quote:

Originally posted by michael458:
Right Or Wrong?

Do you think it boils down that easy? I think not. Most of it comes to personal preference, objectives based on personal experiences, along with a mixed bag of some factual data.

Above all, regardless of what barrel length you choose, somewhere in the mix there will always be this;

Compromise! or possibly a better term is Trade Off

Define "trade off"

a balance achieved between two desirable but incompatible features; a compromise


Trade off and compromise is in nearly any aspect of shooting that I can think of.

I don't know much about double rifles, never claimed to. What I do know is that the break open action of a double is weaker than your standard bolt gun. We figure here based on the test work that Sam and I have done with pressure gages that somewhere in the area of 45000 PSI is max safe pressures for day in day out use. For your standard Win M70 big bore I figure 65000 PSI max safe pressure, but normally run somewhere between 60000 and 65000. Cartridges sometimes can be a limiting factor as well, I am speaking now in general terms.

The big bore Nitro Cartridges traditionally run bullets lets say at or around 2150 fps, most of that is based on I believe 26 inches of barrel. Because of the limiting pressures, powders, cartridge design, and many other small factors when you start loosing barrel normally you start loosing 40-50 fps per inch. By the time you are down to say 20 inches you may be down to 1900 fps or so, depending on many of those factors. Now, with proper bullets, 1900 is ok, but still 2100 is better almost in all cases. Do you need a 20 inch double? Stock length and other variables of course come to play, but a 23-24 inch double should be about the same Overall Length as a 20 inch bolt gun, or there abouts. We cannot increase powder charges, pressure limitations, so it is difficult to get the efficiency from the big nitro cartridges based on these actions. Manipulation of modern powders, primers, and other factors can assist, but the biggest issue is the Pressure Limitations of the action.

I am sure there are other factors that I don't know, or forgot, but very little that will be of any consequence.

Cartridge Efficiency???? Is there such a thing? When the short WSMs and RUMs and things like that came on board, I did not buy into that mumbo jumbo very much, and did not pay it much attention. To this day, when you go below 338 caliber, I still think its a rather moot point. It is there, there is some degree of Efficiency in a shorter fatter cartridge, but it absolutely begins to diminish as bore size goes down. What I found, with shorter fatter cases as bore size increases, then so does the efficiency of that cartridge. And I have followed that from calibers 9.3 to .500 and seen it first hand.

In some of my efforts to get a shorter barrel "effective" big bore, I have cut down 416 Remingtons, 458 Winchesters, 458 Lott, 470 Capstick from 24 to 21 and 22 inches. All these of course are H&H based cases. Compared to the 404 Jeff, and now the big RUM cases, the H&H based cases are much smaller in diameter, powder column is taller and narrower. With 458 Lott and 458 Winchester I lost on average 50 fps per inch, Same with the 470 Capstick, just slightly more with the 416 Remington at 60 fps per inch. All this was still a reasonable trade off, or compromise for me, as I was still running big bore bullets at reasonable velocities. I lost the most with 458 Winchester, but compromised by dropping bullet weights.

With the coming of the RUM and WSM cases, loosely based on the old 404 Jeff diameters, I started cutting and testing. I was amazed at the unexpected results. I figured 20 inches of barrel with a 2.25 inch case in .458 caliber would be needed to get desired results, case capacity equal to the 2.5 inch 458 Win Case. I expected less than 458 Winchester results. What I got in 20 inches exceeded 458 Winchester, and taking two more inches off the barrel made it equal 458 Winchester. I did not expect that. In 458, 474, and .500 caliber the loss in velocity per inch of barrel was running between 10 or less, to 15 fps with most any given load. Hell of a reduction in velocity loss, and opened up options. As I dropped to 416 caliber this efficiency started to diminish somewhat. With lighter bullets, from 300-350 I saw losses back to 30-50 fps depending on powder, bullet, and these sort of factors. With some of the 400 gr loads I saw less velocity loss, and in one case, no loss at all in going from 20 inch standard to 18 inches. As caliber dropped to 9.3 losses again increased to levels around 50 fps or more, per inch. All this with the same 2.25 inch RUM case, only change was caliber. So as caliber increased, we increased the cubic inches of burning area inside the barrel, therefore increasing the efficiency rate with roughly the same amount of powder being burned, which again is perfectly logical.

