Loose bolt/headspace

[Pofoo]

I have a old FN bannered 98 Mauser that has a loose bolt when the chamber is empty. Cocked and locked, it will move fore and aft a little.
When I chamber a mil spec round, it locks up tight--neither the bolt or the round rattles around, and there is a little restistance for the last 1/4" of bolt travel.
I have tied the gun to a tree and used a rope on the trigger to fire the gun while protected and it shoots. It does misfire 30% of the time. I'm using surplus 8mm Turkish ammo that shoots fine in my other Mausers. Seems to be a light firing pin strike.
So, any thoughts??
Headspace??
Eroded firing pin??

[TRAP55]

Sounds like headspace, does the serial number on the bolt match the receiver serial?

[Pofoo]

Yes, numbers match.
It seems odd to me that the bolt doesn't lock up tight without a round in the chamber.

[TRAP55]

Same here, specially on an FN. I would have a smith check the headspace. Any problems opening the bolt after firing a Turk round?

[SVT-40]

Number one are you sure the rifle is chambered for 8mm? As far as "head space" being the "problem" to a "loose" bolt when there in no round in the chamber. Well that cannot be the case. Head space can only be checked with a gauge.

If you fired a round you can look at the casing, Looking for evidence of excessive head space. This would consist of the casing being longer from the base to the shoulder than a un-fired cartridge.

More than likely the cause of the misfiring is a combo of hard primers on the military surplus ammo (very common) and a weak firing pin spring.

The bolt rattle when unloaded is not a big deal, and of no relavence to head space.

[Fate]

Number one are you sure the rifle is chambered for 8mm? As far as "head space" being the "problem" to a "loose" bolt when there in no round in the chamber. Well that cannot be the case. Head space can only be checked with a gauge.

If you fired a round you can look at the casing, Looking for evidence of excessive head space. This would consist of the casing being longer from the base to the shoulder than a un-fired cartridge.

More than likely the cause of the misfiring is a combo of hard primers on the military surplus ammo (very common) and a weak firing pin spring.

The bolt rattle when unloaded is not a big deal, and of no relavence to head space.

Agree with this diagnosis.

[Pofoo]

Thanks for the info.

[TRAP55]

Diagnosing a problem on the internet is difficult at best. The process of elimination is the easiest process.
If the bolt is closed and moves forward and back on an empty chamber, there's a good chance you may have lug set back. That would also account for light primer strikes.
Without a set of headspace gauges handy, the first question would be, is the bolt hard to lift after firing a round?
If the answer is no, has someone lapped the lugs?

[Pofoo]

Diagnosing a problem on the internet is difficult at best. The process of elimination is the easiest process.
If the bolt is closed and moves forward and back on an empty chamber, there's a good chance you may have lug set back. That would also account for light primer strikes.
Without a set of headspace gauges handy, the first question would be, is the bolt hard to lift after firing a round?
If the answer is no, has someone lapped the lugs?

Hard to lift after firing a round? No
I doubt that the lugs have been lapped as it appears to be a standard military rifle with no apparent custom work.
Head space--Yea, I'll need to find some gages.
But, question on head space.
With the captured round feeding of a 98 Mauser, doesn't the extractor spring hold the cartredge against the bolt face so that the firing pin should hit it even if the headspace was over? And, the bolt does tighten up when a shell is loaded.

[SVT-40]

Hard to lift after firing a round? No
I doubt that the lugs have been lapped as it appears to be a standard military rifle with no apparent custom work.
Head space--Yea, I'll need to find some gages.
But, question on head space.
With the captured round feeding of a 98 Mauser, doesn't the extractor spring hold the cartredge against the bolt face so that the firing pin should hit it even if the headspace was over? And, the bolt does tighten up when a shell is loaded.

The firing pin has nothing to do with head space. All "head space" is is a measurement of the chamber. In the case of a 8mm Mauser rifle the measurement is from the shoulder of the chamber to the face of the bolt.

Usually there are two gauges used a "GO" and a "NO GO".

The "GO" gauge is used to check that there is enough "head space" so MOST factory cartridges will chamber in the rifle. (In the case of the Mauser controlled feed extractor the gauge will need to be carefully loaded form the mag, or remove the extractor).When using the "GO" gauge you place the gauge in the chamber and you want to bolt to close with very light pressure on the bolt handle.

The "NO GO" gauge is used to check for excessive head space. As above the gauge is chambered and with VERY LIGHT PRESSURE you attempt to close the bolt. You do not want the bolt to close. If using light pressure on the bolt handle will close the bolt there is to much head space and the rifle should not be fired before it can have it's barrel either replaced or set farther back by a qualified gunsmith.

There is also a "FIELD" gauge, use of a field gauge is not necessary. As a dummy cartridge or unloaded unfired brass case can suffice .

NEVER PULL THE TRIGGER with any gauge in a firearm, as you may damage the gauge.

Can you post some photos of the receiver area of your rifle? just out of curiosity.

[jamesob]

turkish 8mm ammo sucks. i have a turkish mauser that misfires about 50% of the time and a yugo mauser that also misfires with the turkish stuff about the same. try different ammo.

[Pofoo]

Can you post some photos of the receiver area of your rifle? just out of curiosity.[/QUOTE]

No, I don't do pictures. It is just a FN script logo.

[spaghettithrower]

It is common for rifles, Mauser or otherwise to have somewhat loose bolts when there is no pressure on them from the mainspring or a loaded shell (grab a new 700 Remington and decock it and watch how much fore-aft play there is on an empty chamber.) On your Mauser when you put it on safe the mainspring is drawn off of the sear and you may feel a looseness in the bolt that may be fine. You may have a headspace issue, and that could be felt if the bolt had set back, but I would check your firing pin protrusion along with headspace. If both are in spec I would guess it is ammo related.
Good Luck