Failure to Fire Tikka 223

[rugger7622]

I've posted this on another forum, but still haven't figured out my issue.

I have a tight chamber barrel (will close on a go gauge, but takes a lot of force) and I have random Failure to Fire with LC brass. I bought 100 Starline pieces of brass and have had zero FTF with this brass. I've swapped firing pins and still had random FTF's. I've both swagged and cut the LC brass and even uniformed the primer pockets over the winter.

Today I shot 30 rounds had two failure to fires, both went off on the a second bolt cock. All FTF primers have shown positive strikes on the 1st failure. The brass that failed has been set back by the impact .007 compared to starting. I can't for the life of me figure out the issue or the next steps. I could just buy more starline, but I don't know it's happening with LC brass. Also, I'm crushing the primers around .006. I'm using CCI 450's and have tried 3-4 different packages. The brass grows very little if all fired in my chamber.

Should I:

1. Pull the barrel and reset it to easily close on a go gauge, I don't why this would be a problem? It's a barrel nut fit barrel
2. Buy new Starline brass and move on.....tough for me to do because it doesn't make sense to me!
3. Try something different?

I will say the gun shoot a legitimate 10 shot .75" groups with both 75ELDM's and 77TMK's.

Just not sure next steps.

 

[M-61]

The brass that failed has been set back by the impact .007 compared to starting.

I don’t understand what you mean.
Can you clarify?

 

[SpencerC87]

The brass that failed has been set back by the impact .007 compared to starting.

Can you elaborate a little more what you mean by this? What are you measuring? How are you determining how much to size your fired brass?

 

[Coyotefurharvester]

So you only uniformed the LC brass pockets? Any LC brass you haven't uniformed? Have you tried seating at no crush, just bottomed? Do you know pin protrusion?

 

[M-61]

The brass grows very little if all fired in my chamber.

That’s actually good and not part of your problem.

 

[rugger7622]

Pin extrusion was fine, when I test last year, don't have the number off the top of my head. I've uniformed, not uniformed LC brass with the same FTF rate. I have basically zero growth after firing measured on a comparator. I'm setting back .002, which, by my comparator .002 below sami zero.

 

[rugger7622]

That’s actually good and not part of your problem.

I agree, but can't get to why I'm having this issue with just LC brass - by the way, I have 1,000 piece across many years of lot numbers.

 

[rugger7622]

I was not seating at crush and was convinced that was my issue so carefully measured and crush everything on these 30 and was sure that was my issue.......but it doesn't appear to be it.

 

[rugger7622]

A smart guy might just buy more starline and move on but I can't do that without understanding why!!!

 

[M-61]

The brass that failed has been set back by the impact .007 compared to starting

I don’t know what this measurement is?
Clarify

 

[M-61]

I have a tight chamber barrel (will close on a go gauge, but takes a lot of force)

This is not a tight chamber.
It is headspace. Just to clarify that

 

[rugger7622]

I measured the shoulder at starting point of .0 and the ones that failure to fire are at least .007 shorter...to me indicating they are getting a solid firing pin strike, but not going off, my guess is the bolt re-cock combined with the 1st pin is doing this? Just strange that the bolt is hitting with enough force to set the shoulders back but not going off. I see basically zero growth on brass that does fire the 1st strike.

 

[rugger7622]

This is not a tight chamber.
It is headspace. Just to clarify that

Ok, thank you. In my case, I don't think it's the issue, do you?

 

[rugger7622]

To add to this, I have 3 firings on the Starline brass, with me bumping the shoulders .002 and no failure to fires.

 

[M-61]

Ok, thank you. In my case, I don't think it's the issue, do you?

Absolutely not

 

[DShortt]

I've posted this on another forum, but still haven't figured out my issue.

I have a tight chamber barrel (will close on a go gauge, but takes a lot of force) and I have random Failure to Fire with LC brass. I bought 100 Starline pieces of brass and have had zero FTF with this brass. I've swapped firing pins and still had random FTF's. I've both swagged and cut the LC brass and even uniformed the primer pockets over the winter.

