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Page AR-15 » Optics, Mounts, and Sights
AR Sponsor: bravocompany
Posted: 1/21/2021 2:51:30 PM EDT
Hi everyone I’m new so sorry if I’m doing this wrong. I just mounted a BCM detachable carry handle on my PSA M4 upper. I mounted it forward towards the barrel and hand tightened and went another 1/2 turn with a quarter. When I charge the rifle it works it’s way backwards towards the stock. Is there a tourque setting I should be using and if not is it ok to tighten harder to the receiver? It’s at about 20 lbs/inch right now. TIA!
Link Posted: 1/21/2021 3:32:08 PM EDT
[#1]
There's supposed to be 2 crossbolts and/or a recoil lug in the slots to prevent this.
Link Posted: 1/21/2021 4:09:23 PM EDT
[#2]
I wonder....: pics of the carry handle?

Were the crossbolts drilled into the carry handle too high?
Link Posted: 1/21/2021 4:17:14 PM EDT
[#3]
Hand tight and then another 1/4 turn has always worked for me.
Link Posted: 1/21/2021 4:22:08 PM EDT
[#4]
How far are we talking?  There might be ~1mm slop between the cross bolts and slots.
Link Posted: 1/21/2021 7:49:42 PM EDT
[#5]
Thank you all for your answers. So the carry handle has 2 cross bolts and it fits on the receiver perfectly. I’m just wondering why after a day at the range it slid back towards the stock after charging the rifle about 10 times. I did the quarter trick and checked it and was about 20 lbs/inch using that method. I’m wondering if maybe I should increase or if that would be bad for the receiver. I was thinking maybe going to 30 and trying blue 242 threadlocker. I’m trying to upload a picture now.
Link Posted: 1/21/2021 7:52:46 PM EDT
[#6]
Also, it didn’t slide back too far but it was about the thickness of a quarter. Doesn’t seem like much but shouldn’t be moving since at further distances will mess up my zero a few inches.
Link Posted: 1/21/2021 9:05:25 PM EDT
[#7]
I think 20 lbs torque should be fine. Threadlocker is a great idea for anything that attaches with screws onto a firearm.
Link Posted: 1/21/2021 9:05:25 PM EDT
[#8]
Push it to the rear of the slot and tighten it.
Link Posted: 1/21/2021 9:14:06 PM EDT
[#9]
I was thinking of mounting it back towards the stock. I think the charging has more recoil than a 5.56 round. Thoughts?
Link Posted: 1/21/2021 10:04:36 PM EDT
[#10]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I was thinking of mounting it back towards the stock. I think the charging has more recoil than a 5.56 round. Thoughts?
View Quote


The pic slot is larger than the crossbolt so the crossbolt has a little room to move within the pic slot.  Charging the gun migrates the handle rearward.  Shooting the gun will migrate the handle forward.  Physics 101.  If you want it to stay in one place shim the gap on one side of one of the crossbolts or/and tighten them more.  While your OCD might trigger, I doubt that slight bit of for and aft movement is going to affect zero in any meaningful way.
Link Posted: 1/21/2021 10:15:22 PM EDT
[#11]
Much appreciated. What do you mean by shim the gap? How would I do that. You’re 100% on point with the OCD. I just wonder why my red dot won’t move once it mounted but it seems like this moves back towards the stock even though it’s very minimal.
Page AR-15 » Optics, Mounts, and Sights
AR Sponsor: bravocompany
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