Had my first case head separation today. spoiled the range session. Not max loads. looking for convergence point for a Merkel SXS with about 2100 fps with 286 bullets.

Well, the session ended when one brass separated and the other barrel showed the line of separation. My gunny showed me how to remove with a .375 brass brush, and also showed me that the fully seated round had headspace beyond the rim which could be fingernailed at several thousandthes...

Joe Told me to just reload 2 or 3 times, and not 4 or 5, and the thinning would be OK.

Is there any fix for this? I miked my NORMA and RWS brass, and both were within two thousandths of the .050 rim thickness spec.

Did Merkel ream too deep? Did I screw up by running the sizing die too far into the case?
Is there a quick fix? for now I will be backing off the sizing die so the taper and shoulder catches to require pressure before fully seating the bullet, and tossing brass after two reloadings.

Any ideas?

PS this is the best group op folks I know to help with this question.

Like a belted case yours headspaces on the rim. But most belted cartridges are in bolt rifles that have more camming power than a SXS. So the belted cartridges can be sized to headspace on the shoulder most of the time. Your SXS should be sized to easily chamber a round.

I would make a feeler gage from a coat hangar wire and bend the end to a tiny hook to feel inside the cases for insipiant head separations. When you feel one that concerns you saw that case in half and you will see what it looks like. You will also see that the separation is not uniform thus the need to turn the case and use the feeler gage in more than one place inside the case.

To increase the case life the load can be cut in pressure. Also the chambers could be polished if your smith agrees that they need it.

There is a headspace dimension and tolerance for your cartridge and it can be measured. I don't have the data for that one but it's possible that it's wrong. You can make a headspace gage yourself by soft soldering some solder on the on the front of a rim of a unprimed case and filling it until it chambers. Measure this with a caliper and compare it to the specifications. If the gun is new it might be possible to return it.

Perhaps there is another source for your brass where the rim is thicker?

Over all however the rifle is in the DGR catagory and should be used with like new cases.

Hope this helps.

Jameister Many of us here on the forum have 9.3X74R double rifles. Most of us are only getting two firings with Norma brass. If I try to shoot it the 3rd time I will get separations. My loads are not "hot". I even bought a neck sizing die to see if it would prolong case life...it did not. Some have reported longer case life with RWS cases. I have some I am going to try, and I will post the results.
Other than the short case life the 9.3 double is my favorite rifle under 40 caliber.

Savage99 has it right, the 9,3x74R can be sized to headspace on the shoulder (the latter is small but present, nevertheless). However, most double rifles being artisanal, they frequently have slightly different chambers, so that one has to compromise when sizing (BTW, this is true for all doubles, caliber notwithstanding). Consequently, case life may be extended but don't expect the same as with a bolt action. WARNING, don't overdo partial sizing to the point you're forcing the breech to close on too tight a case. Although case life will benefit from it, it's the fastest way to loosen up a double...

Jameister,

What brand of brass were you using when you had the separation?

I've had problems with Norma - incipient separation. In my more limited experience with RWS brass, it has held up much better. This is all in the same Kettner SxS double rifle. I'm ordering more RWS brass and just throwing away the Norma stuff as it wears out.