I'm new to this forum and this is my first post. I have three rifles chambered in 30-40 Krag: one original 1899 cavalry carbine, one sporterized 1898 stalking rifle and a 1980's Browning copy of a 1895 Winchester.

I'm having problems with case necks splitting.

Background:

I have a slick sporterized Krag (headspace checked out by gunsmith) and an '80's Browning rendition of the 1895 Winchester. I reload the 30-40 Krag, and duplicate the original military load with 220 grain Hornady .308 round nose soft point bullets.  I'm using DuPont IMR reloading data to recreate the classic load of 40 grains IMR 4350 under a 220 grain round nose soft point. Hand loaded cases were trimmed to overall length of 2.304" +0.000/-0.0025". Bullets were seated to SAAMI maximum COL of 3.089". Brass was once fired. Loaded cartridges are not touching rifling. Cases are extracting easily. I also had some 180 grain Winchester SP factory loads on hand, and shot them to reclaim the brass for the mild 220 grain loads. Cases are properly head stamped 30-40 Krag and are NOT Enfields. Brass was either once fired or new. Dies are by Hornady.

Problem:

Had 7 case necks split from both lots. No other problems noted, just split necks. 20 Loads were shot between both rifles, cases randomly split from both. Not sure what's happening. Haven't had the problem before.

About half were new Winchester factory loads (180 grain bullets). The others were hand loads using the classic 40 grains IMR 4350 under a 220 grain round nose soft point.  Brass was once fired.

Has any one else encountered this?

Thanks.

7/20 is certainly a high percentage.  I've got cases I've loaded umpteen times without annealing and I only get an occasional split neck.  The majority of mine are Remington.  I'm at a loss to explain your problem.

First... welcome to the forum!

Well, to start with, the 220gr RN Hornady over 40.0 grains of IMR-4350 is about as close as you're going to get to the original .30 Army round.  Split/cracked necks is nothing new in reloading for 30-40... we've all experienced it.  However, all is not lost. 

1. I can't stress this enough:  Anneal your case necks!  I use my LEE Trimmer collet and chuck them up in the drill.  I spin the case while heating the case neck until it changes color (and no more).  I then drop them into a metal bowel to air cool.  Some people drop them into water, but I believe this to be unnecessary. 
2.  Neck Size Only!  Keep your brass separated to a specific rifle and once they're fire-formed, neck size the brass only, which will prevent unnecessary working of the brass.  I use LEE Pacesetter dies and back my sizing die out one full turn. 

Follow these two rules, and your brass should last a very long time.  I'm well over twenty reloads on some of my brass, and still occasionally get cracks... but they'll certainly last far longer!

Thanks, guys.

I've not had to anneal rifle case necks before. Most were straight wall 38-55 or 45-70. The .260 Remington & .308 never gave me problems with splitting, just experienced splitting with the .303 British and the .30-40 Krag.

I did full-length size the .30-40 brass for use in both rifles. The 1895 needed it. I'll segregate the brass now into two batches and neck size the Krag's. The Hornady annealing kit is now out of print, so to speak. I've been looking for components to make my own. The drill spinner idea sounds good to me. Saw a spinner pair online that gripped the primer pockets, but not sure how that would work.

I will need to full length size the 1895's brass, though. Fortunately, I did score 100 new brass cases and 100 rounds of 180 grain commercial loads recently, so have more to go with the cases I already on my bench.

Again, thanks.

I've automated my annealing redneck style.  Use a battery drill with a square drive adapter that lets you use 3/8 sockets.  With a 9/16 deep well socket in the adapter in the drill I set the propane torch on my work bench, secured with duct tape (hence redneck) flat on the bench with the flame facing away from the bench.  Drop a Krag case  base down in the socket and hold the inner cone of the flame at the junction of neck and shoulder at about a 45 degree angle.  Rotate on low speed for 7-10 seconds until you see a color change.  Low light works best and time is dependent on how you set the flame.  Once you do several just time the anneal.  I drop into a metal cookie tin set on a chair under the flame.  It is not necessary to drop in water, in fact it makes no difference in hardness after the annealing.

The real question here is - why are these cases failing on first or second firing? Possibilities include:

Dodgy metallurgy.
Scratched/burred drawing dies/punches
Storage conditions (corrosion?)
Inadequate anneal during manufacture.
Oversize/rough chamber.

Annealing before further firing can address only some of these issues.