Early Pressure Signs - Tikka Prefit 25 creed

[heavyhorns]

Could use a little help....I am experiencing inconsistent early pressure signs - heavy bolt lift and extractor marks(some are really deep). Here are the details....

Tikka Action
Proof Carbon Prefit 22" 25 creed

Handloads...
Alpha Brass 25 Creed
CCI 450 SRP
H4350 - 40-41 Grains
2,727 fps average on Garmin Xero

Factory
Hornady ELD M
2,750fps

This is my first prefit that I assembled. The guns shoots incredibly well. The action/barrel were tightened to 90 ft lbs. About 2 out of 10 rounds of the handloads show extractor marks and also experience heavy bolt lift. I backed down to 40 grains and experience the same behavior in the handloads. I decided to test some factory Hornady ELD M and it ran 2,750...shot 6 consecutive shots...4 out of the 6 had heavy bolt lift and extractor marks.

When I assembled it the action closed on a Forster NoGo Gauge. After talking with Proof, I added a single layer of scotch tape to the NoGo and it would not close. I decided to take it into a local gunsmith and he took a look at the headspace and said it was fine...it would not close on his NoGo. I'm scratching my head. The dang thing shoots lights out (1/2 MOA) but some of this brass is damaged enough that I won't load it again because it won't sit flat when you stand it up on a flat surface. Is this an action issue possibly? Maybe try new brass? Try new powder? Really frustrating to have a gun shoot so damn good but have issues like this. Am I missing something here? Appreciate the feedback.

 

[43.6N]

Sounds broken beyond repair. Better send it to me.

Jk jk.

Here are a couple of my thoughts:

1. How hot was it when you were shooting?
2. Are your reloads jammed into the lands? How long is your freebore?
3. Do you have solvent or grease in your barrel or bolt? Running an acetone soaked bore snake through the barrel/chamber, and cleaning your firing pin/spring is an easy thing to check.

All three of the above have given me unexpected pressure signs.

Also consider the following:
Alpha brass is notoriously tough, and has slightly smaller internal volume compared to other brass mfg. And all the Proof barrels I’ve been around have had a really high polished chamber.
This can result in higher than expected pressures, and excessive bolt thrust for the first firing. After the brass starts relaxing and gripping the chamber walls, pressure “signs” start going back to normal.

I would drop down another full grain of powder for the first firing. Try working up to higher (normal) charge weights after the brass and barrel is “broken in.”