Primer Strike Question - Tikka T3 custom build with Bix n Andy Trigger

sjstrey

sjstrey

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Looking for some advice here from someone with experience with Tikka/Sako Bixn'Andy triggers before I start tinkering.

I have a Tikka T3x sporter, originally in 223, that JC out east rebarrelled to 222rem a few years ago. Last year, I replaced the trigger with a Bix n' Andy that I currently have set to just around 1.5oz. It cocks reliably and fires with a crisp, consistent pull, but I'd say one in every 500ish rounds, I get a misfire - and, I've noticed that since the new trigger was installed, the dimple on the primer is a little bit smaller than it used to be.

Some details: T3x action, trued and headspaced by JC Custom Barrels, B&C stock, single-shot adapter used, BnA Pecision trigger (not the Dakota).

At first, I suspected a headspace issue with a new batch of unfired brass, but I've ruled this out. I only bump the brass back about 3 thou when I size, so I doubt this is it.

I use Lapua brass and CCI BR4 primers - so I highly doubt it's a consistency issue with my components (though I suppose it IS possible)

Inside of the bolt body, firing pin and spring are spotlessly clean - no grease/rust/oil/etc.

Here are my questions:

1) when hanging the trigger on the action there is a little bit of play until it is tightened up - could the trigger be hung a thou or two too far forward or rearward, affecting the sear engagement, shortening the pin travel or moving the pin off the axis of the action when it is cocked?
2) could this trigger placement cause a little bit of drag, slowing the pin down?
3) can setting the pull weight too light cause this (someone told me this is possible, but for the life of me I can't picture the mechanics of how this could be)?
4)The sear engagement seems right - I don't detect any drag when I move the pin forward and back with the trigger pulled, but could the drag be happening somewhere in between the cocked and fired position?

Any other thought or suggestions?

As I said, this is so intermittent (2 or 3 shots a year - and I shoot a lot), I can't really rule out the possibility of a few bad primers for sure, but now it's winter and I'm bored enough to want to try and sort this out. The part that nags at me is the slightly smaller primer strike dimple since changing the trigger.

Thanks in advance

Steve
 
My first thought is to make sure the primers are seated as deep as they will go. Stand a loaded round on a flat surface.. if it rocks at all the primer is not fully seated and is not fully sensitive.
 
Did the amount of firing pin fall change when you swapped out triggers? When was the last time you swapped out your firing pin spring/striker assembly?
 
As mentioned above I would measure firing pin travel should be around .230 a trigger change can make a difference.
 
Bdb, I went with the trigger change because, for a bench/target rifle, the tikka trigger just wouldn’t adjust down far enough and still break consistently. There’s really no comparison between the BnA and the stock trigger.
 
I got my stock T3 trigger down to 1.5# and I didn't even change the spring.

All I did was remove the 'washer/spring' that is under the trigger assembly retaining screw (it's only really there to provide forward pressure on the stock magazine, I have a chassis with AICS mags so it's not needed).
Doing this allows the head of the trigger assembly retaining screw to move slightly higher, allowing the adjustment screw to back out a skootch more, which got me to a reliable 1.5# and it feels just as crisp as as if it was set at the standard 2-2.5# that you normally can get a T3 down to.

Sometimes lightening a trigger will reduce firing pin force (although I can't say for certain it would do it on a T3), I had a Gevarm .222 that once you reduced the trigger pull below a certain weight, it would only reliably light Federal and Winchester primers, it would not light Remington or CCI. It was because the way the sear engaged the cocking piece, lowering the weight would allow the firing pin to move slightly closer to the case head when cocked, so you got slightly less travel from cocked to not. Once you increased the pull weight, it would ignite everything.
 
I was able to overcome that short pin travel by increasing the sear engagement (which, if overdone, would affect the trigger pull and possibly cause drag). Thanks again everyone I think I’ve got it sorted now. It was a combination of sear setting and the trigger not being hung as far to the rear as possible. All fixed up now.
 
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