View Full Version : Off Center Receiver Extension?
Hey guys, i dont know why i just noticed this but my receiver extension appears to be off center by about 10-15 degrees. My stock doesnt line up properly with my pistol grip.
Im honestly not sure if i bought the gun this way or if i managed to knock the receiver extension out of alignment at a recent class.
The castle nut i still staked properly and i am not able to remove it. I tried to use my wrench to get it off but the bastard wont budge. I dont have a proper bench vise to put my lower in so im not really interested in applying too much torque for fear of damaging something.
I have enclosed some pictures. Any help i can get in regards to remedying this would be greatly appreciated OR on the off chance that the gun is SUPPOSED to be aligned by this a simple "you're a noob, its supposed to be like that" will suffice. :)
Thanks guys!
http://img292.imageshack.us/img292/8291/offcenterbuffermn1.th.jpg (http://img292.imageshack.us/my.php?image=offcenterbuffermn1.jpg)
http://img177.imageshack.us/img177/5163/offcenterbuffer2jy9.th.jpg (http://img177.imageshack.us/my.php?image=offcenterbuffer2jy9.jpg)
Robb Jensen
09-07-08, 17:25
This is one of those things that you check before staking. It can be really bad on commercial tubes as they can many times turn more easily with in the receiver end plate vs. a mil-spec tube. The mil-spec tubes notch there is a little deeper and unlikely to turn within the plate but sometimes does as well.
By the way, i forgot to mention that this is an LMT defender 2000 lower with a milspec tube.
So, what do i do to fix this? Remove the castle nut, straighten the tube and then re tighten?
It seems pretty elementary but i cant seem to get the darned castle nut to budge since its staked. Id rather not take it to my local gun shop since they dont believe in staking and their approach to everything is..."LOCKTITE THE BITCH!"
Thats not acceptable to me so im guessing im going to have to perform a home remedy.
EDIT: Just saw this thread, very informative but unfortunately i must be the antithesis of the hulk because i cant get my nut off lol.
https://www.m4carbine.net/showthread.php?t=18844
Also, i know that this information is probably somewhere on this site but what are the torque specs for re-tightening a castle nut?
Robb Jensen
09-07-08, 17:42
By the way, i forgot to mention that this is an LMT defender 2000 lower with a milspec tube.
So, what do i do to fix this? Remove the castle nut, straighten the tube and then re tighten?
It seems pretty elementary but i cant seem to get the darned castle nut to budge since its staked. Id rather not take it to my local gun shop since they dont believe in staking and their approach to everything is..."LOCKTITE THE BITCH!"
Thats not acceptable to me so im guessing im going to have to perform a home remedy.
I mount the lower in a lower receiver block in a vise, use my TCU stock wrench and a brass hammer and knock the nut loose. Then pull the receiver extension counter-clockwise until it's straight. Tighten down the castle nut and restake......or you could send the lower back to LMT.
See this thread: https://www.m4carbine.net/showthread.php?t=18844
Thanks for the info Gotm4, sorry for the semi duplicate thread, i did read that thread and then edited my own with more questions.
By the way, i forgot to mention that this is an LMT defender 2000 lower with a milspec tube.
So, what do i do to fix this? Remove the castle nut, straighten the tube and then re tighten?
It seems pretty elementary but i cant seem to get the darned castle nut to budge since its staked. Id rather not take it to my local gun shop since they dont believe in staking and their approach to everything is..."LOCKTITE THE BITCH!"
Thats not acceptable to me so im guessing im going to have to perform a home remedy.
EDIT: Just saw this thread, very informative but unfortunately i must be the antithesis of the hulk because i cant get my nut off lol.
https://www.m4carbine.net/showthread.php?t=18844
Also, i know that this information is probably somewhere on this site but what are the torque specs for re-tightening a castle nut?
Since you dont have the right tools/ equp call LMT and ship it there and they will take care of it for you.
Emailed LMT.
I just want to add one more thing. For anyone that says, "locktite is enough" i dare you to remove a properly staked castle nut. ;)
The keyway in the buffer tube or end plate is damaged and needs to be replaced.
You cannot simply loosen this and retighten to solve this problem.
Hrm...
How hard did i have to hit my rifle buttstock to do something like this?
Pretty hard.
It was probably like this from the factory.
A few years ago on one my visits to Diemaco - now Colt Canada. I asked one of the engineers about the fixture they use to torque the castle nut. He showed me on the floor and allowed me to take pics and measurements to have one cloned. I never got around to making it in steel but when I saw what Mike from Plastixs Plus was making I asked if he could do it. Sure enough he did and made it part of his line. Here is the item:
http://img.photobucket.com/albums/v91/Boltgun/diemacostandcopy.jpg
The orginal is made out of steel and bolted to a bench. I wanted the ability to transport this so I use either vise grips or small clamps to secure to table when working.
The back part has a notice for the lug where the locating holes are on the RE. It keeps it in line for torquing. You can also use the stand as a cleaning stand. The only thing I would do different this time around would be to put edges on the base to help it stay stiff and for small parts.
Boltgun
ETA - if you are mechanically inclined - I would assume so if you are using one of these stands - then you could also build an extension for the mag well block to go up through the mag well and then mount a spring loaded plunger also to catch the hammer when dry firing while doing trigger jobs. If you are using the brownells trigger job jig you could just mount off set so it goes outside the mag well too.
