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Faxon Q&A #4: Chamber types, heat, headspace and more!



Part 4 of ongoing our barrel discussions with Faxon. In this one we discuss chamber types, heat dissipation, headspace and quite a bit more as well.

00:41 What’s the difference with chamber cuts? 223, 556 NATO, match, Wylde, etc. What are all these things and are they relevant and why?

06:37 Commentary: For most real world and practical applications, match grade and tight chambers aren’t worth the trouble.

08:51 Discussion about what tight versus loose chamber cuts actually even mean in terms of dimensions. Radial and dimension differences between .223 and 5.56 NATO.

10:44 What does it take to get to “subMOA”?

12:53 The gun design itself is important when attempting to get to “subMOA”. Some designs lend themselves towards accuracy more than others.

18:38 What is the difference between a true match and a “subMOA” barrel?

21:16 The definition of what a “match” is has changed over time and therefore the requirements for what you need to shoot a match have changed as well.

25:00 What is the difference between lapping and honing?

30:25 What is headspace and how is it measured?

40:04 Some guns have adjustable headspace. What can happen when headspace is outside of safe boundaries?

42:41 What can be done to mitigate headspace problems?

45:00 Thermal dissipation - weight versus function? Pencil barrels aren’t intended for sustained high ROF, but that wasn’t the goal. Barrels designed for sustained rates of fire are heavier & thicker - it’s all a compromise.

49:14 The BAR & the Chauchat had overheating issues because of barrel design. The M16 was not designed to be a SAW.

51:00 The full auto switch on an M16 can’t be used as a panic button which then can result in overheat and total failure. This doesn’t mean we shouldn’t have full auto, but it has a specific purpose.

52:59 Fitting extensions to receivers and what is the accuracy effect in doing so?

55:28 The AR15’s locking recesses are part of the barrel assembly, not the upper receiver. This is different than many other designs.

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