Tikka T3X Failure to Fire

[Rugger7622]

When you see brass, especially cheap brass, sized based on a gauge that is not your chamber for measurements, chances are those pieces got over sized and are causing your problems.

Oversized brass will cause exactly what you’re seeing. There will almost always be variation in sized brass, and varying amounts of spring back.

Agree, however when I was in the middle of trying to figure this out, I sized and measured each case to make sure it was +/-.001 using a Wilson chamber gauge, the spin on type gauge vs my comparator set. The Wilson gauge has SAMI marking to indicate 0. I really like the Wilson to measure, it’s slower than my comparator and calipers but very repeatable.

 

[Choupique]

Make it a bit less tight?

That's what id do. It being tough to close means something is being stretched or squeezed. At best, it means you have almost no tolerance on the tight side. When things start getting that tight, it doesnt take much of anything to cause problems. It might be such that just having some dust on the case means fhe difference between full closure and not. Its not likely THAT tight, but you get the point. Tolerance stacking is likely what's getting you.

 

[Lawnboi]

Agree, however when I was in the middle of trying to figure this out, I sized and measured each case to make sure it was +/-.001 using a Wilson chamber gauge, the spin on type gauge vs my comparator set. The Wilson gauge has SAMI marking to indicate 0. I really like the Wilson to measure, it’s slower than my comparator and calipers but ver

I’d put next to zero merit in the Wilson gauge. Iv got a few in the scrap metal bucket.

I’d be measuring with a comparator and going from there. I’d also not touch verified saami minimum chamber.

 

[Rugger7622]

I kept saying Wilson, but meant Whidden. I agree with you on the Wilson. This is the gauge I’m talking about. What would you do to measure the shoulder when installing the barrel?

 

[Rugger7622]

I guess if I pull the barrel, where/how would I set it? Use the gauge but a little more?

 

[Choupique]

Screw it down on the go gauge, back it off a hair, tighten the nut and then check it.

 

[Rugger7622]

Got it

 

[Rugger7622]

Mechanically, can someone explain why a tight chamber would lead to FTF’s, I would expect a tight chamber to eliminate those issues? Factory brass fits, my reloads fit with no issues. I can’t get my head around why if I I increased the headspace .001 would accomplish anything in this actual issue. I know it’s a variable but I don’t see what changing it would do.

 

[Jordan Smith]

Mechanically, can someone explain why a tight chamber would lead to FTF’s, I would expect a tight chamber to eliminate those issues? Factory brass fits, my reloads fit with no issues. I can’t get my head around why if I I increased the headspace .001 would accomplish anything in this actual issue. I know it’s a variable but I don’t see what changing it would do.

In and of itself, a tight chamber wouldn't cause those issues. But tight chambering, such that the bolt doesn't close and cock the FP spring all the way, could. As could over-sizing your brass and creating excess headspace, even with a tight chamber.

While I agree that correcting the headspace issue would be a good idea, it's a known issue for primers that are not fully seated in somewhat loose pockets to cause FTFs, as the FP uses its momentum to seat the primer while also denting it, decreasing the impulse of the primer material itself (i.e., reducing the rate of deformation that causes ignition). It would be interesting to measure the seating depth of the primers that failed to fire versus those that fired correctly. It could be caused by variance in primer pocket tightness combined with primers not being fully seated, any maybe even combined with excess headspace from oversizing or a bolt not full closed and FP spring not fully cocked, for some serious tolerance stacking.

 

[Jordan Smith]

I guess if I pull the barrel, where/how would I set it? Use the gauge but a little more?

The bolt should close without any effort on the GO gauge, and should not close at all on the NO-GO gauge.

As was said, screw the barrel lightly snug against the GO gauge, and just back off a hair to reduce the snug fit. Tighten the barrel nut and check fit with both gauges.