Nucleus Light Primer Strikes

ThePretzel

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Dec 17, 2017
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This last weekend I had the chance to take my new Nucleus action out to the Gunwerks Monster Steel Challenge PRS match (big thanks to Traust for the positional bag I was lucky enough to pick up, it was on my to buy list already!) and put it through its paces when I noticed a few issues.

I ran about 250 rounds through the gun at the match, all loaded in virgin Lapua 6BR brass, and ended up having 6 different light primer strikes throughout the day. I'm in the process of getting ahold of ARC to figure out a fix, whether it be a new spring or simply a small tweak, but I was curious to see if anyone else noticed a similar issue with their Nuclei.

I know Lapua brass can sometimes be a little bit on the small side for SAAMI specs, but I headspaced the barrel off of a medium sized piece of brass. Some rounds chambered smoothly and some chambered a little bit tight since my spot in the match was last minute and I was running low on time to size all of the brass before loading. Since the runout on the headspace of factory Lapua brass is usually only 2 thousandths or so I'm pretty sure that wasn't the issue causing the light primer strikes.

That being said, I loved the action at the match. I was feeding 6BR without issues from magazines both with and without spacer kits both days. The second day was a field match course of fire with some wind, so the action got pretty dusty and dirty (inside and out) but by the end of the day it still felt smooth and had no issues with the bolt binding or feeling gritty. That's what I was hoping for since I've shot a lot of field match courses of fire and had issues with other tightly fit actions feeling gritty or stiff when the dirt and dust inevitably makes it way past your cover into the action.
 
Just wanted to update with some relevant information I realized I had left out. I'm using CCI BR4 primers, so not quite as hard as the 450's but still probably firmer than Federal or Winchester primers.

That said, Jon from ARC actually just reached out to me before I had the chance to contact them and offered up a solution for the issue I was seeing, which is definitely A+ customer service.
 
You could probably start by removing the striker assembly. Ted covers it in one of the videos. The pin is adjustable for protrusion as well.

Not trying to be harsh here, but fiddling with protrusion on a pin is the last thing people should be doing when they experience light strikes.

I've had over 2 dozen guns of various actions show up at my shop with "light strike problems, they keep getting worse no matter how much pin protrusion I give it"

Here's what to check and why screwing with a pin protrusion is a bad idea:

Step 1: Measure your pin protrusion. If it is anywhere in 0.030-0.050" leave it alone. There is PLENTY. You only need about 0.025" for extremely reliable ignition IF you have everything else right.

Step 2: Check your ammo to see if you have any primers that aren't seated to the base of the pocket. Typically the issues brought to us are from folks that use hand primers and somewhere in the marathon batch of priming brass while watching TV their hand got tired and some primers slipped through not quite fully seated.

The reason Step 2 is critical is because if the pin has proper protrusion and the primer isn't set properly the energy from the strike is robbed to push the primer to the base of the cup.

"I checked this, all the duds were seated all the way"
Correct, they are seated all the way because the firing pin impact finished the seating process.
It also didn't have enough strike left to set off the primer.

Had they been checked before being a dud it is highly likely that it would be discovered that they were just a little bit proud. Even dead flush isn't enough. Modern brass has relatively tight constraints for primer pocket depth and that sets up so that the primers (arguably one of the most consistent parts of modern ammo) is going to be a couple thousandths sub flush.

Step 3: After having some duds, go back and check the rest of that batch and see if you find any others that are not sub flush. Sometimes it's just enough that they go off; sometimes not.

Step 4: Take anything you find that is a proud primer and separate into 2 piles, split it in half. Take half and reseat the primers in a press so that they're properly seated in the case. Take those half and the half that is suspect and go to the range. Note which is which and shoot them.

If the ones you reseated go off (mind you, once a poorly seated primer is struck it isn't likely to go off on a second time hitting it) and the ones that are still suspect have fail to fires you found the culprit.




