GO/NO GO gauges? Lol...
I've installed a lot of Knight cans over the years and what I've come to learn is they are definitely "custom" as no two are alike. It is why we absolutely require the can to be in our possession when pinning the barrel. Ignoring this results in one of two things happening:
1. A can you install/remove with a hammer or impact gun.
2. A can that rattles onto the barrel like a marble in a coffee can.
On the random chance it actually fits as intended, run and buy a lotto ticket...
I'll put some of this into a better perspective. From 2006 to 2009 I was a security contractor working for Triple Canopy on the Baghdad Embassy Security Contract. I was initially hired as a gun plumber. The contract grew over time to include the REO's (Regional Embassy Offices) scattered throughout the theater. The job metastasized into a courier and traveling range officer gig to these locations as well. (Ankawa, Kurdistan, and Basrah in southern Iraq). This meant I had a lot of interaction with other companies. "Bee Dub" (BlackWater as it was known at the time), and DynCorp. (A bunch of others, but back then there were only 3 able to bid on DoS contracts).
Anyway, BW had the WPPS contract and that mandated DDM's. (Defensive Designated Marksman). Filling that slot required monthly recertification on the weapon systems. The M24 bolt guns and the SR25's from Knight. It was interesting that BW guys only shot the bolt guns for this exercise. You almost never saw the gas guns come out of the cases. Now we move forward to the 2008-ish time frame. BW was in hot water over an incident so they were the focal point of all things from the DoS point of view. The most feared entity in security contracting is not a terrorist or insurgent. It's actually a Department of State Contract Compliance Officer. One stroke of that pen will shut you down and that means millions of dollars per week down the toilet. No shit.
A gent showed up one day and told them the DDM's were going to do an on the spot re-qual. No biggy. They pull out the bolt guns and go to work. They are told to put them away and get the SR's out. Shoulders and heads drop like no other.
The failure rate was over 90 percent. Because BW could not document these guys qualifying on these guns as directed by the contract (years in some cases) the audit conducted stuck them with a fine that approached $50 million dollars. They were going to go under if forced to pay it. A formal protest was issued and DoS flew in WPPS DDM instructors from Quantico to evaluate the guns.
The long and short of this is that the guns were total shit and incapable of delivering the performance standards dictated by the contract. BW got to keep all of their money and those guns were pulled from service. Keep in mind the round count on these things was minimal (because they didn't work).
In 2012 I was home, fat, and happy. Triple Canopy reached out to me about a complete overhaul as they had inherited a bunch of this stuff when they were awarded the WPPS contract in 2009/2010. I said sure and a semi-truck of the stuff arrived a short time later. I had my work cut out for me. They were an absolute mess and Knight Armament was ZERO help. In fact, they were irritated that I was working on them as they tried like hell to just sell new guns to TC.
So, new barrels and yadda, yadda... FWIW the rifles were used by students at the Tiger Valley facility and the very next class posted some of the highest scores in the history of the WPPS DDM course.
It served as a valuable lesson: Using parts that aren't junk does help.
C.
EDIT: Just for clarity. There's no reason to use a 5 axis mill when fitting up a barrel for a Knight can. We use a 4 axis machine for this. A 5 is the wrong answer for this as it would just overcomplicate the work holding and programming. I DO use my 5x for retrofitting MARS rails originally intended for M700's to the Stiller MK13's though. It's the perfect machine for that.
We write all of our own code. Nothing is sourced from any other entity. Ever...