I read that federal primers are soft and fire when the bolt is slammed shut on a M1 Garand because they have a free floating firing pin. I was gonna reload some .223 and all I have is federal primers in small rifle. My question is does the AR-15 have a free floating firing pin and will I have a problem with federal primers? If they are a problem what would be a good primer to use? Thanks in advance.
The mods are going to move this to the reloading forum most likely...
As for your question. I don't think anyone has a problem with any primers. However, some are softer than others, so it *might* make a difference between a slam fire or no slam fire. There's those folks like me who are a little paranoid and want all the safety margin possible, and those who've tried it all and claim there's no real difference.
I use the CCI #41 aka "5.56" primers. They are the military hardness primers. Note that they are also magnum strength, so adjust your loads accordingly. For example, I am at a MAX load with my 69gr SMK using Winchester military brass, and 24.8gr of AA2520 with the CCI military primer.
AA's manual says 25.9gr gives you 2983fps. I'm at 2977 avg. For the NRA loads (which are like NATO sorta), 27.0gr gets you 3044. 1.1gr more on the saami load, and 2.2 more on the NATO load than I am using. This is why a little research and working loads up slowly from mininium is very important.
People say the Remington primers are almost indistinguishable from the CCI military primers when it comes to hardness, but instead, they are better for accuracy and not as hot. I don't know from personal experience, just internet speak.