AR-15 Pistol thread: How to build an AR-15 pistol info

[Quarterbore]

Crime Bll as it applies to Pistols:
Note that the Federal Crime Bill expired on 9/14/2004 so for most of us the following laws no longer aplly!
Also Note that SOME STATES still need to live with state versions of this law!!!

Following is from http://quarterbore.com/library/law/crimebill.html

Semiautomatic assault weapon {in the context of a pistol}

(c) A semiautomatic pistol that has an ability to accept a detachable magazine and has at least 2 of--

(1) An ammunition magazine that attaches to the pistol outside of
the pistol grip,

(2) A threaded barrel capable of accepting a barrel extender, flash
suppressor, forward handgrip, or silencer,

(3) A shroud that is attached to, or partially or completely
encircles, the barrel and that permits the shooter to hold the firearm
with the nontrigger hand without being burned,

(4) A manufactured weight of 50 ounces or more when the pistol is
unloaded, and

(5) A semiautomatic version of an automatic firearm;

Definition of Semiauto pistol:

Semiautomatic pistol. Any repeating pistol which utilizes a portion
of the energy of a firing cartridge to extract the fired cartridge case
and chamber the next round, and which requires a separate pull of the
trigger to fire each cartridge.

[dlt223]

Hello All,
My name is Dave and I live here on the west coast in Portland Oregon.
I am 53 years old and a long time Gun Enthusiast/Collector.
I own half a dozen AR's in various configurations.
Recently Joined this Chat board in hopes of getting some input to
resolve a problem I have been having with an OA-93 pistol upper.

Just after the AWB expired a group of us ordered a dozen AR Lowers
and had them all registered as Pistols.
From one of these I assembled an OA-93 using Olympics Upper.

This firearm would not cycle reliably when first assembled.
Experimented with many different types of ammo and found that
only the Federal Lake City Brown box would cycle more or less reliably.
None of the ammo tested would Lock the action open after the last round.
Emailed Olympic's Support people and never received an answer.

So now I am on my own. Dissassembled the Upper and found the following.
The Gas port was set at .0625" (1/16) and it had the straight gas tube.
The recoil spring seemed way too stiff. It's dimensions were as follows:
OD=.440" OAL=7.5" Wire Dia.=.047" Coil Pitch=.1875

Opened the Gas Port just slightly to .070" and added a pigtail Gas tube.

I have Inquired all around and spent Hours searching the web to find a
spring with a little softer rate and have had no luck.

So I started cutting off coils and retesting, I now have a spring that is
just barely 6.0" long. The Federal Lake City ammo now reliably Locks
the action open every time. The other ammo now cycles But they
will not Lock the action open.

At least now the OA-93 functions, But it is not the optimum situation.
I would still like to find a spring that will allow a wider variety of ammo to be
used while still functioning correctly.

Anyone that has any thoughts on this subject please respond.

Dave

[prebancolt]

I built a pistol using the OA93 upper but I used a RRA lower. My OA93 upper came with a pigtail gas tube and it usually functions fine, not perfectly fine, but fine, as I consider it nothing more than a cool toy. I've noticed that my recoil spring seems pretty stiff, also.

I would love to find a replacement, as I want to begin construction on a 9mm OA93 upper to match. Let us know if you if you find that spring anywhere. Thanks.

J