How Much Firing Pin Clearance?

Andy

Andy

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Generally how much clearance is suggested, i.e. how much bigger should the firing pin hole in the boltface be than the firing pin?
 
In a high pressure rifle a thousands of an inch is desirable. More clearance does nothing benificial... primer cratering and the associated problems occur with excessive clearance and higher pressures.
 
Is normal rifle firing pin protrusion not between .028" minimum and .036" maximum? This is what most of my books suggest anyway.
I think Dennis' keyboard misfired there. Better check the key protusion.
 
I thought the question was, "Generally how much clearance is suggested, i.e. how much bigger should the firing pin hole in the boltface be than the firing pin?"...

I believe protrusion from 35 to 50 thou is acceptable.

I still think a thou clearance between the firing pin diameter and the firing pin hole is good... :D
 
Casull said:
Oops sorry, I missed the point of the thread entirely. I though it was about protrusion. Better get my monitor checked, or learn to read.
Click to expand...

...... well it is early Monday.. the weekend got to you..:D
 
True enough and it was quite a weekend. When I read your first post, it made sense but appeared you missed typing the 35-50 bit. No excuse for missing the initial point of the thread except Monday stundness, sometimes happens well into the week for me too.
Anyway, then you make a firing pin hole normally .001" larger than the firing pin diameter? This explains why old actions are often bushed with smaller pins installed on smaller high pressure rounds.
 
as for dia. clearance you also need to be aware of if in case of rupture is the gas escape in front of bolt face or thru the bolt itself, if it's entirely thru the bolt more clearance is needed for venting While only a few actions are vented in this manner, it is something to considered
 
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