Tikka T3 Firing pin / chambering issue

[Flashman]

Hello.

I'm looking for some help. I replaced a cracked firing pin assembly last week (second time around, the first being in 2019).

Today at the range my first five shots fired (300yds) without a problem and landed in the vbull. At this poiny inheard what i can only describe as a metallic click to which i opened the bolt and ckosed again. On my six shot my Elevation dropped dramatically around 8 inches. I then fired a 7th and 8th which did the same. Checked my moderator and all was fine. The then noticed that the next round wouldn't chamber properly and withdrew from the range. I've stripped everything down and checked and I cant appear to see anything wrong. I'm using Hornday 168 amax TAP ammunition. Same batch that was working fine before my firing pin broke originally. I checked the chambering with and without the new pin assembly, then with the old one back in and then chose a different box of ammunition and it's chambered these ok. Could this simply be a bad box of factory ammo, or does this seem too coincidental and an issue with the new firing pin?

Any help would be greatly appreciated as I'm stumped.

Regards

 

[Johnerz]

Have you measured the case on the unfired round to new rounds to see if it’s a case sizing issue?

 

[Flashman]

Hi mate

Thanks for the reply. Turns out it was a broken scope ring cap. The audible ping that I heard was ot snapping under tension. Everything was torqued to manufacturers specs too. Just one of those odd things!