22 creedmoor early pressure issues

[Bojangles21]

I picked up a cheap donor CA action a few years ago, took it straight to a well known smith to tear it all down and true it all up and throw a benchmark carbon on it, chambered in 22 creed. After I picked it up, I loaded up some 88 eldms to break in the barrel, with well below “safe” starting point data, and I hit pressure right off the bat. Thought I may have messed up the powder dispense, so I went and pulled all bullets and doubled checked and loaded up some more. Pressure right away once again.

I think ended up loading a very slow load and shot 150ish rounds to see if anything would change. Nothing changed.

A few months later I ordered a bartlein carbon 24” 1:8t and had a different, very well known gunsmith check it all out and throw that new barrel on. Tried another load work up, early pressure once again. I’ve now given up on trying to figure out why it won’t get to that “22 creed speed” everyone loves. I settled on the 75 eldms in Peterson lrp brass with h4350. It’s shooting 3275fps, groups great and is a pleasure to shoot, but I feel a 24” should be quite a bit faster. Has something similar happened to anyone else?

 

[swavescatter]

3200 fps out of my 16.5" Proof 7 twist. Alpha brass, 77 TMK's, 42gr H4350.

I did have pressure signs with the first barrel I had that had a FUBAR'd chamber job and zero throat, but with a competent 'smith and 169 freebore that went away.

How many rounds down the barrel? What pressure signs? What's your freebore? COAL?

 

[Barred]

See you are using Peterson brass. I also use Peterson for my 6.5 CM. Honestly the brass is finnicky in my opinion. It does have a reduced powder capacity mine is around 50.5-51 H20 capacity. They also sometimes have soft bottoms which can appear to be pressure sign when in reality you are safe.

 

[Bojangles21]

3200 fps out of my 16.5" Proof 7 twist. Alpha brass, 77 TMK's, 42gr H4350.

I did have pressure signs with the first barrel I had that had a FUBAR'd chamber job and zero throat, but with a competent 'smith and 169 freebore that went away.

How many rounds down the barrel? What pressure signs? What's your freebore? COAL?

I have at least 400 rounds down the barrel now. Very stiff bolt lift, hard ejector marks. Both have been standard free bore. The load I’m at now is 2.690” if I remember correctly.


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[Barred]

I have at least 400 rounds down the barrel now. Very stiff bolt lift, hard ejector marks. Both have been standard free bore. The load I’m at now is 2.690” if I remember correctly.


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Based on the load data I am seeing on the internet you look to be right on the cusp of over pressure and if you are loading those Peterson case with a non reduced load due to the more limited capacity that may explain it.

 

[Fred@Exterra]

Same reamer?


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[Bojangles21]

Same reamer?


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Nosir, different.


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[UnckleBob]

Does it show pressure with factory ammunition? If it does and it was my rifle, I would be concerned there is something wrong with my rifle.

 

[Bojangles21]

Does it show pressure with factory ammunition? If it does and it was my rifle, I would be concerned there is something wrong with my rifle.

No pressure either factory ammo


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[43.6N]

Both have been standard free bore. The load I’m at now is 2.690”

I had unexpected pressure issues early on also.
My setup/chamber was very similar to you.
Saami freebore, Manson reamer. I started by seating 77TMK at the Vhitavuori book OAL of 2.618”.

Had immediate raised ejector marks in alpha brass 2gr below book max. I found out I was jammed into the lands when I chambered and extracted a round but the bullet separated and stayed in the throat.

After measuring my throat, I was 30thousands jammed into the lands, leading to the early pressure.

I shortened my load to 2.518, pressure went away, and I was able to get up to book max charges without further issue.

 

[Bojangles21]

I had unexpected pressure issues early on also.
My setup/chamber was very similar to you.
Saami freebore, Manson reamer. I started by seating 77TMK at the Vhitavuori book OAL of 2.618”.

Had immediate raised ejector marks in alpha brass 2gr below book max. I found out I was jammed into the lands when I chambered and extracted a round but the bullet separated and stayed in the throat.

After measuring my throat, I was 30thousands jammed into the lands, leading to the early pressure.

I shortened my load to 2.518, pressure went away, and I was able to get up to book max charges without further issue.

You were jamming 30 thou at 2.618” with standard freebore? I may be mistaken but that seems off. Hornady states 2.700” is max


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[43.6N]

You were jamming 30 thou at 2.618” with standard freebore? I may be mistaken but that seems off. Hornady states 2.700” is max


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Yes. Imagine my surprise. I had assumed I was well back from the lands.

I made a dummy cartridge and took measurements directly off of that going forward.

It’s a variable that’s worth running down in your case. I reached out to my gunsmith who confirmed what I was measuring, and touched up the chamber for me.

 

[Bojangles21]

Yes. Imagine my surprise. I had assumed I was well back from the lands.

I made a dummy cartridge and took measurements directly off of that going forward.

It’s a variable that’s worth running down in your case. I reached out to my gunsmith who confirmed what I was measuring, and touched up the chamber for me.

For sure. I had my gun make a dummy round and measured it and I am not touching lands. That would be quite a surprise tho.


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