PDA

View Full Version : Stronger? bolt action VS. single shot.


ky hunter
February 13, 2010, 10:36 AM
which has a stronger action. a bolt action, or a single shot-(break open action or falling block?)

garvick
February 13, 2010, 10:50 AM
i would say that they are about the same. i have shot both but if there is a weaker one it will be the single shot due to the latches that

keep it closed.my opinion only

longranger
February 13, 2010, 10:56 AM
I will take stab at answering your question.In looking at reloading tables for the 45-70 there are loads listed for the Trapdoor Springfield(low pressure weak action)Then there is the modern bolt action loading data for the same.Then there is seperate load info for the Ruger #1 which is a falling block action.Shiloh Sharps says there actions are up to or exceed the Ruger #1 ,again another falling block action.Owning all of the described the falling blocks have a massive amount of modern high quality steel around the chamber.I would have to say the falling block is stronger.
But the bolt action rifles are chambered in much higher pressures than the falling blocks ever were.I don't know if a falling block would handle the pressures generated by a .338 Lapua or the like.
I digress and will say the bolt action by the mere fact all of the high pressure high performance cartridges in eccess of 60,000 psi all have been chambered in bolt action rifles and not the falling block.
Bolt action is stronger !

TheManHimself
February 13, 2010, 11:01 AM
Probably a bolt action of the Arisaka type. I believe it was Ackley that proved the strength of that action by cutting a .30-06 chamber in a 6.5mm Arisaka and firing .30-06 loads out of it. That's a .308" bullet being fired down a .264" bore. IIRC, he kept running hotter and hotter loads through it until he eventually blew the barrel off, with the action remaining largely undamaged.

thekyrifleman
February 13, 2010, 11:14 AM
Read the first chapter of Vol 1 of P.O. Ackley's two volume treatise....It's all about his study of deliberately blowing up actions...to see which one was stronger.

fisherman66
February 13, 2010, 11:15 AM
Weak ----> Strong

Break Action....Bolt....Falling Block

Now these are generalizations that hold true typically for modern guns. There are sure to be sum exceptions.

Crosshair
February 13, 2010, 11:19 AM
Unless you start giving specific examples then we can't answer the questions. There are strong bolt actions and weak bolt actions, strong single shot actions and weak single shot actions. It all depends on the specific design.

Slamfire
February 13, 2010, 11:20 AM
In my opinion, the strongest actions support the cartridge case best.

I recommend you buy and read Vol 1 of “The Bolt Action” by Stuart Ottenson. His section on the Mauser 98 provides a clear basis for bolt action design.

The cartridge case is the weakest link , an action is “strong” in so far as it supports the cartridge case. If you properly think of the cartridge case as a gas seal, not a structural member, then one trade off is designing the mechanism to protect the shooter after the seal ruptures. Even at the expense of losing the mechanism.

Most people lump “safest” action with “strongest” action, and there is overlap. You could build any action as large as you want. But not many people want to carry a 50 pound rifle that shoots a .22LR. The trick is not making the action as heavy as possible, but making the action as light as possible.

There are tradeoffs to consider. For example, if you don’t want to use a ram rod to knock the case out of the breech, then you must have an extractor. Extractor relief’s require a small amount of unsupported case head. The more unsupported case the weaker the action.

Action lugs and receiver recesses are designed to support the backthrust of the cartridge. The back thrust of the cartridge is calculated by the highest combustion pressure (in psia) divided by the surface area of the base of the cartridge. Frictional losses of the cartridge case are totally ignored. The resultant number will be the force in pounds exerted by the cartridge on the bolt face.

A designer will then calculate the thicknesses of metal it takes, which depends on the alloy, and add a safety factor. Typically the safety factor is 2:1 to allow for imperfect materials and manufacturing tolerances. Lugs and recesses are designed for an infinite number of loadings at SAMMI pressures.

How this effects reloaders is that if you exceed SAAMI cartridge pressures, you are eating into the safety margins and fatigue lifetimes designed into the mechanism.

You will read loading advice from people who all the time are shooting loads that greatly exceed published data. They will typically claim what they are doing is safe because they are not blowing primers and not having extraction problems. Without pressure data it is hard to exactly dispute their conclusions, but regardless, if they are operating outside the design envelopes of the action, what they are really doing is increasing their risk of an accident.

For hand held, man portable small arms, depending on lug size and breeching, there is no difference in strength or shooter protection between a well designed bolt action and a well designed single shot rifle.

But action design depends on application.

