TECH TIP: Check Your Cases for Signs of Over-Pressure
With the relentless pursuit of more velocity and the “next higher node” by many reloaders, it is important to pause and think about safety. And one has to remember that most brass will not hold up to high pressure the way Lapua or RWS does. Many readers have asked us: “How does one detect excess pressure?”. Well first, one can obviously monitor the primer pockets and measure the diameter of the case near the web. Excessive stretch or pocket loosening is a sure sign you’re running too hot. There are also many visible signs of over-pressure which you can see. Reader ScottyS provided this comparison photo of cases, showing the tell-tale signs of over-pressure.
Scotty tells us: “These samples were from a lot of Federal soft-point hunting ammunition that were fired in a custom .308 with a chamber on the tight side (although still allowing a .308 Winchester GO gauge). Among the pressure symptoms were heavy recoil, sticky bolt lift, and the left case had to be manually removed from the boltface. This demonstrates why: 1) you should never assume that all lots of factory ammo are the same (and safe); and 2) you should ALWAYS wear eye protection. This also shows how high pressure can spike once you approach maximum load levels.”
Scotty noted that there was a big pressure difference between the left case and the right case, although both were fired sequentially, and both were from the same lot of ammo. So take heed–always take precautions when testing new ammo, even if it is factory-loaded.
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This was very helpful in diagnosing why my savage 10fp bolt broke this morning at the range. Wife was diagnosed with ms two weeks ago and I did not pay attention to the primers I used which had a great deal to do with a normal near max charge. After looking at the cases fired, primers that fell out and miking, the problem was clearly evident considering the same loads fired two weeks prior functioned flawlessly including delivering outstanding accuracy. If one has a traumatic incidence in their life either pay extra close attention or don’t load at all. You could add insult and injury. All remaining loads were dismantled and discarded.