I've been around and around on this with several prototype actions that I've had from companies where I worked to help develop from a prototype to a production model.

I stopped hand priming because of this.



So, I didn't yet address why pin protrusion is the wrong avenue to mess with.
When the bolt is in battery in the action the bolt face is the line of reference.
It can be assumed that the primer is sitting against that face. We've discussed that a properly seated primer should be slightly subflush so therefore this is a conservative estimate of impact energy. Nevertheless it makes the discussion easier to digest if we ignore that complication for the time being.

A spring has a given amount of potential energy in it while assembled in the gun.
It has PE when it is decocked because there is preload in it.

The PE is defined as 1/2 * mass (spring and pin together) * compression distance ^2 * springrate

compression distance is defined as "X"
PE = 1/2 * X^2 * k

PE when it's assembled and uncocked is PE0
PE when it's cocked and ready to fire is PE1

PE1-PE0 = PE of the system to impart on a primer.
Ignoring outside losses and inefficiencies (I'm going to assume energy is conserved, which we know it isn't but it works for this discussion)

The kinetic energy at the instant the pin crosses the bolt face plane cannot be larger than PE1-PE0 aka PEstrike

Now:

The cocking piece and cocking cams have a given lift imparted to the firing pin no matter what happens.
In a Bighorn this value is approximately 0.2"
In a Nucleus it's very similar.
In a Remington 700 it's closer to 0.28"

If the pin is adjusted further out at decocking then the amount of distance that the pin is retracted behind the bolt face during cocking is reduced.
Remember, the cocking lift is a fixed value and cannot change. Therefore if the pin used to be pulled from 0.05" forward of the bolt face and it's retracted by 0.2" it is now 0.15" behind the bolt face.

The potential energy stored is actually higher than when the pin is fully decocked but that's useless storage to set off the primer, you can't get it out of the system because the primer is strong enough to withstand regular pin forces while decocked. Try it sometime. Put a piece of primed brass in the chamber and hold the trigger while closing the bolt slowly. Open it back up.

There may be a tiny witness mark on the primer but the primer didn't go off nor did it dent the primer.

So, this is important because if we cannot get that energy back into the pin tip during impact we're never going to setoff the primer.
Back to the energy of the spring while it's cocked.

At full cock on a 0.05" pin protrustion the system has a given amount of PE
If we pull that pin back by 0.02" to a protrusion value of 0.03" then we have given 0.02" more travel on the pin before it crosses the reference plane to hit the primer.

Since we had 0.2" to begin with total, less 0.05" protrusion

We had 0.15" lift useful.
Now we have 0.17" lift useful.
The mass and springrate hasn't changed, just the X value.
so PE15 = 1/2*k*(0.15"+preload)^2
PE17 = 1/2*k*(0.17"+preload)^2
In a bighorn there's about 1" of preload in the spring

when we look at a ratio of the values PE17/PE15 everything cancels except the X^2 values

1.17^2/1.15^2

Doesn't look like much but it's about 3.5% difference in energy available to start with.

A more extreme example would be an action presented to us by someone who was tired of dealing with "it must be the Jewell trigger" from his last gunsmith. The guy had charged him for 3 triggers total and every time he got it back he had a brand new trigger installed and more firing pin protrustion.

It was so bad that the thing wouldn't set off primers at all and then got to the point that it would have extremely hard closing on teh bolt on factory ammo.

When I got it the pin was unable to retract through the bolt face any longer. It was protruding nearly 0.015" just in a cocked condition. That explained the heavy bolt closing. As the bolt was being closed it was cocking the action off the trigger...

I adjusted the firing pin protrusion back to 0.032" and it set off every primer we threw at it, including the notoriously hard machine gun primers from CCI the #41's

So in a less severe but similar example that came in from an adjustable pin action the customer had extended the pin out to 0.07" travel and "it keeps getting worse, I think I have a defective action"

0.2" lift with a target of 0.035" protrusion is 0.165" delta
At 0.07" protrusion they had 0.13" lift available

0.13^2/0.165^2 = 0.621 or 62.1% of the strike energy that it should have had. It was not going off 90% of the time, I was amazed that anything went bang to be honest.

