Nucleus Light Primer Strikes

[Concrete shooter]

I contacted ARC by telephone Tuesday and explained the issue I was having. I was told that the issue was most likely remedied by cleaning the grease from the firing pin. When I asked about a heavier spring they told me to order one one online... I wasn't so impressed with that part, considering it is a known issue. I believe I was speaking with Ted, which is a plus that you can call them up and not wait however long to hear back.

 

[ThePretzel]

Fair point on contacting ARC, I will contact them tomorrow to see if I can get a refund on my spring. Overall I like the action. It is fast and smooth.

It seems as if I’m not the only one having the issue, and it seems as if the issue is not isolated to just one trigger. I was at the range last Wednesday and there were two different nucleus actions with two different triggers, both had failure to fires.

Have you disassembled the bolt fully and cleaned the grease/oil out from the internals yet? If not, it's kind of a moot point since it's an operator failure (and a user manual failure, they should mention that in the papers that ship with the action).

 

[tomcatfan]

Have you disassembled the bolt fully and cleaned the grease/oil out from the internals yet? If not, it's kind of a moot point since it's an operator failure (and a user manual failure, they should mention that in the papers that ship with the action).

I did that before I fired the rifle when I swapped over bolt heads. And you got a user manual? My rifle didn’t come with any paperwork. Just two washers and the screw for the bolt.

 

[ThePretzel]

I did that before I fired the rifle when I swapped over bolt heads. And you got a user manual? My rifle didn’t come with any paperwork. Just two washers and the screw for the bolt.

Hence the reason I said there's a failure on that front. I didn't get anything besides the warranty paperwork and had to look everything else up. Would've been nice to have 1 sheet of paper with some brief disassembly instructions for the bolt and a warning that you should clean the grease out of the action and bolt before use.

 

[Anderson_A]

I ordered a 19lb spring for my nucleus as a precaution and recieved a set of 3 springs anyone else? I’m guessing they sent a set of the 3 availible spring weights but no notes or anything

 

[tomcatfan]

I ordered a 19lb spring for my nucleus as a precaution and recieved a set of 3 springs anyone else? I’m guessing they sent a set of the 3 availible spring weights but no notes or anything

I just got the 1 spring in on Monday. If they are 3 different springs, how would you tell them apart? The only difference I could tell was the 16 lb spring was shorter than the 19 lb spring.

 

[Anderson_A]

I just got the 1 spring in on Monday. If they are 3 different springs, how would you tell them apart? The only difference I could tell was the 16 lb spring was shorter than the 19 lb spring.

I measured the diameter of the wire and they are all pretty much identical I’m not sure if they just sent three of the same spring by accident they do seem to be coiled slightly tighter between the three like finer pitch thread but I don’t think that makes one heavier than the next I’ll have to call tomorow but they are all the same length as each other I will have to take my spring out and compare it to the new ones

 

[hereinaz]

I took my LA 7 mag Nucleus, without cleaning the bolt, to the range. It has a Diamond Trigger Tech and every one of my rounds went bang.

Did it as a test of sorts. I'll clean the bolt now.

 

[NorthWesterner]

Getting about 15% fail to fire with a long action cci250 primers. Not sure what spring the long actions come with but my primers are seated, protrusion good along which good headspace. I hope I can get this resolved quickly.

 

[PinesAndProjectiles]

Getting about 15% fail to fire with a long action cci250 primers. Not sure what spring the long actions come with but my primers are seated, protrusion good along which good headspace. I hope I can get this resolved quickly.

Have you tried taking the bolt apart and cleaning the firing pin spring?

 

[NorthWesterner]

Have you tried taking the bolt apart and cleaning the firing pin spring?

I haven’t yet.

 

[PinesAndProjectiles]

I haven’t yet.

I would start there. If it doesnt work, order the 19# spring.

 

[NorthWesterner]

I would start there. If it doesnt work, order the 19# spring.

So you know the long action comes with 16lb spring?

 

[PinesAndProjectiles]

It's my understanding that all of their actions come with a 16# spring. I could be wrong.

 

[NorthWesterner]

Just took it apart. Looks like my smith removed it and cleand/light lubed it.

 

[ThePretzel]

Just took it apart. Looks like my smith removed it and cleand/light lubed it.

There's your problem.

It needs to be bone dry. The instructions that come with the action specifically say DO NOT add lubricant inside the bolt.

Clean it, thoroughly. Do not lubricate it when you are finished. The light strikes will disappear.

