Blanking primers

[Flash42]

New 6mmbra barrel on my tikka t3. Started load dev with magtech srp, 29gn n150, virgin lapua brass and 109gn eld m. Had a couple blanked primers out of 10 at that charge. Went down to 28.5gn incase it was pressure and shot 2 sets of 10 rounds without blanking, final set of 10 rounds had 3 blanked primers. Throughout this all the rifle has consistently shot half moa or better 10 rounds groups, with sd around 6-8 including blanked primers.
Measured pin protrusion at 72 thou, spoke to ny smith and he recomended reducing protrusion by 10 thou and seeing if this changes anything.
Loaded 10 with magtech and 10 with ruag srp. Magtech blanked 2, and ruag blanked a couple. Reduced length again by 5 thou bringing it to circa 55 thou protrusion. 15 consecutive rounds with no blanking and an sd of 6.9. And again 10 round group under 0.5.
Looking to change the primer to something harder before i persue getting the bolt bushed as its not as easy process here in the uk as it is the other side of the pond.
My options are cci 450 or remington 7.5. The remingtons are much easier to actually get my hands on in terms of distance and roughly 60 bucks cheaper per 1000. But also concious that the 450 may be the better optimion. Anyone able to lend advice in terms of the hardness characteristics of the two different primers?

Thanks

 

[Walt Krafft]

Try the Remingtons. I have shot thousands without any problems.

 

[DaveTooley]

A primer change may help but only so much. You will still be limited on pressure. It's been my experience firing pin protrusion does not have an affect of blanking primers. Pressure, firing pin hole diameter, firing pin hole shape, firing pin diameter and firing pin tip shape are the leading influencers.

 

[Flash42]

A primer change may help but only so much. You will still be limited on pressure. It's been my experience firing pin protrusion does not have an affect of blanking primers. Pressure, firing pin hole diameter, firing pin hole shape, firing pin diameter and firing pin tip shape are the leading influencers.

Yeah realise it may not be the cure all! Just trying to avoid the drama of getting it bushed if i can avoid it. As its a pressure bearing part in the uk it must be re proofed at the proof house which can be many many weeks, faff and money for rfd transfers etc.
In terms of tip shape is there any in particular which tend to help? Standard tikka being a large pin with a very round tip.

 

[SKWERLZ]

Try the Remingtons. I have shot thousands without any problems.

This, the 7 1/2 or #450 are definitely more durable than many small rifle primers but they can only do so much if you have an unhappy pin/pin hole for small primers.

 

[CJ6]

Remington 7 1/2 BRs will take some pressure.
I use them in a couple rifles.

 

[DaveTooley]

Yeah realise it may not be the cure all! Just trying to avoid the drama of getting it bushed if i can avoid it. As its a pressure bearing part in the uk it must be re proofed at the proof house which can be many many weeks, faff and money for rfd transfers etc.
In terms of tip shape is there any in particular which tend to help? Standard tikka being a large pin with a very round tip.

A long time ago a very wise man, Ed Shilen and I were having a conversation about gun stuff. He volunteered he thoughts on tip shape. Consider that pressure, distorting the primer leads to blanked primers. The primer conforms to the shape of the firing pin. A full radius pin allows the primer to flow further down the side of the firing pin, thus putting it under higher stresses than the center of the pin. The best design is a flat tip with a slight radius on the edge. It makes perfect sense when you consider we use a puckered primer as one of the signs of pressure. This illustrates that there are no hard rules that transfer from rifle to rifle. Each has its own personality and has to be treat as an individual.
I've spent time in the London Proof House with a pile of rifles all chambered in wildcat calibers.

 

[243winxb]

Reduced length again by 5 thou bringing it to circa 55 thou protrusion

A more normal protrusion.
Dropping the powder charge seemed to help also.
cci 450 or remington 7.5 both work .

 

[243winxb]

The chart is about 100 years old. The CCI400 flowed. I switched to Remington 7 1/2 , no flow. In 223 Rem.

 

[kyotekiller25]

I shoot the 7.5s in a bolt 223 wylde at high pressures and don't have any issues. This was after getting the R700 bushed however. Before that, I had a few pierced primers and horrible cratering even with starting loads. Pierced 2 with CCI 400s and 1 with the 7.5 Again, that was before the bolt was bushed. Haven't had a single issue since. No cratering and no pierced primers even with very warm loads.