15-22 firing pin protrusion

[chuck s]

Right, Brett

Unless there's been a design change the 15-22 firing pin is physically limited in forward travel. Remove your bolt and press on the firing pin. Press hard. It only goes in so far before it meets a solid stop. Keep pressing forward and look at the face of the bolt. Note that in this pushed forward position the firing pin sticks out the face of the bolt. If it didn't it couldn't fire the cartridge. See Brett's photos.

Good so far? Push it all the way forward again and note that the rear of the firing pin is now flush with the rear of the bolt.

If your firing pin does differently -- and you understand the face of the bolt is the area within the recess -- let us know.

Unless the firing pin protrudes thru the face of the bolt it can't reach the primer and the rifle will not fire. Or did I say that already.

-- Chuck

 

[Brett248Vista]

Chuck,

I think what they are saying is that with the back side of the pin flush with the back side of the bolt it is not protruding into the Bolt Face. But that's not as far as the firing pin will go, you can push the pin further into the bolt (past flush). I believe that's the ONLY reason these rifles in question are firing at all, inertia is making them fire. Yes there is a hard stop (the inside of the bolt) that limits the travel, but something is out of spec on the two rifles mentioned, when the pin is flush, it's not exiting the firing pin hole, but if you push it just a little past flush on the back side, it's protruding ever so slightly.

The hammer can't hit it past flush, because the hammer also strikes the bolt, but the force of the hit is enough to keep the pin moving past flush and it barely hits the primer.

Understand what I am trying to describe?

 

[ChattanoogaPhil]

I thought this was already settled?

IIRC..... A dime was put between the bolt and chamber; trigger pulled; hammer engaged the FP; FP struck the primer. Right? Or am I missing something?

 

[tacticool22]

Chuck, you covered it pretty good.
Bolt Face (′bōlt ′fās)
(ordnance) That portion of a gun bolt that abuts the base of the cartridge case.

On .22 firearms, the most forward part of the bolt, or back of the breech is called the headspace datum face.They should touch and share the same datum plane.

Headspace on rimmed firearms is the gap from the bolt face to the back of the chamber where the cartridge rim rests. The acceptable range of this gap is .042" to .049". Ammunition rim thickness varies from .037" to .044". if the gap is too excessive the case may not be supported and could possibly bulge or rupture. What can also happen is the firing pin may not be able to reach the case or hit it hard enough for reliable ignition if the headspace is excessive. If the headspace is too tight it may compress the rim enough to ignite the cartridge.

Headspace in a standard double-action centerfire revolver that fires a rimmed cartridge, such as the .38 Special, is measured from the point on the cylinder that supports the cartridge rim to the vertical face of the frame, or breechface, directly behind the cylinder. The gap between these two points must be large enough to permit the cartridge case to fully seat in the cylinder chamber yet small enough to support the head of the case when the cartridge is fired.
Data found around the internet. Not Mine.

 

[corpulent]

It only goes in so far before it meets a solid stop...Note that in this pushed forward position the firing pin sticks out the face of the bolt.

Good so far? Push it all the way forward again and note that the rear of the firing pin is now flush with the rear of the bolt.

If your firing pin does differently -- and you understand the face of the bolt is the area within the recess -- let us know.
-- Chuck

Chuck,

I think what they are saying is that with the back side of the pin flush with the back side of the bolt it is not protruding into the Bolt Face. But that's not as far as the firing pin will go, you can push the pin further into the bolt (past flush). I believe that's the ONLY reason these rifles in question are firing at all, inertia is making them fire. Yes there is a hard stop (the inside of the bolt) that limits the travel, but something is out of spec on the two rifles mentioned, when the pin is flush, it's not exiting the firing pin hole, but if you push it just a little past flush on the back side, it's protruding ever so slightly.

The hammer can't hit it past flush, because the hammer also strikes the bolt, but the force of the hit is enough to keep the pin moving past flush and it barely hits the primer.

What Brett said, mostly. On my rifle, the pin extends past the face when pressed from behind FURTHER than flush. When held flush it does not exit the hole. My dents are as deep as in the previous photos.

"My dents run deep, so deep, so deep, put her a-- to sleep"

So, anyway, it works fine as is. If not for this forum, I would never have even thought that anything was wrong or out of spec. Still don't know if I think that.

If I were to opt for repair, could just the bolt assembly be sent in? Kamikaze1a?

 

[kamikaze1a]

corpulent, S&W wanted the complete rifle. I guess they want to check it out after "repair". The CSR that responded to my email probably not the tech who will be repairing my 15-22 so I don't blame him for telling me to send the whole thing...

As for the bolt face/headspace datum/headspace gap, I would say that a stop would be necessary due to the "rim"fire nature of the 22rf. If not for the stop, the fp could slam into the breech when dry fired. In my case, I think that stop was stopping too soon.

The 15-22's Momma, the AR, can have the same problem with insufficient fp protrusion when chambering imported steel case ammo with rebated primers. But in the AR's case, the solution is easier. Remove a few thousandths from the tail of the bolt.

 

[chuck s]

OK if I can get an "Amen" that the face of the bolt is the surface from which from which, in the sketch below, the headspace is measured we have either manufacturing tolerances, manufacturing errors, or a design change.

My rifle is in the DTM1200 serial range and the firing pin protrudes when a flat object is pressed across the rear surface of the bolt and the pin will project no further (at not measurably).

-- Chuck

 

[tacticool22]

Amen.
My firing pin protrudes into the headspace when pushed all the way forward. But it does not go past the datum plane, no matter how hard I push. When I push on the back of the firing pin with a small punch, it bottoms out on some kind of hard stop. The face of the firing pin does not go past the datum plane. In fact, it is .007 inches back from the datum. This allows for the primer to be crushed enough for firing and still protect the breech from being impacted. The back of the firing pin is exactly flush, with no over or under travel.

