Rastoff
US Veteran
Thanks gents. Some very good info here. Allow me to add some info that might help narrow things down even more.
This new build, should I actually get it off the ground, will be a .223Rem (or 5.56 NATO, but want to stick with Rem pressures) caliber. The max distance I intend for this will be 500 yards. To go further, I have a .308Win bolt gun. It will be used mostly off a bench or prone. I already have a couple 16" guns and one 20", but none are anything special. So, if I'm going to drop some coin on a barrel, I want to wring out the best I can for my $$.
Since I already have a 16" gun that works fine for less than 200 yards, I thought I'd build a more precision piece. Thus the question about length.
There is another aspect when it comes to shot shells; powder to ejecta mass ratio. Just because you have a long barrel doesn't mean you'll burn all the powder. The pressure built by the powder ignition and ejecta mass needs to be matched to get a complete burn. If the ejecta mass is too small, not all the powder is burned. If the mass is too large, all the powder is burned, but not effectively used. The goal would be to have the powder charge match the ejecta mass. Shotguns are not precision tools. Therefore, if this ratio is not found, it makes little difference to the performance of the shotgun. So, most shotgun guys don't care about this. However, I expect that it's something a rifle shooter would try very hard to achieve.
So, the question on my mind is, how long does it take to burn all the powder in a .223 shell? How do you find that sweet spot where the powder charge is right for a certain bullet mass?
This new build, should I actually get it off the ground, will be a .223Rem (or 5.56 NATO, but want to stick with Rem pressures) caliber. The max distance I intend for this will be 500 yards. To go further, I have a .308Win bolt gun. It will be used mostly off a bench or prone. I already have a couple 16" guns and one 20", but none are anything special. So, if I'm going to drop some coin on a barrel, I want to wring out the best I can for my $$.
Since I already have a 16" gun that works fine for less than 200 yards, I thought I'd build a more precision piece. Thus the question about length.
Well, I'm still learning about rifles, but for shotguns, longer does not deliver more accuracy. You see for the average shot shell, the powder is all burned by the time the ejecta reaches 22"-24" down the barrel. So, more length than that doesn't give you any advantage as far as ballistics are concerned. There are other advantages, but that's not part of this thread.It's the same as shotguns (or handguns). Longer barrel is generally more accurate, all things else being equal.
There is another aspect when it comes to shot shells; powder to ejecta mass ratio. Just because you have a long barrel doesn't mean you'll burn all the powder. The pressure built by the powder ignition and ejecta mass needs to be matched to get a complete burn. If the ejecta mass is too small, not all the powder is burned. If the mass is too large, all the powder is burned, but not effectively used. The goal would be to have the powder charge match the ejecta mass. Shotguns are not precision tools. Therefore, if this ratio is not found, it makes little difference to the performance of the shotgun. So, most shotgun guys don't care about this. However, I expect that it's something a rifle shooter would try very hard to achieve.
So, the question on my mind is, how long does it take to burn all the powder in a .223 shell? How do you find that sweet spot where the powder charge is right for a certain bullet mass?