 

[NorthWesterner]

There's your problem.

It needs to be bone dry. The instructions that come with the action specifically say DO NOT add lubricant inside the bolt.

Clean it, thoroughly. Do not lubricate it when you are finished. The light strikes will disappear.

I’m not convinced there is enough resistance from the very small amount of light lube to cause light primer issues. I can see how over time it will attract debris, but it’s brand new. Only 30 rounds through it.

 

[lead ƒarmer]

@NorthWesterner what kind of trigger are you running?

 

[NorthWesterner]

@NorthWesterner what kind of trigger are you running?

Trigger tech diamond

 

[Lonestar1027]

My BnA tacsport needed a low top sear from bullet central then all my light strike issues disappeared

 

[Skunkworx]

How’s the timing with the low top sear?

 

[craigos]

My BnA tacsport needed a low top sear from bullet central then all my light strike issues disappeared

Yeah the sear bar on the geissele is too high it wont fire at all ...

 

[NorthWesterner]

How’s the timing with the low top sear?

No idea how to check this.

 

[NorthWesterner]

How’s the timing with the low top sear?

Just did some research on how to check teigger timing. It appears to be dead nuts perfect.

 

[tomcatfan]

Just took it apart. Looks like my smith removed it and cleand/light lubed it.

I'm not so sure it was your smith that lubed it. The only thing my FFL did was remove the action from the box to get the serial number off it. I had the same failure to fire problem. When I disassembled the bolt to change over to the 19 lb spring, I had to clean the firing pin assembly during the process. I run it completely dry with the 19 pounder and I haven't had an issue yet.

 

[NorthWesterner]

How’s the timing with the low top sear?

Just did some research on how to check teigger timing. It appears to be dead nuts

I'm not so sure it was your smith that lubed it. The only thing my FFL did was remove the action from the box to get the serial number off it. I had the same failure to fire problem. When I disassembled the bolt to change over to the 19 lb spring, I had to clean the firing pin assembly during the process. I run it completely dry with the 19 pounder and I haven't had an issue yet.

my Smith is VERY thorough and it has his token grease on the cocking lugs, so I know he had it apart. I think your right, I need a 19 lb spring. Everything else is in order.

 

[Lonestar1027]

I didn't really notice a difference in timing, but it definitely tightened my groups/SDs up. I wasn't getting a good and consistent primer strike with the medium height top sear

 

[ThePretzel]

I’m not convinced there is enough resistance from the very small amount of light lube to cause light primer issues. I can see how over time it will attract debris, but it’s brand new. Only 30 rounds through it.

Believe me, I thought the same thing when I first put it together and left some of the oil it shipped in on the firing pin and spring assembly. It's a pretty light oil, meant for light lubrication but mostly preservation.

I wiped 90% of it off and had tons of light primer strikes when I first used it. Even swapping to a 19# spring I still had light primer strikes because I never thoroughly cleaned the firing pin and assembly.

From the day I dropped it into the ultrasonic cleaner to remove all oil/grease and put it back together (grease on the cocking cams, of course) I have had 0 light primers strikes. I guarantee if you clean that lube off you'll see the problems disappear, because the instructions that come with the rifle specifically say there should be no lube present at all on the firing pin. It's also exactly what I experienced, even with what I thought was a small amount of a light oil.

 

[lennyo3034]

Believe me, I thought the same thing when I first put it together and left some of the oil it shipped in on the firing pin and spring assembly. It's a pretty light oil, meant for light lubrication but mostly preservation.

I wiped 90% of it off and had tons of light primer strikes when I first used it. Even swapping to a 19# spring I still had light primer strikes because I never thoroughly cleaned the firing pin and assembly.

From the day I dropped it into the ultrasonic cleaner to remove all oil/grease and put it back together (grease on the cocking cams, of course) I have had 0 light primers strikes. I guarantee if you clean that lube off you'll see the problems disappear, because the instructions that come with the rifle specifically say there should be no lube present at all on the firing pin. It's also exactly what I experienced, even with what I thought was a small amount of a light oil.

Would you have confidence in the 16# spring again now that the pin is clear of oil and grease?

 

[NorthWesterner]

Would you have confidence in the 16# spring again now that the pin is clear of oil and grease?

This is what I want to know.

 

[NorthWesterner]

Believe me, I thought the same thing when I first put it together and left some of the oil it shipped in on the firing pin and spring assembly. It's a pretty light oil, meant for light lubrication but mostly preservation.