Today I shot 30 rounds had two failure to fires, both went off on the a second bolt cock. All FTF primers have shown positive strikes on the 1st failure. The brass that failed has been set back by the impact .007 compared to starting. I can't for the life of me figure out the issue or the next steps. I could just buy more starline, but I don't know it's happening with LC brass. Also, I'm crushing the primers around .006. I'm using CCI 450's and have tried 3-4 different packages. The brass grows very little if all fired in my chamber.

Should I:

1. Pull the barrel and reset it to easily close on a go gauge, I don't why this would be a problem? It's a barrel nut fit barrel
2. Buy new Starline brass and move on.....tough for me to do because it doesn't make sense to me!
3. Try something different?

I will say the gun shoot a legitimate 10 shot .75" groups with both 75ELDM's and 77TMK's.

Just not sure next steps.

What EXACTLY do you mean by 'The brass that failed has been set back .007 by the impact compared to starting'?

What are you measuring?

How are you measuring it?

What is the before measurement being taken from?

What is the after measurement being taken from?

Given that the Starline brass hasn't caused a FTF issue, I'm going to guess that your LC brass has been sized too much and your cartridge base to datum line measurement is under spec, but that's just a guess. No way to know until you answer my first 4 questions.

 

[rugger7622]

What EXACTLY do you mean by 'The brass that failed has been set back .007 by the impact compared to starting'?

What are you measuring?

How are you measuring it?

What is the before measurement being taken from?

What is the after measurement being taken from?

Given that the Starline brass hasn't caused a FTF issue, I'm going to guess that your LC brass has been sized too much and your cartridge base to datum line measurement is under spec, but that's just a guess. No way to know until you answer my first 4 questions.

1. With a Whidden gunworks chamber/case guage and comparator. The sized brass is -.001 on the Whidden guage and only grows to .000 after firing. Confirmed with Miyatoyo caliper with comparator before and after firing as well.
2. Whidden case gauge and comparator
3. -.001 on gauge before firing
4. Same gauge

Starline and LC brass sized to the same measurements, using the same Forster FL sizing die

 

[Janeau]

Just a wild guess..that LC brass..was it fired in your chamber prior or first time for this once fired brass in your gun ? Did you measure shoulder to case rim - comparing your fired starline brass dimension with the LC brass that do not fire ?

As other posters -that .007 measure after firing mean nothing to all of us who try to understand and help. Normally a case will take all headspace and conform to chamber so tight - that case have to be resized - bumped .002 at the shoulder and base. (ok - there is exception to dimension for Benchrest gun and other match competition gun)

If I was you - I would set up my gun with proper headspace with a no go gage or with a piece of tape on the rear of the go gage - gentle bolt closure on it. There is nothing to gain by having your gun set up like it is now.

 

[M-61]

I measured the shoulder at starting point of .0 and the ones that failure to fire are at least .007 shorter...to me indicating they are getting a solid firing pin strike, but not going off, my guess is the bolt re-cock combined with the 1st pin is doing this? Just strange that the bolt is hitting with enough force to set the shoulders back but not going off. I see basically zero growth on brass that does fire the 1st strike.

I’m really trying to follow this. Now from what I’ve read I’ll give this a whirl. I’m attempting to see your measurement.
Prepare a case. Do your measurement. Chamber the round. Do your measuring. Ie it possible that your headspace is so negative you are pushing the dhouldr back with your bolt and your chamber?
I really reaching because.007 is so great I have to question your measuring.
I still don’t think I’ve helped with the FTF…yet

 

[DShortt]

1. With a Whidden gunworks chamber/case guage and comparator. The sized brass is -.001 on the Whidden guage and only grows to .000 after firing. Confirmed with Miyatoyo caliper with comparator before and after firing as well.
2. Whidden case gauge and comparator
3. -.001 on gauge before firing
4. Same gauge

Starline and LC brass sized to the same measurements, using the same Forster FL sizing die

OK, so are the same primers being used in both the LC and Starline brass?

And this still doesn't explain the .007 difference in the 'before' and 'after' on the LC brass.
The cartridge base to datum is .007 less, or the primer is seated .007 deeper in the pocket, or ..... ???