Keyholing bullets

[jrainw]

Just in case you wondered, this is what happens when a barrel is worn out. I have put 6-8000 rounds through this barrel, almost all mag dumps with a registered M16. Seen it glowing cherry red dozens of times. This was from 15 yards.

About half the rounds shoot straightish, the other half keyhole, tried three different kinds of ammo and had the same results.
Funny thing is the barrel looks really good at first glance, bright shiny bore, good crown, throat not terrible. I'll be sighting in the new barrel tommorow, should be alot better.

 

[Bigtanker]

I have heard that a slow barrel twist such as a 1-16 and a heavy bullet weight can produce the same effect. The slow rate does not spin the heavy bullet fast enough resulting in a key hole.
Same principal with fast twist 1-6 or 7 and light weight bullets. In some instances, the bullet will actually come apart in the barrel from spinning it way to fast.

 

[Harleyrider_50]

Just in case you wondered, this is what happens when a barrel is worn out. I have put 6-8000 rounds through this barrel, almost all mag dumps with a registered M16. Seen it glowing cherry red dozens of times. This was from 15 yards.

About half the rounds shoot straightish, the other half keyhole, tried three different kinds of ammo and had the same results.
Funny thing is the barrel looks really good at first glance, bright shiny bore, good crown, throat not terrible. I'll be sighting in the new barrel tommorow, should be alot better.

Called 'Tumble'.......ol' skool term

 

[popsmoke]

I have heard that a slow barrel twist such as a 1-16 and a heavy bullet weight can produce the same effect. The slow rate does not spin the heavy bullet fast enough resulting in a key hole.
Same principal with fast twist 1-6 or 7 and light weight bullets. In some instances, the bullet will actually come apart in the barrel from spinning it way to fast.

^^^ Haven't heard that one before. Makes perfect sense though.

 

[Indy_Guy_77]

What weight bullet and what twist rate? The above poster is on the right track about bullet stability with the improper combination.

 

[woodshed]

Too slow of twist for speed of projectile, just a guess. Hope that helps.

Scott

 

[HamsterStyle]

Too slow of twist for speed of projectile, just a guess. Hope that helps.

Scott

I'm pretty sure he knows what the cause is. I think this is more of a PSA than a question. . Basically, he's saying that M16's rock!!!!

 

[jrainw]

Same results with four different brands of factory loaded 55 grain .223. It didn't used to do this

 

[tradertator]

I'm pretty sure he knows what the cause is. I think this is more of a PSA than a question. . Basically, he's saying that M16's rock!!!!

Agreed. Barrels eventually wear out, and automatic weapons are exceptionally abusive.