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Messiah Jones
12-30-06, 15:50
The noble Bonesaw and I just traded uppers. I have an Armalite lower and the upper is a Colt. The Colt upper front pin hole is larger in diameter than the hole in the lower so there is a spacer to match them up. With the spacer in place there is a gap between the upper and lower large enough to prevent rounds from being stripped from the mag and the bolt-hold-open feature from working. If I remove the spacer and hold the upper and lower together by hand it seems to function perfectly.

So, the question is, how do I get the upper and lower to align properly? It seems fairly simple but I thought I'd ask first because someone must have dealt with this before. The simplest way seems to be to fill the larger pin hole in the upper at the bottom of the hole to pull it down tight against the lower. But how? I can't weld and I want it to be permenant. JB Quick would work but I don't trust it long term.

http://img.photobucket.com/albums/v23/Gamonman/UpperLower002.jpg
http://img.photobucket.com/albums/v23/Gamonman/UpperLower004.jpg
http://img.photobucket.com/albums/v23/Gamonman/UpperLower2002.jpg

M4arc
12-30-06, 16:06
It looks like someone had a large hole lower but a standard upper so they drilled the upper out. IMO the only way to fix this properly is to replace the upper receiver.

Robb Jensen
12-30-06, 16:10
I used a peice of copper tubing on my wife's SBR to make up the difference I can't recall it's diameter. It's a large pin Colt SP1 upper on a newer small pin RRA lower. Just buy a couple inches of different sizes at the hardware store that are close in diameter to the diameter of the upper receiver.

http://img.photobucket.com/albums/v408/gotm4/10-5.jpg

Messiah Jones
12-30-06, 16:18
Well, I have the correct size spacer, but with the spacer in place the upper rides too high. It's as if I need to put a spacer in there, but only at the bottom of the hole, to pull the upper downwards. Somehow I need to fill in the hole at the bottom only.

K.L. Davis
12-30-06, 16:28
you can get an excentricated bushing... like the ones in this kit (http://www.bushmaster.com/shopping/lowers/we-003.asp) - the holes between the upper and lower are not on center and the busing has to have the hole off center.

It would be much better to locktite a piece of aluminum rod in that hole and redrill it... but it does look like the hole is pretty low on the upper, are you sure it is stock Colt? If it is a hack job, and for no more than an upper receiver costs, you may be better off just changing it out.

Messiah Jones
12-30-06, 18:02
you can get an excentricated bushing... like the ones in this kit

It would be much better to locktite a piece of aluminum rod in that hole and redrill it... but it does look like the hole is pretty low on the upper, are you sure it is stock Colt? If it is a hack job, and for no more than an upper receiver costs, you may be better off just changing it out.


Thanks again. I think it's a stock Colt pin hole. It is blued inside and shows no sign of drill marks etc. If someone did open it up they must have reamed it out and reblued it. The spacer I have is a stock part from DPMS designed to fit Colt uppers to DPMS lowers and it fits in the hole exactly. It's just not working quite right with this Armalite lower.

I'd like to try that "reverse offset pin" in the link you provided. Should I assume that since the DPMS spacer doesn't work that the "reverse offset pin" won't either? I don't understand exactly how it works.

CV-23
12-30-06, 18:36
Just repaired mine tonight after reading this thread. The front sight will only rotate a bit left or right. The milled cuts in the barrel will only allow "some" adjustment. This keeps the gas port somewhat centered and operational. My 11.5" CAR 15 front sight was canted left and took 20 clicks (out of 30) left to zero. It now only takes 10. Not perfect but alot better. Not sure who made this barrel (no markings and not even a proof mark)....shoots great with Reloader 7 (no flash) and has tons of muzzle flash with 335 ball powder on humid days. This upper came on a used Bushmaster Lower that was like new. The Upper in an Olympic Arms and fits perfect to my lower. I had my Gunsmith check the mounting/headspace on this barrel and it was off a bit. At first I was 30 clicks left! With his help and my tinkering....she shoots better now. It's nice to have an Indoor .22 Range at my house to do some testing. My Colt .22 Conversion worked great in only a 10.5" barrel. I'll fire some 5.56 on Monday for her final shake-out cruise but she looks good for now, Mike.

CV-23
12-30-06, 18:46
Sorry about the previous post...wrong thread. I have a few different front hole size Colts....what a pain for no good reason other than to make them "more sporting", Mike.

Kisara
12-31-06, 00:12
Your photo isn't too clear on my screen, but is the "Spacer" the same diameter all the way around? If so, I can answer what's wrong and show you how to correct it.

Stickman
12-31-06, 01:54
It would be much better to locktite a piece of aluminum rod in that hole and redrill it...


Sleeve retainer?

K.L. Davis
12-31-06, 02:03
Sleeve retainer?

Bearing and stud mount...

Elwood: This is glue. Very strong stuff!

