Measuring to cut my barrels.

[Benmuncie]

I have 2 rifles that are both 308. One is a sporter barrel and one is varmint barrel. I am going to cut them down and also thread the varmint barrel. I am wondering where the correct place is to begin measuring. If someone says they have an 18 inch barrel, is that 18 inches overall length, or 18 inches from the end of the barrel nut threads, or from some other place?
Thanks for your help.

[Hersh5317]

Measure from the face of the bolt when headspace is set and the bolt is closed for length installed. For uninstalled barrels, measure from breach face toward muzzle.

[Benmuncie]

Thank you.

[FW Conch]

You can go down to 16 inches on a rifle. If You do so, be sure to use the breach face method, or stay at least at 161/2", just to be safe.

The Fed's measure barrel length by putting a rod down the barrel to the breech face and measure to the barrel crown.

If a muzzle devise is used, like a break, it can be included in the length, "if it is permanently attached". Pinned, welded, etc. Don't mess this up. The Fed's take their stuff very seriously. Just ask Randy Weaver.

[RC20]

Tradition (and Fed) the RIFLE barrel is measured for the full length from one end to the other. Threads and all. 1/2 inch safety factor is a IMPORTANT and should be mandatory to stay out of any possible trouble.


annoying when you really want to know how much actual bullet travel you have and how that translates to velocity.

A 7mm is going to have less real working length than a 308 (does more with less)

A revolver is measured by its barrel.


A semi auto is back to the whole length.

Logic seems to be if the chamber is integral tot he barrel its included.

[Benmuncie]

Thanks for all of your input. RC20, your comparison of 7mm and 308 was where I talked myself out of overall length and thought I should ask. (I am in the process of trying to talk myself out of getting a 7mm mag). I thought that maybe the feds have a way of measuring the barrel that accounted for different calibers. I guess not :-)

[FW Conch]

Rifle= breach face to muzzle end, measured with a rod down the bore, must be at least 16". Believe it!

I would not want a 7mm Mag with less than a 24" barrel. There are much better choices for short barrels.

[RC20]

The OP is talking 308, not 7mm. That was just an extreme example of how different it can be for the same measured barrel.

22 inches seems to be the shortest realist barrel length for a 308.

[FW Conch]

Depends on what you want to do with the 308Win. I have one 16.5"s total length barrel that works just fine for Me out to 300yds.

[squirrel_slayer]

I shoot my 18.5 to 950 with good success. it will shoot 208 amax's at 2525 loaded long with 2000mr which is supersonic to ~1400yds. just got alot of practice ahead of me to get out there.

I cut down a 300wm sporter to 20" just for fun and threaded/recrowned it. I just used the cleaning rod method. close bolt drop cleaning rod down bore, put a piece of masking tape on rod, remove rod, measure to the tape, subtract amount to get to desired length, mark, then cut away. remember measure twice, cut once. :eagerness:

[Benmuncie]

My model 12 is not back from savage (bad barrel) so I have not been able to cut it down yet. I have looked at a lot of competitive shooters' setups and noticed that long barrels are common. If shorter barrels provide more consistent shots (all other things being equal) and the velocity drop is minor, why do competitive shooters have longer barrels instead of shorter barrels. I'm not trying to start an argument. I just want to be 100 percent sure because I am not very good at stretching barrels back to full length if I realize I made a mistake cutting it down. :-)

[RC20]

Good question. I like 26 inch for the stability (weight)

[ninner]

When I thread and crown sporter barrels I usually cut at 18" to make sure there is enough meat to tighten the brake against. That and I still have plenty of room if I screw up hand threading the barrel. My Chinese lathe sucks at cutting threads.

[big honkin jeep]

My model 12 is not back from savage (bad barrel) so I have not been able to cut it down yet. I have looked at a lot of competitive shooters' setups and noticed that long barrels are common. If shorter barrels provide more consistent shots (all other things being equal) and the velocity drop is minor, why do competitive shooters have longer barrels instead of shorter barrels. I'm not trying to start an argument. I just want to be 100 percent sure because I am not very good at stretching barrels back to full length if I realize I made a mistake cutting it down. :-)

They shoot longer barrels for the additional velocity. Several articles I read before cutting one down say that 20FPS per inch is pretty close to a constant and they backed this up by cutting down a barrel 1 inch at a time and checking using federal gold medal match. I have not done it this way myself to check their claimed results, but do have a sporter I cut down to 16" and I couldn't be happier with the results. It's really easy to read and analyze way way too much on the internet.
The kick in the pants I needed to move me forward was just looking at the real results some guys are getting with 12" and 14" striker handguns. I saw some well documented very impressive results on targets at 600. I figured if they could shoot their handguns like that at 600 yards, Then surely my little carbine project for what needs killing around the farm, and a super handy truck/tractor grab and go carbine would be a success. Man, I absolutely love the resulting lightweight short powerful rifle that resulted. I like it so much I'll probably do another in a right handed version just as a project soon. For all the hype surrounding the negative effects of "velocity loss" please nobody tell anything in the cross hairs that it doesn't have worry cause my barrel is too short.

[rosewood]

A longer barrel gets more velocity. Also, it is easier to hold steady on a rest as it has a greater moment of inertia and more resistant to movement. However, a longer barrel is less stiff and more prone to vibrations which affect point of impact. Also a longer barrel is more difficult to cut the rifling consistently as you have more chances for error. A shorter barrel is stiffer and most likely more accurate in itself than a longer one. However, the improvement of the shorter barrel accuracy may not outweigh your ability to hold it steady. So one person may shoot the longer barrel better and someone else may be better with a shorter one. It seems to me the shorter barrels are easier to find an accurate load than the long barrels which I attribute to the stiffness.

Rosewood

[RC20]

The "Secrets of the Houston warehouse claimed that 20 3/4 (or closer to that) inches was optimum barrel length for accuracy.

May well be valid.

[earl39]

The "Secrets of the Houston warehouse claimed that 20 3/4 (or closer to that) inches was optimum barrel length for accuracy.

May well be valid.

For that particular cartridge.

[Robinhood]

[QUOTE=earl39;389910]For that particular cartridge.[/QUOTE ]

with no wind and short range.