Todd and Mac had an interesting exchange on the vintage vs. new double rifle thread about monometal bullets and OSR in double rifles. Here's my take on this. Despite all the assurances, I am still a bit nervous about a steady diet of monometals, steel solids, and dual core bullets in my doubles. So, what to do? For everyday shooting, I try and stick with 4th generation softs. In my 9,3, 375, and 500/416, I am lucky that there is a perfect cup and core soft nose bullet from Hornady and that's what I usually shoot at the range. However, I don't think it will hurt your rifle to shoot monometal bullets on a hunt. North Fork solids and cup point solids and that wonderful CEB#13 solid would be my pick. I think Michel's tests are a pretty good indicator that they are safe in your double. Todd, I don't know why but I am still nervous about using a TSX or a banded solid in a double although I have shot a bunch of banded solids without incident. In addition, I just can't believe that Barnes would sell a bullet that would damage your double. I guess my advice is when in doubt, contact your manufacturer and see what they suggest.

quote:

Originally posted by Dave Bush:
Todd and Mac had an interesting exchange on the vintage vs. new double rifle thread about monometal bullets and OSR in double rifles. Here's my take on this. Despite all the assurances, I am still a bit nervous about a steady diet of monometals, steel solids, and dual core bullets in my doubles. So, what to do? For everyday shooting, I try and stick with 4th generation softs. In my 9,3, 375, and 500/416, I am lucky that there is a perfect cup and core soft nose bullet from Hornady and that's what I usually shoot at the range. However, I don't think it will hurt your rifle to shoot monometal bullets on a hunt. North Fork solids and cup point solids and that wonderful CEB#13 solid would be my pick. I think Michel's tests are a pretty good indicator that they are safe in your double. Todd, I don't know why but I am still nervous about using a TSX or a banded solid in a double although I have shot a bunch of banded solids without incident. In addition, I just can't believe that Barnes would sell a bullet that would damage your double. I guess my advice is when in doubt, contact your manufacturer and see what they suggest.

Dave it is not pressures that causes OSR but strain on the barrel walls! The newer bullets like North Fork, GS custom and CEBs are fine for use in even vintage double IMO! It is the mono-metal bullets that have pressure bands that are too wide, and made from the much harder bronze like the original Barnes SUPER SOLIDS, with no bands at all. Even the steel jacketed solids are questionable to some folks, not for me though. The steel jackets are mild steel, and with the soft core underneath gives the steel a place to move away from the rifling, but with the solid bronze the displaced metal has no place to go but being pushed off the back of the bullet. This not only strains the barrel walls, but sends pressures though the roof as well.

IMO, the NF,GSC, and CEBs are of no concern in even vintage doubles as long as the rifles doesn't have a bore and land measurement that is not standard for the chambering. This happens sometimes when the rifle was made very shortly after the smokeless powder became the new thing.

There are many who do not believe OSR even exists, and that is thier right,I just happen to not be one of them!

...........................................................................................

Well, what it comes down to is whether you believe the "opinions" that have been passed down over the years or whether you believe the data that Michael and Sam have repeatedly demonstrated. That Hornady you seem to be happy with produces, consistently, in what ever caliber tested, the second and third highest barrel strains of all bullets tested. The CEBs produce the lowest barrel strains. The TSX produced strains somewhere above the Woodleigh Soft but significantly below the Woodleigh FMJ which BTW, consistently produced the HIGHEST barrel strain.

The manufacturers are regulating their rifles with the 2nd and 3rd highest barrel strain producing bullets (Hornady DGX and DGS), so if you deem them safe in your double rifle, by all means shoot them. If you prefer to believe the repeatable and measurable data Michael and Sam produced, then logic pretty much says that anything on the market today is safe in these rifles since every bullet other than the Woodleigh FMJ produces less barrel strain than the two Hornadys. If you don't believe the data, and prefer to go with "so and so shot their rifling out the end of the barrel 15 inches" and statements like that, then by all means, stick with the 2nd and 3rd highest barrel strain producing bullets, (the Hornady pair). None of this begins to address the terminal performance of said bullets!!