When we reset it back to 0.035" of protrusion it went off 50 times in a row with primed brass at the shop.
Long story short, the VAST majority of the time adding firing pin protrusion is not the answer. There are other much simpler reasons for light strikes.

In an action that's brand new from the factory it's possible but I know that ARC has a jig setup to set the pin protrusion from the start and they have a design that cannot come loose and wiggle further out.

Some designs can do that and I've seen it where over thousands of cycles the locking screws work loose and the pin wanders forward. The light strikes are inconsequential at first but then they get to a critical point and all of the sudden it seems to be endless light strikes and ultimately completely failure of the system.




Not enough protrusion is a possible failure as well but even back at 0.015" I watched a bolt action that went off 47 times out of 50 rounds. The pin was an accidental setup part that was mixed in with good ones but even at 0.019" short of the design nominal it still went off a LOT... The customer discovered it when the weather turned cold and he got a lot more failures.

Replaced the pin, set it to 0.032" protrusion and it's been back for 2 more barrel replacements without a single reported failure since.
 
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I think that may be a part of the problem. If I recall right, the owner of AO posted a video with an unnamed trigger that he says robs the firing pin of momentum. People were speculating that it was a Timney.

I agree, though in this case I've had a TE in a Nucleus for more rounds than anyone else as of yet. The problems arose with a dirty action and a firing pin spring that was a weak prototype that had been cobbled together for SHOT show and not replaced. It still took dirt and 400rd and unknown thousands of dry fires to have a problem show up.

Timney also updated the design of the CE's recently, in the last 3-4 months. The last couple batches of CE's that we received from them had a different arrangement than the originals that I have in my rifles.
 
I agree, though in this case I've had a TE in a Nucleus for more rounds than anyone else as of yet. The problems arose with a dirty action and a firing pin spring that was a weak prototype that had been cobbled together for SHOT show and not replaced. It still took dirt and 400rd and unknown thousands of dry fires to have a problem show up.

Timney also updated the design of the CE's recently, in the last 3-4 months. The last couple batches of CE's that we received from them had a different arrangement than the originals that I have in my rifles.


Meant to say 4000rd not 400
 
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As far as primer seating depth goes, I've been seating all of my primers on my Forster Co-Ax press and have loaded approximately 2,000 rounds with CCI BR-4 primers (same lot as these) prior to this without experiencing even one light primer strike. I also measure the CBTO on every round I load with a Hornady bullet comparator, and when primers are proud (I used to have this once in a while on my Hornady press if I wasn't careful) it will read a bullet that's loaded longer since the primer would be protruding.

I can feel when the primers protrude at all because the round rocks around on the calipers instead of feeling solid as though your calipers are going over the top of the primer and sitting flush with the base of the case all the way around. This should help address the concerns of the primer batch or the primer seating depth. I do appreciate, however, the very in depth post about firing pins and above, I learned a fair amount from it.

As far as the Calvin Elite model that's in it, it's borrowed from a Christensen rifle bought back in around 2015 while I wait the last week or two for my TriggerTech Diamond. This could well be the problem, but I don't know for certain. Jon has offered to help me with a heavier firing pin spring, which is much appreciated and I'll use it until my new trigger comes in. Once the Diamond is installed I'll see if the standard spring works without issues again.
 
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I talked to Ted about it today and we have been back and forth over 16# vs 19# springs in the Nucleus. He's been testing the 16# springs and hasn't had issues but he was concerned that it was on the ragged edge. I didn't want to say anything prior to speaking with him but if you're getting a 19# spring through Jon that sounds like you're in good shape.

