Failure to fire

[DShortt]

Yes, if it can (or can't ) it will at some point.
My guess is the primers not properly seated in virgin brass.

So, the primer has to be seated deep enough to set the anvil for proper ignition, correct?

Is the suspicion that the primers arent set deep enough? Or that they're set too deep? That appears to be what some are mentioning above. But, if the primer isn't seated deep enough to set the anvil, that will cause FTF, correct?

Not trying to argue, just making sure I'm following the thought process.

 

[Vandelayindustries]

So, the primer has to be seated deep enough to set the anvil for proper ignition, correct?

Is the suspicion that the primers arent set deep enough? Or that they're set too deep? That appears to be what some are mentioning above. But, if the primer isn't seated deep enough to set the anvil, that will cause FTF, correct?

Not trying to argue, just making sure I'm following the thought process.

I was under the opposite impression. My primers are set too deep. The ones that fired are flush. All the ones that don’t are .008-.014 below flush. Never had an issue with any other rifle seating below flush.nut this one seems pretty sensitive to depth.

Edit: corrected a mis typed measurement

 

[Vandelayindustries]

I have had that happen twice on 2 different rifles. Random FTF. First time, it drove me nuts until I finally figured it out.
Second go around, I arrived at that conclusion much faster.

Going to edit the post to include checking the firing pin protrusion as well.

I've had a lot of weird things happen over the years. Just 'lucky' that way.

Edit - post #15 already mentioned pin protrusion.

I’m now suspecting it may be the firing pin protrusion. As I just mentioned in my last post .008 below flush should fire in my limited experience with other rifles. I’d like to check the protrusion but I’ll have to order the firing pin disassembly tool from defiance.
Maybe it’s just gummed up with grease from the factory or maybe it’s too shallow? I’ll call defiance tomorrow and see what they say.

 

[64Rambler]

EDIT: The depth below flush measure .013-.014 on average

That would do it!

 

[Vandelayindustries]

That would do it!

.013 yes agreed. But I had a couple at .008 below flush. That right on the edge of Sammi spec. That’s why I wonder about the firing pin protrusion now.

Apologies for repeating myself. Doing my best to answer everyone

 

[Vandelayindustries]

I’ll edit the original post to add more of this info
One more data point which confuses me more… I set one primer at .0045 below flush I’d did Not fire. But it did push the primer to .0095. All the sig factory ammo that fires and my hand loads that fire are flush.

 

[K22]

Having loaded thousands of rifle and pistol loads over the past 50 years, I only ever had one failure to fire.

I traced it to a faulty primer (Federal 205M). There was no priming compound in the primer. It was a highly isolated case but it happened, nevertheless. Ever since, I check primers in a primer tray for this defect but have never seen it again.

Also, although when I used CCI primers I never had a misfire, they tend to be harder than Federal and Remington primers. I knew pistol shooters in the past that had trouble with CCI's failure to fire.

 

[luckyshot52]

Driving the primer deeper w/ftf would show that affect of moving primer is absorbing force and not hitting primer hard enough to cause primer ignition.

 

[Cloudrepair]

Have you checked the factory rounds from base to datum.

 

[Vandelayindustries]

Driving the primer deeper w/ftf would show that affect of moving primer is absorbing force and not hitting primer hard enough to cause primer ignition.

Okay so that’s a normal affect of a FTF and points to the firing pin protrusion or spring?

 

[DShortt]

I was under the opposite impression. My primers are set too deep. The ones that fired are flush. All the ones that don’t are .008-.0014 below flush. Never had an issue with any other rifle seating below flush.nut this one seems pretty sensitive to depth.

Well, someone may have different information to set me straight, but.

My understanding is that the primer needs to be seated to the bottom of the primer pocket with enough additional 'crush' to seat the primer anvil for reliable ignition.

So it would seem that the combination of these primers, the depth of the primer pockets and possibly firing pin protrusion being a bit shallow are stacking up and causing your ignition problems.

Seating a primer shallow and not to the bottom of the pocket is not a viable option as I understand ignition.

If someone has contradictory information from a verified source, I'd seriously like to have a look at that. It would be new information to me, and I'm always open to learning new things.

Edit to add - the reason the primers on the fired cases are flush with the case head is because the chamber pressure drove the primer back against the bolt face during firing.

 

[Vandelayindustries]

Have you checked the factory rounds from base to datum.