I hate to bump an old thread but i purchased another lower today and guess what, i got it home and low and behold the darned receiver extension was off center JUST like my other lower.
Both guns have serial numbers that are about 600 apart and both lowers were bought by the same dealer at the same time, ie january 2008.
Fool me once, shame on you, fool me twice, shame on me. I cant believe i didnt look at the darned extension at the store before i brought it home. I called LMT again to see if they would take care of this issue for me...again...
Is this a persistent problem?
Magsz,
Is it possible that the dealer purchased these as lowers and then assembled them at his shop? Do you in fact have a MILSPEC or commercial lower receiver extension? As gotm4 mentioned this seems to be an issue more with commercial tubes than MILSPEC ones. I would contact LMT again and speak with them directly. When I remove a LRE that has been staked I put the wrench on the castle nut and apply pressure and at the same time I grasp and hold the stock/tube so that it doesn't turn. Works 99% of the time.
I hate to bump an old thread but i purchased another lower today and guess what, i got it home and low and behold the darned receiver extension was off center JUST like my other lower.
Both guns have serial numbers that are about 600 apart and both lowers were bought by the same dealer at the same time, ie january 2008.
Fool me once, shame on you, fool me twice, shame on me. I cant believe i didnt look at the darned extension at the store before i brought it home. I called LMT again to see if they would take care of this issue for me...again...
Is this a persistent problem?
Iraq, i have a milspec CTR that fits perfectly on both tubes.
Also, without measuring the only visual difference between commercial and milspec stocks is the fact that commercial tubes are slanted at the rear of the tube, correct?
If thats the case, both of these tubes are milspec.
I wouldnt be surprised if they assembled these lowers. When i originally bought my first "complete" LMT MRP my lower had a full auto hammer in it which was what was causing my trigger pins to walk.
Im really not sure why i keep going back to these guys. Its convenient and i feel like supporting the local guys. It kind of seems like im being hosed despite my generosity.
Im waiting on a reply from LMT in regards to my issue. I emailed Gene Swanson at the request of the rep that i spoke with via phone. I will have to see what he has to say.
Magsz,
Iraq, i have a milspec CTR that fits perfectly on both tubes.
Also, without measuring the only visual difference between commercial and milspec stocks is the fact that commercial tubes are slanted at the rear of the tube, correct?
Negative- the difference is in the outer diameter of the tubes and the commercial tubes are actually weaker. Most of the MILSPEC tubes that I have seen the corners at the rear portion of the tube are rounded. Commerial ones are squared. I have Bushamster 4 position tubes that are not slanted in the rear.
If thats the case, both of these tubes are milspec.
I wouldnt be surprised if they assembled these lowers. When i originally bought my first "complete" LMT MRP my lower had a full auto hammer in it which was what was causing my trigger pins to walk.
A full auto hammer will not cause the trigger pin to walk. As far as I know LMT and Colt have the same size pin diameters .155 inch. The trigger pin is held in place by the legs on the hammer spring. The hammer spring is retained by the "J" spring inside the hammer. So it is quite possible that they either swapped out parts or they were stripped lowers that they put together using whatever crap was available. BTW- the selector lever should have LMT in small letters stamped on it. At least mine do.
Im really not sure why i keep going back to these guys. Its convenient and i feel like supporting the local guys. It kind of seems like im being hosed despite my generosity.
Yeah, sounds like it may be time to seek another source. I am all about saving money and patronizing a business that doesn't screw me over.
Im waiting on a reply from LMT in regards to my issue. I emailed Gene Swanson at the request of the rep that i spoke with via phone. I will have to see what he has to say.
If these were in fact factory assembled, the serials would indicate an issue with the QC person. The fact that they are close together could easily mean someone was having a bad day/week at work. No excuse, but forseeable.
Boltgun
SingleStacker45
11-13-08, 22:38
My M&P15T came that way from the factory. Looked like it creeped a bit when they tightened it down. I got the brownells wrench and loosened the nut. I put a little blue loctite and used a torque wrench to tighten it per the brownell's instructions. Should I have it restaked? It seems to be OK, I've shot it a couple of times since. I'm usually pretty comfortable with blue loctite and a torque wrench.
Mule
Yes, you should have restaked and no you should not have put Loc-Tite on the threads. But, don't just take my word for it. I would break the castle nut loose, clean the crap off it and the lower receiver extension and put a small amount of anti-seize or molybdenum on the threads and tighten and stake properly.
My M&P15T came that way from the factory. Looked like it creeped a bit when they tightened it down. I got the brownells wrench and loosened the nut. I put a little blue loctite and used a torque wrench to tighten it per the brownell's instructions. Should I have it restaked? It seems to be OK, I've shot it a couple of times since. I'm usually pretty comfortable with blue loctite and a torque wrench.
Mule
SingleStacker45
11-14-08, 07:07
Yes, you should have restaked and no you should not have put Loc-Tite on the threads. But, don't just take my word for it. I would break the castle nut loose, clean the crap off it and the lower receiver extension and put a small amount of anti-seize or molybdenum on the threads and tighten and stake properly.
Should I replace the plate? Looks like the staking marks are lining up with the notches. Might be hard to restake.
Mule
I would say that if the receiver end plate looks crappy and you don't think that it will stake properly then yes I would put a new quality end plate on there first.
Should I replace the plate? Looks like the staking marks are lining up with the notches. Might be hard to restake.
Mule
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