Threading Barrel for SiCo/SWR Spectre II?

[Meridian]

I'm thinking about having the barrel on my Savage MKII BTVS threaded for my SWR Spectre II. I've looked at the Thread Specs on the SiCo website, and that left me with a couple of questions:

1. Should I have the barrel threaded per the 1/2×28 Thread Specs drawing only, or both the 1/2×28 Thread Specs and the Rimfire O-Ring Thread Specs drawings?

2. What is the consequence of threading the barrel per the 1/2×28 Thread Specs drawing without the O-ring engagement groove?

Any help would be appreciated.

Edit: Fixed spelling in subject.

[quiettime]

Sico rimfire cans have an o-ring just past the threads to help keep them from backing off. You can run them on pistol threads (short) with no consequence but rifle threads for some reason are longer and will cut into the o-ring. Some companies do offer precision-ground spacers to compensate for the added length of the rifle threads.

If it were me I would thread it Sico style

[John A.]

I don't think you'll find many folks here who have had issues of their rimfire suppressors walking off if the threads are right and it's installed correctly.

[Meridian]

So, if I understand you guys correctly (and I'm reading the drawings correctly), the options are:

1. Thread the barrel up to the muzzle per the 1/2×28 Thread Specs drawing. However, the o-ring in the can would not be engaged, and that could make it easier for the can to back off on its own.

2. Thread the barrel with the o-ring relief at the muzzle per the Rimfire O-Ring Thread Specs drawing. This allows the can to screw further down on the muzzle and the o-ring to engage the barrel near the muzzle where the threads have been moved back away from the muzzle.

All things equal, Option 2 makes more sense to me. Are there any drawbacks to threading it with the o-ring relief - e.g., would make it troublesome to mount other 1/2-28 cans?

[ECCO Machine]

Rimfire cans are light and not subjected to much recoil, so there's really no problem with the reduced thread engagement of Silencerco's spec. That said, I like to grab more than the 6 threads available with SiCo's spec. My standard rimfire threading is a hybrid of the two specs you posted. .450" tenon with .050" beveled undercut fore and aft and .010" chamfer on the snout.

[Meridian]

I'm assuming that the only problem with having threads where the o-ring relief would normally be is that over time it could tear up the o-ring?