Compared to many on this forum, I'm a babe in the woods experience wise with doubles. I've been shooting them for 5 years. Many like Mac have been at it for a hell of a lot longer than that. But this data concerning barrel strains is new. It appears to me to be scientific and repeatable. I place more value on objectivity than the subjectivity that has been handed down and associated with comments like the one about "shooting the rifling out the barrel". I'm sorry but that kind of talk doesn't sound very logical to me. Statements such as being able to see rifling on the outside of the barrel if held just right to the light, well ... I've seen that with at least one bolt rifle right out of the box so I don't put much value in those statements either.

In those short 5 years of shooting double rifles, I've fired a hell of a lot of bullets down range. A while back I said that I have never, fired a non-monometal bullet in any of my double rifles. Thinking back, I forgot that I got tired of waiting for my reloading dies when I purchased my 500NE and subsequently purchased a box of 10 A-Square Lion Loads. I shot 7 of them. Those are the only non-monometal bullets I've ever fired in my doubles. Absolutely no issues what so ever. The facts are that the monometal bullets of bore rider design (of which I place the TSX in that catagory as well), when tested, produce less barrel strain on the barrels than the conventional cup and core bullets. The notable exception off the top of my head being the TSX slightly above the Woodleigh Soft. All the North Forks were significantly below the Woodleigh Soft as well. So were the GSC bullets. With the CEBs being the lowest of all.

Dave,

PM sent.

Here's my opinion. It's your money, your rifle! You ought to shoot what you want to shoot.

quote:

Originally posted by Todd Williams:
Well, what it comes down to is whether you believe the "opinions" that have been passed down over the years or whether you believe the data that Michael and Sam have repeatedly demonstrated. That Hornady you seem to be happy with produces, consistently, in what ever caliber tested, the second and third highest barrel strains of all bullets tested.

Todd:

Go back and reread my post. When I was talking about Hornady bullets, I was talking about ordinary Interlocks, not the DGX or DGS bullets that are made of steel. The Interlocks are ordinary cup and core bullets and they don't produce much barrel strain and I think they are great practice bullets. I also think the plain old 286 grain Hornady 9,3 bullet would be a heck of a bullet for North American hunting with your 9,3X74R.

PM answered.

So what's your opinion of the Federal Trophy Bonded Bear Claws and Sledgehammers?

Mike:

Don't have any experience with the Bear Claws but have shot some Sledgehammers in a .375 bolt gun I used to have. I think the above posters are correct. In my doubles, I wouldn't hesitate to shoot most cup and core bullets. I love the Woodleigh softs, the North Fork solids, and the BBW#13s solids. I agree with Mac, I don't think these bullets will hurt the bore of even a vintage double. I would shoot the Woodleigh steel solid but why do so now when we have better alternatives from North Fork and CEB. Flat nose bullets seem to penetrate better and you don't have any feeding concerns with flat nose bullets in a double.

Gents:
At one time I put OSR in the same file as Elvis and UFO sightings. At SCI a few years back I saw it and held the rifle. Scary stuff to see a find double in such a sad state.

I think there are many variables here. It is not just bullets that are too hard but also the diameter must come into play and also velocity and/or pressure.

I have shot four boxes of Barnes Banded Solids in my Wilkes .600 with no problems. The bullets are .002 undersize (approximately) and shot to regulated velocity. I think if any bullet fits the bore, pressures can't reach the over stressed level. Now, if the Barnes bullets I shot were .002 oversized then I'd be in the danger zone.

I prefer traditional style bullets but it was an interesting experiment.
Cheers,
Cal

Cal

I'd add also the type of steel used in some of the early guns, around / after the turn of the century and the thickness of said barrels on top of all the other factors listed.

.

Well said Mac.!

quote:

Originally posted by cal pappas:


I have shot four boxes of Barnes Banded Solids in my Wilkes .600 with no problems. The bullets are .002 undersize (approximately) and shot to regulated velocity. I think if any bullet fits the bore, pressures can't reach the over stressed level. Now, if the Barnes bullets I shot were .002 oversized then I'd be in the danger zone.

