.243 firing pin problem

[ditch1234 0]

hi there im new to all this but i have a problem with my rifle.

i have a .243 bruno and the fireing pin punches through the precusion cap and on some caseings it is burnt at the bottom. any ideas on what to do

many thanks

[matt_hooks 188]

What load are you using? This sounds more like an overpressure rather than a firing pin problem. Are the caps flattened too? Are you running home loads, or factory ammunition?

[ditch1234 0]

if it was the load doing that it waould make sense i was using 108 grain norma rounds. it is putting holes straight through the cap. they are factory ammo

[matt_hooks 188]

The holes in the primer, and some showing leakage, would definitely make me suspect overpressure. Do you have any amunition from other batches? It could be that that particular batch has been loaded hot by mistake (unusual for Norma, normally very reliable, but mistakes happen). Also be worth running it over a chrono to check velocities. I would recommend trying a different batch to see if it causes similar issues. Your chamber might be on the low end of the tolerances, which can cause the pressures to ramp up. There are all sorts of reasons for high pressures, a lot of them to do with how the rounds have been stored/transported.

[SNAP SHOT 194]

i suspect your bruno is a 1 in 10 standard factory twist, the 108gr i suspect is of the VLD type.... and therefore long, do you feel resistance on bolt closure...?

 

And when you fire the round the pressure build up is because the bullet is touching the rifling, and leading to a pressure build up before the head leaves the case....

 

you need a 1 in 8 twist to shoot the 108g in .243 with any accuracy i suspect.... and a deeper throat area too instead of the factory standard..

 

Snap.