Why am i blowing primers ( Rem 7 1/2 br) ONLY

[Adam 6mm build]

I'm having issues with blowing Rem 7 1/2 br primers please give some advice to correct the issue thanks Adam

 

[Mastershot]

Too much headspace? Maybe start with a lower charge or go with a slower powder. Went through this when I switched to my 6mm rifle.

 

[Twdmar]

7 1/2s are kinda little flame throwers

 

[JB10]

No more detail about what they are used in?

 

[Tokay444]

If we had less information, we’d definitely be able to nail it for you.

 

[Adam 6mm build]

My 6br 1-8 twist 29grn varget 105s am I not setting them deep enough (more crush)

 

[timeout]

Action make and firing pin size? I don't have a reloading manual in front of me so not sure how hot or mild your charge weight is? You may need to have your bolt bushed and firing pin sized to .062" @carlsbad on here can fix you up.

 

[mousegunner]

Carbon ring?

 

[JohnKielly]

My molied 105-108s would be comfortable with that load, but it might be on the edge with naked bullets.

 

[foxguy]

I shoot a Savage M12. 105 gr bullets with 29 grs of Varget is ok for fire forming in my rifle( Altho- I use CCI-450 primers).

Is this new brass, or has it been fired a few times?
If fired brass, when sizing your brass, are you adjusting your die for a .002-.003 thousands headspace?

Members are going to need more Information in order to help you out.

 

[Adam 6mm build]

40 x action bushed firepin it only does it with rem 7 1/2 primers

 

[Adam 6mm build]

By no means is it every load it seem to be 1 or 2 out of 50 rds this last episode cost me a trigger for repair back to Jewell

 

[bozo699]

I think 7 1/2 are thinner like 205’s use 450’s or BR 4’s and your problem will probably go away.
Wayne

 

[LCazador]

My 6br 1-8 twist 29grn varget 105s am I not setting them deep enough (more crush)

You need to get your firing pin hole rebushed!

 

[Adam 6mm build]

It is bushed

 

[LCazador]

40 x action bushed firepin it only does it with rem 7 1/2 primers

I've got several 40X and none had that problem after the bolt was bushed. Rebush!

 

[bozo699]

If it doesn’t like 71/2 and only has this problem with them why use them?
Wayne

 

[LCazador]

It is bushed

who did the bushing job? Did you send it in for the bushing job or did you buy that way?

 

[Adam 6mm build]

I have set them aside for now I'm using 450s I'm just looking ahead when I have no more 450s with the way things are and I have to go back to the 7.5 5000 in the ammo box may be last resort

 

[taylorw]

40 x action bushed firepin it only does it with rem 7 1/2 primers

Did you develop your load with other primers? If so, how close to bolt lift/pressure were you from your powder charge that you settled on?

Rem 7.5s& 9.5s have always shown pressure early in my testing. I have developed loads with CCi’s or Fed’s and then do primer testing with Rem’s being in the mix and you will normal see them flattened out or cratered (depending on firing pin slop) more than the others. They do work well with several powders but just can’t handle as much pressure, IMO.
Edit: If your running a large firing pin, instead of small, I’d stick with BR4’s or 450’s if you’re planning to run a node that’s close to pressure.