jungle carbine

If the firing pin is punching a hole thru the primer it could either be excessive firing pin protrusion from the bolt face or a chipped/broken firing pin tip. If you are using handloads it could also be due to high primers not fully seated in the primer pockets. A closeup pic would be useful.
 
With .303 cases with thin rims and a rifle at maximum headspace you can have .016 head clearance or "air space" between the rear of the case and the bolt face. With this excessive head clearance after the firing pin hits the primer chamber pressure forces the primer back over the firing pin. This rearward movement acts like a cookie cutter and punches the hole in the primer.

Below is a animated image of a .303 cartridge being fired, the primer backs out first and then as the chamber pressure increases the case is forced back to meet the bolt face.

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Below is from the Sierra manual and in a normal rifle with minimum headspace settings the biggest cause is a misshaped firing pin.

primersa-1_zps144ecb5f.jpg


Below a .223 fired in a AR15, excessive headspace and thin primer cups caused the problem. The primers anvil tip is sticking out of the hole in the pirmer. Over gassed AR15 rifles still have pressure in the barrel when the bolt starts moving to the rear creating even more head clearance. This is why military ammunition has crimped primers that prevents the primer from backing out of the primer pocket.

piercedprimer-2_zps2d386fad.jpg
 
These rifles left military technical control many years ago and there are many possibilities for bolt heads to be swapped and various unserviceabilities to occur in civilian hands. It's always a good precaution to have the headspace checked with a set of gauges. The amount of firing pin protrusion can also be checked with a gauge to verify that it is within limits. The firing pin tip should be smooth and round. A visual check will determine if it is chipped or broken.
 
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