I ordered all the Hancock actions with 19# springs just to be cautious as it's a production rifle that has narrow margins. There isn't room to risk shipping bolts back and forth for customers that have light strikes because of a spring problem.

Another friend has both spring types in his 2 Nucleus actions and he cannot feel a difference in bolt lift. It's measureable with a proper setup but the difference is negligible so Ted said to me today that they will ship the actions with 16# springs and if anyone has an issue they will send a 19# out to them.

@ThePretzel you said it's small rifle primers which are known to be the hardest to set off. I haven't seen any issues with 16# springs in LRP cartridges in fact I didn't see issues for a long time with a cut down 16# spring with LRP but when it got wet and sandy there was an issue. Replacement of the spring to a standard 16# fixed it and I had no further issues with the prototype here.

It sounds like it's just on some actions that are on the ragged edge of ignition with SRP's or magnum SRP's so the fix of a free replacement spring from ARC is a pretty good solution. I'm erring on the side of caution and making all the JHR's with 19# springs since we have a mix of small and large primer cartridges and a platform that's advertised as having replacement barrels from the factory.
 
It sounds like it's just on some actions that are on the ragged edge of ignition with SRP's or magnum SRP's so the fix of a free replacement spring from ARC is a pretty good solution. I'm erring on the side of caution and making all the JHR's with 19# springs since we have a mix of small and large primer cartridges and a platform that's advertised as having replacement barrels from the factory.
This seems like it's probably the case. I know the SRPs, especially CCI since they're known to be harder to ignite than other primer brands, are going to cause more trouble. I'm not too worried about the bolt lift either, considering it already honestly felt lighter than the bolt lift in the Christensen rifle I was previously using. Just seems to be a combination of about every worst case scenario for primer strikes (dusty, hard primers, potentially also compounded by the specific trigger I'm using). The firing pin is, however, impeccably fit to the bolt face and it's the first action I've personally owned that didn't require bushing the firing pin to avoid primer cratering when using SRPs.

Funny enough the bolt lift got lighter when I installed a barrel on the rifle, to the point where it felt like it took only about half the effort compared to just cycling the action with no barrel inside my chassis. It could just be the extra weight on the rifle at that point (it's about a 25 pound gun with the bipod attached), but regardless it feels nice and smooth still and I can cycle the action without it coming off target.

The free spring replacement is better than I was expecting, honestly. They're helping me out by shipping it straight to my door, and quickly too even though I made sure to let them know I don't have a need for the rifle again until the 11th. I'll pop that spring in and I imagine I shouldn't have any further troubles. I can update with my thoughts on the subjective difference in bolt lift once it arrives.
 
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I've had three light strikes so far out of 116 rounds, using new Lapua brass, and CCI 450s. My trigger is a Huber two stage. I seat until the primer is just a few thousandths deeper than the case head. Out of the 3, two of them I was able to cycle the bolt and hit them again, both of them firing. The third did not, even after multiple attempts. When I set the headspace, I used a go gauge and a piece of scotch tape.
 
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I've had three light strikes so far out of 116 rounds, using new Lapua brass, and CCI 450s. My trigger is a Huber two stage. I seat until the primer is just a few thousandths deeper than the case head. Out of the 3, two of them I was able to cycle the bolt and hit them again, both of them firing. The third did not, even after multiple attempts. When I set the headspace, I used a go gauge and a piece of scotch tape.
Sounds like you're on the ragged edge too. A quick phone call to ARC and they should get you fixed up with a swap out spring.
 
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Some Lapua brass is on the small side of headspace. Couple that with hard 450 primers and you will get light strikes in almost any action(even my Panda). Using cci 400 primers in new brass has solved this for me or just jamming a bullet a few thou. Once they are fired and headspace is tight, no more issues.
 
