Buy the proven brands since we basically know what to expect from many, many documented, proven batches.
If those new primer companies had plenty of data with various powders, loads, they would share it. Apparently, they don't. The new brand(s) have little track record, they are worth a pause. Find the name brands, that is all.
While staying with known domestic brands of decades past is a good practice, those in need of primers during component shortages had no choice but to buy whatever primers were available, even having to test unknown foreign brands.
I remembers having to reluctantly test Wolf and Tula Russian primers along with PMC, Magtech, Fiocchi and S&B primers in more recent years because my preferred CCI/Winchester primers were simply "unobtainium". But as THR members have suggested and found out for themselves, slightly larger cup size of Metric primers require greater seating force to seat them fully to pre-load anvil tip against the priming compound or first primer cup strike won't ignite the priming compound.
We recently discussed the reliability of lesser known foreign/Metric primers here with increasing number of THR members reporting relatively reliable to very reliable testing -
https://www.thehighroad.org/index.p...-and-discussions.778197/page-11#post-12576848
FWIW, primers are generally manufactured tough to withstand vibration/shock of long transport and moisture of humid storage conditions.
G&A article covered primer construction and interestingly reliability of primers -
https://www.thehighroad.org/index.p...-and-discussions.778197/page-11#post-12417636
"Based on the SAAMI-specified drop test, statistics will tell you that our [Winchester] primers are 99.9997 percent reliable ... A lead-styphnate primer is probably one of the oldest and most reliable devices on the planet."
Article noted that Black Hills Ammunition (Which uses Winchester primers) who test fires more than 100,000 rounds per year and sells tens of millions of rounds each year, their investigations over the years identified misfires were the result of a defective primer in only a very small number of cases.
"Primers are not perfect — nothing man-made is — but they are very reliable. Statistically, you might encounter a defective primer, if you shoot enough ... 99.9997 percent reliability ... means you might hit a misfire every 300,000 rounds.
Over the years, the average is one rejected primer in about every 250,000, but most of the flaws are minor defects or damage such as slightly out-of-round primers that would have no effect on reliability."
Article attributed most common cause of primer misfires to:
- Insufficient primer cup indent - Primer was not struck with sufficient force from damaged firing pin (bent or chipped tip) or weak/dragging firing-pin spring or dirty/obstructed spring channel.
- Excessive headspace - Straight walled semi-auto cartridge, instead of headspacing off case mouth, shorter case headspace off extractor
- Improper reloading technique - Primer not seated firmly to the bottom of primer pocket moves deeper in the primer pocket when hit by firing pin but anvil tip does not detonate priming compound against the cup
- Shooter/firearm induced misfires - Slide or bolt is not returned to full battery before firing
"... try this demonstration the next time you go to the range. Unload your rifle. Double-check to make sure it is unloaded. Close the bolt, then raise the bolt very slightly. Squeeze the trigger while watching the bolt handle. You can see the bolt handle snap closed. The energy to make that happen is being robbed from the firing-pin velocity and energy normally used to strike the primer."
- Variations in brands and lot numbers - Different brand and lot of primers can vary in sensitivity and primer cup hardness (often by design or source material)
- Contaminated ammunition - Light penetrating oil and long-term storage in damp conditions or submersion in water can desensitize primers
Since misfires due to a defective primer is rare, if you experience a misfire, investigate above list of possible causes to determine the cause to fix the problem.