Headspace issues are very uncommon with the Krags, even with switching bolts, as we have discussed many times on this forum. They are not unheard of, though. You could have issues with a barrel that has been switched and not chambered properly. There could be significant wear or build up of crud in the chamber that is affecting proper seating of the bullet and closure of the bolt.

We have found issues, though, more commonly with the ammo. You didn't mention what ammo you were using, factory or re-loads or whether the ammo was old and might have some case integrity issues. I have found some older cases I've bought to be reformed .303 brass that is shorter than official .30-40 ammo.

Sometimes people have filed or altered the bolt.

These possibilities are in addition to some you mentioned but just some to think about.

Please give more info about the history of your rifle, any changes you see that might affect shooting and please, if you can, post pictures. Sometimes the pictures reveal the answer to us right away.

And, you'll hear lots more possibilities from others. The Krag forum has many experienced Krag shooters.

Welcome to KCA!

I didn't see if the Remington was factory and fairly recent vintage or reloaded Remington.

I guess by your comment it was factory. That would eliminate some factors.

What do you mean by wearing through the case in the receiver lug recesses?

I agree with 'Whig' that the first bolt may be altered.

Metal may have been intentionally removed from the rear of the locking-lug.

This was a popular practice in the old days.
The thought was, that it would make the action 'stronger' by having the bolt in contact with the receiver at the front-lug and the rear of the bolt-rib.

(Unfortunately, IMHO, this increased 'head-space', often excessively, unless a totally new barrel was installed and head-spaced properly).

It is normal that a correctly fitting Krag bolt will allow some fore and aft movement, if the striker mechanism is 'un-cocked' and no cartridge case is in the chamber.

You mentioned Bannerman's in connection with this Krag. The truth be told, they were not known for great 'gun-smithing'.

Attached photo shows feeler gauge at slight gap that should be present on U.S. Krags. This is often just 2 or 3 thousandths of an inch.

Either a "Bannerman" or DCM. A very good job of conversion, whoever did it.

I'm much more familiar with Mausers than Krags, which is why I'm wondering if the US Krags are susceptible to lug recess wear.

I didnt really want to go dig out my feeler gauges which is why I used a business card.

No. U.S. Krag receivers are not, IMHO, subject to 'lug-recess wear'.

However, if some previous civilian owner, put valve grinding compound on the lug & lug-recess, and worked that bolt until the guide/safety rib made contact with the receiver, who knows where all the metal was removed from?

I'd like to see some clear pictures of the 'fired'/damaged brass. That usually tells all.

BTW - In the late 1920's and 1930's, every gun-smith in the U.S. was turning Krag rifles into handier 'so-called DCM/NRA carbines'. The workmanship on many was very good. Krags cost a $1.50 and 1903 'banded' front-sight were readily available.

Only a DCM Order and Benicia shipping-ticket can establish that one of these "DCM carbines, sold to NRA members" is a real Benicia 'altered' Krag.

Just the "Field" gauge (.070 to .073 inches) will serve your needs.

For a 'home-made' check, a washer filed to .007" thickness and glued to the base of a .30-40 cartridge case, will work as a stopgap gauge.

Remove the striker/bolt-sleeve/extractor assembly and use just the 'bare' bolt (with light finger pressure) when verifying that a bolt does not fully close on gauge.

I attached a photo of the locking lugs of 2 bolts. The one on the left is brand new old stock (machine marks visible), the one on the right has a wear spot that does not take up the whole surface. The reason the wear spot takes up so little of the surface is the gun was probably purchased unused by my grandfather and been sitting unused now for 80 years. With a little more use it could have the typical burnished finish on the entire lug.
We tested about 100 bolts for functional size from the lug to the cartridge face and found only one with .010 difference. It was probably lapped on purpose. That one is mine and I made a custom barrel to fit with minimal headspace.

The last person here that was told he had excessive headspace by a gunsmith ending up buying a field gauge and finding out that his head space was fine with probably .005 to go before the gauge would close and probably another .005 till it would be a real problem.

Since you have a problem with fired cases, I think getting the field gauge is your best next step. You would only need the go and no/go if you are chambering new barrels. If the field gauge goes or goes with just a little play, then we should consider a damaged or modified chamber as the source of the problem.

If you have one of the fired cases on hand a good photo might help us figure something out while you wait for the field gauge.

You guys that have seen a lot of Krags were there any Ackley improved 30/40s made?