Which primer for small rifle 6mm CM brass?

[ShtrRdy]

For 6mm Creedmoor brass with the small rifle primer, which manufacturer/type primer are people using?

 

[redneckbmxer24]

Most are using CCI 450's for all the larger case small primer stuff. They work well, very hard thicker cups. The Remington 7.5 BR's also work incredibly well. Both give me the same numbers and performance, I can interchange them with no difference.

Just stay away from the standard small rifle primers which use thinner cups.

 

[WinJim1863]

I was about to post a similar question. I've moved to Lapua brass for 6.5 CR and will soon also load 6.0 CR. On the first 6.5 Lapua ladder test (using virgin Lapua- which may invalidate everything so I will do over with fire formed and sized brass) I used H4350 and CCI 450s. SDs ran between 5.5 and 8.5 FPS (5 shot strings). This is about the same as I have run with Hornady brass and BR2s.
A recent article recommended regular SR primers in Lapua saying propagation was more uniform and would give lower SDs. Has anyone done a comparison of 450s to BR4s in 6.5 or 6.0 CR with Lapua. If so how did SDs and velocity compare?
Thanks

 

[redneckbmxer24]

450’s and BR4’s are the same primer.

 

[ShtrRdy]

Why is it necessary to have a harder primer cup?

 

[BurnOut]

Why is it necessary to have a harder primer cup?

The thinner cups on primers like the CCI 400 will get pierced with moderate pressure loads, essentially giving false indications of being over pressure.

 

[Triggs75]

Federal 205m worth it? I always shot large primers and just got some srp and got a bunch of the 205m’s to use

 

[ShtrRdy]

The thinner cups on primers like the CCI 400 will get pierced with moderate pressure loads, essentially giving false indications of being over pressure.

Does that imply that cartridges that use a small rifle primer don't operate at as high of pressures?

 

[spife7980]

Does that imply that cartridges that use a small rifle primer don't operate at as high of pressures?

It’s not “harder”, just dimensional differences.

The 450 is still a small primer, it is a thicker cup material though so it is more able to resist deformation under equivalent pressure.

 

[redneckbmxer24]

Federal 205m worth it? I always shot large primers and just got some srp and got a bunch of the 205m’s to use

205M's are thin and soft, they wouldn't be my first choice for a high pressure round burning 40+gr of powder like the creedmoor.

It’s not “harder”, just dimensional differences.

The 450 is still a small primer, it is a thicker cup material though so it is more able to resist deformation under equivalent pressure.

View attachment 6989749

CCI cups are definitely harder. Take a rifle that has a little more clearance around the pin and run remington 7.5's and CCI 450's or BR4's. The Remington 7.5's will get a little primer flow around the pin, never had it with CCI's. Not that it's a problem as long as it's not excessive, but to me it shows that CCI's use a harder material.

Have noticed the same thing with large primers, others may get a little flow when CCI won't. The downside is all the primers I've ever had not go boom are CCI's. Had it happen a lot with a R700 with a high speed firing pin running 250's, and also had one not go off with my Q but I also had several hang fires the same day which I attribute to the small primer brass and the extreme cold so I can't say for certain it was a light strike.

 

[spife7980]

CCI cups are definitely harder. Take a rifle that has a little more clearance around the pin and run remington 7.5's and CCI 450's or BR4's. The Remington 7.5's will get a little primer flow around the pin, never had it with CCI's. Not that it's a problem as long as it's not excessive, but to me it shows that CCI's use a harder material.

Whoops, I completely missed the comparison to rem 7.5s, I was thinking you were talking about compared to the 400s. My bad.

 

[Danattherock]

I have shot over 2000 6 Creedmoor this year for PRS. All I use is federal 205M's, as are many others I know. Great primers and SD is always 3-5. They can be hard to find, just like the Fed210Ms, but are great primers.

 

[ShtrRdy]

I have shot over 2000 6 Creedmoor this year for PRS. All I use is federal 205M's, as are many others I know. Great primers and SD is always 3-5. They can be hard to find, just like the Fed210Ms, but are great primers.

Thanks for your first-hand experience. I sure appreciate it. -- Todd

 

[10ring1]

It’s not “harder”, just dimensional differences.

The 450 is still a small primer, it is a thicker cup material though so it is more able to resist deformation under equivalent pressure.

View attachment 6989749

I've never seen this...Thanks for posting. Just curious, the LR primers all seem to be .027", is that right below where the image is cut off?

 

[spife7980]

That’s the full image from accurate shooter. Not sure what you’re referring to as being right below.

 

[Mad_Charlie]

You may want to consider GM205MAR's...

 

[ShtrRdy]

Since I first asked about this I've been trying different primers that I've had. I'm getting the lowest sd number by using the CCI small rifle magnum primer.