Some Lapua brass is on the small side of headspace. Couple that with hard 450 primers and you will get light strikes in almost any action(even my Panda). Using cci 400 primers in new brass has solved this for me or just jamming a bullet a few thou. Once they are fired and headspace is tight, no more issues.
The Lapua brass is not the issue. I headspaced directly off the brass, not off a go gauge, which meant it was set up so that all brass would be within 1-2 thousandths of correct headspace since the run-out on Lapua brass is low. I also used CCI BR4 primers, not 450 primers.
 
The Lapua brass is not the issue. I headspaced directly off the brass, not off a go gauge, which meant it was set up so that all brass would be within 1-2 thousandths of correct headspace since the run-out on Lapua brass is low. I also used CCI BR4 primers, not 450 primers.
CCI BRs and 450s have the same cup thickness at around 0.025" and the BR2s sit a bit shorter in the primer pocket.
http://www.accurateshooter.com/technical-articles/primers-and-pressure-analysis/
 
I am looking to dig a little deeper into this:
"Step 2: Check your ammo to see if you have any primers that aren't seated to the base of the pocket. Typically the issues brought to us are from folks that use hand primers and somewhere in the marathon batch of priming brass while watching TV their hand got tired and some primers slipped through not quite fully seated.

The reason Step 2 is critical is because if the pin has proper protrusion and the primer isn't set properly the energy from the strike is robbed to push the primer to the base of the cup."

I have always bottomed out my primers by feel with my hand primer and havent had issues, however I have seen info about tools with the ability to adjust primer seating depth and have always questioned this. Given the quoted info above, doesnt this imply that not bottoming out the primer my lead to primer failures? Also, if primer pockets are too deep either from the factory or by primer pocket uniformers, then I question if the case is even reliable.
 
I am looking to dig a little deeper into this:
"Step 2: Check your ammo to see if you have any primers that aren't seated to the base of the pocket. Typically the issues brought to us are from folks that use hand primers and somewhere in the marathon batch of priming brass while watching TV their hand got tired and some primers slipped through not quite fully seated.

The reason Step 2 is critical is because if the pin has proper protrusion and the primer isn't set properly the energy from the strike is robbed to push the primer to the base of the cup."

I have always bottomed out my primers by feel with my hand primer and havent had issues, however I have seen info about tools with the ability to adjust primer seating depth and have always questioned this. Given the quoted info above, doesnt this imply that not bottoming out the primer my lead to primer failures? Also, if primer pockets are too deep either from the factory or by primer pocket uniformers, then I question if the case is even reliable.


It depends on how tight the cup is. If the primer is flush and the pockets are very tight then you will get good ignition.

If your brass is loosening up and there is little resistance seating the primers then you're apt to get more issues.

The seating depth adjustment tools I've seen have all been for very large calibers like 50BMG benchrest use. The fire control in 50's is a different animal entirely and we're talking about far more spring and a lot less concern from owners talking about bolt lift feel on a given action.

Uniformers and pocket cutters can readily overcut the pocket on brass and ruin it if you don't know what you're doing, that's long been known as an issue. Rarely are the pockets too deep from factory, it's one of the most consistent things on modern brass because it's swaged by hard tooling, it's not a drawing process.
 
Just an update to the situation. Went out to a local prone match this afternoon to test out the new 19 pound firing pin spring. Fired ~60 rounds and ended up with one light strike that wouldn't go bang, so it's definitely at least an improvement. The one that didn't go bang I don't blame on the firing pin spring because I loaded these rounds in a hurry last night and didn't clean primer pockets, so it's possible this one didn't get pushed all the way in and it simply compressed some carbon in there.

The bolt lift was more or less unchanged, at least as far as I could tell. I didn't notice it being any heavier and the action ran nice and smooth the whole time.
 
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Well I’m joining the Nucleus light primer strike club. Guess I will purchase the spring. I had 9 out of 40 light strikes. Put all 9 in another rifle. Bang. Finally talked with someone at ARC. They don’t like to talk about light strikes or failed CRF.
 
