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Posted: 1/8/2021 4:15:33 PM EST
Hi,

Any secrets or recommendations on install BCM KMR barrel nut? I did try install last night and recommended max torque 40-50 ft-lb, but  on 30 lbs I did strip nut very badly.
Link Posted: 1/8/2021 4:31:32 PM EST
i always push the wrench towards the nut with one hand and use the other hand (and my body weight to a degree) to torque down.
Link Posted: 1/8/2021 4:31:39 PM EST
Pics? Did you strip the threading on the nut or upper, or did you strip the wrench notches out?
Link Posted: 1/8/2021 4:50:46 PM EST
Wrench notches. Now, impossible to install handguard.
Link Posted: 1/8/2021 4:59:07 PM EST
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Originally Posted By yankee86:
Wrench notches. Now, impossible to install handguard.
View Quote


Yeah, depending on the condition of it you may need to pick up a new barrel nut. Thankfully, they're cheap and in stock. If your wrench is FUBAR as well they've got that too.

The main thing for putting it on is making sure that your pressure is being applied evenly. You want to have the receiver secured (I'm a fan of reaction rods, but a vice block works fine as well), hold the wrench flat against the nut with one hand, and then wrench down on it at a happy 90deg angle with the other. If you aren't all squared up and evenly applying force, you're just going to FUBAR another nut, and that's no fun for anyone.
Link Posted: 1/8/2021 5:09:42 PM EST
Yes, I did purchase new one, last night. Wrench, I think is fine. To hold, I am using Magpul BEV Block.
Link Posted: 1/8/2021 5:15:00 PM EST
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Originally Posted By berkeleygiraffe:
i always push the wrench towards the nut with one hand and use the other hand (and my body weight to a degree) to torque down.
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This.

I have done all this with all 3 of my titanium V7 barrel nuts to avoid stripping.
Link Posted: 1/8/2021 5:32:51 PM EST
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Originally Posted By yankee86:
Wrench notches. Now, impossible to install handguard.
View Quote


Link Posted: 1/8/2021 5:58:46 PM EST
This was my next question, about Titanium Nut.
Thanks
Link Posted: 1/8/2021 7:20:43 PM EST
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Originally Posted By yankee86:
This was my next question, about Titanium Nut.
Thanks
View Quote

Not sure how many barrel nuts or castle nuts you've worked with, but if you don't keep forward pressure on the "teeth" then you will strip it. Titanium barrel nut is fine as long as you keep that pressure forward.
Link Posted: 1/9/2021 8:59:56 AM EST
I'm trying to wrap my head around how you stripped the nut. There are four slots for the BCM wrench to fit two bosses into. You stripped all four slots?

No disrespect intended, but if you have a hard time putting on the BCM barrel nut, should you be working on a gun that might blow up in your face?
Link Posted: 1/9/2021 10:35:00 AM EST
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Originally Posted By PineappleDevil:
I'm trying to wrap my head around how you stripped the nut. There are four slots for the BCM wrench to fit two bosses into. You stripped all four slots?

No disrespect intended, but if you have a hard time putting on the BCM barrel nut, shouldn't you be working on a gun that might blow up in your face?
View Quote


But aren't AR's like Legos?
Link Posted: 1/9/2021 11:02:59 AM EST
a gun that might blow up in your face
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Drama, much???
Link Posted: 1/9/2021 4:59:57 PM EST
[Last Edit: 1/9/2021 5:02:42 PM EST by yankee86]
cancel
Link Posted: 1/9/2021 5:01:42 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By PineappleDevil:
I'm trying to wrap my head around how you stripped the nut. There are four slots for the BCM wrench to fit two bosses into. You stripped all four slots?

No disrespect intended, but if you have a hard time putting on the BCM barrel nut, should you be working on a gun that might blow up in your face?
View Quote


Do you have any suggestions or recommendation? Or just dummy question?

Yes, all four. I think, problem with wrench - it not going all the way in these notches.
Link Posted: 1/9/2021 6:52:37 PM EST
[Last Edit: 1/9/2021 6:53:35 PM EST by GunnyFitz]
**SUBSCRIBED**
Seeking Handguards that will fit a BCM 14.5" Upper Receiver. The manner in which the BCM Handguards connect to the Receiver leaves me to believe that any other Brand Handguards will NOT fit with the same fashion. Only reason I'm looking for BCM MCMR (MLOK) is because I never should've bought the Upper with its Cheese Frater Quad Rail Handguards. Any advice ANY of you can provide - OR- A- Same size Handguard would be greatly appreciated.
THIS is the part which leads me to believe they're different than other Brands.

Attachment Attached File

Attachment Attached File
Link Posted: 1/9/2021 6:59:09 PM EST
Depends on how well you can judge torque, but I've used this:



The local specialty tool dealer had a torque wrench calibrator that he let anyone use to test their wrenches. It was always fun to see how close you were to a specific value without looking.
Link Posted: 1/9/2021 8:23:02 PM EST
The kmr barrel nut is quite soft metal. Even with great seating, the wrench tends to deform the small barrel nut notches, and that interferes with the rail sliding on. It's better to have help with one person keeping the wrench flush. If mildly marred, try using a small, lightweight hammer to peen the surface flat, or V7 Weapon Systems sells a titanium barrel nut thats a bit sturdier.

As for install, try using a small rubber/plastic double hammer. Tap evenly on the front or rear ends of the rail to replace and remove, respectively. The taking off bit is hard as mallet strikes have to be done alongside the upper.  It might take several tries to align the antirotation notches, and if I recall correctly, the assembly instructions even call for using flat metal gauges between the upper and rail for seperation by a cunt hair.

