Primers can make a difference.

[RichCoyle]

I used the same brass for both groups. They were all full length resized. The first group was shot at 200 yards and the second group was shot at 100 yards.

 

[FireFlyFishing]

You changed the primer and the range and your results were different. Sorry, seems like a no brainer. When you change multiple variables you surly will get a change on the paper…the problem, you don't know what change in variables changed what you're seeing on the paper.

I guess I need you to help fill in the blanks. Are you happy with the results? What you expected?

 

[Dmagna]

yes there is a difference between magnum LR primers and large rifle primer. There's a lot of powder in that case.

 

[Rosebud]

What's causing the near 200 FPS difference? Sure you're chronograph is working perfectly?

 

[Bob Wright]

Just pick a yardage and repeat the differences in speed versus powder weight. Not much to tell with what is presented. I see a node in the lower velocity of the 100 yard group. But you're not done yet.

 

[Rosebud]

My bad, didn't see the powder charge change. My caffeine has worn off.

 

[Mikecr]

Too many changes at once. Nothing stable to act on

 

[Varmint Hunter]

I must be missing something. The only change that I see is the primer. The first target indicates "200yds" the second target doesn't indicate distance. The velocity spread is about 40-50fps, not 200fps.

I've got to be missing something.

I'm going to try this with my 7PRC - it seems that a lot of guys are seeing good results with regular LR primers.

 

[xsn10s]

It looks like on the first target the powder charge was changed at 1.0 gr per round. Like the others said too many variable changes. No baseline for a comparison.

 

[birddog 68]

Only difference is primers and yardage.
I like federal 215's but this combo seems to prefer the CCI 200's which is surprising with 90+ grains of powder.

 

[xsn10s]

Only difference is primers and yardage.
I like federal 215's but this combo seems to prefer the CCI 200's which is surprising with 90+ grains of powder.

Actually I think both targets show a charge weight change for each round.

 

[birddog 68]

Actually I think both targets show a charge weight change for each round.

I read it as the same charge of 91 up to 95 grains for each and only a primer swap. I'm sure we'll find out eventually.

 

[RichCoyle]

My bad, didn't see the powder charge change. My caffeine has worn off.

Sorry I was not clear. The only thing I changed was the primer. Even the brass was the same. First shot contained 91 grains and each subsequent shot contained one more grain.

With the large rifle primer there were no stiff bolt lift like with the magnum primers.

 

[MagnumManiac]

It's a simple fact that there really is no NEED for a magnum primer. I often use a standard primer even in my wildcats on the 416 Rigby Improved case where loads run 120+ grains, never have issues until a ball powder comes into the mix, which usually isn't quite compressed at all and the primer blast blows through the powder column, a magnum primer provides more pressure which compresses the powder and stops it blowing through it. It is visible on the pressure trace as a rise then dip in start pressure using a standard primer, it goes away when a magnum is used.
I often switch between the 2 in standard cartridges too.

Cheers.