BCL 102 catastrophic failure
- Thread starter slash547
- Start date
I think the indexing may have been a cause of the problem; can't see how a case failure would have caused the barrel to rotate.
Referring to SudburyShooter's photo, how much torque would it take to drive the indexing pin into the receiver?
Referring to SudburyShooter's photo, how much torque would it take to drive the indexing pin into the receiver?
You can see in Sudburys pics, that threads are cracked just above the index pin. I wonder how many rounds it saw before the material failed.
Theres absolutely no way that a index pin will fit under there without cracking the threads. I think its a faulty design of the barrel nut contributing to it. Theres no material from the barrel nut reinforcing the structural integrity on the threads.
Theres absolutely no way that a index pin will fit under there without cracking the threads. I think its a faulty design of the barrel nut contributing to it. Theres no material from the barrel nut reinforcing the structural integrity on the threads.
Is that the standard BCL102 barrel nut? If it is, those holes are a serious problem. The index pin shouldn't be able to deform the receiver material (i.e. go underneath) like that in a normal design since the steel nut would be supporting the aluminum receiver all around. The introduction of those holes ("speed holes?" lol) could have contributed to a failure like this.
While we wait for him to answer, I googled and came up with this.
https://www.reddit.com/r/canadaguns/comments/72gxpz/bcl_102_forend_and_hardware_is_a_bit_porky/
wapitiwhacker
CGN Regular
- Location
- East Kootenay B.C.
Is there any evidence of abnormal wear to the gas key or the end of the gas tube?
The gas tube definitely doesn’t look centred in the first picture of the latest ones posted.
Are the barrels and receivers assemble buy hand? Do they use a jig?
Did the barrel index pin slide out of the index notch while buddy was threading on the barrel nut and not notice?
Then just torqued it down, driving the pin under the receiver? And the big hole at the top of the barrel nut provides some space for the receiver thread to expand into?
GC
Did the barrel index pin slide out of the index notch while buddy was threading on the barrel nut and not notice?
Then just torqued it down, driving the pin under the receiver? And the big hole at the top of the barrel nut provides some space for the receiver thread to expand into?
GC
That post seems to be from about a year ago. The nut could have been changed in the Gen 2 variants.
It also looks like the backside of the locking lugs are chamfered on both sides like that from the factory. Haven't seen anything like that on other bolts. The ones I have on hand (CC, Stag) only have slightly rounded edges.
Add speed holes in barrel nut > index pin deforms unsupported receiver > barrel extension doesn't clock properly > bolt sticks in barrel extension and causes malfunctions
The solution? Chamfer back of bolt lugs.
Chamfered bolt lugs coupled with a severely misaligned barrel extension could have resulted in a situation where over time the barrel extension lugs or the cam pin get bent or worn to the point where they no longer lock properly and the gun basically goes from DI to blowback.
If this turns out to be the case, my conclusion would be that they added unnecessary and problematic changes to the design which caused a chain of failures resulting in this (and perhaps at least one other) KB.
The more I think and read about it, I bet the index pin slide under the receiver treads while torquing the barrel nut. The big hole in the top of the barrel nut is not supporting the the alum threads. Would explain why it happen to more than one rifle.
Does the big 12:00 hole in the barrel nut serve a purpose. To attach the hand guard? Or to simply make it lighter?
Bad barrel nut design? Bet a big recall is coming.
GC
Does the big 12:00 hole in the barrel nut serve a purpose. To attach the hand guard? Or to simply make it lighter?
Bad barrel nut design? Bet a big recall is coming.
GC
That post seems to be from about a year ago. The nut could have been changed in the Gen 2 variants.
It also looks like the backside of the locking lugs are chamfered on both sides like that from the factory. Haven't seen anything like that on other bolts. The ones I have on hand (CC, Stag) only have slightly rounded edges.
Add speed holes in barrel nut > index pin deforms unsupported receiver > barrel extension doesn't clock properly > bolt sticks in barrel extension and causes malfunctions
The solution? Chamfer back of bolt lugs.
Chamfered bolt lugs coupled with a severely misaligned barrel extension could have resulted in a situation where over time the barrel extension lugs or the cam pin get bent or worn to the point where they no longer lock properly and the gun basically goes from DI to blowback.
If this turns out to be the case, my conclusion would be that they added unnecessary and problematic changes to the design which caused a chain of failures resulting in this (and perhaps at least one other) KB.
Looks more like the material has been peened.
Thanks, definitely chamfered.
Oh I wish. Gun is on route back to BCL
I agree that there was very little engagement area, but the bolt lugs don't look like they sheared. The bolts come like that. https://theammosource.com/black-creek-labs-enhanced-bolt-for-308-win/
Looks like they added the chamfers at some point and called the new version "enhanced" after the initial batch of rifles came out based on the photos in these reviews:
https://calibremag.ca/bcl102-review/
https://www.huntinggearguy.com/rifle-reviews/bcl102-review/
Your second link shows the barrel nut. It is a BCL barrel nut. One of the areas where they manage to cut weight without thinking of the consequences.
https://www.huntinggearguy.com/wp-content/uploads/2018/12/barrel-nut.jpg
