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Posted: 6/25/2006 3:36:59 PM EDT
I've been hearing about it for a long time, and I finally got to hear one on a customer's P7M8. Yup, it was as quiet as everyone says  |
Yup, I sold another one that way yesterday. But again, the show stealer was the Blackside on my Glock 21. I'd hoped to run the EVO-45 too, but apparently the .578-28 thread used by Gemtech isnt the same .578-28 thread used by AAC, so I cant install the EVO-45 
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Don't you hate that shit? I am surprised that it's so difficult to get a product threaded without issues. It seems all this high-tolerance stuff has teething issues. (I've had Noveske brakes and my Evo become issues on new barrels threaded to spec) I ran an ajustable tap over the stock threads on my PacNor; that solved the Noveske issue, the Evo took like three hours of lapping the booster with flitz. (another 20% of a turn... loosen, water cool/flitz repeat). I didn't have that 5/8-24 ajustable tap. It would be nice to see some industry standardization of thread specs. |
The guy who does my shop work threaded my barrel to match the Gemtech threads. The AAC threads are smaller and wont thread. I'm not sure which is supposed to be "spec", but the Gemtech threads are definitely bigger. |
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You can check with a thread micrometer, or a set of thread wires and a standard micrometer to see if he threaded the barrel oversize, but I can tell you right now that he did. You can run a die over it to bring the barrel into spec. The Gemtech can will still fit fine once you do this as it is likely also in spec. In other words, I would bet that both cans are in spec, but the barrel is not. It is better to use a set of go/nogo thread ring gauges than a silencer to cut a barrel. They are costly, so most machinists will use thread-wires and a reference table of mix/max values -- which is every bit as good but slower. The AAC piston is very precise and has some dims called out to +- 0.0003 and they are done in large batches by CNC and thread plug gauge-checked. They are verified in spec for the thread standard. |
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We thread and mic over wires. When steve brought us the barrel and can (blackside) we began threading, when we were still 0.008 away from finish according to the wires, we attempted to screw the blackside on and it went with no wobble and went all the way back to our shoulder it seemed like a very good fit. We contacted Gemtech and were told that AAC + Gemtechs thread were slightly different in tolerance and that they WERE NOT INTERCHANGABLE. When steve got his AAC can it would not even start on. We threaded another barrel to what the wires read were correct for a .578 - 28 thread and the AAC went on just fine. Im not trying to bad mouth anyone, I would agree that the AAC can is in spec, but it does seem as though the Gemtech can is oversized. After cutting the second barrel to what the wires showed as "in spec" the Gemtech can was SLIGHTLY wobbly. |
I never learned to use thread wires since I bought the thread micrometer. But the wires are technically even more accurate because there are more sizes than I have anvils. |
Robert- you are getting better. Normally you'd have made the statement in red and just left it at that. Thanks for explaining it immediately so it didn't turn into a poop storm... |
For the 0.578-28 (2A) threads at Gemtech we use a set of ring gauges when threading barrels. The pitch diameter is 0.5537" MAX, 0.5499" MIN with a tolerance of 0.0038" for class 2A fit. A set of ring gauges is not inexpensive. The mounts we use will accept the GO plug gauge and will reject the NO-GO gauge. Plug gauges have a definite lifespan, and the rate of wear varies with whether the operator is heavy-handed and tries to force a GO gauge into a slightly tight hole. Generally, the life is in the vicinity of several thousand holes, and a worn-out plug gauge will result in a slightly undersized threaded hole in the mount. A worn ring gauge will result in a slightly oversize barrel thread. With the tolerance in the 2A specification, it is quite conceivable that if a barrel is threaded to fit a specific suppressor with the mount at the upper range of tolerance rather than to a standard, it might not fit another suppressor that is threaded to the same specification but which may be at the tighter end of the tolerance range. For this reason, it is usually best to thread the barrel to the correct thread specification. My personal experience has been that I am more comfortable using a thread micrometer or commercially manufactured ring gauge than the 3-wire method. Our 0.578-28 (same as 37/64-28) ring gauges were made by Master Gage Company. Hope this helps. Philip H. Dater/Gemtech |
I am not certain about others' threads, but ours are correct and can be used as a thread gauge. I think that steel plug gauges would last a lot longer than a few thousand uses when using aluminum threads. |
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