I cancelled my Nucleus pre-order (was very early in line) to buy an AI instead. The AI is arriving in 2 weeks but this thread and the experiences of some people here are making me feel pretty good about the decision.
 
I didn't have any issues up until 350 rounds. Drove 14 hours this weekend for a match, shot two stages just fine. Stages 3 and 4 I couldn't get anything to fire.

Called ARC today and spoke to Justin. He said he was going to put the springs up on the website today. Sure enough, they are now there. I ordered a 19 pound spring. a 22 pound spring will be available in October.

Kinda BS that the shipping is more than the spring but I dont know where else I would get one so I ordered it.

I'm not bothered by the issues. It's a new release and I never expected things to be perfect.
 
I didn't have any issues up until 350 rounds. Drove 14 hours this weekend for a match, shot two stages just fine. Stages 3 and 4 I couldn't get anything to fire.

Called ARC today and spoke to Justin. He said he was going to put the springs up on the website today. Sure enough, they are now there. I ordered a 19 pound spring. a 22 pound spring will be available in October.

Kinda BS that the shipping is more than the spring but I dont know where else I would get one so I ordered it.

I'm not bothered by the issues. It's a new release and I never expected things to be perfect.

I agree. New releases will have issues. But I’m a little peace’s at having to buy a spring. Especially if they knows issues are arising. And the shipping is more than the spring.

But my biggest beef is that Justin seemed bothered by the call and didn’t offer any help. Just rushed to tell me to buy the spring. He did, however, call me and tell me they were listed on the site. Which was nice.
 
I agree. New releases will have issues. But I’m a little peace’s at having to buy a spring. Especially if they knows issues are arising. And the shipping is more than the spring.

But my biggest beef is that Justin seemed bothered by the call and didn’t offer any help. Just rushed to tell me to buy the spring. He did, however, call me and tell me they were listed on the site. Which was nice.
I imagine it's stressful having issues like that with a new release. I hope they'll just ship Nucleus actions with the proper weight spring going forward though. My 2017 Mausingfield works fine but new actions can be headaches.
 
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As an additional update, I did further testing. It looks like it's an issue, at least for me, with the combination of the Timney Calvin Elite single stage trigger and the Nucleus action. I heard wind on Facebook that there were a couple other people having trouble with the Timney CE and their Nucleus, however, so there must be some sort of poor fit between those two particular products.

I've since received my TriggerTech Diamond and dropped that into the rifle. Since that was put into the gun I haven't had a single issue. No light primer strikes, and I took some of the light strike rounds that didn't go off from before and shot those without problems as well. I like the trigger better too (I got the flat face trigger, which I prefer), so it's a win-win for me and is the trigger I had originally intended to be using anyways.
 
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My Nucleus is probably not due until Christmas, but I've been watching and reading the many reports of light strikes and will admit that it is somewhat concerning. In the big Nucleus thread, a question was asked regarding what trigger was being used and two so far have used Timney (510 and 517). As the 517 is my go to basic trigger, that is duly noted, especially after comments above about Timney CE having the same issue.

The engineer in me immediately wonders what the common detail is on a Timney that might not interact well with the Nucleus. The realist in me is happy that I happen to have both a TriggerTech Special and a Huber 2-stage that are cooling their heels in my safe. It sounds like time to break one of them out soon.
 
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When I had the two triggers out side by side I didn't see anything immediately obvious in terms of the difference, but after installing the TriggerTech it seemed pretty clear that it was an improvement. I have yet to try the original 16 pound spring in the action again yet, but I might give it a whirl to see if I can use it without issues later on this fall.
 
I didn't have any issues up until 350 rounds. Drove 14 hours this weekend for a match, shot two stages just fine. Stages 3 and 4 I couldn't get anything to fire.

Called ARC today and spoke to Justin. He said he was going to put the springs up on the website today. Sure enough, they are now there. I ordered a 19 pound spring. a 22 pound spring will be available in October.

Kinda BS that the shipping is more than the spring but I dont know where else I would get one so I ordered it.

