doublegunshop.com - home Forums General Discussion Double Rifles, Paradox Guns & Gauge Rifles @ doublegunshop.com Double rifle "strength"

I don't know a great deal about double rifles having never owned one (not for lack of wanting!)
In a recent discussion I was told break open actions such as these are a relatively weak design in comparison to a bolt action.

I was a little surprised by this, as I am sure there are some fairly high pressure cartridges available in a double, and that the action design was in fact a reasonably strong one, though, admittedly perhaps not quite up to a bolt action but not that far behind surely.

What say ye?

Greg:
At the time of their inception, break-open double rifles were not as strong as Mauser-style bolt-rifles. Accordingly, nitro-express chamberings turned up little more than 17 or 18 tons max working pressure. At the time, Mauser rifles were quite content with cartridges generating well over 20 tons, up to 25 tons or so.

Modern double rifle design and better quality steel (and more consistent manufacturing standards) mean that today's double rifle is a far stronger action than those of 100 years ago. As a result, many European and a couple of American makers are happy to chamber just about any cartridge you like!

In a destruction test, I'm sure the double would fail before a modern bolt-action, but you never know.... !

That's my take on things, other opinions..?

GregdownunderI agree with almost everything MARAKAI had to say on this matter. Certainly the more modern steels used today in the makeing of double rifles is a real plus in the strenth of the rifles! However, simply because some companies chooses to yeald to the wants of customers, doesn't necessarily make that a good idea. Some of the new doubles are made heavy enough to stand these high pressures for a time, at the expence of weight, and handleing. the new steel asside there is no difference between a double made in 1870, and 2006, in a given action type. the break top double rifle is basiclly 18th century technology, and by nature is "springy" compaired to a bolt action.

That disclaimer asside, more important is the type of cartridge being chambered in a double rifle. If the rifle is simply a deer rifle, then things like single triggers, and rimless cartridges are fine. The problems these things cause, are not life threatening, and small cartridges like the 30-06, though considered high pressure rounds are encasesd in barrel butts that have pleanty of chamber wall thickness! If this type of rifle fails in any way nothing other than a shot at a deer is lost.

If, however, the rifle is to be used as DGR (dangerous game rifle) then the sittuation changes considerably! Useing cartridges like 458 LOTT, and 460 WBY, are not the best idea anyone ever had! These cartridges are asking for a frozen action, that will not open, and busted stock, putting the rifle out of service, the premature "OFF FACE" condition of the rifle. Then when you top this off with a single non-selective, or fixed selection trigger, this further complicates these choices.

All I am saying is first and foremost, and cartridge for a double rifle should be of the rimmed type! it should be in the 40,000 psi chamber pressure or under. The rifle should be equiped with double triggers.

Well, I won't speak for tonnage pressure wise, but lets look at the era. Many of these cartridges were comming off of the old blackpowder setups, and pretty rapidly. Cordite was the new standard, adn mechanisms were being advanced. An friend of mine asked why I would choose a sxs .318 or .400 nitro over a bolt action magnum. I told him that back in the day, a double gun not only meant you had a quick back-up shot, but that you had TWO INDEPENDANT MECHANISMS-which meant less of a chance that both would fail at a critical moment. In one on one human combat, if technology fails, you can bash the other fella with whatever you have. If you fall to a charging animal, their sense of self preservation is stronger, and you need to deliver a killing blow before they are close enough to get you. Anyway, Holland and Holland actions are "idiot proofed" (not my term), so if it happens that a very strong load gets fired from them, gun damage may happen, as well as shooter damage-but not from the gun separating. There is a rumor of them not being able to keep the action together on their prototype .800 nitro express as of yet, at least after replicating the newer surviving 2-bore cross locking mechanism...maybe they should make it a cordite only cartridge...

There is a common misconception that the old double rifle cartridges ran low pressure because the rifle was not as strong as a bolt action. The situation is actually the reverse. The bolt action MUST run high pressure to get the job done because the cartridge length is constrained by the action length. The double or single shot has no constaint on cartridge length so there is simply no need to run high pressure unless you are chambering for a moderb bolt action cartridge such as the 458 Winchester because of ammo availability. if there's no need for high pressure why run it? Lower pressures are less likely to produce difficult extraction.

A double admittedly has less extraction power than a bolt action but when you blow one up it's generally a barrel failure and not an action failure.

Stress on the action is not a direct function of pressure. It's back thrust that counts, pressure times insdie case head area. A 12 gauge shotgun works up as much backthrust as many high powered bolt action rifle cartridges.

Doppelbuchse by Sodia of Ferlach. Double Purdey underbites plus Kersten cross bolting, that's FOUR way fastening. Hellishly strong!

I've fired about 100 ea. .45-70 cartridges, both factory and hi-octane hand-loads from my new Kodiak MK IV
Double made by Pedersoli of Italy. She locks up like a bank vault, and I cock both barrels for a quick second shot. No problems. Recoil is less than a Garand. Over 10 pounds of good Italian steel make for a strong shooter that will, hopefully be still shooting long after I've passed it on.

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:

The pressure vs extraction was an issue in the days when smokless powder first appeared and the brass was not quite up to the task. That's less of an issue with today's improved brass. On the other hand there's simply no reason to have high pressure if you are using a cartridge designed for a double. High pressure is only required when you are trying to use a bolt action cartridge in a double.

The rimless vs rimmed issue IS an issue. Rimless extractors are more complex and compromise reliability. Even without breaking they have the potential for a case haed to get under the extractor and tie things up.

Back thrust is a a product of both pressure and head area. Either one taken alone means nothing as far as action strength goes.

I've seen a side by side in 9.3X74R with kersten fasteners. This rifle was so light that I would have been afraid of the recoil. Which goes to show a double needn't be heavy.

Go to http://www.doublegunclassics.com/

There is a full article with very graphic pictures about .577 failure.

Pete

Where is the 577 failure article? Looked around for a bit and couldn't find it.

Nevermind. It is in the July-Aug 2006 issue.