Pierced primers

[KYyeeter]

I just switched over to a 6gt on my prs rifle. I’m shooting factory hornady ammo. I’m having some deep primer strikes and even a few that are completely pierced, see light through it. The last time it happened the bolt got stuck, took a few tries to get it open. It’s an impact action, never had anything like this until switching to 6gt. Not sure what to do about it.

 

[4O6shootist]

Barrel specs? 236 bore? I had it happen with an impact and a 236 bore krieger, granted hand loads, but they weren't hot, 2940 with a 108bt and rl16. Barrel was carbon ringed and the tighter bore spec just made it worse. Scrapped it and went with a 237 bore in my last 3 gt barrels all been good. What primers is Hdy using? 205s? 450s? Who knows, but there all NOT created equal unfortunately.

 

[KYyeeter]

My initial thought was my barrel. I bought it off here from a reputable member. I’ll have to reach out and ask him.

 

[4O6shootist]

My initial thought was my barrel. I bought it off here from a reputable member. I’ll have to reach out and ask him.

Don you have velocity numbers? I have few friends shooting that ammo in a bartlein and proof. The velocity was 2890-2915, proof faster as its a tighter bore than the bart. If you're up to 2950 or higher, it could the the barrel creating more pressure than the hdy brass likes. Who knows what primers they get either, cuz they come in by the truck load, probably in a variety of whats available and it gets thrown into the machines.

 

[spife7980]

Take the firing pin out of the bolt body. Any small circles of primer material fall out? How’s the tip look, smooth and polished or rough and etched?

 

[FisherT&C]

I replaced a firing pin recently that looked okay to the naked eye, under a 40x jewelers loupe it had sharp edges and the tip was starting to form a needle like point.

 

[BuildingConceptsllc]

Take the firing pin out of the bolt body. Any small circles of primer material fall out? How’s the tip look, smooth and polished or rough and etched?

What would be the cause and effect of this?

 

[KYyeeter]

This action barely has 1000 rounds on it. My velocity is around 2905 avg. I’ll give the pin a closer look.

 

[4O6shootist]

I replaced a firing pin recently that looked okay to the naked eye, under a 40x jewelers loupe it had sharp edges and the tip was starting to form a needle like point.

Lone peak by chance?

 

[FisherT&C]

Lone peak by chance?

No, it was an Impact but we'll used.

 

[KYyeeter]

What kind of negative effects can continuing to shoot it like it is have on action or barrel? Safety concerns? I only ask because I have a training class this upcoming weekend.

 

[FatBoy]

If you’re piecing stop. It can not only fire etch your firing pin, it will burn your bolt face and can break your firing pin and/or trigger.

Check:

pin protrusion (can this be set on that action?)

Pin clearance in firing pin hole

Excessive headspace on brass (more than .009” IMO)

Other over-pressure signs (swiping, extractor damage to rim, etc)

 

[KYyeeter]

It was 2 pierced out of 160 shot. Does that make it lean towards one particular thing possibly?

 

[4O6shootist]

The more you pierce, the flame will start to damage the pin, and it'll get worse. My buddy pierced a handful forming dasher brass, and it ate the firing pin hole on bolt face, and the pin was damaged. He needed a replacement. Another friend pierced 3 primers on eagle eye 6gt ammo(its pretty warm, and even warmer in a 236 bore Kreiger with 1k rounds) and it broke his TT trigger(Impact 737). So shit can and will eventually go wrong in the action/trigger.

 

[spife7980]

What would be the cause and effect of this?

When it pierces that primer material gets pushed through the hole in the bolt face and can jam it up making it difficult to extract because the pin is pinching that material against the bolt body.
That’s independent of the brass swelling in the chamber in the event of overpressure. Doesn’t have to be over pressure to pierce though.
Once the first pierce happens, due to bad brass/primer/whatever the cause is, the pin gets torched a smidge and each time it gets more and more cut up making it more and more likely to pierce a subsequent primer.

