Looking for Advice; Obsidian 45 on a 9mm PCC

So, I plan on installing an Obsidian 45 on a 9mm PCC that has a 1/2x36 threaded barrel. The can comes with a 45 sized piston whose thread (if I understand correctly) will not fit the 1/2x36 threads. Correct me if I am wrong, but I THINK I can do one of the following:

1. Get a Rugged Obsidian Fixed mount in 1/2x36 $80
https://www.silencershop.com/rugged-obsidian-fixed-mount.html

2. Get a 3 lug adapter (1/2x36) and an Obsidian 3 lug mount $215
https://www.silencershop.com/rugged-3-lug-adapter-male.html
https://www.silencershop.com/rugged-obsidian-3-lug-mount.html

Is this correct, and is the 3 lug mount worth it? It seems like the 3 lug would be secure and convenient.

Definitely go 3-lug. Never have to worry about it walking off and the locking feature gives you that peace of mind. Just make sure to properly torque it to spec.

I would also recommend Rocksett over Red loctite, Rocksett is water-soluble and not affected by heat. If ever you need to remove the 3-lug adapter, you just soak it in water for a couple of hours versus using a torch for the red loctite.

Thanks for the tip…. I woke up yesterday wanting to mount my Obsidian to MPX…. Saved me a little time.

The 3 lug mount is only as good as how you mount it on the barrel.

I use direct thread and I've put a lot of ammo through my PCC. Not once have I ever had a problem.

On the other hand I did have a problem with a QD mount coming loose and ended up with an end cap strike.

I think QD mounts give people a false sense of security.

Rockett and loctite both degrade with heat, which is easy to achieve after a couple boxes. Or a fast PCC match stage with 15 targets, half of which you've missed.

carbon buildup cements the suppressor on the barrel.

real security is a crush washer, and with a crush washer it doesn't matter whether you use direct thread or QD mount. not matter what, check your mount periodically.

camo556 said:

real security is a crush washer, and with a crush washer it doesn't matter whether you use direct thread or QD mount

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Use of a crush washer is almost universally advised against by suppressor manufacturers. They often do not crush square with the shoulder of the barrel, which is typically what the suppressor or suppressor mount indexes off of. This also increases likelihood of baffle strikes, so you’re simply trading one potential problem with another. Griffin Armament did a special run of one of their suppressors for LEO or gov that ran a modified baffle stack to account for use of crush washers, but I don’t believe they ever made it available to the public.

A direct thread suppressor, tri lug mount, or muzzle device should be torqued to manufacturer spec on any fixed barrel firearm (using timing shims if needed for muzzle device, e.g. a muzzle break). If torqued to proper spec and inspected on occasion you should not have any issues. Rocksett, loctite, or anti seize can be used if desired, but aren’t 100% necessary. Also be sure to check concentricity with a gauge or using the flashlight method.

fbi_surveillance_van said:

Use of a crush washer is almost universally advised against by suppressor manufacturers. They often do not crush square with the shoulder of the barrel, which is typically what the suppressor or suppressor mount indexes off of. This also increases likelihood of baffle strikes, so you’re simply trading one potential problem with another. Griffin Armament did a special run of one of their suppressors for LEO or gov that ran a modified baffle stack to account for use of crush washers, but I don’t believe they ever made it available to the public.

A direct thread suppressor, tri lug mount, or muzzle device should be torqued to manufacturer spec on any fixed barrel firearm (using timing shims if needed for muzzle device, e.g. a muzzle break). If torqued to proper spec and inspected on occasion you should not have any issues. Rocksett, loctite, or anti seize can be used if desired, but aren’t 100% necessary. Also be sure to check concentricity with a gauge or using the flashlight method.

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Yet I have a pile of them that came in the package with the mounts lol. DONT USE THIS THING WE SENT YOU. lmao. Also have a qualified gunsmith do it! Maybe I should have said real security is pinning and welding the supressor to the barrel lol. My point was that there is not really a foolproof way to mount a supressor. no matter what... check it and re check it.

This bold is important... invest in a 75$ bore alignment rod. I just carry it in my bag now to check before shooting.

So reading the fine print; looks like the fixed mount is for a 90 degree shoulder - I suspect that's the case on the PCC but I need to check if I go that route. I think getting a proper straightness gauge is also a great idea.

camo556 said:

Yet I have a pile of them that came in the package with the mounts lol. DONT USE THIS THING WE SENT YOU. lmao. Also have a qualified gunsmith do it! Maybe I should have said real security is pinning and welding the supressor to the barrel lol. My point was that there is not really a foolproof way to mount a supressor. no matter what... check it and re check it.

This bold is important... invest in a 75$ bore alignment rod. I just carry it in my bag now to check before shooting.

Click to expand...

Which suppressor manufacturer is sending you crush washers? I have about 15 cans and have never received anything other than timing shims.

After reading these comments, given that the 3 lug adapter introduces another possible source of concentric error, I think the fixed mount might be easier. OBTW - the bore alignment rods (esp. if you want 5.56) are not in stock. 9mm rod availability is better.

fbi_surveillance_van said:

Which suppressor manufacturer is sending you crush washers? I have about 15 cans and have never received anything other than timing shims.

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Yep, I have 4 and none were sent with crush washers

I mean, if you don't mind needing to match the finish, you could put a tiny spot weld on it once the muzzle device in torqued in to place. If it is very small you could still break it loose with torque or at worst it s very tiny amount to file off.

Don't think I'd ever do it, but if you really wanted a "it'll never walk off" installation, that is your best bet.

As for attachment, the issue is that the QD adapters end up adding up if you are swapping it between a lot of devices. My Obsidian 45 is going to end up costing me a fair amount extra because of all the other stuffs. But if you are mounting it on pistols you'll need a QD piston and a QD fixed mount. Then you'll need muzzle devices for every single thing you want to mount it on. In my case, if I wanted to mount it on my G34 and 17/19, and G21, and a lever gun and a 300BO I'd end up needing 5 or more muzzle devices possibly. That's around $300-500 depending on what I was getting. For the pistols, I'd also need to take the muzzle device off to remove the barrel from the slide for deep maintenance.

Yeah, three different thread mounts for .45, 1/2x and 5/8x and a piston for 9mm and for .45 adds up too. But it is somewhat less. And way easier with the pistols for deeper maintenance. The overall package weighs several ounces less (typically you are looking at probably 4-5oz extra between the QD mount on the can vs a direct thread mount and the muzzle device itself).

I can see an "operational" need to swap a can on and off quickly and securely. If hot, a tri lug can comes off pretty fast if you are going to drop it in a heat resistant pouch and head home. Versus sitting there with gloves or a mitt unscrewing and unscrewing and unscrewing. And security on how it is mounted/snugged up I can see being important if you have to use the can in a context of things shooting back at you. But hunting, range shooting, all you need to do is every once in awhile reach out there and make sure it is snugged up. It isn't like every round. Every mag would be more than enough if paranoid/careful. Every 2 or 3 mags would generally be sufficient. I usually do that and I've never noticed my 22 or .308 cans loose once.

calicojack said:

After reading these comments, given that the 3 lug adapter introduces another possible source of concentric error, I think the fixed mount might be easier. OBTW - the bore alignment rods (esp. if you want 5.56) are not in stock. 9mm rod availability is better.

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Three lug is a proven system. You do you but it’s what I use on my PCCs. Never had issues with the Dead Air Wolfman or the Griffin Optimus 9.

Direct thread is just fine too.