Re: difference in small rifle primers
What the above article does not cover is the relationship between primers and the ignition energy required. I covered part of this in
http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1491032#Post1491032
Different manufacturers use different formulations in primer mix as well as different mixing methods. One was known as "dry mix" which was extremely dangerous to the personnel making the mix and the other is "wet mix" which the primer boys I know say does not help things insofar as uniformity goes.
I had a long discussion with Homer Powley about this and it was his opinion was based on what he had seen in the plants that CCI had the best methodology at that time but he also said he did not have any data to support that conclusion but was based on the work he did at Frankford Arsenal. You older guys will have read articles he wrote many years ago.
It is well known some primers are hotter than others and some tend to give more uniform ignition than others but since there are different lots, a single test result showing small SD is not indicative of primer performance from lot to lot.
Primers are tested in drop fixtures wherein a steel ball of a given weight is dropped from differing heights onto a fixture holding a primer. There are different ball weights for different primers running in the ounce range like 2 oz. 4 oz etc.
Hundreds of primers are tested to determine the min all fire drop height and the max all NO FIRE drop height.
Once the all fire drop height is ascertained the primer is replaced with the copper (mentioned in thread above) and the ball is dropped. The copper is removed and placed in a bench inspection gage when the depth of the indent is recorded.
Different primers have differing all fire heights. For instance the hardest primer to ignite in the US small arms inventory is the Cal 50 BMG primer.
Next below that is the primer used in M193/M855 etc 5.56MM ammo utilizing MILSPEC primers. The spec calls for .022” indent on copper from M16 variants.
Next down the list is the large rifle primers and standard small rifle primers. If memory serves me correctly the all fire drop height on large rifle primers is .012" indent on copper and the all no fire drop height is .009" or thereabouts. Anywhere in between you will get misfires at various rates per million. Obviously the closer the indent energy is to .009" the higher the misfire rate will be and the closer it is to .012" the less misfires will be sustained.
The next hardest to ignite is magnum pistol primers followed by the easiest to ignite is the small pistol primers.
As stated in the other thread the industry recommendation now is for .016” copper indent for large and small rifle which I personally disagree with. Previously it was .020” indent but a few years ago for some unexplained reason the indent requirement was dropped. On my target guns I strive for a min of .020”.
So what is the big deal? Basically the drop test delivers indents to the dead center of the primer where the apex of the primer anvil is. You guys start looking at your fired cases for striker indent centrality. If you are off center your ignition reliability is lowered after .020” offset per the Frankford Arsenal Report I have.
OK so you have offset, just because it goes off doesn’t mean it was ignited in an ideal manner. Kind of like striking a match on a box. The ignition goes quicker the faster you move it and the slower the match is moved the slower the ignition. Anything except a dead center hit is likely to affect the ignition mechanics.
If one looks at the nice custom actions made today for the Palma game, one will see the primer indents on fired cases are pretty much dead center as they have found out a bore line and a action center line being straight is the best of all worlds and a dead center ignition only helps.
Some might say “why not .012” copper energy on new rifles”. One must remember there are things that go on in rifles that can affect striker velocity like some trigger groups have been found to impart a drag on the striker and not allow it to achieve a clean release. Next the striker has to move in a striker tunnel and the striker rubs on the striker spring. Don’t believe it? Look at inside of old striker spring and look at inside surface of new ones. The old ones will have flats where it drags on the striker which removes material and the new one will be round. Logically if you have a marginal spring and you take material away from it, it has to weaken the spring.
Primers need two things for reliable ignition. Energy and VELOCITY . There is no way the average guy or even the factory to determine striker velocity on every rifle for handgun coming off production but the copper is the trade off to massive instrumentation. For instance if you drop a 2 ounce ball from 20” you get the same energy delivered from dropping a 20 ounce ball from two inches. The second scenario will result in 100% misfire as the falling 20 ounce ball did not achieve velocity. This is why you can take primers out of cases without having them go off and even crush them without ignition.
Then there is the problem of oil/grease in the striker channel which can thicken over time acting to retard striker movement. I knew a guy who constantly drowned his guns in WD40. Finally it thickened up so much he got misfires. We cleaned his bolts and no more misfires.
Thusly the more energy you can start with the better your ignition reliability.
Why are handgun primers so sensitive? Handguns generally by their design do not impart lots of striker energy. That I know of the M1911A1 design is the hardest hitting striker of all the pistol designs save for the XP100s etc that start life as a rifle.
The hardest hitting striker I ever had was a 98 Mauser Corona action which gave a .024” indent on copper.
I have a 1911 Swiss straight pull that still delivers .022” indent and nearly a hundred years old! ! !
Which rifle has the best design striker system? Hard to say but I know what I have seen and that is a Grunig & Elmiger (picture of one on another thread). My buddy brought one over a few years ago and he pulled bolt down to clean it and it was absolutely amazing how massive the striker spring was. The wire diameter was almost twice what I have ever seen in a US rifle.
If I were to sell all I had and keep one rifle, the G&E would be the last to go.
http://www.gruenel.ch/
They are THE rifle in Europe for 300 meter shooting.
Another rifle with a great striker & spring design is the Mannlicher Schoenauer M1905. I have one in 9MM M-S and I would hate to part with it but then again I can’t see the iron sights on the short barrel any longer and should pass it to a younger guy who can still see close sights.
If you want to get a feel for what different primers do, you can dupe a test series I ran.
I took 33 cases and loaded them with same propellant three times using three different primer vendors and loaded them all with same bullet. Cases were neck sized and reloaded quickly and fired again in the same temperature. I fired first three rounds to foul the barrel, then fired 30 continuous rounds through the Oehler 33 recording all shots and taking SD every ten shots and at end of 30. I cleaned the barrel, reloaded with different primers, same charge etc and ran the test again. It was amazing to see the variations.
I changed primer lots, same vendor different lot number and this changed as well.
I changed propellants and ran test, changed everything.
Even more amazing I changed calibers and ran the test again and again the ranking was different. Nothing ever duplicated!
Bottom line here is selecting the primer is only going to get you so far if you don’t have a excellent ignition train to get it going uniformly. Changing one thing like propellant or primer lot will change everything. I already knew changing propellant lots would do me a number and canister lots are blends and bulk lots are not.
What to do. Buy in 5M cases and if possible get several cases of the same lot number. Then you know where you are for a while. Keep careful records of results.
Warning: This will cause gray hair and loss there of in a somewhat violent manner.