Of course, if you shot Hornady bullets that were .002 oversized, then you'd still be in the same danger zone. However, I doubt that danger zone would cause the rifling to spit out the front of the barrel or even press the rifling through to the outside of the barrel. I'm thinking you would have a pressure problem that might split the barrel or cause stretching to the action, not OSR.

Also Cal, I think it of great importance to the credibility of the fellow you met with that he refused to go with you over to the Barnes booth and speak with them about it if it was truly caused by a Barnes bullet. Let's all remember the negative press the Barnes X bullet received across the board when it first hit the markets. IMO, that bad PR was more of a reaction by the other manufacturers realizing that a new concept had been introduced and that they were now going to have to catch up.

Interesting tidbit. Do a google search for OSR or Over Stressed Rifling. Check the first 10 pages or so of results. What you'll find is that 95% of the results are attributed to 2 people. Mac here on AR and his other name of Dougaboy on NE (I think that is it, sorry Mac if I don't have that one just exactly right), and 500 Grains both here on AR and NE. There is also Cal's one statement on it from the article he referred to above.

There really isn't much corroborating evidence of this phenomenon. Statements like "shooting the rifling out the end of the barrel" don't lend much credibility with me.

Let's think of it another way. The issue with barrel strains on a double is the fact that the two barrels are soldered together, right? Well, if there is an issue, it would be that excessive strain would cause damage to the solder joint. The issue isn't that excessive strain will cause the rifling to spit out the end of the barrel or cause the rifling to all of a sudden, appear on the outside of the barrel! If that was really a threat, why would that not also be an issue with a bolt gun. Does a solder joint down the length of the barrel all of a sudden put that barrel at risk of spitting the rifling out the muzzle? That's CRAZY talk! YMMV

Todd:
This post, like your others on a variety of subjects, are well thought out and also well written.
Cal

When I started collecting and shooting doubles in the late 80s and early 90's, I was impressed with the original "X" bullets and began loading these.

I had a Heym 470 double and after a while, the solder from the quarter rib leaked down into the breech and I had to have that rib resoldered. Did not realize at the time it might have been due to the bullets I was loading. I gave up on that "X" bullet as it also caused terrible copper fouling. Had to get an Outers electrolytic copper fouling removal setup to clean the barrels.

At the last SCI show I stopped at the Kreighoff booth on 2 different days and asked 2 different Kgun reps (I got their business cards) specifically about using Barnes monometal bullets, both expanding and solids in my 450/400.
The response I got back from both of the reps was the same.... as long as the ammo was properly constructed as to bullet diameter, velocity, pressure, over-all length, etc. there is absolutely no harm in shooting Barnes monometal or any other monometal bullet from their rifles.
In my opinion, Kreighoff should know what their guns will take and what they won't. If they say it's OK then I'll go with it.

I had to jump in,I have a Chapuis 9.3x74 that I will never shoot the Barnes TSX in ever again,my second day in Africa,on my first trip to Africa,I was shooting Barnes TSX loaded by Superior ammunition,the gun would not hit the side of a barn,it got to the point where the PH tested the gun himself,at 25 yrds we now had a gun that would not shoot worth s..t!
yes we now have all this wonderful data,but like Rusty said it's your gun and you shoot what you like,and I will not shoot those bullets again out of any double that I own,before anybody jumps on me for saying what I have just said,I will happily shoot some more as long as you cover my damage
BTW,my gun was re-regulated by JJ at Champlin Arms.

quote:

Originally posted by Todd Williams:

Of course, if you shot Hornady bullets that were .002 oversized, then you'd still be in the same danger zone. However, I doubt that danger zone would cause the rifling to spit out the front of the barrel or even press the rifling through to the outside of the barrel. I'm thinking you would have a pressure problem that might split the barrel or cause stretching to the action, not OSR.

Todd, There is a great difference between compressing a soft lead core jacketed bullet, that is .002 over and compressing a solid brass mono-metal bullet that has a baring surface that is groove diameter without thin pressure rings and wide spaces between them of a diameter between the rings being just under rifling depth so the displaced metal by the rifling engraving has a place to go! This seals the gas to push the bullet, but also reduces the strain on the barrel walls as well.

