Krag Chamber: How Big Is Too Big?

[Themoose]

Fired newly acquired 96' Krag with Rem factory ammo. Noticed bases of fired brass were noticeably larger. Mic'd new @ 0.457 and fired were 0.470 - 0.471. No signs of excess pressure seen. Is this a safe condition. Plan on neck sizing only so not to overwork brass. The only limit I found in specs in Chamber dimensions was @ + 0.011 mine is + 0.013 to + 0.014.

[Der Gebirgsjager]

First, you are correct to neck size only the brass for as long as that is possible, and this will extend the life of the brass greatly. However, after several loadings you may find it necessary to full length resize it, as they will eventually become too tight in the chamber for easy loading and/or extraction. After that you may begin to get cracks in the area of the bright ring and need to discard the brass, but nothing lasts forever. The increase in size at the base of the case after the first firing is very likely due to excessive headspace rather than an oversized or worn chamber. I can tell you that this condition is found in about 9 out of 10 Krag rifles existent today. Why? Well, due in part to the metallurgy of the day, the 1896 version being 120 years old now, and the design of the single locking lug. These rifles were fired for thousands of rounds by the military, often re-barreled and fired for thousands more. Then they were sold off as surplus, shot by target shooters and hunters for hundreds (and perhaps thousands) of more rounds, often using hand loaded hotter than spec ammo. With every shot that single locking lug takes a little tap as if with a small ballpeen hammer, and eventually the molecules in the steel compress and the headspace increases. If you wish to eliminate the ring around the brass you must correct the headspace. There is really only one practical way to do it, and that is to change out the bolt body for one that is still in spec. Apparently this problem, which occurs to all of them eventually, was known by the military because they produced a large supply of extra bolts, and some of them may still be acquired in unissued condition. It is rare to find one that can't be corrected by using a new bolt. After correcting dozens of them I've only encountered one which needed to be re-barreled, and have a small box full of out of spec bolt bodies in my shop. Re-barreling in the conventional manner will work with the original bolt if the increased headspace condition is taken into account and the appropriate measurements taken and used to cut the new chamber; but which process, is the more practical--a re-barrel or a bolt swap? You can not just change barrels using a good condition take-off barrel from another rifle (there are no new surplus barrels) because the internal features of the receiver limit the depth to which the barrel can be screwed, and if it was out of spec before it will still be out of spec using the same bolt. For the last several years there was a fellow name of Stu Barlow that sold new bolts on E-Bay, but I don't know if he is still to be found. The good news is that if you can get along with neck sizing there is no reason to do anything, and your rifle is perfectly safe to fire.

[WineMan]

I played with one (1898 rifle sporter) for a while. Came with several boxes of fired brass and reloads. Ran a bunch through the F/L die. Got a bunch of head separations. Some of the brass was FA-04 (1904). The unsplit stuff I sent to a collector. With a Lee Loader, no problems encountered. It did fail a "Field" coin H/S gauge. With cast and moderate loads it shot great. I tried to see if the bolt was cracked (gasoline test etc.) but was not able to see any. Sold it after that for what I paid. Man that action is like racking a bolt in a vat of 10W oil. There was a guy at a CMP match. He had the rapid reload down to a fine science: two in the mag, two in the door and one on the tray, shoot the next five! A pleasure to watch.

Dave

[leadman]

I would go ahead with your neck size only plan and see what happens. If does not work out then you can either sell it or look for a way to repair it.
I have an old Krag also but my chamber is in decent shape. Been sporterized probably in the 1920s or 30s from what I have been able to determine from the unmarked Lyman receiver sight and the bakelite used as a grip cap on the stock.

[Themoose]

Thanks one and all for the information...I may want to do some more research on my bolt as Der Gerbirgsjager suggests. Not sure how to measure it, but I can research it or perhaps try a friends bolt in the rifle to see if the brass is similarly affected. The brass has become difficult to find and pretty expensive.. so fixing the problem if it is only a bolt swap out may be the least expensive alternative. I had always thought brass got stretched(longer) if there was excessive headspace, never figured it would get fatter... guess that I also must have excessive headspace from a worn bolt as I'm a whole lot fatter than I was in high school...thanks to Wineman and leadman for your input also. Your comments are reassuring that the rifle is safe to shoot...

[Tedly]

Head space gages....

[country gent]

Another way ypou mighthelp your brass to last longer and fit better I read about in an old NRA manual. It was an easy way to make a fitted sizing die. Ive never tried it but it sounded like it would work. Cut a piece of steel tubing 3/4" ID slightly longer than the case. fill case mouth with a dowel or pin fitted straight and tight. Today super glue cound be used to hold in place. Wrap pin evenly with tape to dia of neck and above the length of the tube. Rough inside of tube with coarse sand paper. I would make a washer snug to rim and od snug to pipeFill extractor groove with clay. Clean and coat cartridge with release agent several coats. assemble centered and square in tube. tape into place and set upright. Mix a good epoxy and fill gap between cartridge and tube slowly from one side slowly so air can work up and out the other side. (small vent holes could be drilled thru tube and coved with tape as epoxy passes them)fill to level with tube or just above it. Let epoxy cure. when cured clean up ends with a file and break sharp edges. You now have a die sized to your chambers cases that can be used in a vise or small ahrbor press. ( these are very similar to the Lee loaders kits). Not fast but it should work for small batches of ammo. not over sizing the case body and necks. I would use a good lube also.

[leadman]

A headspace gauge would not show up an oversized chamber at the base end. Most gauges for rimmed cartridges are of the button type with some actually checking the shoulder location. Same with a belted magnum case. Just checks the depth of the chamber recess for the belt to bolt face.
The Krag and the 303 British both seem to suffer from the oversized chambers. Both can be helped by a new or different bolt because they might be out of spec for headspace as well.
I have an Encore with a 28" 7mm Rem Mag barrel and if I do not fireform the brass using Unique and Cream of Wheat cereal the brass is very short lived. I tried to find a manufacturer that made brass longer than Remington, Winchester, or Federal and could not find any. Norma, Hornady, Nosler, and Lapua all suggested I buy cases for other belted magnums that were longer, like the 300 Win Mag, and sized them to fit my chamber.

[Themoose]

I did order a set of headspace gauges and have found a source for new bolt body. I am holding off in ordering the latter until I get and use the gauges. I'm also looking for another sizing die to use for neck size only after I fire-form the cases in my rifle... again, thanks to all that are providing me with some solutions....

Thanks again,
TheMoose