Primer Test

[Vulture]

I am new to this web site and I have picked up some valuable information and thought I might contribute a little info. Today I did an informal test on the effects of 2 different brands of primers used with the same powder, case and bullet for a given load. I have a .223 Savage that has a stainless Douglas barrel 24" long, Savage varmint contour. I was playing with some new Winchester brass and I have been using Winchester primers,WSR) and recently bought some CCI 400 primers to try. Here are a couple of pictures of the results with just changing the primers. Both loads use same powder charge, bullet, and cases. I actually used the same 3 cases for each three shot group.

 

[Forum Boss]

Wow,

That's a dramatic difference. Using the same brass gives it more validity as a test, but realistically you'd probably want to shoot at least one 10-shot group with each to eliminate "driver error" variables.

Still, based on your photos, I know what primer brand I'd try first. Thanks for the post!

 

[Vulture]

I really did not realize how much a certain primer could have this much effect until I did this. These scans are just 2 of the 5 tests I did with these 2 types of primers. I could'nt believe it at first but every time I loaded the same 3 cartridges with the Winchester primers the results were very similar to these. I used the same 3 cartridges with CCI primers also and the group immediately tighted up. I guess I learned something new today.

 

[Forum Boss]

If you have access to a chronograph it would be interesting to see if there is a velocity difference. Perhaps the CCIs are putting those bullets in a speed range they like better.

 

[jb1000br]

The groups show VERY SIMILAR vertical,about a bullet and a half), so the horizontal could have been you OR the wind.

how were conditions?
windflags?

I would also shoot the test blind -- so you dont know which primers you are shooting till after they are shot.

These groups pictured dont tell us anything significant unfortunately.

If you started the test thinking the CCI primers were best, maybe you subconciously coerced yourelf into shooting them better

With differences like you have shown, 10-shot groups are definitely needed! It would say a LOT if the 10-shot groups shared the same differences that your pics do!!

JB

 

[chino1969]

You have some data which appears to show that the CCI primers are contributing to a tighter group. I would personally perform a re-test using four five shot groups and have someone else prime your brass so that you don't know which primers you are shooting. For example: load five cases with the CCI primers, five with the other, five with the CCI, and five with the other. Have someone segregate the cases so that you have two five shot groups of CCI and two five shot groups of the other primer so that you don't know which is which. Shoot four separate five shot groups and then compare your results. If two of the groups are definitely tighter and they are CCI, then you are on your way to validating your data.