I'm not bothered by the issues. It's a new release and I never expected things to be perfect.

Was that you at the Border War match yesterday? I'm the other guy with a Nucleus. If it was you, I was bummed out to see you go through a whole mag and not get a shot off. I mentioned this in the other Nucleus thread.

I'm using a Timney CE, 2-stage with Prime 6.5C and so far no issues. I'm going to order a 19lb spring right now as a backup.
 
Was that you at the Border War match yesterday? I'm the other guy with a Nucleus. If it was you, I was bummed out to see you go through a whole mag and not get a shot off. I mentioned this in the other Nucleus thread.

I'm using a Timney CE, 2-stage with Prime 6.5C and so far no issues. I'm going to order a 19lb spring right now as a backup.

Hi Gabe. Yep, that was me. I've got a Huber two stage trigger in my rifle so that rules out just the Timneys having issues.

When I got home, I measured the shoulders of my brass with a comparator. Fired brass was about .0015" longer than what my reloads were bumped to, so it's not a headspace issue.

I ordered a spring last night. Hoping it gets here before the weekend. There's a match in Martin, SD next weekend and I would really like to get this rifle sorted out so I can shoot it.

I've got a Tikka that I just rebarreled but I have yet to put any rounds through the barrel.
 
Thanks. It was nice meeting you as well. I see you shot pretty decent in the match. Well done!

And just for others' reference, I'm running CCI 450 primers in SRP Lapua brass and I have the 19 pound spring on order.
 
Hi Gabe. Yep, that was me. I've got a Huber two stage trigger in my rifle so that rules out just the Timneys having issues.

When I got home, I measured the shoulders of my brass with a comparator. Fired brass was about .0015" longer than what my reloads were bumped to, so it's not a headspace issue.

I ordered a spring last night. Hoping it gets here before the weekend. There's a match in Martin, SD next weekend and I would really like to get this rifle sorted out so I can shoot it.

I've got a Tikka that I just rebarreled but I have yet to put any rounds through the barrel.
I did the same thing with brass and the go and no go gauge. The light brass was a little short but nothing out of spec. Protrusion was .050.

You having a Huber concerns me. I’m pulling out my Timney and putting my Huber in. Spring in order as well.
 
Anyone ha
I did the same thing with brass and the go and no go gauge. The light brass was a little short but nothing out of spec. Protrusion was .050.

You having a Huber concerns me. I’m pulling out my Timney and putting my Huber in. Spring in order as well.

I measured pin protrusion yesterday. .042". If I had another trigger laying around, I would give it a shot.
 
You guys are starting to worry me now. Who here is running CCI SR Mag (450s) primers and not having issues. Nucleus shows up today and will be running it on Saturday. Now I'm concerned about ignition since I didn't know about the heaving spring originally. Also have Federal 205 match I could use instead.
 
You guys are starting to worry me now. Who here is running CCI SR Mag (450s) primers and not having issues. Nucleus shows up today and will be running it on Saturday. Now I'm concerned about ignition since I didn't know about the heaving spring originally. Also have Federal 205 match I could use instead.

I ordered 19# spring on Monday afternoon, arrived this morning (priority usps mail). You may be able to get one by Friday..
 
It likely has something to do with the Timney sear sitting further forward and reducing the amount of inertia gained by your firing pin spring upon bolt close. It could also be riding the top of the sear after release which would further rob the firing pin of power.
 
It likely has something to do with the Timney sear sitting further forward and reducing the amount of inertia gained by your firing pin spring upon bolt close. It could also be riding the top of the sear after release which would further rob the firing pin of power.

Possibly, but I measured the distance from the back of the bolt shroud to the back of the firing pin. Mine (with Triggertech diamond) measured .063". A friend's with Timney CE measured .060". So his was actually slightly further back with the CE than the triggertech. He hasn't shot his yet, but I haven't had any issues with CCI 450s.