A lot of rifles come to us for a rebarrel because the owner wants something shorter, lighter and handier than the factory tube. Almost every one of those customers asks the same question first: how much velocity am I going to give up? The honest answer is that the internet's favourite numbers, usually somewhere between 25 and 50 feet per second per inch, are a rough average that hides huge variation between cartridges. Cut four inches off one rifle and you will barely notice. Cut four inches off another and you have changed its effective range by a hundred yards.
Here are the numbers we work from, where they come from, and the other effects of shortening that matter more than most shooters expect.
When a cartridge fires, the propellant burns and produces gas pressure that accelerates the bullet down the bore. Peak pressure arrives early, within a few inches of travel, but the gas keeps expanding and keeps pushing for as long as the bullet remains in the barrel and the pressure behind it stays above the friction holding the bullet back. Each additional inch of barrel is another inch of push. The catch is that the push is not constant: pressure falls fast as the volume behind the bullet grows, so the first inches of barrel are worth far more than the last ones.
That is why velocity loss per inch is not a fixed number. Near the muzzle, the gas pressure in a .308 might be down to a few thousand psi, so the final inches contribute little. In a big overbore case burning 80 plus grains of slow powder, like a .26 Nosler or .300 Remington Ultra Mag, there is still meaningful pressure at 24 inches, so every inch cut takes a real bite.
These are the bands we quote when a customer is deciding how much tube to keep. They come from published load data across barrel lengths and from chronograph work on customers' rifles before and after cuts on our own bench. Treat them as planning figures, not guarantees, because individual loads and powder choices move them.
The pattern is simple: the more powder the case burns relative to its bore, the more each inch is worth. Underbore cases like the .308 tolerate shortening well. Overbore magnums do not.
Velocity is only the first line of the ledger. Shortening a barrel also does the following.
Handling improves more than the inch count suggests. Weight comes off the front of the rifle where it matters for balance, and the rifle swings and carries better. A 20 inch 6.5 Creedmoor with a moderate contour is a genuinely nicer rifle to walk all day with than the 24 inch pencil it replaced.
Muzzle blast and flash increase. Short barrels vent gas at higher pressure. On a magnum cut to 20 inches, shooters beside you will notice, and you will too without hearing protection, which you should wear regardless. If the rifle is getting a muzzle brake or suppressor anyway, the blast question mostly answers itself, and a suppressor adds back length and a little weight.
Velocity spread usually stays fine, but verify. Cutting and re-crowning does not inherently hurt precision. We have seen short barrels shoot as well as long ones consistently. What occasionally changes is the load: a barrel of a different length shifts the pressure and timing slightly, and a load that shot well before may need re-developed. Budget a few range sessions with your old loads before assuming anything is wrong with the steel.
Sight radius and velocity assumptions in your ballistics app change. If you shoot with iron sights, the shorter radius costs practical accuracy. If you use a rangefinder and ballistic solver, the drop chart must be rebuilt around the new chronograph figures, not the old ones.
For a general sporting rifle, 20 inches is the sweet spot for .308 and 6.5 Creedmoor: handling improves, you lose well under 100 fps, and the cartridge's character survives. Sixteen inches works for .223 and .308 if the rifle is meant for dense cover or vehicle work, and it is the practical floor before blast and flash start to dominate. Keep magnums at 24 inches or accept that you are converting them into something closer to a standard cartridge with a bigger powder bill.
There is also a length worth keeping for the future: if you may ever want to thread the muzzle for a suppressor, leave enough material that a thread job does not force the barrel below your acceptable minimum. Cutting twice is always an option, and the first cut is cheap. Adding steel back requires a full rebarrel, which brings us to the real point.
If your existing barrel is accurate and you simply want it shorter, a cut and re-crown is a modest bench job. But if the barrel is worn, or you are ordering new steel anyway, specify the finished length up front. Ordering a 26 inch blank and cutting it to 20 throws away barrel you paid for, yet it is sometimes the right call because it lets you finalise length after test firing. Ordering a pre-shortened premium blank in 416R, which we compare against chrome-moly in our steel writeup, keeps costs down and stiffness high.
Length also interacts with the other specification you are choosing at the same time: contour. A shorter barrel of the same contour is stiffer and handles heat differently, which we cover in our piece on contours and fluting. And if you are shortening because the barrel is at the end of its life, read our barrel life guide first so you know whether a cut is postponing the inevitable.
Come to the conversation with two numbers: the shortest length you would genuinely be happy with, and the velocity floor your shooting actually requires. Between those, the right length is usually obvious. To talk it through, use the enquiry page or read through the process first.