Is there a standardized spec for firing pin protrusion? I would imagine there is so cartridge manufacturers can be assured of proper ignition.

Most of the answers I have gotten from the good folks here say it should be right around .060" and I believe that, just want to know if there's something like a SAMMI spec for it.


Thanks, Rob

yes... generally .050

jeffe

jeffe,

I'm sure you've forgotten more than I'll ever know about this stuff so please believe me when I say I'm not being argumentitive, but "generally .050" doesn't read like a standard spec.

I have these 3 actions with the pins protruding .045-.047 and I need to know if I should be concerned about the protrusion being correct. I have heard that it should be anywhere from .050 to 065, generally agreed that close to .060 is ideal, and .045 is a long way from that.

I'd rather not wait until the guns begin to have ignition problems, one is a gift for a friend so I'm trying to get my duck in a line and nip it in the bud. I wanted to know if there's a spec I can quote from an organization like SAMMI about what is ideal, upper and lower limits, etc.


Thanks for putting up with me,

Rob

From Gunsmith Kinks volume II, by Bob Brownell:

Centerfire rifle: Min= .060“ Max=.065â€

Rim Fire: Min= .035“ Max= .040“

Shotgun: Min= .060“ Max= .065â€

He states to ALWAYS use the minimum that will provide reliable ignition.

Thanks Rick, dumb bastard I am, it made me think to check some of the books I've been collecting for years.

Kuhnhausen's Mauser book says .055 is the minimum and
.065 is max.

James V. Howes "Modern Gunsmithing" says the same, .055 to .065, with .060 being ideal.


Thanks, Rob

Rob

The firing pin protrusion figures are a good starting point but not safe for all firearms.

Center fire rifles with small primers for example .222 Remington, protrusion is .050 plus or minus .001.

.223 Rem and 5.56 when used in AR-15 and M-16 protrusion is .039. If you had .060 in either of these rifles you would definately get a slam fire when dropping the bolt from a locked back position.

According to firearms instructor Robert Dunlap, you have 2 kinds of protrusion, primary and absolute. An example would be a Colt 1911 design when you lower the hammer to the fired position would be primary and if you measured how far the firing pin continued moving forward past that point by inertia would be absolute. You can take a punch and push a firing pin in that gun a good .250 to .350 protrusion, the firing pin spring and inertia governs it's amount of protrusion when being fired.

Shotgun protrusion is dependant on head spacing and breeching. If it is a new Remington 1100 for example the factory service manual lists a minimum of .030 to a maximum of .060. Other brands call for .075 to .085.

Bottom line is when checking firing pin protrusion, consult factory manuals, if not available consult working gunsmiths.

Thanks for the explanation Craftsman.

The actions are bolt action .308Win. After reading Kuhnhausen I knew enough to check the protrusion with the pin pushed hard forward and still came up with the short measurments.

Rob