I wiped 90% of it off and had tons of light primer strikes when I first used it. Even swapping to a 19# spring I still had light primer strikes because I never thoroughly cleaned the firing pin and assembly.

From the day I dropped it into the ultrasonic cleaner to remove all oil/grease and put it back together (grease on the cocking cams, of course) I have had 0 light primers strikes. I guarantee if you clean that lube off you'll see the problems disappear, because the instructions that come with the rifle specifically say there should be no lube present at all on the firing pin. It's also exactly what I experienced, even with what I thought was a small amount of a light oil.

Did you ever test this theory by installing the original 16lb spring? Or did you continue with the 19 lb spring?

 

[tomcatfan]

I installed the 19lb spring and honestly I can't tell the difference in bolt lift. Which begs to question, why would ARC sacrifice reliability for a marginal decrease in bolt lift?

 

[NorthWesterner]

I installed the 19lb spring and honestly I can't tell the difference in bolt lift. Which begs to question, why would ARC sacrifice reliability for a marginal decrease in bolt lift?

My guess is because it works on 99% of actions well. Cci250 is a very hard primer. In addition to this, I’m using new brass that isn’t fire formed. I’m sure a 19 will fix my issues, I just doubt there is a lot of issues with all the actions out there.

 

[MarkLeupold]

I installed the 19lb spring and honestly I can't tell the difference in bolt lift. Which begs to question, why would ARC sacrifice reliability for a marginal decrease in bolt lift?

It probably shows on paper more than in practice as well. There is an obvious increase in bolt lift weight when moving to the 19 pound spring due to physics, but my guess is that in the field it doesn't matter as much as the math said it would.

 

[NorthWesterner]

It probably shows on paper more than in practice as well. There is an obvious increase in bolt lift weight when moving to the 19 pound spring due to physics, but my guess is that in the field it doesn't matter as much as the math said it would.

It diffinatly doesn’t matter if it fails to fire. It is what it is.

 

[ThePretzel]

Did you ever test this theory by installing the original 16lb spring? Or did you continue with the 19 lb spring?

Would you have confidence in the 16# spring again now that the pin is clear of oil and grease?

After the cleaning I installed the 16# spring again to see if it would work. That's the spring I've been running for the last 400ish rounds without problems, post bolt-assembly cleaning.

 

[NorthWesterner]

After the cleaning I installed the 16# spring again to see if it would work. That's the spring I've been running for the last 400ish rounds without problems, post bolt-assembly cleaning.

What primers? Long or short action?

 

[ThePretzel]

What primers? Long or short action?

Short action, CCI BR4 primers. Harder than a CCI 400, not quite as a firm as the CCI 450's. I can pick up a hundred 450's to test out though if there's interest, since I got a bunch of 105 Hybrids to play with as a Christmas gift.

 

[lennyo3034]

Good info, thank you.

I notice the difference between the 19lb vs 16lb spring. My rifle does not tilt when lifting up with the 16, but does with the 19. If I can get reliable ignition with the 16, I will go back to that.

 

[chadrp]

Does tearing the spring apart to clean it mess with the pin protrusion? If so how do I make sure I get it back correct?

I haven't taken it apart to clean mine yet for fear of messing it up and haven't found any good video or instructions on it. I've seen teds on disassembly but nothing on reassembly so want to make sure I knew I'd get it right. Been shooting factory 140 eldm with no issues but would like to get it cleaned and dried like it should be.

 

[tomcatfan]

Does tearing the spring apart to clean it mess with the pin protrusion? If so how do I make sure I get it back correct?

I haven't taken it apart to clean mine yet for fear of messing it up and haven't found any good video or instructions on it. I've seen teds on disassembly but nothing on reassembly so want to make sure I knew I'd get it right. Been shooting factory 140 eldm with no issues but would like to get it cleaned and dried like it should be.

Yes it does. And you are right, there are no instructions that I could find that say how to reassemble correctly. The first time I reassembled mine and went to fire the rifle, I was getting extremely light primer strikes even with the 19 lb spring. The castle nut can change pin protrusion. If you don’t screw that down enough, you can eliminate just about all pin protrusion. Screw it in to far and you will have too much protrusion. I found that out the hard way. Lennyo contacted Josh at Pva and was told that 0.035" pin protrusion was a good place to start.

 

[NorthWesterner]

Yes it does. And you are right, there are no instructions that I could find that say how to reassemble correctly. The first time I reassembled mine and went to fire the rifle, I was getting extremely light primer strikes even with the 19 lb spring. The castle nut can change pin protrusion. If you don’t screw that down enough, you can eliminate just about all pin protrusion. Screw it in to far and you will have too much protrusion. I found that out the hard way. Lennyo contacted Josh at Pva and was told that 0.035" pin protrusion was a good place to start.

