Good point. Also got a response from Velocity and they said to take a look at the lock screws and make sure they're TIGHT. Haven't done so yet but will do that before heading to the range on Saturday.
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Cycling question, lightweight bolt carrier group and case dents
- Thread starter Ape_Factory
- Start date
Per Velocity's request, I tightened the installation screws and lock screws. Went to the range yesterday after having a previously successful outing and had another double tap. Gave rifle to my friend who is far, far more experienced (NRA rifle instructor, former operator) and he also had a double tap. I audibly heard him lift up on the trigger after the double tap and heard the trigger click. So he fired, held the trigger back and it still double fired. So it's not a trigger finger bump fire.
Separating the lower and re-examining the trigger, if you cock the hammer, pull the trigger and HOLD the trigger back, you can, with finger strength, grasp the hammer on either side with your index finger and thumb and separate the hammer from the disconnector. If you then reset the hammer, pull the trigger and release the trigger, I cannot separate the hammer from the disconnector. So the weak hammer to disconnector interface comes when you're holding the trigger back. Trigger is clean as far as I can tell. I'm going to pull it today and give it a thorough examination. Ran my BCG dry yesterday too.
I was going to try heavier buffer weights but my friend was pretty convinced it was the trigger and I had a ton of .308 rounds to test and I needed to get something done on that front as I didn't have all day to fix and test. I'm going to try to head out to the range some time this week for more troubleshooting on just the AR15.
Separating the lower and re-examining the trigger, if you cock the hammer, pull the trigger and HOLD the trigger back, you can, with finger strength, grasp the hammer on either side with your index finger and thumb and separate the hammer from the disconnector. If you then reset the hammer, pull the trigger and release the trigger, I cannot separate the hammer from the disconnector. So the weak hammer to disconnector interface comes when you're holding the trigger back. Trigger is clean as far as I can tell. I'm going to pull it today and give it a thorough examination. Ran my BCG dry yesterday too.
I was going to try heavier buffer weights but my friend was pretty convinced it was the trigger and I had a ton of .308 rounds to test and I needed to get something done on that front as I didn't have all day to fix and test. I'm going to try to head out to the range some time this week for more troubleshooting on just the AR15.
Velocity trigger sent and received. They did modify "something" but not sure what. Taped a $5 bill to the paperwork and sent it back.
Made it to the range this evening, and the double taps manifested yet again, sporadically. So can't be the trigger (logically) at this point. I took out the Odin buffer and added one tungsten, one stainless and one aluminum. Still managed to get a double tap with one trigger pull. At this point I'm thinking firing pin length or primers. Rifle cycles just fine with everything from 50gr to 77 gr. without issue, bolt is open on empty mag.
I did have one actual, full fledged slam fire. Was single loading and dropped the bolt release and bam. First time ever. For the record, the primers are now set lower than flush. Many people get zero slam fires ever with the cci 400's but I seem to be getting them. I do have some 41's but I have a ton on primed cases using 400's. I guess the next step would be to prep a few with the 41's and see what does or doesn't happen. Will measure the firing pin and make sure it's in spec.
Made it to the range this evening, and the double taps manifested yet again, sporadically. So can't be the trigger (logically) at this point. I took out the Odin buffer and added one tungsten, one stainless and one aluminum. Still managed to get a double tap with one trigger pull. At this point I'm thinking firing pin length or primers. Rifle cycles just fine with everything from 50gr to 77 gr. without issue, bolt is open on empty mag.
I did have one actual, full fledged slam fire. Was single loading and dropped the bolt release and bam. First time ever. For the record, the primers are now set lower than flush. Many people get zero slam fires ever with the cci 400's but I seem to be getting them. I do have some 41's but I have a ton on primed cases using 400's. I guess the next step would be to prep a few with the 41's and see what does or doesn't happen. Will measure the firing pin and make sure it's in spec.
