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Spigot threads on barrels.
Posted: Fri Jul 22, 2016 8:23 pm
by Sim G
Birth of my RPAs are factory threaded with 17x1 spigots. Is it really necessary to have the thread in a moderator cut as such, will a 17x1 thread without the spigot make that much difference?
I've ordered a new mod for the 7mm-08 and believe it or not, the makers have sent a 17x1 threaded mod three times!!! FFS! But do I really need the spigot? I would rather, but is it important considering how many times it's been cocked up?
Re: Spigot threads on barrels.
Posted: Sun Jul 24, 2016 8:05 pm
by Sim G
Anyone?
Re: Spigot threads on barrels.
Posted: Sun Jul 24, 2016 8:08 pm
by bradaz11
i think a picture might explain more...
what do you mean by a spigot thread? that the thread doesn't go to the end of the barrel?
Re: Spigot threads on barrels.
Posted: Sun Jul 24, 2016 8:23 pm
by Sandgroper
Sim G wrote:Birth of my RPAs are factory threaded with 17x1 spigots. Is it really necessary to have the thread in a moderator cut as such, will a 17x1 thread without the spigot make that much difference?
I've ordered a new mod for the 7mm-08 and believe it or not, the makers have sent a 17x1 threaded mod three times!!! FFS! But do I really need the spigot? I would rather, but is it important considering how many times it's been cocked up?
According To Jacksons rifles -
http://www.reflexsuppressors.co.uk/ the spigot is "to ensure precise alignment in conjunction with the close-fitting barrel bush at the rear of the suppressor." So in your case it would depend how well the particular moderator aligns itself to the barrel to determine if you need a moderator with a spigot.
Re: Spigot threads on barrels.
Posted: Mon Jul 25, 2016 6:22 am
by ovenpaa
Spigots seem to be peculiar to specific manufactures and offer more support for your sound mod. Blaser and Accuracy International spring to mind... The spigot offers more support and ensures the sound mod is correctly aligned. As the shoulder behind the thread is only slightly greater than the major diameter of the thread a standard threaded sound mod will not have a reasonable shoulder to lock up against hence the need for a specific sound mod. It does make sourcing something to fit a PITA.
Re: Spigot threads on barrels.
Posted: Wed Jul 27, 2016 7:42 am
by Nick Hulme
It's a common system for chuck alignment on older lathes, a short parallel section and a shoulder behind the thread provides a precise register for alignment, the thread serves only to pull the part down onto the register surfaces,
Regards,
Nick
Re: Spigot threads on barrels.
Posted: Wed Jul 27, 2016 8:16 am
by Nick Hulme
I missed the time slot to add this in an edit but to use a moderator manufactured to fit a thread to a shoulder should only require an accurately turned ring to provide a shoulder for the moderator at the base of the thread, it would have to be determined that adequate alignment was achieved this way before calling it "Job Done" but from an engineering standpoint it's sound,
Regards,
Nick