Little Confused. Updated with more info.

[Downhill]

Barrelled a Tikka T3 with a Krieger 12 twist, 95 Palma chamber at 26" long. Loading the Sierra 155 Palma 10k out. Using Varget in Lapua cases my sight in and fouler load was 43.5 gr then working up to 45.5. At 43.5 had clickers and flattened primers. Pulled loads and tried 43 gr, flattened primers. I am well below any recomended starting load. I ran 46 gr in another rifle with no issue. Question is tight bore? Hotter lot of Varget?(same jug has worked fine in my 6BR's). Federal Gold Medal shoots with no issue. Has me scratching my head.
Tried again this morning but with Hornady brass( don't care to trash the Lapua until issue resolved).
Hornady once fired and annealed; Sized Fired
Shoulder 1.608 1.622 ?
.200 Line ,468 .470
Neck .322 w/bullet .336 .344
Trimmed 2.005 2.009 to 2.011
Adding .002 of tape to bottom created slight resistance to bolt closure.
Started at 42.5 Varget stopped at 44gr. Clickers from 42.5 to 43. 44 grains extracted correctly but primer flattened. Ran two separate beam scales to verify charges. The only issue with measurements I see is the .014 difference at the shoulder measured with a comparator. Extraction does get easier with the higher charge but the flattened primer and extractor swipe is alarming. Will look at a different powder but I don't feel this is the issue as it has always worked in my 308's.

 

[hogpatrol]

New cases or ones shot in another rifle/chamber?

 

[Downhill]

Cases once fired, anealed and re sized to new chamber. Bolt closes with no effort.
Was waiting to chrono until an accurate load was found. Will try 41.5 to 43 with chronograph next outing.

 

[searcher]

Excessive headspace can result in flattened primers (even with light loads) as the case gets "smacked" against the bolt. If the headspace is not the issue, I'd not discount the load just being too hot for that particular barrel. Since you are firing a new barrel and have no brass known to have fully blown the shoulders forward fully, how did you arrive at where the shoulders should be when setting your die? If it was based on your fired brass from the prior barrel, it could be that the prior barrel had considerably shorter headspace than your current barrel. Did you anneal the brass to allow it to better conform to your new chamber?

 

[Lone Hunter]

Pulled loads and tried 43 gr, flattened primers. I am well below any recomended starting load.

Do you think there might be over pressure happening with too light a load. If you are well below any starting load I would be concerned about this happening. Here is a good read from A/S several years ago.

Under Charge and Overpressure

Can someone point me in a good direction to understand why excess pressure happens when a load isn't fully charged. I have read some explanations but still don't understand. This isn't a question about wrong powders but about a less than full charge resulting in dangerous pressure. Thanks

forum.accurateshooter.com

 

[Mark W]

The only time I had something like this happen was when I received a .268 neck 6 BRA that was suppose to be a .272 neck. I was getting pressure signs at starting loads until I figured it out and turned the brass to fit. Problem solved.

 

[coldboreshot]

Add some pics of the flattened primers. Sometimes there is an underestimate or overestimate about pressure indicators. Are the primers also displaying cratering. A factory Tikka is most likey not gunna have a bushed bolt to eliminate cratering.
I don't recall mention of if this brass was fired in a different rifle or not but the clickers may be coming from the sizing die which is not sizing all the way to the base at the .200 line. May have to "reset" brass with a small base die and form for this chamber.

 

[SeabeeKen]

The only time I had something like this happen was when I received a .268 neck 6 BRA that was suppose to be a .272 neck. I was getting pressure signs at starting loads until I figured it out and turned the brass to fit. Problem solved.

This was my first thought, a tight neck. Id do a chamber cast or possibly long pin gauge to find the neck size.

 

[Webster]

Barrelled a Tikka T3 with a Krieger 12 twist, 95 Palma chamber at 26" long. Loading the Sierra 155 Palma 10k out. Using Varget in Lapua cases my sight in and fouler load was 43.5 gr then working up to 45.5. At 43.5 had clickers and flattened primers. Pulled loads and tried 43 gr, flattened primers. I am well below any recomended starting load. I ran 46 gr in another rifle with no issue. Question is tight bore? Hotter lot of Varget?(same jug has worked fine in my 6BR's). Federal Gold Medal shoots with no issue. Has me scratching my head.