I have to agree, however, the SPITTING of the rifling out of the barrel is a bit far fetched, and like you I simply do not believe that! That much pressure would likely blow the barrel wall before that could happen. The shear factor would not allow a longitudinal separation, and would come miles closer to pressing the rifling beyond it’s ability the recover, or OSR. Not only that but Cal’s post, about that claim is the first time I ever heard that one.

It wouldn’t surprise me that if this had been simple OSR that the guys was reluctant to confront Barnes with it considering the flack one takes from everyone when even mentioning OSR. Even so, Barnes wouldn’t admit there was a problem with their bullet, but quietly change the format, which they ultimately did from the MONO-METAL SUPER SOLIDS!

quote:

Interesting tidbit. Do a Google search for OSR or Over Stressed Rifling. Check the first 10 pages or so of results. What you'll find is that 95% of the results are attributed to 2 people. Mac here on AR and his other name of Dougaboy1 on NE (I think that is it, sorry Mac if I don't have that one just exactly right), and 500 Grains both here on AR and NE. There is also Cal's one statement on it from the article he referred to above.

There really isn't much corroborating evidence of this phenomenon. Statements like "shooting the rifling out the end of the barrel" don't lend much credibility with me.

First off simply because 500Grains and I are the most vocal about this, is likely the reason that is all you found. The simple fact is there are many who have seen OSR firsthand, but are reluctant to post because of being beat down by those of an opposing opinion. Mark (400Nitro) was even run completely off the internet because of his OSR statements based on visual evidence. Evidence, I might add, that I saw as well. Graeme Write author of SHOOTING THE BRITISH DOUBLE RIFLE. Volumes 1, 2, and 3 is one who has made reference to and cautioned against OSR in all three of his books. The opposing opinion is based on nothing more to than if they haven’t seen it, it must not exist.

It is true that things like claiming of spitting of rifling out of the muzzles tends to question the credibility of the claimant. That however simply doesn't mean that OSR doesn't exist. Where is the evidence that it DOESN'T exist? You cant see something that doesn’t happen, but I assure you, it can be seen when it happens! There are very credible people who HAVE seen the result of OSR. IMO the fact that it has been seen by far more experienced folks than me, is not OPINION, but fact.

Which do you think is the more reliable evidence? Having seen doubles with OSR damage indicating it’s existence? or Never having seen an example of OSR indicating that it doesn’t exist? It must not exist if you have never seen it RIGHT?

As I have always said the only examples I've seen have been on Vintage doubles, and virtually all of those have had very thin barrels in the last 10 inches just behind the muzzles. Modern doubles and certainly bolt rifles, not only have modern alloys in very thick barrel walls all the way to the muzzles. But the steel is much more elastic.

quote:

Let's think of it another way. The issue with barrel strains on a double is the fact that the two barrels are soldered together, right? Well, if there is an issue, it would be that excessive strain would cause damage to the solder joint.

The solder joint has been an issue as well! One case was posted on AR about a new Chapuis double that came un-soldered and suddenly lost regulation. That NEW rifle was sent back to Chapuis for repair. It was repaired, and sent back to the owner! After a few shots it lost regulation again and was sent back to Chapuis a second time. The people at Chapuis asked what he had been shooting in the rifle. When the customer told them he was shooting mono-metal solids in the rifle he was told they were going to fix the rifle again, but if he shot the monos in it again he was on his own. That owner posted this here on AR several years ago, and his post may still be in the archives someplace! Personally I think in modern rifles the biggest danger is to the solder joint more than OSR to the barrels.

Todd is fully convinced that OSR is a myth because he has not seen pictures of it, or in fact the example he has seen he doesn’t believe the Mono-metal bullets that were improperly made caused it! That is his right, and he has every right to state it here. Cal. on the other hand, is not, IMO, totally convinced that it is a myth only that it is rare, and it is, thankfully. Nobody is required to agree with me on any matter!

