Barrel threading

I would not like to rely upon that after all 1/2" is 12.7mm so at most you will have only 0.020" shoulder that's 0.5mm. it would probably work with a spigot for the moderator to align onto but your asking a lot of that twenty thou IMHO.
 
This is a good case for a close tolerance spigot mod fitment as Brithunter said. - A thin whippy barrel can often encourage the mod to unscrew if there is not enough shoulder face area to lock up on, -- wobbly mod soon knackers the threads making it worse still -- accuracy then suffers & there is a stronger likelyhood of an accident/breakage.
An option may be there to shorten the barrel to leave more shoulder - or my favourite, don't fit a mod.

Ian
 
You'll get away with a 21" barrel on this with no discernible loss of velocity or accuracy. I recently reduced the barrel on a 243 wssm and it shoots very well. If you measure the barrel back at 21" you may find you'll gain a slightly better dia for a good shoulder, as said, a spigot would work fine but isn't necessary if your shoulder suitable.
I would also opt for either a 14x1 or 1/2" unef 28 Tpi.
 
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I'd have it threaded at ½ x28 with a spigot, you could use any moderator that has a removable
thread unit.

Neil. :)
 
You'll get away with a 21" barrel on this with no discernible loss of velocity or accuracy. I recently reduced the barrel on a 243 wssm and it shoots very well. If you measure the barrel back at 21" you may find you'll gain a slightly better dia for a good shoulder, as said, a spigot would work fine but isn't necessary if your shoulder suitable.
I would also opt for either a 14x1 or 1/2" unef 28 Tpi.

+1 Fully agree with James
 
can someone explain about a spigot.

Try this first which thread for mod on browning x-bolt 308 win
Then you will find the thread specs on the Jackson Rifle web page.
A spigot thread can be done in any size you like, the stumbling block is the moderator.
Any of the mod's with a removable thread section could be used, either by getting a blank
thread unit to machine at the same time as the barrel is threaded, or by ordering a special.

Neil. :)
 
A good thread cut by some one who knows what they are doing does not need a spigot to align it, it aslo does not need a shoulder for the mod to butt up against, you cant screw a mod on any further then the thread length allows.

Ian.
 
A good thread cut by some one who knows what they are doing does not need a spigot to align it, it aslo does not need a shoulder for the mod to butt up against, you cant screw a mod on any further then the thread length allows.

Ian.

Unfortunately there are a lot of "gunsmiths" out there that will take a short cut and not remove the barrel to cut the threads between centers on a lathe.

SS
 
A good thread cut by some one who knows what they are doing does not need a spigot to align it, it aslo does not need a shoulder for the mod to butt up against, you cant screw a mod on any further then the thread length allows.

Ian.

i agree whole heartedly regarding spigots, not necessary at all if you cut your thread to within a thou and everything is dialed in. however, not having a shoulder to butt up against means the thread is running into the unthreaded portion of the barrel and is going to pinch the barrel and damaged the moderator thread. i'm not saying it wouldn't be functional, but it's not something i'd be happy with.
 
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