Keyholing with a new barrel

[DShortt]

I'd like to see before and after pictures of a crown that caused keyholing that was repaired and the keyholing stopped.

Not lopping an inch of more off a barrel and recrowning it. Not counterboring the muzzle end. Just the crown.

If it were me, I'd check the bore diameter.

For that matter, check the diameter of your bullets.

 

[L.Sherm]

Should be a quality barrel. I think the bearing length of the bullet is related to stability. Either the Berger or Sierra website that has a stability chart.

The Berger stability calculator says the bullet is marginally stable.

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

A 1-7 says 1.9 sg

 

[snod85]

I have a 6GT 1:12” twist barrel with four shots through it. Could’ve swore I ordered a 1:7.5” blank. Now have a new blank back with my gunsmith. All on me. Didn’t check and didn’t keep the receipt. I did learn how to check for twist rate using a cleaning rod though so I learned a couple of things from my only keyhole experience.

 

[dellet]

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?

It’s not just the Berger 133 that has a problem, which by the way Berger lists as a 1/8 minimum.



The Hornady bullets should have no problem with stability, but…..

Without load data, specifically velocity, the Berger bullet probably survives, the Hornady bullets are questionable.

1/7 @ 2900 fps = 298,286 rpm.

 

[Jerald]

Took the barrel to a gunsmith. He said it's a 1 in 7.25 twist. The barrel was chamber for a 25 creedmoor but the bore was 6.5. He is rechambering it to a 6.5 creedmoor

 

[M-61]

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?

I’m unfamiliar with cartridge.
ALL keyholes is quite impressive.
My only experience from keyholes is certainly not that or even close.
Problem for me:
Way too heavy a bullet with way too slow twist.
eg: 69 grain 222 in a 1/14 twist.
Could successfully get one of 5 to keyhole.

 

[LVLAaron]

Took the barrel to a gunsmith. He said it's a 1 in 7.25 twist. The barrel was chamber for a 25 creedmoor but the bore was 6.5. He is rechambering it to a 6.5 creedmoor

That'll certainly do it.

 

[M-61]

Took the barrel to a gunsmith. He said it's a 1 in 7.25 twist. The barrel was chamber for a 25 creedmoor but the bore was 6.5. He is rechambering it to a 6.5 creedmoor

Well nothing at all to add.
.257 rattling down a .264 bore!

 

[Jonnyofalltrades]

Took the barrel to a gunsmith. He said it's a 1 in 7.25 twist. The barrel was chamber for a 25 creedmoor but the bore was 6.5. He is rechambering it to a 6.5 creedmoor

Thanks for updating!

 

[DLT]

I have a 6GT 1:12” twist barrel with four shots through it. Could’ve swore I ordered a 1:7.5” blank. Now have a new blank back with my gunsmith. All on me. Didn’t check and didn’t keep the receipt. I did learn how to check for twist rate using a cleaning rod though so I learned a couple of things from my only keyhole experience.

Well, we don’t rent pigs. I like it !!! My favorite movie

 

[DanSavage]

Was going to say pic 3 is a ebco accuracy barrel lol

 

[Fast14riot]

Took the barrel to a gunsmith. He said it's a 1 in 7.25 twist. The barrel was chamber for a 25 creedmoor but the bore was 6.5. He is rechambering it to a 6.5 creedmoor

"Hot dog down a hallway" comes to mind...

Enjoy the new 6.5 creedmoor!

 

[Webster]

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?

"Hot dog down a hallway" comes to mind...

Enjoy the new 6.5 creedmoor!

The original post was Oct 2024.

 

[DShortt]

The original post was Oct 2024.

And the OP updated the thread with the cause yesterday at 9:41 am.