Little Confused. Updated with more info.

[M-61]

I am well below any recomended starting load.”

Why?

 

[gmr4]

Your comments concerned head space or shoulder indicate .010 excess or more and that will cause these issues. “.014 difference”…… sized the brass too far…

 

[cb186]

First thing I'd check would be the bore diameter. Second would be to switch to small primer brass.
If a 95 reamer was used, there shouldn't be any neck clearance issues.

 

[Martin52]

Shoulder moving from 1.608 to 1.622 - is that correct ?

As others have suggested, I'd move to new cases and re-test.

What's your COAL ?

 

[Downhill]

Shoulder moving from 1.608 to 1.622 - is that correct ?

As others have suggested, I'd move to new cases and re-test.

What's your COAL ?

2.890. 10k off lands. Averaged over 10 readings.

 

[divingin]

Have you measured case base to shoulder on your fired and sized brass vs the factory new GMM? The GMM should be much shorter. Factory stuff is usually around SAAMI minimum length. Your fired (and subsequently sized) brass should end significantly longer than a factory cartridge (up to about .010", though that depends on your chamber cut as well.)

 

[Doom]

2.890. 10k off lands. Averaged over 10 readings.

You can't directly compare FGMM to your your reloads nor can you readily compare standard reloading data to your rounds seated 90 thousandths longer and 0.010
' (+/-) off the lands. Your chamber has different freebore than the 308 and the 95 reamer is not set up for the 2156 Bullet.

 

[Webster]

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.

What happens if you take a fired case and reload it without any sizing and fire it?

 

[6.5 forever]

What happens if you take a fired case and reload it without any sizing and fire it?

The bullet will probably fall into the case! Don't try it.

 

[std7mag]

I think that @M-61 has hit the nail on the head!

When I was starting out, I had loaded my first batch below starting point in the manual.
Flatened primers, kicked like a mule!

Come to find out that pressure spikes occur when you go too low.

Almost if not equally as dangerous as overloading.

 

[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.
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.

Just checked my Sierra Reloading Manuel.
For the 155 gr Palma Match king bullet and Varget powder.
41.4 gr minimum 44.8 maximum.

Your lightest load was 42 gr of Varget. Your should not be getting light charge pressure problems based on those numbers. You still had clickers at 44 gr. From Tony Boyers book I believe he says clickers are from the case body expanding and sticking against the chamber wall. The clicker is from the bolt breaking the case free???

 

[Bob3700]

What vintage is ur Krueger bbl? Recent manufacture or an older Palma bbl? Some of the older Palma bbls were tight bores. Those bbls won’t take the loads a 308 bore bbl .

I have one of the tight bores Kriegers with a 95 Palma chamber. It will require a full 1 gr. reduction of Varget with a 2155 SMK. I use Lapua and Winchester brass and Fed 210Ms.

 

[Downhill]

Guys, when I get back home I'll look at my records. But from memory the blank was bought 4 to 5 years ago and machined about 3 weeks ago. I start low with a new barrel just in case. Will try Benchmark and 748 at 2.8 OAL next outing. Like I said , first time since the early 90's a 308 has give me trouble. Would like to try my proven Palma load but this barrel has me shy of running it hot.

 

[Hengehold]

Your comments concerned head space or shoulder indicate .010 excess or more and that will cause these issues. “.014 difference”…… sized the brass too far…

+1. Agree with this comment that a shoulder bump of .014 sounds like the obvious place to start addressing a problem. At the very least, this is definitely too much shoulder bump if you are planning to reload the brass multiple times.

None of the information provided by the OP raises any red flags to me except for the amount of gap between shoulder & chamber, and the lower than minimum charge weights.

I would do the following things to move forward:

1. Jam the bullets into rifling ~ .015-.020”. This will allow you to properly fireform the brass to the chamber while case is firmly against the bolt face. Try this with the same powder charges that were previously tested and make sure you also try the minimum charge weight published in a reloading manual. This alone could eliminate the pressure issue.

2. Adjust sizing die for only .003” shoulder bump with the bullet jumping as you did in the original test. Use powder charges from original pressure test and make sure to work up to at least the published minimum pressure load.

3. If # 1 & 2 do not resolve the situation then does a bullet drop freely into a fired case? If not then perhaps your chamber neck is too tight and contributing to the pressure problem.

 

[boltfluter]

+1. Agree with this comment that a shoulder bump of .014 sounds like the obvious place to start addressing a problem. At the very least, this is definitely too much shoulder bump if you are planning to reload the brass multiple times.

None of the information provided by the OP raises any red flags to me except for the amount of gap between shoulder & chamber, and the lower than minimum charge weights.

I would do the following things to move forward:

1. Jam the bullets into rifling ~ .015-.020”. This will allow you to properly fireform the brass to the chamber while case is firmly against the bolt face. Try this with the same powder charges that were previously tested and make sure you also try the minimum charge weight published in a reloading manual. This alone could eliminate the pressure issue.

2. Adjust sizing die for only .003” shoulder bump with the bullet jumping as you did in the original test. Use powder charges from original pressure test and make sure to work up to at least the published minimum pressure load.

3. If # 1 & 2 do not resolve the situation then does a bullet drop freely into a fired case? If not then perhaps your chamber neck is too tight and contributing to the pressure problem.

This is very good advice. If you still have problems try some new brass, as brass does have a memory, and it will drive you crazy trying to figure it out. Good luck and keep us posted.
Paul

 

[Downhill]

Finally got time to try again. Went back to Lapua brass, CCI LR primer, 43.5 to 46 gr Varget, 155 Sierra Palma seated this time at 2.80". Fired some M852 Match this time too. M852 had resistance closing the bolt but held sub .75". The pics show 44.5 Varget, red target 3 rounds (#2 out right was me not watching flags) at 100 yds. Black target 8 rounds same load and distance, now I have something to build off of.