I shot it for a few mags with the factory installed brake. It shot like a laser with the NXS 1-4 and CBC 77gr SMK and ADI 69gr SMK (out to 500 yards). It was obnoxious shooting in a little indoor/outdoor training class.
I took the brake off and screwed on a Smith Vortex G6A3. The brake was TIGHT. Like I thought I was going to crush the barrel blocks or the barrel in the vice and I had to pull out a longer Snap-On wrench to get it off. I installed the Vortex per instructions with hand torque, let it shoot itself tight.
I expected a POI shift. Went to re-zero the gun and spent the next three weeks chasing my tail with poor groups and a wandering POI. Tightened up my mounts, re-locktited everything, was really down on my shooting skills, just having a bad time.
Today, out of curiosity I pulled a brand new A2 flash hider and crush washer and installed it. It took a little over a full revolution of ‘crush’ to time correctly and I was worried it was too tight.
I popped on a bipod and set a target at 100 yards. Accuracy is back. I shot 4 5 round groups and one 10 round group of ADI 69gr SMK with a 5 gusting 12 mph cross wind and ALL groups were hovering right over 1moa.
Put the smith vortex back on to verify, then return to sender.
I wonder if you put a cleaning rod or maybe a tight fitting wooden dowel through the smith vortex and down the barrel a bit, maybe you can see if it isn’t off kilter a bit.
Consistency in torque is fairly important.
If you really want to see what’s going on, put the Vortex on at 20 ft/lbs and see if it improves.
I find it surprising that they didn’t give a torque spec for installation.
Vortex’s torque spec is thread it on by hand until it stops. Shooting will tighten it to where it needs to be.
I did not torque it with a wrench, but I did remove it a couple of times to make sure it was threaded all the way on. It required a wrench to break loose each time.
I’m not touching the barrel anymore now. It’s shooting good and I’m not takin’ any chances.
The Vortex has a slight twist that runs opposite the thread. The idea is that the gases will torque the device into place. By most accounts it is a very accurate muzzle device and physically cannot loosen under firing conditions.
I understand the concept, but disagree with the process if precision is the goal.
This is much better to hear.
10 ft/lbs is a bit over hand-tightness.
Most optic hard-mounts are attached at 65 in/lbs (5.4 ft/lbs) and anything with less leverage than a T-handle torque wrench takes a pretty strong dude to even reach that.
Still not sure that I’d want to use it as a suppressor mount with such low torque and the expectation of the venting muzzle gasses to continually tighten the device, but that’s just me.
With the above info, my recommendation would be to tighten to precisely 10 ft/lbs and try again.
I’ll parrot what others have said here. Torque it to 10lbs. and if it’s still shooting patterns, send it back to Smith for a replacement. If it still does it with the replacement, then evil demons have found their way into your rifle and you need to burn sage (careful to blow plenty of smoke down the barrel), douse the entire rifle in holy water, then hire a Wiccan to perform some cleansing rituals on it. If that doesn’t work, take it to your nearest Catholic church and ask if they do exorcisms on inanimate objects.
