doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com An education in cross bolt locking systems please

I had always thought a cross bolt on a side by side was called a Greener cross bolt and the cross bolt lock on an over under was a Kerstan cross bolt. I also thought that Kerstan cross bolt consisted of two ears, one on each side of the barrel. Lately I've run across the two eared version being called a Double Kerstan and now I see the spelling of Koerstan. I had believed the the cross bolt on an O/U to a German invention. So I wonder now if I have been spelling it wrong of there is some subtle differences of which I am not aware. Some enlightenment on the subject would be very appreciated. Thanks!

Koerstan is nothing more than the Anglicized version of the German O-umlaut. I can't put that into this reply but think Boker (pronounced Becker) knives. See this link for explanation.

http://en.wikipedia.org/wiki/Umlaut

Koerstan gives you the phonetic spelling and Kerstan is likely further shortening. I bet it comes from Korstan (o-umlaut or with a pair of dots above). Anytime you see a Germanic name in America that includes "oe/oer" think phonetic spelling for o-umlaut.

Shoot straight,

Bird

I have thought that a "Greener" cross bolt was a round (in cross section) crossbolt that protruded from the action when the action was open, and If the crossbolt was square in cross section, then it was a "Scott" cross bolt. Either of these could also be tapered to "wear in", and i am not certain if the same names apply then. I have not thought these names to apply to crossbolts that did not protrude from the action when the action was open

The correct spelling is simply "Kersten", without any Umlaut.
Gustav Kersten was a gunmaker in Strassburg (Strasbourg, in the Alsace), part of the german empire before the 1. war.
In Germany this is also known as "double Greener", meaning two ears, one on each side.

For what I know, there is no "double Kersten".

Regards,
fuhrmann

FYI - William Powell & Son also had a patented (No.493 of 1876) crossbolt action. It is a single bite, snap action with a square bolt. It was produced for both hammer guns and A&D boxlocks.

So what is the proper name for the cross-bolts on the Beretta SO guns, now on their DT guns?

Or this one?

Soviet modification of the Kersten lockup, since 1948

The original Kersten system is the one seen on Merkels: extensions on both sides of the top barrel that fit into slots in the standing breech, and are engaged by round crossbolts that look much like Greeners. The system Beretta uses on the gun shown above is a variation of the Kersten, doing away with the long barrel extensions and replacing them with much shorter stubs fitted to a flat crossbolt. Some would say not as ungainly as the Merkels.

The Kerstens seem to have a larger bosses for the barrels to hinge on and the profile of the gun seem more slender then guns with the under locks as used by guns like Beretta. I may well be wrong as I have never bothered to do a side by side comparison. The under lock seems to be favored but I prefer the Kerstan as the lock is on the higher barrel which is exposed to the greater rotational forces.

Some Berettas had a slim profile in comparison to the Browning guns with there hinge & bolts both below the barrels. These Berettas used trunions on the side of lower barrel to hinge on & bolted via two tapered pins protruding from the breech into holes in a pair of blocks set between the barrels on either side.
Added;
The bolt blocks on each side had an angled front face which turned into recesses milled into the frame walls to assist the hinge pin in handling back thrust. Although I am not particularly an over/under fan this would seem to be a quite excellent design if properly built & fitted.