Gentlemen nobody is telling you not use some mono-metal bullets in your double rifles, just improperly made ones and especially vintage doubles, all we/I’m doing is warning you there may be a problem if you do, and let you decide for yourself! Todd has had zero problem with using them in his double rifles, but as far as I know, his experience with this has been only from modern double rifles, like his Merkel 500NE which are modern steel, barrels quite thick all the way to the muzzles, and are cold hammer forged barrels, which could certainly be the reason for his success with the monos, maybe not but we don’t know that. In any event this is the last time I will address this subject on a public forum. Privately I will help any way I can, however!

............................................................................BYE!

Todd

I know of one Bolt action rifle that suffered OSR. The gun lives in Australia.

It was a 404 J, I think a custom on a Mauser
action. Not sure what caused it to occur on a BA barrel.

.

quote:

Originally posted by longfeather1:
At the last SCI show I stopped at the Kreighoff booth on 2 different days and asked 2 different Kgun reps (I got their business cards) specifically about using Barnes monometal bullets, both expanding and solids in my 450/400.
The response I got back from both of the reps was the same.... as long as the ammo was properly constructed as to bullet diameter, velocity, pressure, over-all length, etc. there is absolutely no harm in shooting Barnes monometal or any other monometal bullet from their rifles.
In my opinion, Kreighoff should know what their guns will take and what they won't. If they say it's OK then I'll go with it.

Did you talk to a Kreighoff employee or a representative from the dealer?

Mac, surely you aren't suggesting the necessity to prove a negative. That's impossible to do. That isn't the way things are done. You have this completely backward my friend. Phenomenon are not proven through the LACK of evidence; to the contrary.

There have been MANY sightings of Elvis working in a Dinner, or Liquor Store, bagging groceries, etc. over the years. But, no pictures of same. No credible evidence supporting it. Every time this comes up, the questions are asked, "Can you prove it? Got any pictures? Can I meet him?". "No, but that doesn't mean I didn't see him."! Yep, until Elvis goes on stage and sings "Suspicious Minds" again, I'm thinking he is dead. Just like this OSR theory!

What exactly does OSR stand for?

Acronym Definition
OSR Office of State Revenue (Australia)
OSR Oilseed Rape
OSR OEM Service Release
OSR Orchestre de La Suisse Romande
OSR Ontario Student Record
OSR Outside Sales Representative
OSR Office of School Readiness (various locales)
OSR Open Systems Resources, Inc (Amherst, NH)
OSR Oil Spill Response
OSR Operational Sex Ratio (biology)
OSR Operating Systems Review (ACM)
OSR Oversampling Ratio
OSR Ohio State Reformatory
OSR Office of Scientific Research
OSR Old San Antonio Road
OSR Overseas Service Ribbon
OSR Optical Solar Reflector
OSR Open Space Reservation (Indian real estate)
OSR Organization Systems Renewal
OSR Optical Scanning Recognition
OSR Off Side Rear (automotive engineering)
OSR Organization for SETV Research
OSR Ontario Southland Railway, Inc.
OSR Operational Safety Requirement
OSR Optical Service Router (Cisco Systems)
OSR Operational Safety Review
OSR On-Site Representative
OSR Optimized Set Reduction
OSR Oxidative Stress Relief
OSR One-Shot Rising
OSR Office of Systems Requirements
OSR Occupational Survey Report
OSR Ostrava Mosnov Czech Republic (airport code)
OSR Official Site Register
OSR Organisation Syndicale Représentative
OSR Ockanickon Scout Reservation (Pennsylvania Boy Scout Camp)
OSR Optical Subrack
OSR Onteora Scout Reservation (Livingston Manor, NY)
OSR Over Subscription Ratio
OSR On-Scene Representative
OSR Optimized Sniper Rifle (LaRue Tactical)
OSR One Step Routing
OSR Officer Selection Report
OSR Office of Standards and Regulation
OSR Optimum Sonar Routing
OSR Outlet Sales Report
OSR Oscillator Statistics Request
OSR Order of the Silver Ribbon
OSR Operational Support Requirement
OSR Original Sound Record Co. (record label)
OSR Out of Service Repair Tag (mining maintenance industry for sending repairable items off site and keep)
OSR Open Source Religion

Hey, what do you know, there is something called OSR!!

