Home Forums Hunting & Shooting Gunsmithing Bolt lock up

I have an FN Mauser action barreled to the 7x57 Mauser round. The gun was originally a .270 Win. so strength was not a problem. I got the .270 back around 1975. It shot good but every once in a while the bolt would lock up after a shot, and that with factory ammo. Anyway, I stuck it back in the closet less than a year later and forgot about it.

Fast forward to about six years ago and and I get the urge to build a neat European syle sporter in 7x57 with a stock similar to pre-war Mauser sporters. I got exactly what I wanted except I'd completely forgot about the bolt locking up. Makes no difference if I shoot the mild factory ammo or one of my handloads that use 7-08 data, the bolt will lock up very tight and it takes quite a bit of force to open the bolt. Brass looks just fine. If it did this on every shot I'd suspect locking lug set back but it only does it every once in a while, maybe once every fifth or sixth shot. I really want to do a hunt with this rifle before I cross the divide.
Any ideas?
PJ

Does the problem occur when dry fired?

Does it have an original bolt shroud safety, custom bolt shroud safety or sliding trigger safety? Any chance something is catching at that end?

If you can open the bolt, it's not "locked up"....those are two different things.

Have you taken the bolt apart and thoroughly cleaned and examined the pin, spring, safety assy, etc?

Does the rifle have an aftermarket trigger...perhaps an older Timney? Thinking maybe heavy bolt lift resulting from incompatibility of trigger and cocking piece.

What happens when you hold the trigger back and open the bolt? -Al

I have an FN mauser action, changed to a different shroud, then it became difficult to open when dry fired, do you know why that would be?

OP sorry for the derail.

Difficult only when dry fired? My 3 - 98s are all based on original pattern C Rings, but I would want to confirm the threads of the new shroud had adequate clearance to rotate freely when cocking. I would confirm the shroud lock isn't causing an issue and basically the clean and lube checks that Al suggests. If it's an aftermarket trigger there may be too much upward pressure on the cocking piece when the pin is in the fired position, that can wedge the tail end of the bolt upward and cause a lot of bind, at least it did initially on my Model 70 with an Anschutz 2- stage conversion. I am away from my rifles in cooler climates at the moment so can't check my M98s. If an aftermarket trigger is installed the over travel adjustment may also come into play.

Severa folks offered good possible causes. I see you are in AZ....Means you travel to a range in AC and you probably live in AC. Taking guns in and out of heat / cold causes moisture in the chamber. If not oiled they will rust.
A Mauser bolt handle does double duty, it turns the bolt body, and in so doing it turns the fired brass slightly, plus pulls the brass back slightly. If you have surface rust in the chamber, you can have intermittent difficulty lifting the bolt handle.

Look at your fired brass carefully, if it has areas with a frosted look, surface rust is the culprit. A 45 cal bore brush on an electric drill with oil, may clean it up for you.

Also look for marks on the fired brass, indicating a defective or rough chamber, such as gouges, scoring, rings, etc. Sometimes a bit of four 0 steel wool rapped around a bore brush can be used to polish a rough chamber.