Primer differences

[Heredoggydoggy]

A regular guy making regular ammo using a regular rifle probably won't see any difference when switching between primers.

Some primers are slightly hotter than others, some cups are slightly thicker or thinner than others.

"Bench rest" or "Match" primers have a little better consistency between them.  I spent a little bit more and loaded my hunting rounds using Federal GM Match primers.  Just because I could.

I have noticed when loading 9mm, that Federal SP primers are softer/thinner and are easy to seat compared to the thicker cups on CCI primers.  Because of that, I don't want to use Federal SP primers when loading .357 Magnum though.  I'll stick to CCIs.

I think the competition shooters I spoke of liked the Federal primers because they were softer/thinner for their guns (38 Spl. revolvers.)  Benchrest shooters can be very picky about components, too.  Once they get the combination they want, they stick to it.  If you are loading for hunting, I don't think the primers are that important, unless you are striving for tack-driving accuracy.  Most pencil barreled hunting rifles are not capable of tight groups shot after shot.  One or two shots is usually all you get any way....

[carpsniperg2]

I have seen many shot side by side threw a chornony. Very little differnce in fps and etc. Don't ask me how or why but when I load federal primers in my 300 wm the groups go from 1" to 1/2" over the cci's. I have never seen anything like it and call me crazy but I have tested it 4 times to see if it was just me.

[Heredoggydoggy]

I have seen many shot side by side threw a chornony. Very little differnce in fps and etc. Don't ask me how or why but when I load federal primers in my 300 wm the groups go from 1" to 1/2" over the cci's. I have never seen anything like it and call me crazy but I have tested it 4 times to see if it was just me.

And yet, the 300 wm that came off the line right after yours probably hates Federal primers.  Every gun has a personality all its own.  Go figure... 

[carpsniperg2]

I agree 100% I bought my first winchester 70 and fell in love with it. AMAZING GUN bought one a few months later and it would not shoot anything worth hell. Traded it off then bought another and the same thing. Thing would just not shoot well. So I guess I got one of the good ones off the line

I have heard from more then one person they have seen the same thing with the federal primers. I am a cci man myself but all my magnums are switched to fed LRM's right now.