Is there really a difference in primers? You might be surprised.

Is there really a difference in primers? You might be surprised.

I’m not sure what’s up with Winchester these days. No one seems to have Winchester primers in stock, either walk-in or online, and backorders aren’t being taken. On the other hand, CCI primers are (at least in my area) available in quantity. Odd.

(Something else odd: I rarely see Remington primers around here, and it’s been that way as far back as I can remember.)

Anyhow, every reloading resource I’ve ever seen is quite adamant about the need to retest a load whenever anything changes – including primers. I know many people who do not heed that advice, assuming that a primer is a primer is a primer. (It’s usually about the time they say this that I make a mental note to stand well behind them when they are shooting.) I, on the other hand, am desirous of maintaining my appendages in full working order. Thus when anything changes, I test thoroughly.

Because of the difficulty in obtaining my favorite Winchester primers (which I’ve used exclusively for nearly two decades), I’ve been reworking some of my loads to accommodate CCI primers. This is more of a pre-emptive move than anything, as I still have Winchesters on the shelf. Doing this before I need to allows me the luxury of testing side-by-side, using the same powder lots.

I’ve found something interesting, and not at all what I expected. The Winchester primers are “hotter” (producing higher velocities) than the CCI, but the CCI primers are more consistent (smaller spreads in velocity from shot to shot.) This appears to be the case in both pistol and rifle sizes.

Example: a 170 grain load in the .30-30 cartridge. Using CCI primers, I could not achieve factory-level velocities without loading “over book” (putting in more powder than specified by the reloading manual.) I have many load manuals, and both the bullet maker and the powder manufacturer pretty much agreed on what was a maximum load. Even at their maximum, the CCI primer still produced a load that was 150 fps under factory ammo velocities.

(Before the emails start: I tested factory loads in MY gun so that I had a real benchmark. Factory velocity data is not to be relied on.)

The Winchester primers produced a load which easily matched the factory offering, but both the extreme spread and the standard deviation of the load increased markedly. This indicates that the primer is not as consistent as the CCI equivalent. (Remember: same powder lot, same bullet lot, same brass from the same lot. The only change was the primer.) This should translate to lessened accuracy for the Winchester primer, but results from a lever action rifle using flat point bullets are so far inconclusive.

When I get around to it, I’ll be doing the same test with my .308 match loads. I’ll post the results of the accuracy tests, where I expect the CCI to clearly best the Winchester.

Stay tuned.

-=[ Grant ]=-

  • Posted by Grant Cunningham
  • On August 27, 2008