I don't think it's a titanium firing pin. If it is, it's coated. Need to find some off the shelf rounds to test too but that's been literally impossible as of late.
Ok...looking at the firing pin specs it's stainless steel with nitride coating. From RCA's page:
Blacknitride+ Enhanced
Enhanced firing pin maintains ignition reliability.
Made from 17-4 Stainless Steel.
Heat Treated to: 42-45RC.
rubbercityarmory.com
The only titanium part on the RCA BCG is the carrier itself. Everything else is steel.
I did a dummy round previously and could not get a bonafide slam fire to happen and I really tried and tried. I'll whip up several dummy rounds this time. Going to test a mil-spec bolt carrier group too, maybe just swap out the firing pin.
I'll take some photos of just the firing pin and post them up later today next to a mil-spec firing pin if there are any noticeable physical differences.
My biggest worry is that it is actually the primers themselves and due to the pandemic, I got an inconsistent lot. Not all are "bad" per se but some have thinner cups than others which lead to the random double tap.
Ok...looking at the firing pin specs it's stainless steel with nitride coating. From RCA's page:
Blacknitride+ Enhanced
Enhanced firing pin maintains ignition reliability.
Made from 17-4 Stainless Steel.
Heat Treated to: 42-45RC.
Firing Pin 5.56 x 45 (.223) - Welcome to Rubber City Armory
Blacknitride+ Enhanced Enhanced firing pin maintains ignition reliability. Made from 17-4 Stainless Steel. Heat Treated to: 42-45RC. Functions with all RCA Bolt Calibers LIFETIME WARRANTY
rubbercityarmory.com
The only titanium part on the RCA BCG is the carrier itself. Everything else is steel.
I did a dummy round previously and could not get a bonafide slam fire to happen and I really tried and tried. I'll whip up several dummy rounds this time. Going to test a mil-spec bolt carrier group too, maybe just swap out the firing pin.
I'll take some photos of just the firing pin and post them up later today next to a mil-spec firing pin if there are any noticeable physical differences.
My biggest worry is that it is actually the primers themselves and due to the pandemic, I got an inconsistent lot. Not all are "bad" per se but some have thinner cups than others which lead to the random double tap.
A titanium firing pin is substantially lighter than a steel pin. Because the pin floats in the carrier, it is allowed to hit the primer of a loaded cartridge upon chambering. If it hits the primer too hard you can have a slam fire, as you have observed. A titanium pin will have less momentum and strike the primers less hard upon chambering. My mostly uninformed opinion is that your titanium bolt carrier is moving substantially faster than a steel carrier, rocketing the firing pin into the chambering cartridge.
We weighed the firing pin last night and it's within .05 of the mil-spec firing pin and the new pin is actually a thousandth or two shorter.
The only difference is it is black nitride coated. I'll swap pins. Can't swap bolts as the RCA bolt is matched to the barrel and the old mil-spec isn't (I know this as a fact). I could potentially swap carriers. Whatever nitriding they use is simply awesome. Almost no visible wear and it's super easy to clean. But...
How bout lubrication migration onto the firing pin? I hadn't cleaned anything since my last range visit and pulling apart the BCG, I did notice the firing pin appeared to have gained some lube from it migrating. Don't remember running any lube on the BCG last time I cleaned it though. Just strip it, CLP it, wipe it down and assemble. Assuming too wet of a firing pin can cause issues.
Took the time to clean out the firing pin channel thoroughly just in case and I'm going to load up about 30 rounds with CCI41 primers. Will test those along with the CCI400's and the mil-spec firing pin next. Looking for a cheap box or two of factory ammo and not having much luck.
After increasing weight in the buffer, one tungsten, one stainless, one aluminum, the gun cycled fine with no adjustment to the gas block. I didn't check ejection pattern as I was using a brass catcher. I've not had to touch the gas at all with any adjustments to the buffer or the bullet weight. It's shot everything, cycled and functioned perfectly, other than the occasional double tap. It's so fast most people don't notice although last trip out, I did get a quick sideways glance from the guy next to me.
