Wartime, home made silencer

[Woodsy]

Question 2: How much larger would the hole through the centre of the baffle need to be than the calibre of the gun; would the hole be only fractionally larger or would there be a reasonable amount of clearance? So if we take the Sten as an example, which we all know is of 9mm calibre, would the hole through the centre of the baffles be in the region of say 9.15mm i.e. very minimal clearance or significantly larger say a 10mm dia hole?

Experience has taught me that the optimum size for the baffle holes is 1.5mm larger than bullet diameter. The reason is that most bullets (particularly rifle) exhibit a certain amount of yaw (wobble about their axis) as they exit the muzzle which takes a few metres to settle down, so that amount of clearance is needed to prevent contact. With over barrel suppressors the accuracy potential for many rifles is actually increased due to the extra support given to the last 150 - 200mm of barrel by the suppressor, and the reduced recoil. The over barrel types feature an internal muzzle brake to direct a lot of the muzzle gases into the back expansion chamber, and also have a snug fitting bush (usually engineering plastic) at the back end which increases support. For semi-autos and full-autos, the rear bush needs to be metal as the barrels often get too hot for the plastic bushes. Such firearms also often need to be tuned in the gas system for reliable operation because of the effect of the internal muzzle brake and the different barrel pressure curve. Semi-auto locked-breech pistols also need a floating muzzle system to negate the extra weight of the suppressor which can prevent sufficient barrel recoil for the pistol to operate reliably. Pistol suppressors need to be quite large to be effective and that size negates their usefulness, so such units tend to be much smaller and less effective.