In this context, "Over Stressed Rifling"!

I kid you not! The suggestion that a bullet going down a barrel can cause the rifling to spit out the end of said barrel or at least cause the rifling to go from the inside of the barrel to the outside of the barrel along the length of said barrel. All supposedly due to a bullet being too hard to compress the rifling into and instead pushing the rifling out the end of the barrel or to the outside of the barrel. Sorry to repeat but it's just too good of a joke to only say it once!!

Anybody have a picture of this phenomenon. or is this kinda like waiting for a democrap to tell the truth...

quote:

There have been MANY sightings of Elvis working in a Dinner, or Liquor Store, bagging groceries, etc. over the years. But, no pictures of same.

I saw ELVIS IN SOUTH AFRICA, a few years ago! I DID! I AIN"T KIDDING!

My wife and I were driving down to visit her dad on the coast, and sure enough, we were going through one of the villages and he was walking down the side of the road! He had the fancy White Elvis outfit on! Hey, I saw this with my own eyes, or I would not be saying it here! He just went to South Africa and become black! Its true!



I apologize, I could not help myself!

Now I will leave!
Michael

Jorge

It is damn hard to photograph - well, the one's I have seen are.

Some are only visible if held to the light a certain way.

Michael,
Next time you are in Houston, give me a shout. Be glad to show you my Hollis.

I'll let you make a report to the forum.

FWIW, I can think of three examples I've seen first hand.

One that belongs to a member here (the one Cal saw in our booth with Graeme Wright), plus two others that do not belong to members here.

It looks like the stripes around a candy-cane, and is quite easy to spot once you know what you're looking for.

quote:

Originally posted by Rusty:
Michael,
Next time you are in Houston, give me a shout. Be glad to show you my Hollis.

I'll let you make a report to the forum.

I'd be honored!

HEH....

Enjoy boys, I will go back to something I know about, but I did see Elvis!

LOL........

Michael,

I didn't realize that they had that much saki in South Africa!

465H&H

I have personaly seen, what is termed OSR [Over Stressed Rifling] on several different double rifles.

OSR is definately real.

I also know of double rifles that have had the solder between the barrel and the rib broken loose when shooting some Monolithic bullets.

I have recovered North Fork Mono Solids shot in my 450 No2 and the shank of the bullet does not touch the rifling, so I consider them safe to shoot in my gun.

The Chapuis Mac talks about in his post was a 9,3x74R, owned by a fella in Australia.

After sending it back the second time Chapuis learned from the owner he was shooting the 286gr Barnes X bullet.

They told him not to shoot X bullets, ANY MORE.

This was before the newer banded X bullets, but I do not have any experience with them.

The Chapuis 9,3x74R is very suspectable to this because their barrels are thinner than most other 9,3x74R double rifles. I have a 9,3x74R Chapuis, and these thin barrels contribute to its light weight and ease of carrying it.

Just use Woodleigh Softs and Solids and Nosler Partitions and you will kill everything you shoot with no problems.

I have a Chapuis 9.3x74R as well. I've probably fired somewhere around 400 rounds through it now. Each round has either been a Barnes Banded Solid, TSX or CEB BBW#13 or Non-Con. No problems at all.

In fact, I just sat back down at my computer from a session at the range where I fired 20 additional CEB monolithic bullets through it in prep for my hunt in 3 weeks. It is shooting just fine and all is well!!

I'm out of here!! See Ya Boys!!!

Todd

The bullets you are shooting in your Chapuis may be fine, I have not tried them in my Chapuis.

But try this.

Wipe down the outside of your barrels real good, then look down them from the chamber end and hold them up to a strong light, checking for "candy cane" circular stripes on the outside of the barrels.

Not saying those bullets will cause OSR, but that is how you check for it.

