rockintheenfields: I would try 'slugging' the bore of your rifle, if it were mine. (Drive a soft lead bullet or round ball of around 8mm diameter into the muzzle with a plastic mallet and then push it down the barrel with a strong cleaning rod). The effort should be fairly consistent. You are looking for a "ringed" or bulged area in the barrel. If the bore is fairly consistent, not obviously bulged, and measures .311-.315 inches inside diameter (and the bolt headspace appears 'OK'), I'd feel safe shooting the rifle. I imagine the gas pressure from the Blank Cartridge propelling a 'gas checked' grenade out of a Cup Discharger clamped to the SMLE nosecap, tested the barrel. However, I doubt there were many failures. The wire wrappings on a 'grenade-launching rifle' were just good insurance against injuring a soldier, who was kneeling and holding the SMLE at a high angle with the butt on the ground.
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