Thread cutting - what size?

[charliefox]

Morning All

I have a BSA Monarch 2nd pattern in .270 Win in it's original state i.e. not screw cut.

I'm considering having a moderator fitted in the near future. My question is what size thread should I go for? I realise that there is no standard size but that I may change the rifle in future. With this in mind, are some threads more common than others? Can adapters be purchased to allow the same mod to be used on different rifles (of the same calibre?). I don't want to spend £300 on a new mod, only to discover it won't fit on any future purchase.

Many thanks for any help

 

[Brithunter]

Of course others may disagree but bearing in mind the muzzle diameter of the BSA which is about 0.560"-0.600" if memory serves me right then you rather tied to something like 1/2" UNF. This is such a thread on std BSA barrel full length not reduced:-

It leaves a good shoulder for the Moderator to butt up against.

I must add this is on a new barrel which had never had sights fitted and it's of slightly heavier profile being a CF2 barrel than the slimmer one found on the Monarch and Majestic.

Of course if one buys a modular Moderator then swapping thread sizes is not much of a problem, at least not in most counties it seems, even Lincolnshire were happy for the one moderator to fit more than one rifle.

Edit:- Oh yes the plan was to machine a small notch in the shoulder so it would positivly locate a removable fore sight. The fore sight slipping over the barrel and being retained by a knurled nut on the 1/2" UNF thread for use with a Lyman or Redfield sporting aperture sight such as this one:-

Not sure if the Monarch 2nd pattern was drilled and tapped to accept them as was the 1st Pattern and Majestic.

 

[Hornet 6]

If the barrel is that thin, then 1/2"x28 (unef) would be stronger.

Neil.

 

[Brithunter]

That is the std profile of a lot of barrels. Of course that was BEFORE the fashion for clubs rather than "sporting rifles"

Muzzles of a Majestic and 1st pattern Monarch both in .270 Winchester chambering. The round hood is of course from a later CF2 as the original profiled one was missing from the Majestic when i acquired it.

 

[charliefox]

Thanks Gents

 

[cyril]

I have three rifles and the thread on all of them is 1/2" UNF.
It seems to be a standard thread and you should have know problem getting a moderator with this thread.

 

[plinker]

most common and easiest to get cans for

 

[Onelesscharlie]

Hi

I would agree with the other chaps.... if your barrel diameter wont stand m14 x 1 then 1/2" x 20 UNF or 1/2" x 28 UNEF

regards

Colin