if you still want to get a snug upper/lower fit you may try these:

http://www.triggershims.com/ar_15_shims.html


AR-15 Pivot Pin / Take-Down Pin Shims
You can use these shims to take out the play between the Upper and Lower Receiver.

Our AR-15 Shims are made by us here in the USA out of American Made Materials.
Fits Standard 1/4" Pivot Pins / Take-Down Pins
Available in 300 Series Stainless Steel.

Six Pak kits come Standard in .005" SS
12 Pak Assortment has 4 X .002", 4 X .003" and 4 X .005" SS
24 Pak kits come Standard in .005" SS
and in a 24 Assortment Pak which has
8 X .005", 8 X .003", 8 X .002" Shims

 Item # AR15-PSP6 Pivot Pin Shim 6 Pak $10.00 Free Shipping
Item # AR15-PSP12A Assortment Shim 12 Pak $17.00 Free Shipping
Item # AR15-PSP24 Pivot Pin Shim 24 Pak $22.00 Free Shipping
Item # AR15-PSP24A Assortment Shim 24 Pak $22.00 Free Shipping