Rear reciever plate fit problems

AR/M4 AR Technical Discussion
1

All,
I decided to switch out the commercial reciever extention on my Colt MT6400 with a Mil-spec tube. All is well except for the reciever end plate. The original plate will not fit over the Mil-spec tube. Both of the tubes fit the rear of the reciever, and the plate fits fine on the comm tube. What am I missing here?? Here are some pictures…
Commercial vs Mil-spec.

Commercial Receiver extension…plate fits fine.

Mil-spec…Plate will not move any further back on the threaded portion. Castle nut (original) fits fine.

Any ideas on what to do would be very helpful. I am thinking I may just have to buy another reciever end plate.
Thank you.

2

I’d rationalize it as an excuse to buy a Noveske QD end plate. :smiley:

3

The Mil-spec thread will have the crest closer to sharp than commercial.

4

I linked this from the internet just to give a visual. Hope it’s OK since it’s not my picture.

5

Ok, so the threads are too sharp??? Is another end plate in my future?? The reason for all of this is lengthly but it boils down to me getting a Magpul CTR stock for another rifle with a Mil-spec tube. Well, I decided on a different stock for that gun so…the CTR is going on my Colt, that had a commercial tube and hence the reason why I want to switch it. I thought about a QD plate but the CTR already has a QD hole incorporated in it so I really don’t need one. Thank you for all the replies.

6

https://www.m4carbine.net/showthread.php?t=101

7

Someone put a commercial RE on a COLT?

8

I’ll gladly take the Colt receiver extension from the trash.

And even pay shipping.

9

Yes they did. I bought the rifle immediately after the sunset of the ban. It came with the muzzle brake, did not have a bayo lug and apparently the seller took off the receiver extention so as to fix a collapsable stock onto the rifle. I am not sure what receiver extension was originally on the rifle. I believe this rifle would have had a “fixed” collapsable stock being that it was originally a “post ban” rifle. Would the tube have been Mil-spec?? Now the rifle has a commercial receiver extension and I want to change it so as to use the CTR stock that I had bought for another rifle that had a Mil-spec tube. I admit, this rifle was bought before I discovered this website and before I knew more. I will read the provided link (Thank you) and continue from there.
Thank you for the replies.

10

Thank you for the link, my search fu was lacking.

11

Was the plate staked on the commercial tube? I have seen plates that are out of round due to staking and will not fit on another tube because of it. I have used a mandrel “make them round again.”

12

I see. I forgot about the ban.

13

No, the castle nut was NOT staked. All the more reason to change out the tube as well as the other reason mentioned above. Made it a lot easier to get apart!:rolleyes::smiley:

14

Just get another endplate. No sense in trying to make a $3 part work. Sounds like you’ve already put more effort than that into it.

15

That’s what I was thinking as well.

16

Thats what I was thinking. New end plate it is.

17

I pulled one off of an unfired COLT 6933 a few weeks back. Paul Bunyon had staked this thing at Colt. The thing was visibly out of round.

Shit… you just need to bend a little metal.

18

I’d vote for a Noveske end plate too.

19

I just got one after reading about them here. Every carbine should come with these already installed

Sent from my brain using Tapatalk

20

Hello,

If you want to stay with high quality COLT parts, here’s the end plate you’ll need. http://www.specializedarmament.com/products/BUTTSTOCK_SLIDING_RECEIVER_END_PLATE-143-4.html