The only difference is it is black nitride coated. I'll swap pins. Can't swap bolts as the RCA bolt is matched to the barrel and the old mil-spec isn't (I know this as a fact). I could potentially swap carriers. Whatever nitriding they use is simply awesome. Almost no visible wear and it's super easy to clean. But...
How bout lubrication migration onto the firing pin? I hadn't cleaned anything since my last range visit and pulling apart the BCG, I did notice the firing pin appeared to have gained some lube from it migrating. Don't remember running any lube on the BCG last time I cleaned it though. Just strip it, CLP it, wipe it down and assemble. Assuming too wet of a firing pin can cause issues.
Took the time to clean out the firing pin channel thoroughly just in case and I'm going to load up about 30 rounds with CCI41 primers. Will test those along with the CCI400's and the mil-spec firing pin next. Looking for a cheap box or two of factory ammo and not having much luck.
After increasing weight in the buffer, one tungsten, one stainless, one aluminum, the gun cycled fine with no adjustment to the gas block. I didn't check ejection pattern as I was using a brass catcher. I've not had to touch the gas at all with any adjustments to the buffer or the bullet weight. It's shot everything, cycled and functioned perfectly, other than the occasional double tap. It's so fast most people don't notice although last trip out, I did get a quick sideways glance from the guy next to me.
As suggested by previous posters, check the ejection pattern. With an adjustable buffer and gas block, you should be able to get perfect 3 o"clock ejection and no marks on the brass as shown. I had a problem that everyone suggested I was over gassed (non-adjustable gas block). The manufacturer said I should try an H2 buffer. It did not work. The ejection pattern confirmed I was actually under gassed. I changed the buffer spring and it worked fine.
Yep, did that a while back. It's literally 3 o'clock on the nose. My buddy's actually at a loss as to what's causing it and he has far more experience building rifles and reloading than I do.
So far to date I've done the following:
-Checked the ejection pattern and confirmed it's cycling and ejecting properly, holds open on empty mag and ejects at 3 o'clock.
-Changed the primer seating depth to sub-flush.
-Sent the trigger in for inspection. They did change the lower spring (sear spring?) and sent it back. I can no longer separate the disconnector using finger strength.
-Tripled the weight of the buffer (at least), going from no weight, to aluminum-only, to the current tungsten, stainless and aluminum weight. I'll weigh it later.
-Removed the Springco Red spring and went to a softer than mil-spec Strike Industries flat wire spring.
The BCG was hand-picked by RCA and I sent my entire upper to them just for that.
Last round at the range, I tested out a few 50gr loads, a 77TMK load and a 69TMK load. My "plinking" rounds are 52gr. Nosler CC's, mild load, they shoot fine and I went through a 30 round magazine for testing purposes (tough thing to do these days) and had one double tap.
First thing I did at the range, with the new trigger installed, is I tested it out with the plinking ammo. I think I shot 10 rounds, no issues. I then loaded up five cartridges for my first powder charge range for the 50gr. bullets and on the third shot, had the double tap. Moved on to single cartridges in the magazine, using the bolt release to chamber the round. That worked fine until maybe my third test load group and I got the actual slam fire. My buddy doesn't think it was an actual slam fire but I literally put the round in the magazine, loaded it into the well, dropped the bolt with the bolt release and bam. First time that's happened.
At first he thought the rifle wasn't fully in battery, judging by the primer, but after looking at the casings, he no longer thinks that.
I loaded up five dummy rounds, no powder, and tested. Same methodology, no slam fires. One off red herring? Maybe. Seriously frustrating as the rifle shoots so well. Really happy with it other than the double tap issues.
I have some of that MPro cleaning solution which doesn't lubricate like CLP. Going to clean the BCG with that this time around and thoroughly. Just to make sure. Understandably, I really really want to eliminate the primers themselves as the issue.
