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Double Rifles, Single Shots & Combinations >> Double Rifles
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DBBill
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Reged: 25/05/03
Posts: 137
Loc: Southern California, USA
Question about high pressure ammo in doubles ???
      #28997 - 06/04/05 05:47 PM

Everything you read tells you that double rifles aren't as "strong" as bolt-actions and that the best cartridges for them are the lower-pressure rounds like the 9.3x74R, the .470 etc so my question is what happens, if anything, when you see a double with 2 sets of barrels....one a 9.3x74R (lower pressure) and the other a 30/06 (higher pressure)? Does the 30/06 "stress" the receiver more than the 9.3x74R? Another example might be the .470 paired with the 375 H&H. I've even seen doubles, mostly O/U's chambered in such calibers as the 7mm RemMag and the 300 WinMag ???

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André
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Reged: 28/06/04
Posts: 254
Loc: Brussels (Belgium)
Re: Question about high pressure ammo in doubles ??? [Re: DBBill]
      #29009 - 06/04/05 07:26 PM

You answered your own questions. The more pressure, the faster the rifle will shoot loose.

--------------------
André
---------------------------------
3 shots do not make a group, they show a point of aim or impact.
5 shots are a group.

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bonanza
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Reged: 17/05/04
Posts: 2335
Loc: South Carolina
Re: Question about high pressure ammo in doubles ??? [Re: DBBill]
      #29019 - 07/04/05 12:24 AM

Not greasing the hinge pin after every time you shoot will wear it out faster than high pressure loads.

Let's look at the real world here with a .375 H&H. If your new (Searcy, Merkel, Chapuis, Krigoff) double was fitted properly and you hand load to slightly less that factory velocity and your gun regulates; you can, with proper care, expect to shoot hundreds of rounds without it coming off face. However, if you shot hot factory ammo, put it away, shot, put it away, etc. You might get 100 rounds before it's off face. There is a lot of "hanger flying" on this forum and good advice. I was properly advised on the feeding and care of my .375 and with well over 500 rounds shot, it's still like new.

--------------------


"Speak Precisely" G. Gordon Liddy.

"Life is absurd, chaotic and we must define its purpose with our actions" Abert Camus

"I''m the dude playing a dude disguised as another dude."

"Yo! Mr. White"

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AussieMike
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Reged: 01/09/04
Posts: 236
Loc: Southern Tablelands, NSW, Aust...
Re: Question about high pressure ammo in doubles ??? [Re: bonanza]
      #29043 - 07/04/05 10:07 AM

One thing to remember is that we use our doubles very differently now when compared to the Bells and Taylors or pre WWII days. Ammo used to come in 5 round packets and I reckon the average pro elephant shooter only fired 100 rounds a year. All factory, no working up loads, no practice, no Big Game Rifle Shoots. I fired 100 rounds from my 470 last week, just working up loads.

So, I think, if you really like your rifle, lower pressure loads are the way to go.

mike

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unspellable
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Reged: 06/03/04
Posts: 187
Loc: Iowa
Re: Question about high pressure ammo in doubles ??? [Re: AussieMike]
      #29087 - 08/04/05 03:57 AM

Pressure is the wrong consideration. It is back thrust and to some extent, recoil that stress the action. It comes as a surprise to most people to find out that a 12 gauge shot shell puts as much stress on the action as many rifle catridges, if not most.

The whole bit of "double rifles can't handle high pressures" nonsense got started during the transistion from black powder to smokeless. The new smokeless loads ran higher pressures. They hadn't perfected the brass and there were a few cases of sticky extraction due to less than perfect brass, occasionally aggravated by pitted chambers. The double does not have the mechanical advantage on extraction that a bolt action has. The first approach to curing this problem was the simple expedient of keeping pressures down. Over time the brass was improved.

There is an additional factor in that there is simply no reason to run high pressures in a double as the cartridge length is not limited by the action as it is in a bolt action.

So, given no need for high pressures and a desire for reliable extraction, cartridges designed for double rifles generally run low pressures. As far as the strength of the action is concerned, the modern double as an action type will handle just as much pressure as a bolt action rifle. With today's metallurgy, both types are ultimately limited by the limits of the brass which dictates that working pressures be limited to 65,000 psi. If grossly overloaded, a double will typically blow out the barrel, just like a bolt action.

The stress on the action is in part due to the cartridge back thrust and partly the tendency of the barrels to whip up and down under recoil forces.

Bottom line? As noted above, cleanliness and proper lubrication. Don't slam it open and shut.

Unless they are cheap junk, most doubles go off face due to abuse of one sort or another.

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new_guy
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Reged: 10/08/04
Posts: 581
Loc: Texas
Re: Question about high pressure ammo in doubles ? [Re: unspellable]
      #29096 - 08/04/05 07:10 AM

That is 100%, the most accurate and logical depiction of DR chamberings and dismissal of the high pressure "fears" that i've ever read on one of these forums.

Congratulations, unspelllable - you nailed it!

but standby... they "nay-sayers" will be here any minute to propagate their 100-year old opinions and rumors.

--------------------
www.heymUSA.com

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