Lapua 6.5-284 Primer Pocket Questions.

[Crackers]

Hello all,

I have only been reloading for 12 months, so please excuse my ignorance.

I have some Lapua 6.5-284 brass for my straight 284, that is on it 2nd firing. I was just preparing some for this coming weekend and I noticed that out of the batch of 100 pieces about 12 have primer pockets that have expanded to the point that I feel they are unsafe to use.

Is this normal for high quality brass?

My loads do not show signs of pressure, (53gn of ADI 2209) and the chrono speeds are only 2825 fps. Is it just a case of some brass just "grow" more than the norm?

Any knowledge to expand my understanding is greatly appreciated.

Crackers

 

[AlanPF]

Crackers,

In my experience, primer pocket expansion is the FIRST sign of pressure with Lapua brass in 284 Win, so you probably need to back off the charge a little. I think you may have a "slow" barrel i.e. for a given pressure you get less velocity than the norm. What weight of projectiles are you using, and what is the barrel length?

Alan

 

[Shynloco]

Crackers,
Just out of curiosity, define "unsafe." I mean are the new primers or old one just falling out on their own or how "unsafe" are they? And did you happened to take a look at any of the primers you took out of the twelve cases you are talking about? I've found that if I suspect pressure and the obvious signs of cratering or flatten haven't occurred to just looking at them, I'll remove the primers from the fired casing and take a mic to them and compare that one to a new one and see what, if any change has occurred. If the height of the primer has changed a few thousandths, that is still pressure and like was said, might want to back off some. But then of course there is the possibility you just may have gotten a bad batch of casings. That happened to me about 9 months ago on a batcn of 6.5 X 55's where I had to toss about 8 or 9 casings that had bent necks where the concentrcity was like .007 - .008 out and were not rehabilitable, not even using a the Expander Mandral Die. Even Lapua has a few bad runs now and then, although they still far surpass any other brands in terms of quality and use life. Still I'd check those primers if you can. Just my thoughts.

 

[spclark]

12% is on the higher side of what I'd want to find in my brass, but consider some factors:

1) What others have already suggested;
2) ALL brass work-hardens with use - as such it may be prudent to fire new brass with somewhat reduced loads until the case heads harden up a bit, which will extend head life with higher loadings later on;
3) Primers vary in diameter, both within a given batch of one brand as well as between different brands - what seems loose to you with your brand of primer may seem quite proper to someone using another brand.

Used in a bolt gun, brass with primers that were easy to insert are generally safe enough to fire again... unless the primers are actually falling out. I'd mark the loose ones for use as sighter/foulers next time, see if the pockets continue to grow. With gas guns (unlikely with your cartridge) loose pockets are a more serious issue where primers can get blown free & then lodge somewhere they don't belong.

There have been tools available from time to time that might help increase the lifespan on cases that have pockets that are bigger than when new but generally they don't seem to get much attention. It takes quite a bit of force to make a pocket smaller, particularly when the brass has hardened up with use as described.

 

[Crackers]

Crackers,

In my experience, primer pocket expansion is the FIRST sign of pressure with Lapua brass in 284 Win, so you probably need to back off the charge a little. I think you may have a "slow" barrel i.e. for a given pressure you get less velocity than the norm. What weight of projectiles are you using, and what is the barrel length?

Alan

Hi Alan, I am using the 180gn Berger Hybrids. Bartlein Barrel 28". I only pull out the Lapua Brass for the Open Prize Meetings, but it still makes it expensive when you pay $136 for 100 cases. Thank goodness I managed to get a few hundred WW 284 brass for club weekends.

Crackers,
Just out of curiosity, define "unsafe." I mean are the new primers or old one just falling out on their own or how "unsafe" are they? And did you happened to take a look at any of the primers you took out of the twelve cases you are talking about? I've found that if I suspect pressure and the obvious signs of cratering or flatten haven't occurred to just looking at them, I'll remove the primers from the fired casing and take a mic to them and compare that one to a new one and see what, if any change has occurred. If the height of the primer has changed a few thousandths, that is still pressure and like was said, might want to back off some. But then of course there is the possibility you just may have gotten a bad batch of casings. That happened to me about 9 months ago on a batcn of 6.5 X 55's where I had to toss about 8 or 9 casings that had bent necks where the concentrcity was like .007 - .008 out and were not rehabilitable, not even using a the Expander Mandral Die. Even Lapua has a few bad runs now and then, although they still far surpass any other brands in terms of quality and use life. Still I'd check those primers if you can. Just my thoughts.

Hi Shynloco,

When I mean unsafe i am not basing this on personal experiance as this is all new. But there is no noticeable difference in force when seating new primers. Using my RCBS hand priming tool it feels like you are squeezing it with no primers loaded. I have never measured my old primers, but it is something I will look at doing next time around.


Thanks all for your replies.

Crackers

 

[Cakes]

Crackers-
I use basically the same setup for my straight 284. 162 amax's under a moderate load of 4831sc and cci or russian primers. IMO flattened primers are a poor indication of high pressure signs. Todays match chambers and actions are so square and "tight" almost every load gives you a flattened primer unless running VERY mild loads. I personally use ejector marks or primer cratering as a STRONG indication of high pressure. I shot 1200 rounds last year for f-class on 150 pieces, annealing after 3 firings and never a problem with primer pockets. If indeed you have loose primers that quick I'd check type of primers, other pressure signs, and also remember seating depth has a big influence on pressures. Wolf/Tula primers will run tighter than others. Hope any of this helps. Eric in DL