Found this gem at Rimfire Central. Thought some folks here could benefit from it, too.
There are all kind of stories on the net trying to explain
why the barrel bushing cracks.
You have probably read opinions about
the barrel bushing cracking because
it is made out of Aluminum, or made of out pot metal,
or made out of wood, or made in China or whatever.
I will not try to conflict any of the above opinions,
but I will suggest the real reason of the barrel bushing failure
and I will show you a way to prevent this.
Those of you who are familiar with
the real (centerfire) 1911 system as it was designed
by Browning, may have noticed the fact that usually
there is a bevelling under the barrel in front of the lug.
The GSG 1911 doesn't have that bevelling, and it has a step instead.
When assembling the slide on the 1911 centerfire,
the guide rod easily slides past that bevelling
and it will stop on its seat in the frame.
However, the GSG guide rod could (and many times WILL) stop on
the sharp step of the barrel and will not reach its rest in the frame.
So, this can happen in the GSG:
And because of this, the fat end of the guide rod
will rest in front of its designated seat in the frame.
In this situation, because the guide rod will work at a different angle,
it will bind against the guide bushing located under the barrel bushing.
Also, the spring will be fully compressed BEFORE the slide recoils all the way back.
Those above are the real reasons the barrel bushing cracks.
To prevent this situation, while putting the slide assembly back on the frame
we want to have the parts in this position relative to each other:
This will ensure the end of the guide rod will get in its seat in the frame.
To assemble the slide with the guide rod in the right position is not
a very complicated operation, but you might need a little practice to get it right.
This is a way to do it (but of course, many of you may find easier ways):
First, put a drop of oil in the frame, especially if you are using
aftermarket buffers, which are a oversized (tighter).
Find a pin, or short rod, or similar thing that has flat ends and that fits
loosely inside the guide rod bushing.
I found that a 10/22 trigger group pin works very well.
Holding the slide like in the picture, press the rod or pin
against the guide rod in order to ensure the guide rod rests against the barrel lug.
The rear end of the guide rod should rest
against the barrel lug, NOT against the thin shoulder of the barrel.
Continue to press the pin firmly with your palm while
slowly pushing the slide back on the frame.
When the slide is completely all the way on the frame,
you will notice the guide rod and pin will come to a stop.
Now it's time to check your work.
Move the slide all the way back.
Look at the notch in the slide and the notch in the frame.
In the rearmost position of the slide,
the notch in the slide should be slightly BEHIND the notch in the frame.
If the above is what you see on your gun, then continue to
re-assemble your gun and you are good to go.
If however, with the slide in the rearmost position,
the notch in the slide is slightly IN FRONT of the notch in the frame
like in the pic below,
that means the end of the guide rod is hanging on the shoulder of
the barrel, and you do not want that.
If the above happened, take the slide out, re-position the guide rod against the barrel lug and try again.
Once the guide-rod rests in its designated seat in the frame,
there is no chance the gun will break the barrel bushing.
Now some people will feel that they should go to the root of
the problem and they will machine/file/grind
a bevel in the shoulder on the underside of the barrel.
Of course it will work, provided they know what they are doing.
However, don't get any ideas about bevelling the fat end of the guide rod.
If you do that, you will reduce the contact surface between the guide rod and
its seat in the frame and it is very possible the frame will get damaged/destroyed.
Enjoy your gun. Stay safe
