I finally got a hold of some primers. I've been using Federal large magnum rifle primers No. 215. What I just received were Federal Gold Medal Match GM215M large magnum rifle primers.

Will there be a performance difference? What & why?

Where did you get them? AIU

No difference, just held to tighter spec.

There could be some difference in that the match primers are allegedly examined and held to closer tolerances than standard primers. If they are to be used in a non-match rifle and seated without regard to the crush, any increased uniformity of performance will likely be negated.

The reason I say "allegedly" is because I have lately noticed a lot more variation in cup height when seating Federal match primers in two cartridges I shoot. These are not magnum loads, but I know the people and process is the same whether the primers being built are large, small, magnum or not.

At one point, I had stopped checking the primers and just seated them to the .002" crush I have been using for a long time in those loads. I had not noticed a match primer being more than .001" taller or shorter for a long, long, time. Then, when reading posts on another forum, I learned that some shooters were doing what I was doing and some were still using the tool I use (K&M primer seater - the one with the dial indicator) in the manner the instructions recommend. I've gone back to doing it right and checking each primer ........ it does make a difference if you're trying to shoot under .25 MOA. I may begin weighing match primers and culling just like standard primers........It does seem a shame to have to do these things when using a match primer, but I checked some standard primers I use for forming brass and they were still much worse as far as variation goes.

Thanks you guys.

AIU,
My local gunsmith had some at home. He felt bad for me when he heard I couldn't find any and was going elephant hunting and needed hunting loads as well as shooting a lot before hand.

What is available using Match Primers is better accuracy, for reasons Old Joe mentions.