 

[BuildingConceptsllc]

When it pierces that primer material gets pushed through the hole in the bolt face and can jam it up making it difficult to extract because the pin is pinching that material against the bolt body.
That’s independent of the brass swelling in the chamber in the event of overpressure. Doesn’t have to be over pressure to pierce though.
Once the first pierce happens, due to bad brass/primer/whatever the cause is, the pin gets torched a smidge and each time it gets more and more cut up making it more and more likely to pierce a subsequent primer.

Ok. That's what I thought but I appreciate the detailed info. But that material would be from the primer being pierced only correct?

 

[spife7980]

But that material would be from the primer being pierced only correct?

I’m sure it’s possible to get other crap in there but I’ve only ever had the little discs of primer cup when using a cci 400 instead of a 450
Here’s a pic from the web of the little discs that get pushed through the firing pinhole.

 

[BuildingConceptsllc]

I’m sure it’s possible to get other crap in there but I’ve only ever had the little discs of primer cup when using a cci 400 instead of a 450
Here’s a pic from the web of the little discs that get pushed through the firing pinhole.
View attachment 8074044

Roger that. Obviously I was asking for a reason just to be sure about something. As usual, you are a wealth of loading information sir and a valuable asset here. Thank you sir

 

[vegashelipilot]

Resurrecting this because I'm having the same issue with the factory Hornady 6GT 109 ammo.

Tikka T3 action with Crown Ridge / X-caliber barrel (barrel nut)

First range trip I shot 80 rounds and pierced 2 primers. Chrono'd the last 50 shots that day and Avg was 2917, max was 2962 fps.

Cleaned the gun this morning, took it to the range today and shot 30 rounds. Pierced 2 more primers, the 2nd was enough pressure to break the chintzy pot metal Tikka bolt shroud so I was done for the day. Unfortunately I didn't have the magneto speed hooked up today.

The majority of the primers look good except for the ones I've pierced. I'm going to check my headspace again. If its not that, not really sure where to go from here. Hoping this Hornady isn't too hot for my build.

 

[KYyeeter]

Resurrecting this because I'm having the same issue with the factory Hornady 6GT 109 ammo.

Tikka T3 action with Crown Ridge / X-caliber barrel (barrel nut)

First range trip I shot 80 rounds and pierced 2 primers. Chrono'd the last 50 shots that day and Avg was 2917, max was 2962 fps.

Cleaned the gun this morning, took it to the range today and shot 30 rounds. Pierced 2 more primers, the 2nd was enough pressure to break the chintzy pot metal Tikka bolt shroud so I was done for the day. Unfortunately I didn't have the magneto speed hooked up today.

The majority of the primers look good except for the ones I've pierced. I'm going to check my headspace again. If its not that, not really sure where to go from here. Hoping this Hornady isn't too hot for my build.

My trouble ended being a bad carbon ring. I didn’t think it could happen that quick to a new barrel but it did. I had to give the barrel a deep scrub. Got it cleaned and haven’t had an issue since. I have since changed up a bit on how clean my chamber just making sure I get all excess cleaner/lube out of there.

 

[Malum Prohibitum]

Resurrecting this because I'm having the same issue with the factory Hornady 6GT 109 ammo.

Tikka T3 action with Crown Ridge / X-caliber barrel (barrel nut)

First range trip I shot 80 rounds and pierced 2 primers. Chrono'd the last 50 shots that day and Avg was 2917, max was 2962 fps.

Cleaned the gun this morning, took it to the range today and shot 30 rounds. Pierced 2 more primers, the 2nd was enough pressure to break the chintzy pot metal Tikka bolt shroud so I was done for the day. Unfortunately I didn't have the magneto speed hooked up today.

The majority of the primers look good except for the ones I've pierced. I'm going to check my headspace again. If its not that, not really sure where to go from here. Hoping this Hornady isn't too hot for my build.

See the 6 GT forum on Facebook. Several reports of pierced primers with Hornady over the counter ammo, even on brand new rifles (including mine).