22 creedmoor

[Joejack]

I have a Xcaliber 22 creedmoor barrel on a tikka t3 it is blowing up 85.5 gr Bergers at 3250fps I only get 5 to 6 shots then it will blow up every one of them I was running them at 3290fps no problem I don't know what has changed cleaned it good looked at it with bore scope little to no fire cracking it is a 1&7 twist any suggestions thanks doug

 

[wildbillb02]

Does berger recommend a twist rate

 

[Jud96]

You're spinning those bullets upwards of 334k RPMs. Anything over 300k RPM and you have the possibility to blow up bullets. The internal finish of the barrel, land and groove geometry, and the number of lands and grooves also affects bullet integrity. High velocities, fast twists, carbon and/or firecracking, and certain land and groove configurations are a recipe for bullet failure. The barrel is most likely getting some carbon deposited and the internal finish is changing and those two things along with the velocities and bullet RPMs is enough to give you problems.

 

[Joejack]

You're spinning those bullets upwards of 334k RPMs. Anything over 300k RPM and you have the possibility to blow up bullets. The internal finish of the barrel, land and groove geometry, and the number of lands and grooves also affects bullet integrity. High velocities, fast twists, carbon and/or firecracking, and certain land and groove configurations are a recipe for bullet failure. The barrel is most likely getting some carbon deposited and the internal finish is changing and those two things along with the velocities and bullet RPMs is enough to give you problems.

Thanks

 

[Varmint Hunter]

Just a thought:

Moly coating bullets leads to less engraving stress on thin jacket bullets launched at high speed. Other bullet treatments probably would do the same. I moly coated and waxed over 1,000 75gr A-Max bullets that I shot at nearly 3,700 ft/sec and never dusted a single bullet.

It may be worth a try.

 

[SealT5]

Doug, any reason to not back down to a lower node?

 

[Joejack]

I may have to but this barrel shoots the best at 32

 

[Joejack]

This barrel shoots the best at the 3250 and 3290 nodes. It just started blowing bullets up at the 3290 node I knew it would blow them at 3325 I may have to slow down

 

[Creedmoor shooter]

Agreed with @Jud96 . The 22 creed is a screamer so with a 7 twist those bullets are really spinning. In a 22 creed id go no tighter than a 7.5. Maybe even 8. The 22 creed is fast enough so you can get away with a slower twist than what alot of these bullet companies recommend.

 

[Joejack]

I gave it a deep clean this morning with Montana copper cream got it down to bare metal velocity dropped to 3250 from 3290 and 30rds made it to the target this afternoon

 

[wildbillb02]

Accuracy there?

 

[Jud96]

I gave it a deep clean this morning with Montana copper cream got it down to bare metal velocity dropped to 3250 from 3290 and 30rds made it to the target this afternoon

Keep up with the barrel maintenance. The barrel may get easier to clean and foul less after you get some more rounds down the barrel. I would try and clean every 50-75 rounds with a good solvent like Boretech Eliminator, Montana Xtreme bore solvent or Copper Killer, Butch's, Shooter's Choice, etc. Use bronze brushes and don't be afraid to scrub it a good 15-20 strokes a couple times throughout the cleaning process. Keeping this barrel clean is going to be crucial to keeping the bullets together.

 

[Joejack]

Accuracy is still there quarter size 5 shot group at 200yds barrel has 450rds on it now guess it has decided it wants to run clean now been using bore tech eliminator on it guess I am going to have to use the copper cream every now and then thanks

 

[Jud96]

Accuracy is still there quarter size 5 shot group at 200yds barrel has 450rds on it now guess it has decided it wants to run clean now been using bore tech eliminator on it guess I am going to have to use the copper cream every now and then thanks

How often do you typically clean?