Changing Primers and Load Results

[Clay Target Guy]

Ok, I started out loading for my Tikka 22-250 1-8 twist with 75 gr ELD bullets using R15 powder. 33.2 gr looked good turning in a low ES and SD with just a little over 3200 FPS, but 33.5gr of R15 showed the best ES and SD both in single numbers with a vel. just over 3250 FPS, but it started to show pressure signs.
I thought I would go back and try to get as close to the 33.5 (as this load was also the most accurate along with the best ES/SD) charge as I could but stay out of the pressure zone so I loaded up some at 33.3 gr.
I had seen where some were using Mag primers, different brands of primers that what I was using so before I started trying to dial in the seating depth, I that I would play with some primers that I had on hand.
The original load was done with Winchester large rifle standard primers, so this would also see if the load would repeat with these again.
I used Winchester LR, Winchester LRM, CCI Mag (did not have any CCI LR primers that I could find), Fed LR, and Fed LRM primers.
The powder,bullets, and cases were all the same, only change was the primers, and each powder charge was hand weighed.
Below are the results from the test. The barrel was allowed to cool between each test of 3 shots.

PRIMER TYPE VEL. FPS ES SD

Winchester Large Rifle Standard 3204 15 7
Winchester Large Rifle Mag 3220 47 23

CCI Large Rifle Mag 3179 38 19

Federal Large Rifle Standard 3164 38 19
Federal Large Rifle Mag 3191 38 19

I know this is a sample size of (1) rifle and one load but still found the numbers a little puzzling in the ES and SD department. I would not have guessed that going to the mag primers would have more than tripled the ES and SD on the Winchester primer. I also found it funny that the ES and SD were exactly the same with the other 3 primers.I also found it funny that I lost vel. across the board with the other primer brands. I did not expect that, seeing as how popular the other primer brands are and I don't see many people using Win. primers when they are posting up their loads.

Just as a FYI, the Winchester LR Standard primers ES/SD were exactly the same as what I tested a few weeks ago. The vel was about 20 FPS slower that the previous test.
It was 84 degrees F. and very humid for the above test, I like to describe it as "air you can wear".

 

[Kansaswoodguy]

This is why Lapua when they released their version of 6.5 Creedmoor brass dropped to small rifle primers instead of large rifle primers for some reason smaller primer flash lends its self to lower SD/ES.

 

[RT2506]

Primers do make a difference in loads but just shooting 3 shots with each really does not give the whole picture. If you were to shoot 20 or more shots each it may show a whole different pattern of results. Plus you have to also take into thought how much fouling effected your results from the first rounds shot than the last rounds shot. Also how much throat erosion, even through it might be slight, effected the results from first shots to last shots. Even through we say we let the barrel cool between our strings what was the barrels actual tempter and was it exactly the same. There are so many factors that effect velocity and SD and ES that it would drive you crazy trying to find which was THE BEST. Even if possible to get it perfect you would probably have shot the barrel out and have to start all over again. LOL
I have mostly just used one set of components and worked up a load suitable for my needs and stopped there. I have witnessed a number of people trying everything in the book to squeeze that last bit of Sd or Es or velocity out of a rifle and by the time they settle on something they have shot the barrel out and it was all for noting. Life is shot, get a quality barrel and use quality components and most will shoot without much fuss. Then go out and have fun because the days you will not be able to do it will be on you much faster than you ever dreamed.