So far to date I've done the following:
-Checked the ejection pattern and confirmed it's cycling and ejecting properly, holds open on empty mag and ejects at 3 o'clock.
-Changed the primer seating depth to sub-flush.
-Sent the trigger in for inspection. They did change the lower spring (sear spring?) and sent it back. I can no longer separate the disconnector using finger strength.
-Tripled the weight of the buffer (at least), going from no weight, to aluminum-only, to the current tungsten, stainless and aluminum weight. I'll weigh it later.
-Removed the Springco Red spring and went to a softer than mil-spec Strike Industries flat wire spring.
The BCG was hand-picked by RCA and I sent my entire upper to them just for that.
Last round at the range, I tested out a few 50gr loads, a 77TMK load and a 69TMK load. My "plinking" rounds are 52gr. Nosler CC's, mild load, they shoot fine and I went through a 30 round magazine for testing purposes (tough thing to do these days) and had one double tap.
First thing I did at the range, with the new trigger installed, is I tested it out with the plinking ammo. I think I shot 10 rounds, no issues. I then loaded up five cartridges for my first powder charge range for the 50gr. bullets and on the third shot, had the double tap. Moved on to single cartridges in the magazine, using the bolt release to chamber the round. That worked fine until maybe my third test load group and I got the actual slam fire. My buddy doesn't think it was an actual slam fire but I literally put the round in the magazine, loaded it into the well, dropped the bolt with the bolt release and bam. First time that's happened.
At first he thought the rifle wasn't fully in battery, judging by the primer, but after looking at the casings, he no longer thinks that.
I loaded up five dummy rounds, no powder, and tested. Same methodology, no slam fires. One off red herring? Maybe. Seriously frustrating as the rifle shoots so well. Really happy with it other than the double tap issues.
I have some of that MPro cleaning solution which doesn't lubricate like CLP. Going to clean the BCG with that this time around and thoroughly. Just to make sure. Understandably, I really really want to eliminate the primers themselves as the issue.
Just to update this thread for future reference and mark it case closed, I've had two successful trips to the range with no misfires, no slam fires, no double taps. After examining everything, I cleaned the crap out of the BCG including the firing pin channel per my friend's recommendation and I ran the BCG with virtually no lube, only adding a thin film to the leading edge of the carrier. That seemed to have solved the issue.
I don't know if changes to the trigger also helped the situation or if that was a red herring.
When I pulled the BCG out and disassembled, I did notice lube had migrated to the firing pin, probably from me lubing the cam pin. The RCA carrier is coated with their black nitride + coating and it's super slick to begin with. Very easy to clean. The lubrication somehow interfered with the firing pin, either gumming up the channel or allowing the firing pin to bounce. Only thing I can figure out. I ran ammo with the CCI400 primers, with CCI41 and after going through at least 100 rounds, I was satisfied it's functioning as it should.
I even went back to a lighter buffer, throwing in two of the aluminum weights and leaving everything else out. I may just go back to an empty buffer.
All I have to say is I'm relieved it's finally functioning and want to thank everyone for their help and suggestions.
I don't know if changes to the trigger also helped the situation or if that was a red herring.
When I pulled the BCG out and disassembled, I did notice lube had migrated to the firing pin, probably from me lubing the cam pin. The RCA carrier is coated with their black nitride + coating and it's super slick to begin with. Very easy to clean. The lubrication somehow interfered with the firing pin, either gumming up the channel or allowing the firing pin to bounce. Only thing I can figure out. I ran ammo with the CCI400 primers, with CCI41 and after going through at least 100 rounds, I was satisfied it's functioning as it should.
I even went back to a lighter buffer, throwing in two of the aluminum weights and leaving everything else out. I may just go back to an empty buffer.
All I have to say is I'm relieved it's finally functioning and want to thank everyone for their help and suggestions.
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