Some gunsmith "specification" questions - revolver, rifle

[AJMD429]

Revolver Cylinder-Barrel Gap:

• what is a 'reasonable' gap?
  does the specification change with chambering or caliber?
  is it different for swing-out cylinder guns?
  is it different for swap-cylinder guns like the 'convertible' Rugers?
  is there such a thing as 'too close' as long as it doesn't bind?
  does too-large a gap actually cause faster wear on the barrel or cylinder?

Centerfire Firing Pin Protrusion:

• what is a 'reasonable' range?
  is it different for handguns and rifles?
  is it different depending on action type?

Sometimes when I buy a recent-manufacture revolver, I cringe at what seems to be a really huge gap between barrel and cylinder.

I have a couple long-guns (one is a lever, so this is "on topic" ) that dent the primers in so far it looks like a shotgun firing-pin dent. As deep, or deeper than, wide, so the 'sides' of the dimple are perpindicular to the face of the primer. I really don't want a primer to 'blow' if I can avoid it...!

[Catshooter]

Doc,

You know the answers to these technical questions are all: it depends.

For example, the cylinder gap. Will you be shooting the Holy Black, or just smokeless? Will you be shooting alot of hot loads, quickly? Black will build up faster on the cylinder face than smokless, the whole firearm expands with the heat of alot of hot rounds fired quickly and with a tight gap things can start rubbing, binding.

For me, the way I shoot I like a gap of .002 to .003.

It doesn't matter between single action, swing out cylinder, or multiple cylinders.

Binding is the defintion of "too close".

I don't know if too large a gap causes wear.

Someone else will have to chime in on the firing pin protrusion but I can say this. My Kahr pistols have the tiniest protrutrion I have ever seen. It must be .050 or .060, but they work great. I have an American Derringer in 45 ACP and it's got to be close .100. I've loaded some very warm to hot loads in it and it's never blown a primer.


Cat

[KCSO]

Factory specs on revolvers runs from 6 to 9 thousands gap. I prefer 4 thou but can live with 6. Yes it can be too close, for example I shot a Merwin and Hulbert that had 3 thou gap and it was almost unusable with black powder, the fouling tied up the gun in 6 shots or less. More than 9 thou won't cause wear on the gun but blow by is annoying.

Each gun has it's own firing pin specs and it also depends on the type of gun and they type of firing pin, frame or hammer mount.