 

[corpulent]

OK if I can get an "Amen" that the face of the bolt is the surface from which from which, in the sketch below, the headspace is measured we have either manufacturing tolerances, manufacturing errors, or a design change.

My rifle is in the DTM1200 serial range and the firing pin protrudes when a flat object is pressed across the rear surface of the bolt and the pin will project no further (at not measurably).

-- Chuck

Amen.
My firing pin protrudes into the headspace when pushed all the way forward. But it does not go past the datum plane, no matter how hard I push. When I push on the back of the firing pin with a small punch, it bottoms out on some kind of hard stop. The face of the firing pin does not go past the datum plane. In fact, it is .007 inches back from the datum. This allows for the primer to be crushed enough for firing and still protect the breech from being impacted. The back of the firing pin is exactly flush, with no over or under travel.

Amen. Mine is a DUR. The pin does not project when a flat object is pressed against the rear of the pin. When pressed further than flush, as with a punch/pencil/etc., the pin extends past the face into the recess, allowing it to strike the primer. It then meets the hard stop, but does not extend far enough to strike the breech (i.e. not past the datum plane, if I understand tacticool22 correctly).

 

[kamikaze1a]

I wonder what's up with this variation. I find it hard to believe that S&W QC slipped up this much. I enclosed a couple of fired brass so let's see what they do...

 

[kamikaze1a]

Just received a call from S&W regarding the 15-22 I sent back. The CSR that said send it in said that the bolt he looked at had a protruding fp. The tech who just called me says that this is the "new style" bolt and uses an inertia driven fp. He said "like an 1911". He went on to say that the previous version had a fp that protrudes and could result in slam firing. I guess IF the hammer followed it could happen. So....looks like I am stuck with lighter strikes and will have to live with it. No reduced power springs for me. Not the end of the world...

 

[corpulent]

Haha! +1 for the inertia driven fp. Did you happen to find out when the change occurred? Somewhere in the late DTxxxx-earlyDUxxxxx range I guess?

 

[kamikaze1a]

He did not say but he did say, "you have the newest version which is the best and safest"... I would prefer stronger fp hits. I guess that's why some protruded and some did not.

 

[john16443]

So....looks like I am stuck with lighter strikes and will have to live with it. No reduced power springs for me. Not the end of the world...

Well this information should pretty much close this topic. Newer 15-22 use an inertia pin, and mine and kamikaze1a (along with many others) are the newer version. In all honesty, I don't think putting a lighter set of springs in would affect function at all kam. I say that because no matter what springs you install, you are not affecting the inertial mass of the hammer once it is released by the trigger and hits the back of the FP. The springs affect how easy it would be to release the hammer, but not how fast the hammer travels and hits the FP. Go with the less powerful springs if you have to, at most you're out less than $15 if they don't work, and you could always sell them to the "non-inertia" FP guys.

 

[chuck s]

Just received a call from S&W regarding the 15-22 I sent back. The CSR that said send it in said that the bolt he looked at had a protruding fp. The tech who just called me says that this is the "new style" bolt and uses an inertia driven fp. He said "like an 1911". He went on to say that the previous version had a fp that protrudes and could result in slam firing. I guess IF the hammer followed it could happen. So....looks like I am stuck with lighter strikes and will have to live with it. No reduced power springs for me. Not the end of the world...

Thanks for this data!

I'm betting on the inertial firing pin ("like a M1911") is the solution for the spate of Out Of Battery (OOB) firing many (most?) of us have experienced. A partial hit on the firing pin when the bolt is not fully closed (not in battery) probably won't detonate the firing pin.

If you're getting light strikes in normal shooting you can install a heavier hammer spring, lighter firing pin spring, or switch to ammunition with more sensitive primers. Or all three! But that might take you back to OOB firing.

You can use a reduced power trigger spring or bend the existing springs to lighten the trigger.

-- Chuck

 

[john16443]

I suspect you're right Chuck. That was my first thought when kam posted the summary of his conversation with S&W tech.

 

[kamikaze1a]

Once it arrives back from S&W, plan to install my old AR massaged, one leg cutoff hammer/bent leg trigger springs. Will post results. Thanks everyone!!!

 

[Tempest 455]

Dug up an old topic. I have tried all of the springs mods mentioned when I searched the forum. I still have light strikes. So I looked at the firing pin.

It looks like the pics above. The protrusion from the actual face where the rim sits is only .030". Not sure if that's in spec but it sure makes less of a pin mark than my other .22's. Overall pin length is 2.121".

Looks like I could machine a few .001 off the end where the hammer hits for a little more travel.

 

[Majorlk]

Looks like I could machine a few .001 off the end where the hammer hits for a little more travel.

How will removing metal from the rear of the pin increase travel. You lost me on that one.

FWIW, if your FCG springs are original and you are having light strikes, I'd talk to S&W. If you've changed springs to something lighter, especially the hammer spring, more likely that is where the light strikes are coming from.

 

[Tempest 455]

How will removing metal from the rear of the pin increase travel. You lost me on that one.

FWIW, if your FCG springs are original and you are having light strikes, I'd talk to S&W. If you've changed springs to something lighter, especially the hammer spring, more likely that is where the light strikes are coming from.

If you take it apart and look at it, the rear part of the firing pin (that looks like the head of a nail) where the hammer strikes is what limits how far forward it moves. Look inside the bolt, there is a step where that "head" rests when it moves forward. That limits the travel.

The "head" of this pin as described above is roughly .070 - .072" thick. If I take .003" from the inside of this "head" (toward bolt) it will move it forward .003".

Going to maching this tonight on my lathe and will report the results.