With the various AR cartridges designed by Jeffe here, this exact same efficiency is seen, and he can obtain 458 Lott velocities I am quite sure in 20 inches of 458 caliber barrel. The AR cartridge is 2.65 inches overall length.

Compromise and Trade Off.

1. Large capacity cartridges, such as 460 Weatherby, burns a lot of powder, and certain lengths of barrel is needed to increase inside cubic inches of burning space. How much, I don't exactly know, since I have never messed with 460 Weatherby, but you cannot expect 2500 fps with an 18 inch barrel, that I know. Large capacity cartridges like this also require bigger actions, longer barrels, and there is no getting around that. How much barrel length you want is a compromise. Shorter barrel, less velocity, some say less performance. Longer barrel, more to carry around. Depends on what you want.

2. Caliber Choice. For a fact, more inside cubic inches of barrel burn increases efficiency. As caliber increases, you can get away with less barrel length, practically regardless of cartridge. As caliber decreases, so does your options for barrel length.

3. Cartridge Choice and Action Choice. No doubt about it, either can regulate just how much or how little your compromise needs to be, and still accomplish the mission. As I know for a fact, you can't go but so short with the barrel, with some cartridge designs before you enter into an area that may start to compromise your mission. Same with choice of action, limited by pressure limitations.

So it all depends on the performance levels that you wish to achieve, and what your mission might require, your bullet might require, or any other number of factors that can determine your desired barrel length.

Sure, some of us who like the shorter barrel rifles, we would gain performance with longer barrels, at least to a point. But, I am more than willing to compromise or trade off what little could be gained in the area of performance by enhancing other attributes of performance by bullet choice and cartridge design, and still keep the portability and handiness of the short rifle.

Those who like the longer barrels may not be willing to make that compromise, and there is nothing wrong with that either. Right or Wrong, really is not relevant in this discussion. Again, personal preference, objectives based on personal experience, and add some factual data to mix it up. Right or Wrong has little to do with it. Like it or not.

Now before the argument breaks out, most everything I said was in general terms, and not specific to one thing or another. Some of the data going from memory, but is close, and I can look it up, if not exactly dead spot on correct. Surely we can speak in general terms without having to fight about some things. And if I am incorrect on any one thing, then that is fine too, I have no problem at all admitting I was wrong about something, there are a hell of a lot of things I DON"T KNOW, and most of those things, I have little comment on, but there are some things that I do know, and know from factual repeatable data gathered over the years.

Michael

quote:

Originally posted by Pyzda:
To get the desired (decent) velocity in a rifle with 16-18" barrel would/could only be done with a purposely designed cartridge.

Something like Michael have done with his line of B&M's. Otherwise you can forget it.

If there was a booming market for 16-18" barreled rifles and the Powder manufacturers would joined the party it would be a different story.

It would need a special fast burning very progressive powder to burn completely in 16-18" tube and not exceed the safe pressure limit.

It probably may be possible to do something similar with duplex/triplex loads, BUT NOT FOR ME, thanks.

With cartridges designed for 24"-26" barrels to cut the barrel down to the 16-18" is plain stupid.

Pyzda

quote:

Originally posted by Pyzda:
It would need a special fast burning very progressive powder to burn completely in 16-18" tube and not exceed the safe pressure limit.

quote:

It probably may be possible to do something similar with duplex/triplex loads, BUT NOT FOR ME, thanks.

quote:

With cartridges designed for 24"-26" barrels to cut the barrel down to the 16-18" is plain stupid.

quote:

Originally posted by Pyzda:
Capoward

If you would have to have an 18" barreled bolt action, What would be your 1st. or 2nd. choice?

Thanks
Pyzda

Jim
"Life's hard; it's harder if you're stupid"
John Wayne

quote:

Originally posted by michael458:
[QUOTE]You take all the apple pie you want, i got more here for you!

quote:

Originally posted by boom stick:
For legality and cost to horsepower the 12GFH is king.
A rimless repeater is a fun concept I think.
The think BMG brass is fun to get creative with.
I wonder if possible and how hard it would be to get a 460 WBY single stack to work with BMG brass.