In terms of massive actions, cannons use cases/charges that have huge backthrust. The cartridges are low pressure but have large diameters. The loads on the breech blocks are enormous. Even though Iowa Class Battleships have magazines (LOL), feed mechanisms, and 60 man loading crews, you can consider the 16 inch guns as single shot. The breech designs have interrupted screws. I have no idea the weight of a breech block, but it could be tons. These actions carry the highest loads and are therefore, from a mechanical viewpoint, the strongest.

uncyboo
February 13, 2010, 12:27 PM
In looking at reloading tables for the 45-70 there are loads listed for the Trapdoor Springfield(low pressure weak action)Then there is the modern bolt action loading data for the same.Then there is seperate load info for the Ruger #1 which is a falling block action.

I'll have to look, but I'm pretty sure my manual has three 45-70 load ranges, as your does, but ... 1) trapdoor, 2) modern lever actions, and 3) Ruger #1 and modern bolt actions.

But the bolt action rifles are chambered in much higher pressures than the falling blocks ever were.I don't know if a falling block would handle the pressures generated by a .338 Lapua or the like.

After a limited amount of research I see 338 Lapua listed at around 61,000 PSI SAAMI specs, and 25-06 listed at 65,000 PSI SAAMI specs.

uncyboo
February 13, 2010, 12:31 PM
In terms of massive actions, cannons use cases/charges that have huge backthrust. The cartridges are low pressure but have large diameters. The loads on the breech blocks are enormous. Even though Iowa Class Battleships have magazines (LOL), feed mechanisms, and 60 man loading crews, you can consider the 16 inch guns as single shot. The breech designs have interrupted screws. I have no idea the weight of a breech block, but it could be tons. These actions carry the highest loads and are therefore, from a mechanical viewpoint, the strongest.

There have been a few rotary breech single shot handguns produced. Some refer to them as "cannon breech" actions. They are quite strong. I love my Lone Eagle 7mm-08.

James R. Burke
February 13, 2010, 01:01 PM
I am not sure which one is now, after reading all the posts. I had and have a few Ruger NO 1's and always thought they had a very strong action by the way they locked up. I even had one in a .416 Rem Mag that I use to push really hard. Never had a problem with presure or extration etc. So I guess at the moment I am not sure anymore.

fisherman66
February 13, 2010, 01:06 PM
Unless you are wildcattin' or sum kind of nutty reloader none of this means much. Stop pushing grains when pressure signs rear their heads.

Scorch
February 13, 2010, 01:12 PM
Several people have correctly stated that it depends onthe individual action design. When you ask which is stronger, you need to specify which bolt action, which single-shot, and which break action.

Bolt action- The Mauser 98 has become a standard, a reference of accepted strength for modern cartridge rifles. The Winchester, Remington, and Savage rifles so common nowadays have strong design ties to the M98. Other designs are also very strong; the Weatherby Mark V is claimed to be the strongest mass-produced bolt action, with 9 locking lugs and a 60 degree bolt lift.

Single-shot- The Winchester 1885 has been chambered for more factory cartridges than any other rifle ever produced, including the high-pressure big bores, and it was first produced in 1879. It is many times stronger than a Sharps rifle due to its massive breech, as opposed to the Sharps' thinner sides. Several cannon-breech single-shot rifles have been produced, but they are harder and more expensive to produce.

Break action- Everyone thinks of NEF single-shots when you talk about break-actions, but there are some produced in Europe that will handle the pressures of magnum rifle rounds. Holland & Holland makes break-action rifles chambered for 600 Nitro Express, a bruiser if there ever was one. Blaser made their name in the single-shot market producing rifles chambered for super-hot cartridges.

Moloch
February 13, 2010, 01:19 PM
The steyr sbs bolt has 4 locking lugs, two of the size of the 98 model, right behind them 2 additional lugs half that size. Pretty much as strong as it gets.

David Turley
February 28, 2010, 01:24 PM
ive heard the single shot tends to be a more accurate rifle and maybe a little stronger ive never owned one though my bolt actions have always worked great for me

fisherman66
February 28, 2010, 01:45 PM
ive heard the single shot tends to be a more accurate rifle

Single shot bolt guns have made quite a home at the target game due to the rigidity of the action. Break actions and falling blocks have too much to overcome by the two piece stock and less stable platform to make a go of it in the top notch benchrest game. That said, I much prefer a falling block for it's over all length of action.

44 AMP
February 28, 2010, 01:50 PM
Modern falling blocks, like the Ruger, are immensly strong. Old bolt actions, like the Krag, are not. Apples and oranges both taste good, which is better?

knight0334
February 28, 2010, 02:45 PM
This comparison between designs is totally faulty. No one design is stronger than the other, only specific examples may be better than other specific examples. The H&R/NEF SB2 break action may be stronger than a Remington 722 bolt action. A Ruger #1 may be stronger than a Marlin 1895 levergun. etc, etc, etc.. ..to boldly state bolts guns, or falling blocks, break actions, or whatever are stronger than others blanketly is a failed argument.

