Which primers are the toughest?

[steamer]

I was working up a 7br load today and started blowing primers. I was using 162 A-Max moly, .010 to .015 into the lands, RP brass, .002 total neck clearance, 30 grains of Varget, going up in .5 grain steps and RWS primers (because they fit this lot of brass best). Rem 700, Tubb speedlock firing pin, 26" barrel.
At 31.0gn  2 primers pierced (2310 fps) and at 31.5 gr 3 primers pierced (2345fps) 45F temp. All fired cartridges extracted easily, no hard bolt lift, no sticky cases. At 30.5gn the average was 2270fps.
Are these velocities a little slow for these loads? Should I be loading the bullet off the lands? The 31.0 group was 1 1/2" horizontal by 1" high, the rest of the groups were 1/2" to 3/4". Are there any primers that are tougher than the rest?
Thanks in advance.

[DanDeMan]

Steamer,

The problem you are having with "blanked" primers, the little holes in the middle of your "blown" primers has nothing to do with the primers.  Remington firing pin holes are way to large for use with Small Rifle primers.  You need to have your firing pin hole bushed to 0.060" to 0.065".  Typical Remington firing pin holes in the bolt face are about 0.080" in diameter.  Since the pressure forcing the middle of the primer through the firing pin hole in the bolt face goes up by the radius squared, reducing the firing pin hole to 0.065" reduces the pressure by a factor of about 1.5.

If you don't want to have that done, the toughest small rifle primers I've tested are the Rem 7 1/2's.

Gre-Tan Rifles will bush your bolt for a reasonable price and do it quickly.

[Troy G]

Certainly get your firing pin hole bushed this will help with your problem.  You should also try some CCI-450 small rifle magnum primers.  The 6BR shooters pushing 107 Matchkings to near 3000fps swear these primers have the hardest cups.  You should back off the powder charge at least a grain if you try these powders as they gave me about 50fps more velocity in my TKS.  Sadly though I could not use the extra velocity as accuracy was terrible.  I backed down to 34 grains from 35 with the CCI primer and got the same velocity as VV-550 load with a 205M primer.

BE SAFE!  

[RamSlammer]

Some times I get a bit excited with my loads so I use REM 7 1/2s these are fairly hard but remember that the popping of primers might mean that you need to back off a bit.

[steamer]

Thanks Dan and Troy:
        Last friday I bushed my firing pin. I tried loads up to 32 grains of Varget at 2410 fps with a 162 A-max, good accuracy, and had only slight flattening of the RWS primers. With the big firing pin RWS primers
were 'blanking' at 31.0 grains.  I did not have any loaded up more than 32.0, but will try some later this week.
        I did make a mistake and ground the firing pin down to .053 dia.
Will this be prone to breaking?