22 Creedmoor issue

[orkan]

Mine was really weird about pressure, sometimes I'd have it on lower charge weights, then it would go away as I moved up, then show back up. Not advised to ignore early pressure signs, I just was ignorant to them and bull headed. PBB opened mine up to .260, and no issued since. 88 ELDm's at 3150 in a 20" bbl.

Yeah, that makes sense. This happens due to the burn curve characteristic of the powder at different times during the bullet release. When we tune our rifles, this is in essence what we are doing. So at certain points in the firing event, the pressure curve would have the barrel opened up a bit right at the neck area, giving adequate release. However, if the burn characteristic of that static powder column is timed incorrectly, we will see a non-uniform or abnormal behavior in the neck/throat area.

People tend to think of pressure as a singular event, but rather it is more adequately understood by thinking of waves. The location of the wave in relation to the movement taking place, can vary the outcome dramatically.

It is these types of things that lead to seeing soot on your shoulders or the body of the case, despite everything else being correct. That timing is critical to having a forgiving node. The brass is quite mailable, while the chamber walls are quite hard... so the way the pressure waves correspond with the bullets entry to the lands play a huge part in how the transition at the tail end of the firing event goes.

Obviously it is significantly more complex than I'm making it out to be here, but this is the high level flyby anyway of why what you saw occurred.

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[haisardao]

Pictures attached. Still need to do the bullet drop test.

 

[orkan]

Kind of hard to see the primary extraction from that pic... the area we need to see is the root of the bolt handle where it hits the cam on the action, with you pulling the handle rearward to remove the slop.

Bit of primer cratering there. Could be false positive due to your bolt face/pin fitment. Potential extractor mark at the "c" on creedmoor. Could also be false positive from machining burr. (you can stone it off if need be)

You can measure a fired case web expansion at the .200 line (last supported area of web) and see if its larger than chamber spec to confirm if pressure is the cause.


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[haisardao]

Bullet drops in the fired case just fine. I shot it today without the suppressor on and still have to pull harder than normal but less than suppressed for sure. I'm gonna drop a grain as suggested, and call Zermatt tomorrow.
Thanks again.

 

[jonboatjockey]

Thanks for the update. Keep us posted!

 

[6xshooter]

Might be h4350 pressure spiking. Try a max load of h4831 and see if the issue still exists

 

[orkan]

Or even h1000… I've seen that before in tight bores.

 

[haisardao]

Might be h4350 pressure spiking. Try a max load of h4831 and see if the issue still exists

Thanks, I loaded 12 rounds today H4350 40.5 gr. let's see what happens tomorrow

 

[haisardao]

Or even h1000… I've seen that before in tight bores.

Where would you start with H1000? 40 gr? I'm also using CCi BR2, any need for a magnum primer in your experience? Thanks

 

[orkan]

Where would you start with H1000? 40 gr? I'm also using CCi BR2, any need for a magnum primer in your experience? Thanks

Wherever you like really. 40 would be fine. Full compressed loads are often where one ends.

Magnum primers are generally not necessary, but might be needed if ES's are sporadic.

 

[haisardao]

Wherever you like really. 40 would be fine. Full compressed loads are often where one ends.

Magnum primers are generally not necessary, but might be needed if ES's are sporadic.

Thanks, I appreciate your input. Funny how life works, I ended up with a 22 Creedmoor by reading info from you guys site/videos.
I just realized Hodgdon has some data, although they don't use H4350 with this weight class bullet, they give numbers for superformance, H1000, 4831, and retumbo.
Rifle shoots a ragged hole with the TMK at 0.020 off the lands. Let's see if I can sneak a range trip tomorrow.
Thanks again.
H

 

[orkan]

Thanks, I appreciate your input. Funny how life works, I ended up with a 22 Creedmoor by reading info from you guys site/videos.
I just realized Hodgdon has some data, although they don't use H4350 with this weight class bullet, they give numbers for superformance, H1000, 4831, and retumbo.
Rifle shoots a ragged hole with the TMK at 0.020 off the lands. Let's see if I can sneak a range trip tomorrow.
Thanks again.
H

Yeah, the slower burn characteristic of H4831SC and H1000 tends to work great. It's just that I've had things stay a bit cleaner and generally get a bit more barrel out of the H4350.

Then too... I shoot a TON of H4350 in so many other cartridges that I've been an advocate for it in the creed for a long time. Never had luck with superformance.

Varget is my go to for the light bullets in the .22creed. You're not running light though.


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[haisardao]

Yeah, the slower burn characteristic of H4831SC and H1000 tends to work great. It's just that I've had things stay a bit cleaner and generally get a bit more barrel out of the H4350.

Then too... I shoot a TON of H4350 in so many other cartridges that I've been an advocate for it in the creed for a long time. Never had luck with superformance.

Varget is my go to for the light bullets in the .22creed. You're not running light though.


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I have plenty of 4831SC I'm gonna give it a try.
H

 

[haisardao]

So I went to the range today, loaded 12 rounds at 40.7, rifle shoots amazing, and almost no extraction issues. As suggested this load was too hot for this rifle/chamber at this point, even though I didn't get a bolt lift, and couldn't see any concerning signs on the brass. I'm loading 12 more at 40.0 gr and see what the rifle does. Thanks,
H