Keyholing with a new barrel

[fisherman987]

An overly quick twist will -prevent- keyholing, not cause it.

You're right, but I was just noting that the twist is too fast especially for the lighter bullets. I shoot the 133 and 135's and found 7.5 worked better than 7.

 

[AlNyhus]

25 creedmoor 1 in 7 twist. 26 inch. A round 30 shots , all keyholed. 133 berger , 117 sst,and 117 round nose bullets. All keyholing. Brass looks normal
But the crowd looks rough. I'm no machinist. And it's a McGowen barrel. Any suggestion?

Following a good look with a bore scope, step #1 is to verify the twist.

 

[DShortt]

As the OP just joined, this was the first post and hasn't logged on since 2 minutes after making this post I'd question his motives. Trying to shoot Subs?

 

[davidjoe]

By process of elimination, he may have a 6.5 creedmoor barrel on the gun, that is not engraving the bullets. The website lists a Creedmoor in both barrel diameters.

A post above says that one of his trial bullets doesn’t need a fast twist to stabilize, but even it keyholes. I am presuming that a 25 creedmoor will chamber up in a 6.5 creedmoor.

 

[swd]

None of those other things will make a bullet hit the target sideways. It's the wrong twist.

A bullet starting to come apart because of a really rough throat can or barrel definitely keyhole. I’ve seen 150SMK’s make perfect sideways silhouettes at 100 then turn into grey puffs a little farther out. I also had a brand new Rem 700 in 17 Rem that had a barrel as rough as a sewer pipe from the factory that as soon as it copper fouled in about 10 shots would key hole.

 

[Tommie]

As the OP just joined, this was the first post and hasn't logged on since 2 minutes after making this post I'd question his motives. Trying to shoot Subs?

Yep. Looks like we’re more concerned than the OP

 

[M-61]

I'd question his motives

Me too.

 

[paperpuncher]

As the OP just joined, this was the first post and hasn't logged on since 2 minutes after making this post I'd question his motives. Trying to shoot Subs?

Baffle strike?

 

[DaveTooley]

By process of elimination, he may have a 6.5 creedmoor barrel on the gun, that is not engraving the bullets. The website lists a Creedmoor in both barrel diameters.

A post above says that one of his trial bullets doesn’t need a fast twist to stabilize, but even it keyholes. I am presuming that a 25 creedmoor will chamber up in a 6.5 creedmoor.

I've shot a 22 in a 6MM barrel. Bullets don't make it 50 yds. down range.

 

[450BM]

I've shot a 22 in a 6MM barrel. Bullets don't make it 50 yds. down range.

Yeah, the velocity would have to be super slow because pressure would also have to be super low. That and zero rpm’s it would be pure luck to hit the target with any shots. It’s possible I guess but like others have said, need more information.

side story slightly related… I did this sort of thing on purpose with a very unreliable box of Hornady 17M2’s. I wasn’t going to shoot anymore of them in my M2 rifles but I wanted the bullets for reloading in my 17 Fireball. I 3/4 filled a 5 gallon bucket with water, added some poly fill to cut down on splashing and fired 30 rounds into it with a 4” revolver from about 2 feet above it. Every bullet was perfect, not rifling marks or crooked noses and the bucket was undamaged too. I tried 3 in the 17FB and they grouped around 1.25” at 100y. I suspect the velocity was too high. One day I‘ll slow them down (3000-3200) and try them again…

 

[Doom]

By process of elimination, he may have a 6.5 creedmoor barrel on the gun, that is not engraving the bullets. The website lists a Creedmoor in both barrel diameters.

A post above says that one of his trial bullets doesn’t need a fast twist to stabilize, but even it keyholes. I am presuming that a 25 creedmoor will chamber up in a 6.5 creedmoor.

Chamber has same dimension to body/shoulder junction so ir will chamber.

 

[joshb]

As the OP just joined, this was the first post and hasn't logged on since 2 minutes after making this post I'd question his motives. Trying to shoot Subs?

Yup…..maybe he expected a quick answer, waited the two minutes and went somewhere else…….like SnipersHide.

 

[FrankG]

An overly quick twist will -prevent- keyholing, not cause it.

Not necessarily. Quality of the bullets/loaded ammo plays a big part. I've seen fast twist barrels key hole bullets. It was a bullet/ammo issue.

The really fast twist basically amplifies the wobble of the bullet and will make the groups worse but will/can also make the bullets keyhole.

Later, Frank
Bartlein Barrels

 

[FrankG]

Also if any of you have been following the 7/6.5PRC testing that we had done.... The test barrel was a 8.25 twist.

The Sierra 197gr bullets need a minimum of 7.5 twist to stabilize. I did load ammo and had those pressure tested as well... and for that weight of a bullet I knew they were not going to shoot great accuracy wise... and none of them key holed. Just group sizes where big but it would still give us pressure data without any problems.

 

[nmkid]

There was too much coffee this morning for me!

 

[Riesel]

And the answer is..........................................??????
Was helping a friend zero his .308 and all was going well until bullet hit about 10 feet left and 12 feet or so low. Chinese fire drill ensued. Culprit, had a few 7-08 mixed in with those .308's
Live and Learn Grasshopper

 

[searcher]

A bullet starting to come apart because of a really rough throat can or barrel definitely keyhole. I’ve seen 150SMK’s make perfect sideways silhouettes at 100 then turn into grey puffs a little farther out. I also had a brand new Rem 700 in 17 Rem that had a barrel as rough as a sewer pipe from the factory that as soon as it copper fouled in about 10 shots would key hole.

I once saw a removed barrel that a gunsmith buddy showed me. His customer came to him to see if he could "fix" his keyholing rifle. Looking into the barrel from the breech end, the chamber had been cut so crooked, and misaligned with the bore, I'm amazed the thing even coughed the bullet out. Looked like someone reamed the barrel using a hand drill and no pilot. A quick borescope peek can tell a lot.

 

[Jerald]

Maybe its a 6.5 barrel.

Tried a 6.5 round and it wouldn't chamber. Going to check the twist next.

 

[Jerald]

McGowen blank, chamber cut by a gunsmith or a McGowen cut chamber? Call the seller get your money back.

Frank

All done by McGowen

 

[DShortt]

Tried a 6.5 round and it wouldn't chamber. Going to check the twist next.

You still might have a 6 Creedmoor. Or no telling what.

You need to verify bore diameter, twist rate and was this factory ammo or handloads?

There are only so many things that can cause keyholes. Start with verification of the basics. If 25 Creedmoor ammo fired in this barrel that only means the primer was close enough to the firing pin to ignite. There's next to no information here. You stated what you *think* you have and keyholes. That leaves a few critical questions unanswered. If the bore is larger than the correct bore for the ammo you fired, a quick comparison of the fired brass and any left over ammunition will make that problem obvious.

Did you keep any fired cases?