Does OSR exist? If knowledgable guys like Mac, Cal, and N E 450 No2 tell me it does, I believe them. However, I think the jury is still out on what may cause it. With vintage guns, perhaps some guys are not slugging their bores and thus, not shooting bullets of the correct size. I would not, under any circumstance, shoot one of the old Barnes bullets in my double. I think most of the newer monometals, especially the North Fork bullets, are safe to shoot in most any double.

Todd, I think N E 450 No2 makes a good point about the Chapuis. The Chapuis barrels are thinner than most. That's why it is such a joy to carry. In my Chapuis, I shoot Hornady Interlocks at the range. For hunting, it would be a Woodleigh soft but I would not be concerned about shooting a NF solid or cup point solid.

Todd does make a good point about bolt rifles. I have never seen or even heard of a case of OSR in a bolt gun. I have shot lots of Barnes TSX and banded solids in my bolt guns without incident. Perhaps they are indeed safe in a double but then again, in a bolt gun, you don't have to worry about the solder at the joints.

quote:

I have never seen or even heard of a case of OSR in a bolt gun.

Dave

Maybe you need to read up the page a bit where I mention the 404 bolt action.

.

quote:

Originally posted by 505G:

quote:

I have never seen or even heard of a case of OSR in a bolt gun.

Dave

Maybe you need to read up the page a bit where I mention the 404 bolt action.

.

Sorry guy, didn't see your post.

Just got home, had 2 sips of Laphroaig Single Malt Scotch, and I had a sudden epiphany...

Maybe the reason that OSR is more commonly seen on double rifles, rather than bolt rifles, is BECAUSE the barrels are soldered together.

Think about this, in a bolt rifle the byllket goes down the barrel and the barrel expands as the bullet procedes down it in an equal amount around its diameter.

A double on the other hand has one section of the barrel soldered to a stiff rib, which is soldered to abother stiff barrel.

So when a bullet goes down a double rifle barrel the barrel cannot expand in a concentric manner. The stress of the expansion takes the path of least resistance, ie the part of the barrel away from the soldered rib [most doubles have a 2 piece rib top and bottom], so it expands more than the area soldered between the ribs. If a bullet is oversize or has a thick steel jacket, or a full diameter monometal bullet, extra force is transfered to the rifling causing it to transfer its shape to the outside of the barrel.

Many double rifles that had OSR have been "filed" down to remove the signs of OSR and the barrel is then reblackened.

Personally I do not think striking down the barrels is a good idea as it removes metal from the outside of the barrel making matters worse, IMHO.

NE 450

I think a lot of people would not see OSR unless it was pointed out to them.

A gun can have OSR and it not be very noticeable
- having seen it on a couple.

505G

You are exactly right.

Also I can see how if any bolt rifle was to have OSR it would be a vintage 404 Jeffery, with a German barrel.

Back in the day many of the 404 barrels were under .423 diameter, some way under. The bullets of the day were tapered and only the rear part of the bullet was .423.
So they swaged down and no damage was done.

Fast foward toward modern times when the entire driving surface of the bullet was .423, and thicker steel jacket solids became the norm, and later the Monometal bullets.

Results OSR in a 404 Jeffery...

Also vitage 450/400 doubles are prime for OSR.

There are two different 450/400's.

The 450/400 3 1/4", usually with .408 diameter barrels, and the 450/400 3", also called the 400 Jeffery, usually with .411 inch barrels.

As you can imagine many times the "wrong" barrel diameter has been used on these 450/400's. Barrels were sometimes not in "spec" to start with and 450/400's have been documented with barrels as small as .406.

In FACT I know of one 450/400 double that has one .408 barrel and one .411 barrel.

So if you shoot a lot of hard .411 bullets in a .408 barrel, it can lead to OSR.

When the 450/400 3" was trying to get CIP certified, there was some Drama over what the barrel, and bullet diameters should be standardized at.

They were set at .410, and Hornady 400 cal bullets for the 450/400 3" are .410 diameter.

So if you have a vintage British 450/400 either 3 1/4" or #' you petter have the barrels properly slugged, BOTH OF THEM, so you know what diameter bullets to use...