Mauser M12 bolt jammed- 300 win mag

[Jon P]

Late update on the Mauser M12 bolt jamming shut, turns out it was the protective oil covering on the SAKO ammunition. Jammed on me whilst checking zero on the rifle in SA.

PH had a look at it and told me to polish the brass prior to use. Spent the rest of that evening taking the protective film of the brass. I have not had an issue since.

 

[Rutland lad]

Are these handloads?
Belted magnums often require a die that will size the are just ahead of the belt. The frequency of the "small base" sizing depends on the brass, the chamber and the load. ~Muir

Reloading Belted Magnum Calibers

This explains the unique problems (and solutions) associated with reloading belted magnum ammunition, and setting accurate chamber clearance at the shoulderfor handloads. It also explaind headspace.

www.larrywillis.com

I have a 300 Winmag. And I reload.
Years ago I bought the Larry Willis die for checking then resizing the case and it reduces the commonly found ‘bulge’ at the lower end of the case.
This allows me to reload cases up to 10 times - I then retired those cases and started again.

I cannot emphasise enough how good this kit is if you’re reloading these types of case.

Before I bought the LW kit I did have an occasional issue with my Steyr Pro Hunter refusing to accept a reloaded case into the breech and quite often would require considerable pressure to chamber a round.
I now know why.

 

[Smellydog]

Late update on the Mauser M12 bolt jamming shut, turns out it was the protective oil covering on the SAKO ammunition. Jammed on me whilst checking zero on the rifle in SA.

PH had a look at it and told me to polish the brass prior to use. Spent the rest of that evening taking the protective film of the brass. I have not had an issue since.

And they say factory ammo is more reliable!