Just re-did a Zastava Left hand Mauser in 458 Win Mag.

Remade the inside of the guard, new pocket floorplate, it now holds 4 rounds in the mag and 1 round in the chamber, redid the rails and ramp for smoother feeding
New magazine follower for the wider rails

In re-working it for the feeding I ran into something that was ODD.

The bolt would come back about an inch and just hit a solid stop.
OK the rear scope base screw is in that area and the screws were a bit long.
So took off the rear scope base and NO CHANGE, the bolt would come back and just stop

This only happened when there was ammo in the magazine box ? no ammo and the bolt worked properly

What I found was that the bottom section of the extractor collar was about .006" too large vs the bolt diameter
So the sharp edge of the collar would come back and hit the end of the case neck in the magazine and cause the bolt to stop on its rearward travel

So a bit of file work and then polishing to make the collar even/smooth with the bolt body and the problem is solved

Its been a long time since I worked on a 458 Win, most cartridges have a shoulder that the sharp edge of the collar would slide over with some marking on the case
But a sharp square edge vs another square edge simply made the bolt stop in its rear travel

Another little note on my wall now to look for

J Wisner

I have had that before; just remove the collar and use my favorite tool; belt sander.

Or hones!

Alwys good to find such things before the customer does!


Once sighted in a M-70 375 build prior to delivery..Nice day, had a bunch of ammo left over, so sat on a hillside and blasted apart a few rocks About 10h round, bolt jammed up solid!

It was that bolt stop lock retaining pin moved forward under recoil.

Dob't know just hows many rounds you have to put through them to cover all bases!

Had a BRNO with a similar issue.

Good tips! Thanks!

I've also had collars with oversized lugs that were too tight in the extractor. It caused hard chambering as the normal fore and aft movement of the extractor was impeded.