As for the tightening nut, do not force the screw through the hole. It will slip through without tension when the rail is at the correct position.  Readjust the rail -- usually more forward because of that gap between the upper and rail.
Link Posted: 1/9/2021 8:52:41 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By check-raiser:
The kmr barrel nut is quite soft metal. Even with great seating, the wrench tends to deform the small barrel nut notches, and that interferes with the rail sliding on. It's better to have help with one person keeping the wrench flush. If mildly marred, try using a small, lightweight hammer to peen the surface flat, or V7 Weapon Systems sells a titanium barrel nut thats a bit sturdier.

As for install, try using a small rubber/plastic double hammer. Tap evenly on the front or rear ends of the rail to replace and remove, respectively. The taking off bit is hard as mallet strikes have to be done alongside the upper.  It might take several tries to align the antirotation notches, and if I recall correctly, the assembly instructions even call for using flat metal gauges between the upper and rail for seperation by a cunt hair.

As for the tightening nut, do not force the screw through the hole. It will slip through without tension when the rail is at the correct position.  Readjust the rail -- usually more forward because of that gap between the upper and rail.
View Quote


Thank you. I will try your recommendation.
Yes, barrel nut - pretty soft aluminum. What about titanium - much stronger or not a lot?
Link Posted: 1/9/2021 10:28:56 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By GunnyFitz:
**SUBSCRIBED**
Seeking Handguards that will fit a BCM 14.5" Upper Receiver. The manner in which the BCM Handguards connect to the Receiver leaves me to believe that any other Brand Handguards will NOT fit with the same fashion. Only reason I'm looking for BCM MCMR (MLOK) is because I never should've bought the Upper with its Cheese Frater Quad Rail Handguards. Any advice ANY of you can provide - OR- A- Same size Handguard would be greatly appreciated.
THIS is the part which leads me to believe they're different than other Brands.

https://www.AR15.Com/media/mediaFiles/434956/20210109_182805_jpg-1772174.JPG
https://www.AR15.Com/media/mediaFiles/434956/20210109_182835_jpg-1772176.JPG
View Quote


The cutout in the second pic fits a little metal tab that's the tab in the first pic. Same anti rotation tab for both just the bottom pic doesn't have it installed
Link Posted: 1/10/2021 1:35:14 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By berkeleygiraffe:


The cutout in the second pic fits a little metal tab that's the tab in the first pic. Same anti rotation tab for both just the bottom pic doesn't have it installed
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By berkeleygiraffe:


The cutout in the second pic fits a little metal tab that's the tab in the first pic. Same anti rotation tab for both just the bottom pic doesn't have it installed


Make sure it's the right orientation of the metal antirotation insert -- little tabs interlock with the front of the upper. There was a post here with someone doing a 180* degrees from correct orientation lol

Originally Posted By yankee86:


Thank you. I will try your recommendation.
Yes, barrel nut - pretty soft aluminum. What about titanium - much stronger or not a lot?


You're welcome! Just experience from a KMR! If an easier rail assembly is of interest, really consider the midwest industries ultralightweight combat rails.
Bootleg and V7 Weapon systems make derivatives of the BCM KMR/Alpha rails, but I really wish BCM would make more magnesium rails like the KMR but mlok. Bootleg is unique for the hybrid mlok/picantinny or keymody/picatinny.

Titanium should hold up well here. Even planning on ordering a spare for a Bootleg pickmod rail.
Link Posted: 1/10/2021 1:41:01 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By check-raiser:


Make sure it's the right orientation of the metal antirotation insert -- little tabs interlock with the front of the upper. There was a post here with someone doing a 180* degrees from correct orientation lol



You're welcome! Just experience from a KMR! If an easier rail assembly is of interest, really consider the midwest industries ultralightweight combat rails.
Bootleg and V7 Weapon systems make derivatives of the BCM KMR/Alpha rails, but I really wish BCM would make more magnesium rails like the KMR but mlok. Bootleg is unique for the hybrid mlok/picantinny or keymody/picatinny.

Titanium should hold up well here. Even planning on ordering a spare for a Bootleg pickmod rail.
View Quote


Yes, I do like Bootleg one, but I already have BCM a while. Also, my first choice was SLR, but I did switch to BCM KMR.
Link Posted: 1/11/2021 7:45:41 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By berkeleygiraffe:
The cutout in the second pic fits a little metal tab that's the tab in the first pic. Same anti rotation tab for both just the bottom pic doesn't have it installed
View Quote


Thanks all. I've obtained some great info on this from a fellow Member (Doc) which was helpful on the BCM platform!
Link Posted: 1/14/2021 8:19:06 PM EST
[Last Edit: 1/14/2021 8:19:39 PM EST by aloo]
I did this install Saturday. Keep forward pressure on the wrench to keep it in the slots. It's a tight fit sliding in the rail so I put my receiver in my freezer after the nut was on and then heated the rail with a hair dryer. Took 2 light taps to finish seating it on the nut and all was good.
Link Posted: 1/15/2021 12:48:20 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By aloo:
I did this install Saturday. Keep forward pressure on the wrench to keep it in the slots. It's a tight fit sliding in the rail so I put my receiver in my freezer after the nut was on and then heated the rail with a hair dryer. Took 2 light taps to finish seating it on the nut and all was good.
View Quote


Just make sure you have the anti-rotation tab in there before tapping it on. Those handguards don't really like to come off once they've been put on. Learned that one the "fun" way...
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