PALADIN-hgwt
12-31-06, 10:58
xxxxx

Kisara
12-31-06, 15:36
K.L. Davis has the right idea (as usual). I replied earlier before I read the other member's replies.

Here's what a good friend did for me as a project a few years ago. It was press-fit in (no glue or Loctite), and is tight enough that you'll need a hammer and punch to knock it out.
http://i17.tinypic.com/483bcif.jpg
http://i18.tinypic.com/2yv9wlt.jpg

The correct size hole was drilled. More importantly, it was drilled in the correct place. This is where most people go wrong by making perfectly circular bushings. And conversly, many who need to enlarge a small hole upper will simply center up the correct size drill bit in the smaller hole, ending up with an upper that has the "right size in the wrong place" bored-out pivot hole.
http://i18.tinypic.com/4hwsgnr.jpg
http://i14.tinypic.com/2mzi4rc.jpg

Finished project had a perfect, flush fit with any small hole lower:
http://i13.tinypic.com/3ychzkg.jpg

Heavy Metal
12-31-06, 15:37
Bearing and stud mount...

Elwood: This is glue. Very strong stuff!


Ahh! The Good Ole Boys! Best name for a country and western band ever!

Messiah Jones
12-31-06, 16:23
This pic looks like exactly what I need. Is there a company that makes these? I have a drill press and can probably do it myself but I'd rather not if I can just buy it.

K.L. Davis wrote:
Bearing and stud mount...
- I'm not really sure what you mean by this.

Thanks for all the help guys. You really helped a lot!

http://i18.tinypic.com/4hwsgnr.jpg

K.L. Davis
12-31-06, 17:25
Stud-N-Bearing Mount, Cylicrical Mount, Bonding and Retaining... all names for various types of really tough "loctite" type adhesives. If you do not already have a tube of 380 (blackmax)... well, you should :D

Keep in mind that these are about as close to permanent as you will get and a lot of folks put stuff together with high stregth solutions, to later wish that they had not... simple rule, is if you think you may have to take it back apart, these are not the greatest choice.

You can get 380 here (http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=330260).

Messiah Jones
12-31-06, 21:20
Here is a product I was wondering if it might work. It's called a Pivot Pin Offset Bushing... http://www.model1sales.com/item-detail.cfm?ID=LRP030&storeid=1&image=lowerparts.gif There's no picture of it so I don't really know what it is but it sounded right. It's the first thing on the list.

I don't think this would work... http://www.bushmaster.com/shopping/lowers/we-003.asp


Have you tried installing the eccentric bushing with the thicker portion oriented at 12 oclock in the hole? That should reduce or eliminate the gap. Also it helps to position the bushing, then hold the upper and lower together, install the REAR takedown pin first, and finally install the front pivot pin. HTH.

PALADIN-hgwt, I'm sorry I missed your reply before. What is the eccentric bushing? It sounds like something that might work.

Like I said above, that picture Kisara provided is exactly what I need, but I'd rather buy one than make one. The upper is the one with the larger hole in my case. Any links to a place I can buy one would be awsome!

Bushytale
12-31-06, 22:43
Paladin has it right, the bushing is listed in Brownells as a DPMS part. It is made to fit the Colt large hole upper and any of the small hole lowers. The eccentric hole allows for adjustment to align the upper and lower as needed. You can also set it with a bearing mount type of glue so that it will not rotate and change the relationship/fit. Brownells # is 231-000-181 on page 27 of catalog #59 for $3.12. They also have the eccentric adapter pin to go from large hole lowers to small hole uppers. They both work great to solve this problem without any headaches or machine work involved.

Good luck, Billy:cool:

PS: Happy New Year to all you M4Carbine types

cz7
01-02-07, 20:09
well the best way is a new upper and get a hole gauge or .25 shanked bolt [no theads for a 2'' long part ] stick in hole for checking play in the take-down pin hole and alinement of the upper vs. lower ...i did this in the early 90's now i am playing with ar's again its better now more parts and fixs !!

Messiah Jones
01-03-07, 20:56
Wow sorry guys, I'm freakin' blind! The spacer I have which is shown in the pic is thicker on one side. I rotated it so the thick side is on the bottom and it tightened right up and feeds fine now. I can't believe I missed that! :rolleyes:

I still need to secure it in the upper with some sort of epoxy or something, so if you guys know of something let me know. I don't think I'm stupid enough to miss a tube of epoxy dangling off the reciever but you never know. :rolleyes:

K.L. Davis
01-03-07, 21:07
Wow sorry guys, I'm freakin' blind! The spacer I have which is shown in the pic is thicker on one side. I rotated it so the thick side is on the bottom and it tightened right up and feeds fine now. I can't believe I missed that! :rolleyes:

I still need to secure it in the upper with some sort of epoxy or something, so if you guys know of something let me know. I don't think I'm stupid enough to miss a tube of epoxy dangling off the reciever but you never know. :rolleyes:
Not to worry... maybe had I spelled eccentricated correctly in my first post, you would have caught it quicker ;)