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.”

 

[mtnbound]

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.

With the heavy bolt and E-marks on both handloads and factory ammo, I would lean towards your chamber/free-bore might be a little out of spec. I would reduce your load by 0.5 or 1 grain and shoot again to see what you get.
What's your velocity goal?

 

[Treelineasassin]

First firing on brass? Alpha brass will do this sometimes upon virgin firing. Take the brass you fired, anneal and size or bumping shoulders -002 and retry them. I give it a 90% chance it goes away. 2750 from a short barrel is a stout load, near saami max, but shouldn't be doing this.

The Hornady saami ammo is loaded pretty warm, they had to do this to make or shine on ballistic tables compared to their 65 ammo. The same psi level in 65cm does the same 2800+ mv.

 

[Castle Rock]

Both new brass and factory ammo is notoriously short.
The wobble you speak of is probably just the primer backing out a bit.
De prime without sizing and try to chamber the fired brass.
If it fits just neck size first time around.
Definitely don’t try to FLS and push the shoulder back even further as suggested above.

Always check new brass for fit before loading.
If it will chamber with out much resistance with a layer or two of scotch tape on the head you should be doing something to control the stretch if you want maximum case life.

 

[heavyhorns]

First firing on brass? Alpha brass will do this sometimes upon virgin firing. Take the brass you fired, anneal and size or bumping shoulders -002 and retry them. I give it a 90% chance it goes away. 2750 from a short barrel is a stout load, near saami max, but shouldn't be doing this.

The Hornady saami ammo is loaded pretty warm, they had to do this to make or shine on ballistic tables compared to their 65 ammo. The same psi level in 65cm does the same 2800+ mv.

Yes first firing. I will give this a try.

 

[heavyhorns]

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.”

Same result when cold or warm outside. 45 thou off lands. I will conform chamber is clean. Appreciate the tips.

 

[heavyhorns]

Well after beating my head on a wall on this deal I figured it out. Shooting w an Ultra 7 suppressor. Removed the suppressor and it solves the problem completely. Put it back on and pressure shows it n the 3rd or 4th shot consistently.

 

[Seeknelk]

Well that's really silly and frustrating for ANY suppressor to be causing those issues ...
So how can this be solved? Obviously your not taking the suppressor off forever?

 

[wind gypsy]

Well after beating my head on a wall on this deal I figured it out. Shooting w an Ultra 7 suppressor. Removed the suppressor and it solves the problem completely. Put it back on and pressure shows it n the 3rd or 4th shot consistently.

Are you typically shooting into a headwind?

 

[heavyhorns]

Well that's really silly and frustrating for ANY suppressor to be causing those issues ...
So how can this be solved? Obviously your not taking the suppressor off forever?

Great question. It works totally fine on a 7PRC and also use it on a 223 a lot w out any issues. Apparently this is known thing that can happen. It may be a combination of things I seriously doubt just the suppressor is to blame. I have about 120 shots through the gun at this point. It shoots amazing. Maybe I need to back it down? Maybe I need to try and different suppressor that deals with back pressure better. I have lots to learn and lots of reading to do. I will let you know if I find a solution.

 

[wind gypsy]

I’ve read about issues with alpha not gripping chamber great on first firing. Maybe future firings will be better? Seems like it just might build pressure a bit fast.

 

[heavyhorns]

Are you typically shooting into a headwind?

Actually yes, almost always into a headwind. 8-12mph is pretty common.

 

[heavyhorns]

I’ve read about issues with alpha not gripping chamber great on first firing. Maybe future firings will be better? Seems like it just might build pressure a bit fast.

I used once fired brass on this latest go round and had some results. The first few shots with a cool barrel is totally fine. Its on the 4th shot that it really gets heavy. Consistently on the 4th shot of a 5 shot string.