From: bartbob@aol.com (Bartbob)
Newsgroups: rec.guns
Subject: Re: M1 op-rod question
Date: 22 May 1997 23:05:27 -0400

Yes, M1 op rods were hand fitted.  They still are by a very few folks who
accurize M1s correctly.

It's best done with a fixture with several gage points that measure the
position along several places from the piston back to the op rod handle.
After placing the op rod in the fixture with it's back end fitted in the
basic alignment points, the front 3/4ths of the rod's position was
compared to the gage points in both horizontal and vertical places.  The
person fitting the rod would then look at the various clearance points and
if any were not within specs, the rod would be removed from the fixture,
then bent by hand at the right places just the right amount.  The op rod
would then be replaced in the fixture for more checks.  This procedure
would be repeated until the op rod was bent correctly.  But this wasn't
the end of it.

The op rod would then be placed in the M1 rifle and checked for clearance
at the lower band at both sides and at the top.  Additional bending may be
needed if clearance and fit here wasn't quite correct.  Proper clearance
under the barrel was also critical.  The front end that went into the gas
cylinder was also checked to be sure that part at the back of the gas
cylinder almost touched the bottom of it.  Finally, the op rod handle
should cam up and counterclockwise a bit on the closed bolt.  One check
that was made at this time was that if the op rod handle was pressed down
on a cocked and closed bolt, then released, it must snap up and
counterclockwise to a full and complete stop.  If any upward pressure on
the handle moved the op rod more counterclockwise, or if it didn't snap
back up, further bending and alignment was needed.

I once watched one of the military match conditioning shop's armourers fit
M1 op rods and they really did all of it quite quickly.  It probably took
about 15 to 20 minutes from start to finish.  Nowadays, few, perhaps 3 or
4, people in the USA can properly fit an op rod to an M1 and get the most
accuracy and reliability out of the rifle.