Primer Selection for Accurate Loads

[Gun5tuff]

In the December 2008 Issue of Handloader the mass of powder was kept constant while the make of primer was varied. The smallest group size determined which primer was best.

The article (on Accurate .308 Loads) acknowledges that different primers cause the velocity to vary. One primer was on or near the sweet spot for the rifle while the others caused the velocity to be above or below the sweet spot.
It seems to me what has to be kept constant is not the mass of powder
but the velocity developed by the primer/powder combination. The
primer that should be chosen is the one that gives the smallest group
at constant velocity.

Could someone comment on this.

 

[ben hunchak]

I don't believe you can pigeon hole this stuff, every load is diff. just like every barrel is diff.,one primer works best(most accurate) in one load, worst in the next. I find you just have to keep try diff. components till you find the best accuracy, including primers, changing only one variable at a time. These articles, while interesting, don't prove much, and they even usually say at the end of the article,"your mileage may vary".

 

[mctonyb]

I've been told the Federal Match Primers are top-notch and will improve accuracy. I'm no reloading guru, but I did experiment a bit with primers. I found a bit more consistency going from the Winchester large rifle primers to the CCI Bench Rest-2's. I found a thread on the net that discusses it a bit further: h__p://forums.handloads.com/forum_posts.asp?TID=8480&get=last

 

[beltfed]

I think decent loads will perform well regardless of which primers are used. Typically match primers will give more consistant velocities and less mean spread. I tend to favour Federals, but will go with any of them.

 

[Eagleye]

Certain combinations will perform best with a specific primer. My Ruger 77V 220 Swift is an example. When I first started developing a 50 Ballistic Tip load, I went with WW Brass, a R-P 9½ primer and IMR 4064. The load shot well [around ¾moa average], but I felt it might be able to do better. I tried WLR primers with about the same success, then, on a lark, substituted the Federal 210M. The groups went up to over 1 moa. I had a few CCI BR-2 kicking around, so as a final trial, I seated 20 of them and loaded the same load I had been using....bingo! This combination averages around ½ moa, with the odd zinger group around ¼moa for 5 shots at 100 meters. Not bad for a factory barrel, I would say! I later tried the standard CCI 200 and it is very close to the same as the BR-2. Needless to say, I am pleased. Regards, Eagleye.

 

[762nato]

I use Federal 210M for most of my rifle, but found they did not ignite RL25 very well....Switched to CCI match and problem was resolved. Experimentation is key, you will know when your rifle likes the combination your are using.
Match grade primers are made the same way as regular, 2 or more additional quality controls and most experienced workers make them..