fitting AR upper and lower

[gringolet]

AR upper and lower do not quite fit properly..the rear takedown pin
holes do not align perfectly...almost, but not quite. Jams pin when trying to remove. What is best cure? have considered using drill bit to open and remove excess material, better options?
thanks.

 

[rcmodel]

Doesn't happen to have a blue plastic "Group Gripper" in it behind the rear pin by any chance?
If it does, take it out and your problem will go away.

rc

 

[gringolet]

no group gripper

no group gripper in it.

 

[rcmodel]

O.K.

Is it miss-aligned up & down or front to back?

Up & Down might just be a rough spot on the upper or lower mating surfaces holding it open slightly.

Front to back is another can of worms.

rc

 

[leftym4]

find out which is out of spec and send back to manufacture for correct pc.

if you can't do that , find out which one is out of spec and which one is

do the work on the out of spec pc other wise you will have 2 out of spec pcs that will not
match up with spec parts should you ever sell or need to replace

using a fine tooth small round file and taking a little off at a time on the edge that is out until it fits should do it

but you still want it tight

 

[gringolet]

hard to tell?

the thing is off by such a small margin it is hard to tell.
I can force pin in with fingers, but removal requires
brass hammer and a punch. Appears to be just a hair
off to the right side-to-side.

 

[rcmodel]

Try a good quality 1/4" (.250") drill bit in the holes and see if it's just a bugger in the hole or something.

Also, lube the takedown pins and make sure the detent & springs are working correctly.

Also, try setting the mag well on top of a bench or stool and putting all your weight on the upper to force the two together.

If you can get it to come out that way by hand, I sure wouldn't enlarge the holes to make it looser.

It will do that on it's own eventually!

rc

 

[Howard Roark]

I shim my lowers with leather under where the rear lug of the upper rests to get a tight fit between the two. I use a brass hammer and punch to drive the pin in and out. No movement between the two is a good thing. Some have bedded the two to eliminate play and some drill from under the rear of the lower and tap the upper lug so that a screw can pull the two together.

 

[gringolet]

thanks

thanks for all the advice.
will start to work, cautiously.
this does not impair the function of the firearm
except that quick opening the the field
is not an option right now, but am not too apt
to get this thing into afghanistan anyway!
just aggravating to me as my other Ar works
like a charm and it has spoiled me!

 

[ben_i]

Yes be careful, I ruined a perfectly good upper trying to fit it to the lower.