Primer experiment

Discussion in 'Ammunition & Reloading' started by amstutz, Jul 25, 2014.

  1. amstutz

    amstutz New Member

    Primer experiment
    Recently I had an opportunity to buy 1000 cci magnum small pistol primers. I had some concern about using them so I conducted an experiment. I loaded 20 identical .40 S&W cartridges and put CCI magnum primers in 10 and regular CCI small pistol primers in the other 10. I fired all 20 thru my chrono and the results were: the average of the ten cartridges with magnum primers was 859 ft per second. The average of the ten standard primers was 854 ft per second. I was surprised with these figures and my conclusion is that, in this application, there is virtually no difference in performance between CCI magnum small pistol primers and CCI standard small pistol primers.
    I am wondering what any of you might make of this information.
  2. Axxe55

    Axxe55 The Apocalypse Is Coming.....

    my understanding is that Magnum primers are for slower or harder to ignite powders, or where a powder charge is less than full in the case. IOW's a Magnum primer throws a hotter fire than a regular primer. now the chronograph may not have show any different results, but if you were to measure the pressure, now than might have been a bit higher.

  3. JonM

    JonM Moderator

    some cartridges it doesnt matter and 40 sw is one of them in general unless your running a glock or other gun with an unsupported web. such barrels are already relying solely on the case to hold pressure. spiking that with a magnum primer may be enough to kaboom on a thin piece of brass.


    this is not solely a glock issue. its just a LOT of glocks have this design flaw, by intention. it also crosses a lot of different guns including some 1911's and is almost always present when someone does a bubba style throat job.

    it doesnt mean a gun that has such a chamber is not safe to shoot it means you shouldnt be using magnum primers when non-magnums are called for, +p +P+ or be anywhere near max saami loadings with such barrels.
    Last edited: Jul 25, 2014
  4. Highpower

    Highpower New Member

    Now try it again, using several different types of powders and varying charge weights. Let us know how how those results compare.
  5. Axxe55

    Axxe55 The Apocalypse Is Coming.....

  6. tinbucket

    tinbucket Well-Known Member

    When loading ammo use the primers and everything else in the data or the laod will end up performing different, or not at all, or dangerosuly higher pressures. getting to where you want to develop your own loads go for it by measuring case expansion, flattening of primers, streching cases and so on, carefully. used Federal Magnum Rifle Primers for one rifle for all loads, because that is what the data from the old Lyman, Speer and others developed. The hot Weatherby and other Magnums need the hot primers for some powders. On 38's I used stadard primers called for and on .357 and 44 magnum etc I use magnum primers. I think mostly Federals. I do have a good supply of Winchester and CCIs though from when they were 9.00 a thousand or less for some. The new Tula and other primers, I don't knwo aanything about them.
  7. bradam

    bradam Member

  8. huffmanite

    huffmanite New Member

    Did a primer experiment once myself, but it was with the 7x57 rifle cartridge. Loaded 4 sets of 3 rounds each. Only difference in the sets was the primer. Used CCI large Rifle Mag, CCI std, CCI benchrest, Mag Tech std. Shot all at same bullseye at 100 yds. Rifle used was quite accurate, so when I'd shot them all, I basically had a vertical hole in my target that was about 1/2" wide and a little over 2" long. Can't remember the sequence of where each primer set hit, but the CCI mag primer ones hit the highest on my target. In other words, each set had a nice clover leaf hole, in a difference place, creating a vertical string on the paper.
  9. locutus

    locutus Well-Known Member Supporter

    I don't use magnum pistol primers any more.

    I've settled on one brand of SP and LP primers. I only have to stock one brand, one type and two sizes now. Simplifies things a lot.