I'm finding that about 2-4 of Winchester's primers are a bit, well, not so much in the QC department.
What does that mean? Please explain.
Seating primer is a two (2) step process:
- Initial resistance we feel is the primer anvil feet hitting the bottom of primer pocket
- Second resistance we feel is the primer anvil feet pushing against the bottom of primer pocket setting the anvil tip against the priming compound under the cup.
If you stop at step #1 (Above flush or flush, depending on depth of primer pocket), then first primer strike may not ignite the priming compound and just leave a shallow dent on cup while pushing the primer cup deeper and second primer strike will ignite the priming compound.
Your primer cup SHOULD be seated until secondary resistance is felt or about .004" below flush.
Repost from another thread and note the comments about Winchester primers in bold -
https://www.thehighroad.org/index.p...mer-misfires-guns-ammo-article-review.872986/
Came across this Guns & Ammo article on primer misfires that will supplement our discussion on primers -
https://www.gunsandammo.com/editorial/the-truth-about-primer-misfires/247980
BTW, THR thread on primer misfire -
https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11386382
US Army AMU on primer seating -
https://www.thehighroad.org/index.p...-and-discussions.778197/page-10#post-11403561
G&A article covered primer construction (cup
, anvil, and priming compound called "pellet") and operation (When cup is hit, indent from firing pin/striker tip ignites priming compound against the anvil tip)
Interesting thing I noticed from the article was the reliability of primers.
"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.
