Quisto56,

 I suppose if you try hard enuf you can blow up any gun. Especially those made from the older "soft" steels.

 When Val Forgett first starting importing his RB's he set about having tests done by an independent lab to see what was possible. My memories a little short on the exact pressure they went up to, but it was at least 150,000 PSI. At that point the lab personnel refused to go any higher. The lock up system held altho some of the internal parts didn't survive. Of course these actions were made out of modern steels!

 The point to remember is that when the original statement, and the Belgium test was made, about not being able to blow out a RB action, the highest PSI that could be obtained with BP was around 30,000 PSI. The RB action goes back well beyond smokeless powders invention. To the RB's credit tho it was able to survive well into the smokeless era, and even today is considered one of the stronger SS actions.

 But, it does have it's problems which are a minor consideration today if you're only shooting smokeless. In the BP era one of Sharps advertising points was that if the firing pin ever got froze in the forward position on a RB you could end up with a slam-fire. Easily done considering BP's fouling and rusting qualities. Since the hammer has to be back when loading this would allow the breech block to rotate back and throw a lot of gas and brass back at the shooter.

PETE

Quisto56,

  Well, I don't know if the test was true or not. Haven't heard, or read anything about it. Probably true tho as they did some pretty weird stuff back then. Similar things were done at Springfield Armory with the Rifle Muskets.

  But, lets look at this test under the light of reason.

  If the gun was a RB how was that much powder gotten into the gun? Would have to be Ml'ed in. How were 40 bullets loaded? Again ML'ed!  Plus two wads, for whatever reason they were needed. No wads would have had to have been needed unless the bullets were grossly undersized.

  The big problem would be getting the mass of the bullets and powder moving. Since the bullets would have had to have been ML'ed they would be a slip fit in the barrel, and at most only a coupla bullets would have been expanded to a tight fit in the bore on ignition.

  Under confinement BP doesn't burn very fast, and as mentioned, can't develop all that much pressure compared to smokeless. PLus it's pressure curve is fairly long compared to modern powders. In fact with that much of a powder charge it's very likely most of the powder charge was blown out the barrel, unless they had a very long barrel. As an example.... When I consulted a gunsmith when making up my .50/90 it was deterrmined that it would take a 34" barrel to completely burn 90 grs. of 1F Goex behind a 600 - 700 gr. bullet. If you've shot much BP you'll have noticed sometimes the "fireflies" coming out of the muzzle. This is powder burning outside the barrel. I wonder how much of this happened in the Belgian test?

  So, even if the test were done it's not particularly valid!

  To get to your question of RB strength....... I'll agree that it's not as strong as a modern Ruger. Different steels and design. Probably no "old" SS design would be as strong unless built of modern steels. But it's much stronger than a Ballard or Trapdoor, which are considered very weak. Probably only slightly less strong than a Sharps or High Wall, if that. Of course we are talking about guns that are within tolerance for their designs.

PETE

I gotta support Pete in everything he says. IMO the roller is exactly as he described it and could easily survive such a test.

Strength concerns with the roller fall into two or possibly three areas: cracking the frame, separating the case head, and blowing out the bottom of the chamber.

Some & maybe all of the early actions have a sharp corner at the front of the block/hammer mortise, where the sidewall sweeps up to meet the rear of the receiver ring. This is the most common spot for the receiver to crack under an overload and we should limit such actions to the lower-pressure cartridges. The later actions intended for the 7mm cartridge have a larger bbl thread & ring OD and, much more importantly, have no sharp edge or corner from which a crack can propagate easily.

The roller has a lot of lost motion built into it and can cause case-head separations VERY easily if an unwary handloader isn't careful. The 'spring' that's built into the action by virtue of its design can amount to quite a few thou, and then you must combine that with the amount of headspace necessary for reliable cartridge chambering and also any normal headspace left by the barrel fitter. Now add extra breechface thrust from a very-heavily-loaded cartridge and you can see that the breech can actually spring back as much as 0.020" under exceptional conditions.

The front of the brass case will be held to the chamber walls quite firmly when firing and if the pressure exceeds ~40-45,000 psi then the case head will follow the block back and the brass in front of it will be stretched accordingly or even split, it's certain that the case head will be stretched & bent if not ruptured.

So even though the action itself may hold the pressure just fine, it's still not a good idea to load a roller too heavily with smokeless unless chambered with minimum clearance all around. And anyone who handloads for a roller should be aware of the bent-case-head syndrome. It's usually not a problem with BP or with a snugly-fitted barrel though.

The third (possible) area of concern is the relief cut on the bottom of the chamber area of the barrel, where the block pin lies. Many 'gunsmiths' unintentionally make this relief cut entirely too large when rebarreling and can actually remove enough steel so that there's danger of the chamber blowing out at the bottom rear if cut for a larger cartridge and loaded very heavily. I've never seen or heard of this happening but it's possible.

I like rollers but they DO have their limitations.
ttfn, Joe

Joe,

 Not being a gunsmith, or all that familiar with the RB I didn't feel qualified to go further in my rundown of that action. I'm glad you chimed in with some of the more common things that can cause problems. As is always said.... be sure and have a reputable gunsmith that's familiar with the problems of the RB, as Joe outlines, check it over before setting one up for any kind of shooting whether black or smokeless.

DonH,

 An excellent idea. I've seen some of Dave's work and it's first rate. He will even work over your old action if you like. A friend re-contoured a 7mm action to a #1 contour, I believe it was, and then sent it down to Dave to have it barreled and finished in .50/90.

PETE

A friend of mine told me he had a rolling block open up on him once, apparently there was enough recoil exerted on the firing pin to drive it back hard enough to open the block that locks the action .  Maybe it wasnt locked up properly to begin with , I wasnt there. Anybody else have that happen? Joe S

Quote:


No, it is not a rumour. It was reported by Charles Benjamin Norton, in his 1872 "American Breech-Loading Small Arms". The book quotes the following (I don't have the book but a magazine article that cites the reference):

The undersigned Director of the Proving-House for firearms at Liege, certifies having proved on behalf of Messrs. E. & L. Nagant, manufacturers of arms at Liege, a Reminton rifle, 50 cal as follows:-
1st proof, 90gr powder, 1 ball, 2 wads.
2nd proof, 750 grain powder, 40 balls, 2 wads.
The rifle has received the two coresponding stamps.
(Signed) ....... The Director
Liege Sept 29 1869   Alph. Polain.

There is an addendum to this statement added by the manufacturers.

The barrel could not receive a stronger charge, as the last one filled its entire length, 750 grains of powder and 40 balls occupying 36.31 inches.
(Signed)     EM & L.NAGANT

However if anyone requires proof that it is possible to destroy a rolling block see the following images!

(You need to Login or Register to view media files and links)

Oh yes.... this happened in 1999. I understand the load was thirty grains of Bullseye.

David

David,

  Just goes to show there's one born every minute! Lets hope this person doesn't reproduce and add to the gene pool!

PETE