Originally posted by Jagermeister:
Doppelbuchse by Sodia of Ferlach. Double Purdey underbites plus Kersten cross bolting, that's FOUR way fastening. Hellishly strong! 
The above quote is absolutely correct, in every way! Austrian, and German made break top rifles and shotguns have always been made on the same actions so they only had to make one action for both! The actions are hardened properly for rifles, eventhough the action may be used in a shotgun (Doppelbuchse) , it is actually a rifle action! The double Kersten cross bolting are rarely used in S/S double rifles,or shotguns, but is usually restricted to
Doppel BOCKBusche ( Over/Under) with S/Ss usually useing a Doll's Head, or Greener cross bolt instead, and some without a third lock-up at all for shotguns, made in many countries.
For instance, Britt game guns were made as light as is possible,in most cases, and are supposed to be used with low brass upland loads, which are low pressure even for shotguns.
In a double rifle, if one is to use high pressure cartridges, the fitting must be absolutely perfect, and the multiple locking systems must be in place. It is silly to say chamber pressure doesn't matter in a double rifle for other than extraction. It is true that most catastrophic failiers, due to chamber pressure, are, in the least, in the ringing of chamber walls, or the extreme, the bursting of one or both barrels a few inches ahead of the chambers. But to say chamber pressure has no effect on the reverse thrust of the cartridge case head on the breech face, is simply wrong, the chamber pressure is what causes this thrust!
The shotgun causeing as much rearward thrust as some rifle cartridges is because of the size of the foot print of the large area of the shotgun case, in comparison the smaller cartridges like the 30-06, or 338 Mag or 458 mag. Though these three cartridges are high pressure they do not do much damage if there is pleanty of barrel meat around the chambers. Now when you start with rounds like the large cases like 416 Rigby, or 460 WBy Mag, added to the very large and long cases, with close to 60,000 cup, you are doing long term damage to the action's barrel to breech face fitting over time. Addtionally, the barrels have to be made heavier, farther down the tubes to accomadate the chamber pressures, effecting weight of the rifle!
Another of the reason these cartridges are not used is, they are dangerous Game cartridges, and they are rimless, or belted rimless cases, and they compromise reliability in a rifle meant for absolute reliability, in dangerous situations, because of the weaker, extractor parts, combined with the threat of reverse thrust hendering opening the rifle, and the possibility of the weak extractor pall being broken in the process, for a quick re-load!
Because something will work, most of the time, doesn't inspire confidence in it, where your life may be in the ballance!
It is a fact, the high chamber pressure does shorten the over all life of a break-top double rifle,more than a treditional NE cartridge, and the immediate concerns of not being able to open the rifle with a Cape Buffalo , or Elephant bull closeing on you fast, with two empty cartridge cases in your chambers, is reason enough to stay away from all but rimmed, low pressure Nitro Express rounds in a DGR double rifle!
This, in no way, henders anyone who wants to take that risk, with not only a rifle worth several thousand dollars, but with his very life, from ordering any cartridge that the maker will chamber for! However, IMO, it is a fool's choice! :rolleyes:
