AR Carrier Hanging Up
Now here is a condition that had me puzzled. My operating handle
was hard to pull when I was using a magazine with the new Yellow or older
Red/White/Blue Sinclair single shot follower installed. With a normal
Bushy magazine installed in my Bushy all I would get for resistance when
pulling the charging handle back on an empty magazine is the spring compression
from the carrier return spring. When I put an identical magazine
with a single shot follower in it, the operating handle would hang up or
blind after being pulled back about ½ to ¾ inch. The
carrier seems to be binding on something, that something being the bolt stop.
The magazine with the single shot follower installed would somehow cause
the bolt release button on the side of the receiver to stick out a little
farther than the normal magazine would. If I pressed on the very button
of the bolt release button arm I can also cause button to stick out a little
further with a normal magazine installed. This little extra rotation
or maximum rotation of the bolt stop would cause the carrier to hang up
and be extra hard to pull back or operate. Now here is the funny part.
The spring compression on the magazine follower appears to be lower on the
magazine with the single shot follower, i.e. the rear of the single shot
follower is much easier to push down than the rear on a normal magazine.
The rear edge on the magazine follower which contacts the bolt stop is a
little higher on the follower in the normal magazine. So by the laws
of physics the normal magazine should press the bolt release button out farther
but it does not. The single shot follower presses the bolt stop higher
and this higher condition causes the carrier to hang up and makes the operating
much harder to pull back.
(Bolt_Catch4.jpg)
I tracked the
carrier hanging up down to the bolt catch wedging or hanging up inside
the grove on the bottom of the carrier. The bolt catch is not pushed
down in a way of my first impression. At first I thought the part
of the carrier which actually pushed the bolt catch down was the same part
of the carrier that pushes the hammer back down. That part of carrier
being the end of the grove on the bottom of the carrier. I noticed
that the edge of the grove on the port side of the carrier was banged up
some. So I stoned the edges on the bottom of the grove. No
help. Next I noticed that the port side of the bolt catch was hitting
the port carrier edge. So I noticed to grind just a little away.
Worst thing that can happen now is get a new bolt catch. So after grinding
just a little off the arm on the port side of the bolt catch I learn that
it did not help and the bolt catch is not centered in the receiver.
The lump on the bolt catch is off center some and favors the starboard side.
About this time I deployed my flat black paint pen and discovered that the
bolt catch is actually pushed down by the starboard edge on the grove in
the bottom of the carrier. The bolt catch is a little wider than the
carrier grove and on the starboard of the carrier center line. The
starboard grove on the carrier pushes the bolt catch down and as the bolt
catch goes down while the carrier continues to precede rearward the actual
contact point on the bolt catch also moves to the starboard. In fact
this contact point was moving off the starboard edge of the bolt catch.
This was the root cause of the bolt catch wedging or hanging up. I
could see the somewhat diagonal line on the top side of the bolt catch that
the starboard carrier grove made in the flat black paint. I could also
see that the starboard side of the bolt catch was getting the paint rubbed
off. So let’s do some more grinding. Bolt catches are not that
expensive. So using my Drumrel Tool with the small one inch diameter
grinding wheel I proceeded to grind a little off the starboard edge of the
bolt catch. Repaint it with the flat black paint pen and test for wedging.
After two of three light grindings all of the wedging or hanging up when
away and the bolt catch would still catch the bolt. So bottom line
it was not single shot follower causing the problem. The single shot
follower only brought it to my attention. Several others shooters on
a High Power Shooting Forum reported having similar problems with single
shot followers and normal followers causing hard to operate charging handles.
So go test your AR. Pull the charging handle back with any magazine
installed. Then pull the charging handle back while pushing on the
very bottom of the bolt release arm and locking the bolt carrier in the
rear position. See if the charging handle is harder and the carrier
is hanging up of the bolt catch. If the carrier is wedging on the bolt
catch you now know why and know how to fix it. That is if it actually
brothers you. I only notice it because I have installed a new gas
manifold which is adjustable. I plan on shooting 600 yard single shot
and manually cycle the action. After installing the new gas manifold
I discovered the charging handle was hard to operate. Much harder
and to the point it would be a pain in the bottom while shooting at 600
yard slow fire. After discovering my normal magazine was not hard
to cycle the quest had begun.
(Bolt_Catch7.jpg)
In the picture above you can see the small line on the top of the
bolt catch along the right side. This is where the right hand grove
rail on the carrier pushes the bolt catch down. You can also see
a small spot on the right edge of the bolt catch where the carrier grove
is still lightly contacting the side of the bolt catch. Somewhere
along the way the right side of my carrier rail was sliding off the bolt
catch. This was allowing the bolt catch to go back up into the grove
and wedge the right side of the bolt catch into the carrier grove.
I could cause this wedging to action to happen by just pushing on the lower
portion of the bolt release button arm, just like you do when you lock the
bolt open to install your OBI. I could feel the wedging while pulling
the charging handle back. I ground off the right hand side of the
bolt catch just a little and everything is fine. I used a flat black
paint pen on the bolt catch to see where the carrier was hitting it.
I kept grinding a little at a time and painting on the right hand side until
the carrier stopped knocking the paint off. Now I can push the bolt
catch all the way up and pull back the charging handle without any hanging
up or extra resistance. You do not have to remove much from the right
side of the catch. Added this Marine Section at the end, starboard
is right facing the front.
Larry Medler
anyrange@comcast.net