I’m building a precision rifle chambered in 300 win mag and want to get a barrel threaded for it. Before buying said barrel I want to make sure it’s thick enough to support 5/8x24 threads. So my question is what is the minimum thickness the barrel has to be so I can get it threaded in 5/8x24?
Barrel thickness for threading
- Thread starter D_behrnes
- Start date
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I guess a better question would be what’s a safe wall thickness after threading and the thread depth would take from this as well I’m assuming? The barrel I’m looking at is .695 would that still leave me enough meat to not have to worry about ruining the bore when installing the muzzle brake (torque pressure on a thin barrel after threading)or it just breaking at the threads if the rifle were to fall
Ignore I’m not mistaking the thickness of the barrel at the muzzle after threading should be .317. Although I’m not sure how deep the threads go regardless that should give me more than enough meat to be in the safe zone right? Just need some more knowledge people than me to weigh in on this
The minimum diameter is 0.6166, that's the bottom of the thread "V". If your barrel is .695 you should be OK. The barrel will have to be turned down to slightly above .623, then threaded on the lathe. For a .300 Win Mag you'll have plenty of meat left. After all, 5/8-24 is the standard thread for .30 cal cans.
Hopefully your bore is concentric. I've done a couple where the bore was slightly off center of the barrel. For those, I had to use the 4-jaw chuck and index off of the bore to turn the barrel down. What a pain.
Hopefully your bore is concentric. I've done a couple where the bore was slightly off center of the barrel. For those, I had to use the 4-jaw chuck and index off of the bore to turn the barrel down. What a pain.
bigjakewelch
Mill Spec
I only use a 4 jaw, and a tapered mandrel with a live bore pilot and 2 indicators. I have worked with some factory barrels that were over 25thou out. The only question I would ask is, are you threading it for a break, or a can? If it's for a break them as long as you have sufficient barrel for your major diameter and around 0.030" overall extra ( so you have something to taper your break into after It's timed) then you're golden. If it's a can, then you're going to need a shoulder to bind on. You'll need to check the can to see how sharp the lead edge/thread is ( be sure it's not chamfered 0.065" or anything like that) that way you know how tall your shoulder has to be to shoulder up. You should cut your threads to at least a class 2A even if it's just a break, to be sure that if you ever decided to run a can on it you wouldn't have to worry about loose threads and baffle strikes. Good luck.
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Last edited:
Bigjakewelch,
Another machinist!
Oh, ten years or so ago, a co-worker's son was getting old enough to start deer hunting. So he bought a used low end Remington .308 at a pawn shop. They couldn't hit anything with it and he asked if I'd check it over. The barrel was bulged right under the front sight, well we know what's wrong with it. Easy fix except that I have a 9x19 lathe, the barrel wouldn't go through the spindle. After some head scratching, I cobbled the barreled action up on the milling machine with the center of the bore exactly parallel to the table. Then I milled the barrel off just behind the bulge. I crowned the barrel by hand and cold blued it. He said not to bother with a front sight, it would be scope only, so I pulled the rear sight too. I also remounted the scope from the receiver up. His son took a buck and two does the first year, he didn't hit any with his .300 Win Mag. His son has taken deer every year with that rifle.
It's always fun when someone brings over a job and they realize how long it can take to set up just to drill and tap a hole. One guy was fussing so I asked him, "Do you want it done done fast or done right?" He sat down and shut up!
Another machinist!
Oh, ten years or so ago, a co-worker's son was getting old enough to start deer hunting. So he bought a used low end Remington .308 at a pawn shop. They couldn't hit anything with it and he asked if I'd check it over. The barrel was bulged right under the front sight, well we know what's wrong with it. Easy fix except that I have a 9x19 lathe, the barrel wouldn't go through the spindle. After some head scratching, I cobbled the barreled action up on the milling machine with the center of the bore exactly parallel to the table. Then I milled the barrel off just behind the bulge. I crowned the barrel by hand and cold blued it. He said not to bother with a front sight, it would be scope only, so I pulled the rear sight too. I also remounted the scope from the receiver up. His son took a buck and two does the first year, he didn't hit any with his .300 Win Mag. His son has taken deer every year with that rifle.
It's always fun when someone brings over a job and they realize how long it can take to set up just to drill and tap a hole. One guy was fussing so I asked him, "Do you want it done done fast or done right?" He sat down and shut up!