Whats the caliber?

 

[joshb]

“I am well below any recomended starting load.”

As mentioned, this might be the issue.
Read up on Detonation. Too much empty space in the case allows for a faster burn of the powder.

 

[butchlambert]

Whats the caliber?

308

 

[G Liles]

Lube on cases?

 

[RegionRat]

Federal Gold Medal shoots with no issue.

Just based on this comment, it tends to point at your test loads and not the gun.

Kudos for keeping some reference ammo on hand. It helps if you have the velocity of the normal rounds to compare with the ones that show pressure and clickers, but at least you have one part of the troubleshooting list answered and it tends to steer the investigation away from the new gun and points at your test loads.

You are just going to have to sharpen the search and double check everything in your loading.

I would suggest you also run the same case inspections on some of that factory FGMM ammo at the same time. This seems redundant, but if any of your brass prep measurements or tools are wrong, you would not get normal readings from the baseline ammo and possibly catch something.

If at all possible, run a reliable chronograph during any more testing till you get to the bottom of it all. Even on that FGMM just to make sure gravity still points down.

Play it safe.

Good Luck and in for the range reports.

 

[Bob3700]

Two thoughts: First, have you tried any factory ammo (Fed GM Match) in the rifle? Always good to have some as a control.
Second: What is the origin of the bbl.? I have one Palma rifle with a Bartline 5R, 12T, standard bore. Will shoot up to 46.5 gr of VGT with a 155.
Second Palma rifle has a Krieger 4 groove, 12T, tight bore. Max VGT load with a 155 is 45 gr.

So, do you know the origin of the bbl on your rifle? Might it be a tight bore 308?

As the cases were not original to this rifle, I would try a small base sizing die. Your chamber may be a bit tight at the base.

Last thought: Have you chrono'ed the loads? What velocity is it generating at those load levels?

Bob

 

[dryhumor]

What dies are being used? That wasn’t mentioned that I saw.

 

[RegionRat]

@Bob3700 RE: testing with FGMM... its in his original post on line 5, and what I quoted in my post above yours. He says it ran FGMM without issues.

 

[358WCF]

Sized Fired
Shoulder 1.608 1.622 ?
.200 Line ,468 .470
Neck .322 w/bullet .336 .344
Trimmed 2.005 2.009 to 2.011
Adding .002 of tape to bottom created slight resistance to bolt closure.

Tape was added to fired or sized cases? The "shoulder" dimensions are measured headspace differences?

The only issue with measurements I see is the .014 difference at the shoulder measured with a comparator. Extraction does get easier with the higher charge but the flattened primer and extractor swipe is alarming.

If so, I think you answered your own question... .014" is excessive shoulder setback on resizing. I stay between .002 & .004" at the very max. for bolt guns. Getting a run at the bolt face can show false pressure signs, i.e. flattish primers & slight ejector mark. I wouldn't be terribly surprised if you develop the telltale shiny ring showing a thin spot somewhere above the .200 mark next firing with that much "shoulder bump".

Re: The original pic. All I could see was a slight line (see red arrows), not a real ejector mark. Is that the "swipe" you're referencing?

Re: clickers. Maybe a stupid question but here goes anyway... Do you keep your locking lugs lubed?

 

[Downhill]

Dies, Forster Benchrest Die set w/ dedicate case holder.
Tape was added to sized case.
Bolt lugs greased after each cleaning session.
Barrel was bought directly from Krieger a few years ago via an Accurate Shooter promo.
I think I am going to try loads with Benchmark and 748 to rule out a powder issue and remeasure distance to lands ( although there is no indication of contact).
First time in 40 years of handloading that a 308 has given me trouble.

 

[RegionRat]

Agree, your charge weight of Varget shouldn't be causing pressure if everything is normal.
So, measure twice and cut once as you go. Double check it all forwards and backwards.

Here is the usual load data off the Hodgdon site for comfort. You should be nowhere near flattened primers based on your charges. If at all possible, track the MV for the next session starting from a squeaky-clean rig and play it safe.

 

[Bob3700]

@Bob3700 RE: testing with FGMM... its in his original post on line 5, and what I quoted in my post above yours. He says it ran FGMM without issues.

If FGGM will run without issues then look at the brass. I would load with some new brass.