Buzzcook
February 28, 2010, 03:13 PM
There is a thread that pops up every once in a while called "12 gauge from hell".
It's almost a journal about making monster rifles.
The fellow involved seems to use falling blocks. That might be because they're easier to machine.

BTW the rolling block is also a very strong action that doesn't get as much attention as it once did. I think Remington has a modern version.

I'm pretty sure that given modern materials any action could be used for the most powerful cartridges out there.

Scorch
February 28, 2010, 03:19 PM
Rolling blocks are not very strong. Rolling blocks are well-known to fail with smokeless powder loads, either by the topstrap breaking out, or the pins peening out the receiver holes and case heads failing due to excessive headspace. For black powder, sure, they're OK.

Webleymkv
February 28, 2010, 04:09 PM
One thing that people seem to forget when having discussions like this is that the power of a cartridge does not necessarily correlate to it's pressure. I've seen references to large, powerful cartridges like .600 Nitro but you must remember that these monsters are actually rather low pressure rounds. Again using the .600 Nitro as an example, the pressure and velocity simply don't have to be all that high to get power out of a 900grn bullet.

Also, remeber that there are wide variations among both bolt-actions and single-shots. A Mauser is quite strong, a Lee-Enfield not so much, and a Krag even less so. Likewise, remeber that metallurgy will affect action strength as much as design will. A break-open NEF is stonger than a Sharps made in the 1880's, but weaker than a Ruger Number 1.

Scorch
February 28, 2010, 05:08 PM
600 Nitro Express
CIP max pressure = 36,000 psi

Not exactly a monster when you think in terms of pressure, but think of the bolt thrust!

Webleymkv
February 28, 2010, 05:27 PM
Not exactly a monster when you think in terms of pressure, but think of the bolt thrust!

I assume you're talking about the rearward force generated by the recoil. This factor actually has relatively little bearing on the strength of the action (the shooter is another matter however). For example, a 12ga shotgun slug usually has quite a bit more recoil than a 30-06 fired from a gun of equal weight. Yet, the shotgun's low pressure allows it to be used in an action like that of a Remington 870 which is considered far too weak for a 30-06.

That being said, many action types are quite a bit stronger than people give them credit for. NEF doesn't seem to have problems with their break-open guns in relatively high-pressure rifle cartridges like 30-06 and .270 Win and the Lee-Enfield design has proven itself to be up to the pressures of 7.62x51 NATO through the so-chambered Ishapore rifles. I do, however, suspect that metallurgy plays a large role as NEF won't fit a rifle barrel to a shotgun, but they will fit a shotgun barrel to a rifle (I'm guessing that the recievers are heat-treated differently).

Scorch
February 28, 2010, 05:56 PM
I assume you're talking about the rearward force generated by the recoil. This factor actually has relatively little bearing on the strength of the action (the shooter is another matter however). No. Bolt thrust is chamber pressure (in pounds per square inch) times head surface area (in square inches). That gives you pounds of pressure against the bolt or receiver face. In the case o the 600 Nitro Express, that translates into 14,491 pounds of force against the bolt or receiver face when the firearm if discharged. As a comparison, a 30-06 generates about 10,000 pounds of force against the bolt face.

Jimro
February 28, 2010, 06:17 PM
In terms of practical matter, it doesn't matter between a strong bolt action and a strong falling block.

Break action rifles are obviously the weakest from a design perspective, BUT that doesn't mean a break action double rifle is a poor choice. The cartridges they were designed for, such as the 470 NE are relatively low pressure rounds.

Modern falling block and bolt action rifles are interchangeable as far as strength goes. The Ruger #1 is offered in 416 Rem Mag which has a max pressure of 66000 psi, I'm pretty sure that the 338 Lapua's max pressure of 68,000 isn't going to cause problems.

A quick google search gives results from folks who have done the Ruger #1 in 338 Lapua and smith's willing to do the work.

From a strictly engineering standpoint, by the time you get to loads that "lock up" either action, you would be WAY beyond max pressure.

Jimro

cafsman
March 1, 2010, 12:47 AM
I own several all the way up to 458 Lott. Go on you tube and watch the nutbags shooting the 577 T-Rex

Art Eatman
March 1, 2010, 08:52 AM
Mechanical strength against the rearward force of the cartridge case is trivially easy. Same for resistance to chamber pressure in any sort of normal loadings.

The strength problem enters mostly from the amount of support given to the head of the cartridge case. For that, the push-feed design is superior to the controlled-feed design--which is the "why" of the Remington 721.