1:8 should handle it all.
I only run steel case in my AK. Gun was made for it. Feed brass in the AR. The Russian crap is too unreliable. Only good for blasting. Nothing like a Lake City head stamp.

[TacticalCowboy]

That’s wild. My 1-8 twist doesn’t like the Russian stuff, but nothing that crazy!!

[Clay C]

Yeah that is wild. I've seen keyhole with crappy ammo, but that looks like it came out a barrel that was completely shot out.

[Killer]

wow never seen that. I would stay away from the cheap ammo. Maybe the length of the bullet had something to do with it not stabilizing in a 1:8"? or as stated above under sized cal.?

[Pstraw]

Can you put a mic. on one of the bullets to verify diameter?

[howabouttheiris]

Can you put a mic. on one of the bullets to verify diameter?

Yes. I have a selection of match ammo at the house, that I can verify against.

Looking at the empty boxes in my shooting bag, it appears that I shot 2 different lot numbers from the same location and same month. I have a few boxes of each lot number left, so I may take them back out to the range and see if I can get it to repeat with 1 or the other... then see what they do in another firearm.

I'll also see if I can get a bore scope done, so I can rule out any wear or damage in the barrel that may be exaggerating this. Not expecting any surprises, as I recently shot this rifle in the Competition Dynamics Team Safari and am really confident of its capabilities (with $1.00 a shot, Black Hills 69gn Match).

[Bowyer]

I saw something similar last weekend. A friend was shooting his 62 grain reloads from his Remington with 1:12 twist and they were tumbling also.
Went back to his 50 grain reloads and could stack them all in the same hole.

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[Top Of Texas]

I saw something similar last weekend. A friend was shooting his 62 grain reloads from his Remington with 1:12 twist and they were tumbling also.
Went back to his 50 grain reloads and could stack them all in the same hole.

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Similar experience for me. Wanted the kids to have plenty of .223 ammo to practice, so purchased cheap foreign surplus in 60-something grain. They tore holes through the paper just like that, and scattered all over. Not what I wanted for kids obviously. Went back to Hornady 55 gr V-max, $1 per round, but drive tacks at 100 yd through my Savage bolt action. Gave the kids .22 for plinking.

[Drycreek3189]

On the other hand, that would put a hurtin on a hog !

[howabouttheiris]

62 grain reloads with 1:12 twist

I have also seen very poor results with heavy bullets in slow twist barrels ... but not really as much when 55 grain are being spun just slightly faster (1:8) than optimal (1:9).

[blaqkpanda]

You can run into over stabilization of light bullets with too fast of a twist. Now, 55gr and 1:8 doesn't sound like you would be in that zone. Since it stabilizes other 55gr, I would try shooting both through a chronograph and see if the un-stabilized bullets are running hot or slow.

[Mike D]

.223 Keyhole / Tumbling

You can run into over stabilization of light bullets with too fast of a twist. Now, 55gr and 1:8 doesn't sound like you would be in that zone. Since it stabilizes other 55gr, I would try shooting both through a chronograph and see if the un-stabilized bullets are running hot or slow.

I don’t believe you can spin anything fast enough out of a 223 for this to occur. Additionally Bryan Litz has stated that overstabilization isn’t a concern. It will cause the Bullet to fly nose high causing a loss of accuracy and BC but otherwise is a non issue.


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[howabouttheiris]

Shot again today... repeated, but shooting 55gn with 2 different rifles to attempt to rule out ammo quality.

Same box of ammo (10 each), same shooter, 40 yds prone, same optics, both 1:8 twist on AR platforms.

Time to send it in for a barrel I think.

[WhiplashTX]

This is super cheap Russian ammo.

Here's your issue. I bet they cheaped out or inadvertently used 5.45x39mm bullets which is a similar Russian round using a .220 bullet