Mine is at 40 thow. I took a little bit out to be at 36 thow now.

 

[ThePretzel]

Does tearing the spring apart to clean it mess with the pin protrusion? If so how do I make sure I get it back correct?

I haven't taken it apart to clean mine yet for fear of messing it up and haven't found any good video or instructions on it. I've seen teds on disassembly but nothing on reassembly so want to make sure I knew I'd get it right. Been shooting factory 140 eldm with no issues but would like to get it cleaned and dried like it should be.

Taking the spring apart will mess with pin protrusion. Just make a note of where the castle nut was prior to starting and replicate that if you can, but also measure it to be sure. Adjusting the castle nut tighter or looser will increase and decrease pin protrusion, respectively.

 

[Kiba]

Put 400 rounds through my new 223AI Nucleus build over the last week using the 16# spring; Using Remington 7.5 and Wolf KVB556M primers. Only had 1 FTF, and that's because that piece of brass had a very deep primer pocket for some reason and the primer was sunk very deep. My 223AI Tikka T3 wouldn't set it off either.

I have the 19# spring on hand, but right now I see no reason to use it. Really liking the action so far.

 

[Skunkworx]

@Kiba , just for reference which trigger are you running?

 

[Kiba]

@Kiba , just for reference which trigger are you running?

CG mod 22. The combo does provide .025" of overcocking on close with an unmodified cocking piece, but I don't notice it running the action normally; you only notice the overcocking on close when running the bolt very slowly.

 

[chadrp]

Thanks guys, I appreciate the help. I will make sure to take some measurements before disassembly.

 

[NorthWesterner]

So is the consensus view that this action with proper pin protrusion and trigger timing with remaining ftf needs the 19lb spring. Just took mine out again and it ignited one of the couple ftf after running it through several times.

 

[EchoDeltaSierra]

Note: I do not represent ARC in any way and this information is subject to correction based on any manufacturer feedback.

I have been working with ARC on a light primer struck issue. Overall, I think the design of the Nucleus is pretty spectacular and relized I had a few months to work any kinks out of my custom build. When I setup the rifle, per the instructions (and driven by curiosity) fully dissassembled and cleaned the bolt and I experience light primer strike issue. I was able to record a bunch of data and had a nice conversation with Ted and Justin at which they sent both a #19 and #25 springs for me to test. Upon testing the #25 spring I continued to reproduce failures across two different brands of brass (Nosler and Lapua) and three different primers (CCI BR-2, 250, and 450). Ted asked my to send my rifle to them, in the exact failure prone state, with the ammo I loaded, rounds that had misfired, cases from rounds that did fire, headspace gauges, etc. I spoke with Ted the day after they received the rifle, and eureka, the problem was discovered and solved. It appears the issue was user induced (by me) because I didn’t have the nut that compresses the spring tightened all the way, and dammit, I though I triple checked that.

I don’t want to speak for ARC, but this appears there might be a symptomatic issue with people not understanding how to properly reassemble the firing pin and spring thus reducing firing pin protrusion. It seems like ARC is now fully aware of this and planning some customer education to correct this. With the bolt reassembled, Ted shared that the #16 spring was able to light off of the rounds I had issue with. All in all, ARC has been spectacular to work with and I’m really please with the action and ready to rock it in the 2019 competition season.

 

[chrismartin]

To that end, I really wish there were some better documentation on the action from ARC. Torque specs, instructions on the firing pin disassembly/assembly, etc. Hopefully ARC will come up with something good.

The only light strike issue I had had was will some mil type ammo from Aquila with known bad primer holes (off center/crap brass) that's 7.62, sealed and crimped primers etc. It's meant for more semi/full auto type applications. The 16lbs setup has been 100% with Federal GMM 308 ammo. I did clean the firing pin assembly (I did not take it apart though) and I'm also running a reduced power top sear spring in my Timney CE 2 stage (Though I had no light primer strikes with the standard spring).

The light spring was used to try to solve a trigger reset issue I was having. Since installing the spring, I have not had any issues with the CE 2 stage in the Nucleus. Timnney tech support was fast and got me the part very quickly. The lighter spring would also help with any sear/striker drag that may have slowed things down (but again, I didn't have any light strikes with the original spring and FGMM ammo anyway).