Primer differences

[Matt304]

Is there a large difference in operating pressures between any different brands of primers?

Also, what are the pressure differences approximately from one size to the next? I'm wondering if it is ok to use magnum rifle primers in a load that calls for a large rifle primer, just because I have some Win WLRMs on hand and no larges.

 

[paperpuncher49]

I'm not sure that is a good idea. Within the last two years or so, I read an article (it may have been in Handloader but I just can't remember the source) where the author had done some testing in a lab (may have been with Hornady's help) to test the difference in pressure between primers. I can remember this much......there was an astonishing difference between standard and magnum primers in some cases, and I found it hard to believe the difference between different manufacturers. Again, I can't remember all the details but either the Winchester magnum large rifle or the magnum large pistol generated 10,000 psi greater pressure than the lowest pressure for the same primer from one of the other manufacturers, which included CCI, Remington, and Federal. If you do substitute magnum for standard, I would absolutely, positively begin with the lowest starting load you can find, assuming you have multiple loading manuals (or other data sources). I will check my latest issues of Handloader and see if I can relocate the article. If I can, I will post it here.

 

[Walkalong]

With any max load, if you change primers, back off 3 to 5% and work back up.

I interchange pistol primers from time to time, but it is with loads that are not max. Rifle as well, unless it is a target load that has been carefully worked up Then I try not to change any component, including using the same lot number of primers and powder, and if it is a commercial bullet, the same run of bullets.

 

[peterotte]

I was advised to use small pistol primers in my hornet for Lil'Gun. The Hornet guys were happy with my Federal rifle primer choice because they are mild. They say that with Lil'Gun, too hot a primer results in erratic pressures and poor accuracy. So primers must make a difference.