Factory ammo measures 1.554
Hand loads are 1.553
Fired factory is 1.557
Fired hand load is 1.5545

 

[Vandelayindustries]

Well, someone may have different information to set me straight, but.

My understanding is that the primer needs to be seated to the bottom of the primer pocket with enough additional 'crush' to seat the primer anvil for reliable ignition.

So it would seem that the combination of these primers, the depth of the primer pockets and possibly firing pin protrusion being a bit shallow are stacking up and causing your ignition problems.

Seating a primer shallow and not to the bottom of the pocket is not a viable option as I understand ignition.

If someone has contradictory information from a verified source, I'd seriously like to have a look at that. It would be new information to me, and I'm always open to learning new things.

Edit to add - the reason the primers on the fired cases are flush with the case head is because the chamber pressure drove the primer back against the bolt face during firing.

That’s my understanding as well and yes I’ve heard of the primer pushing back after firing. That’s why you recap before you take measurements on fired brass. The weird thing with that is all the factory ammo fired no problem. The primers are flush on the loaded factory rounds before and after firing.

.126 is the depth of the pocket on sig
.131 is the depth on the Peterson brass
Cci 200 thickness measures .125

 

[DShortt]

That’s my understanding as well and yes I’ve heard of the primer pushing back after firing. That’s why you recap before you take measurements on fired brass. The weird thing with that is all the factory ammo fired no problem. The primers are flush on the loaded factory rounds before and after firing.

.126 is the depth of the pocket on sig
.131 is the depth on the Peterson brass
Cci 200 thickness measures .125

Well, now we need to look at primer pocket specs.

Based on the information I have, .125" is the spec for large rifle primer pockets.

Your Peterson brass is .005" deeper.

I doubt that's enough to cause a problem, but it depends on your firing pin protrusion.

I apologize if I missed it, have you been able to check that yet?

Edit to add - at this point, I'd be making certain that you are, in fact, seating your primers to the bottom of the pocket with .001" of 'crush'. Because the numbers you have in post #22 do not reflect that.

 

[JMayo]

I Had a CCI 450 that just wouldn't go bang.
Looks beautiful unused except for that big dent in the back of it.

 

[Vandelayindustries]

Well, now we need to look at primer pocket specs.

Based on the information I have, .125" is the spec for large rifle primer pockets.

Your Peterson brass is .005" deeper.

I doubt that's enough to cause a problem, but it depends on your firing pin protrusion.

I apologize if I missed it, have you been able to check that yet?

Edit to add - at this point, I'd be making certain that you are, in fact, seating your primers to the bottom of the pocket with .001" of 'crush'. Because the numbers you have in post #22 do not reflect that.

.061” is what I measured for protrusion

 

[Coyotefurharvester]

Not familiar with the Defiance/trigger tech setup, could there be a drag/clearance issue causing what appears to be light strikes on primers slightly deeper?

 

[DShortt]

.061” is what I measured for protrusion

OK. So, I would make sure you are fully seating the primers and try that. If there are still FTF problems, then something is dragging in the firing pin/bolt assembly or the firing pin spring is weak. Perhaps both.

 

[64Rambler]

I’ll edit the original post to add more of this info
One more data point which confuses me more… I set one primer at .0045 below flush I’d did Not fire. But it did push the primer to .0095. All the sig factory ammo that fires and my hand loads that fire are flush.

Did you re-seat the same primer like you said earlier? The anvil was probably already pushed too far, so the firing pin just pushed it back into the primer pocket again. I'd bet that a fresh primer would work.
What is your primer pocket depth? What is your primer height, cup to anvil? EDIT Sorry - I see this was already answered.

 

[Straightshooter1]

That’s my understanding as well and yes I’ve heard of the primer pushing back after firing. That’s why you recap before you take measurements on fired brass. The weird thing with that is all the factory ammo fired no problem. The primers are flush on the loaded factory rounds before and after firing.

.126 is the depth of the pocket on sig
.131 is the depth on the Peterson brass
Cci 200 thickness measures .125

My first thought was you had particularly deep primer pockets. . . and you do.

My CCI 200's are at that thickness too. And with pocket depths of .131 those primers are at .006" below flush before they even begin to touch. Typically, I like a minimum .003-.004 crush, which would make this ~.010" below flush. That's a pretty long reach for a firing pin and if you pin is on the short side, that'll result in FTF's. So, yeah . . . I think you should really check the protrusion of your firing pin. You many need to use different brass for this gun that doesn't have such deep primer pockets.