Loose primer pockets!

[newmexkid]

Pushing a 90 gr. Sierra Blitzking with 53 grs. of IMR 4350 in my 25.06. TWO loadings and I already have loose primer pockets!! My fired cases show no visible sign of pressure. No shiny spots on the case head and easy extraction. What's going on? These are new Winchester cases.

 

[MagnumManiac]

It may not be the load, but the brand of primer, Winchester primers seat looser than other brands due to not being nickel plated.
Try switching to another brand.
If this doesn'solve your problem, then your load is probably on the warm side, and should be reduced by a grain or 2. How does it chronograph against the book velocity? Primers flattening, ejector/extractor marks only appear well above max pressure, and 2 firings is enough to stretch pockets if the load is warm enough, it also depends on the brand and hardness of your brass. Some lots of brass are softer than others.

Cheers.
gun)

 

[Mikecr]

Give us some history on the gun/barrel

 

[stomp442]

This can fix your brass and get you a couple more firings out of them. I have had to use mine from time to time and it works well.

R W Hart Case Saver Swage Large Primer Pockets

 

[RTK]

If this doesn'solve your problem, then your load is probably on the warm side, and should be reduced by a grain or 2. How does it chronograph against the book velocity? Primers flattening, ejector/extractor marks only appear well above max pressure, and 2 firings is enough to stretch pockets if the load is warm enough, it also depends on the brand and hardness of your brass. Some lots of brass are softer than others.

Cheers.
gun)

Any time I have had premature primer pocket loosening it was because I ran them too hot and I use pretty good brass. Gotta agree with maniac

 

[Gene]

Stomp, I am familiar with the RW Hart case saver. I never purchased one because others say it will squeeze the pockets down for just one shooting, then they are expanded excessively again. Have you found this to be true?

My 6 BR Dasher opens pockets in 3-4 firings using CCI 450's. Then I switch to Wolf-Tula's which are a tad wider. Several firings later, pockets are stretched again, then need to be discarded.

Read what Tony Boyer says about this device in his book. He has no time for them.

 

[Mikecr]

While pressure is the big contributor, I wonder if clearances are the cause of loosening pockets.
Clearance for the case body at webs, and bolt cone to breech.

It's common for some reloaders to see pockets loosen without 'pressure signs' they've come to recognize. But there is a 'pressure problem' sign that is less commonly recognized: Diameter growth at web-ring.
Sure people see it once to a point of poping extraction. But if chronic growth is occuring and masked by big sizing at webs, well then there may still a price for this even if exraction is fine (no pressure sign).

It may not be simple as brass brand and pressure.
But then, Lapua is harder, and I've found that pockets in factory chambers last longer with Lapua over Norma.
I found this article interesting:
X-Ray Spectrometry of Cartridge Brass within AccurateShooter.com