How to move the abutment surface back?

original: forum.m1911.org
Retrieved: December 07, 2011
Last Post: October 29, 2008

Hawkmoon
27th October 2008

Let's say an unnamed tinkerer had a full-size 1911 frame, and an Officers ACP slide, and he wanted to put them together and make a functional firearm out of the mix. It's possible that with judicious choice of recoil spring and ejector length (and profile) the gun could be made to work, but properly... the frame rails should be trimmed 1/10th of an inch and the abutment surface (the step in the recoil spring tunnel against which the recoil spring guide flange rests) should also be moved back 1/10th of an inch.

The frame rails are easy. That can be done on a milling machine, or even with a hacksaw and a file, in a pinch. But...

...how would one go about moving back the abutment surface?


log man
27th October 2008

Can't say that I've done it, but don't see why a 5/8" end mill wouldn't be a reasonable choice.


Hawkmoon
27th October 2008

I was afraid you were going to say something like that.

Now, all I have to do is find a 5/8" end mill... and a lathe or a milling machine to chuck it into.


log man
27th October 2008

...or find a Commander or Officers frame. LOL


John
28th October 2008

Why don't you trim the flange of your guide rod by .05", that will give you half the required distance, it may be enough for you.


sevenL4
28th October 2008

I watched my 'smith do the job on a govt frame I converted to a Commander. He has a sleeve for the shaft of the end mill. He clamps it in the frame with a padded hose clamp and turns the mill with a cordless drill. It took him about 5 minutes, not counting time spent looking for the drill.


niemi24s
28th October 2008

Quote:
...a sleeve for the shaft of the end mill. He clamps it in the frame with a padded hose clamp and turns the mill with a cordless drill.

Now that is indeed a nifty idea - use the dust cover as a built in fixture to align the end mill!

(At least I think that's what he did)


sevenL4
29th October 2008

niemi, you got it. It's just too simple. Hawk, if you do it, make a couple of extra fixtures and offer them here


RickB
29th October 2008

I have "heard" that not all "Commander" frames have all the frame mods. Maybe some companies only cut-down the dust cover.


Jim Watson
29th October 2008

I have read on the Internet that the Baer Commanche 4.25" has G.M. rails and abutment.

As John says, you can steal a little here and there and probably get it to work without frame modifications. Maybe.

Use a Glock recoil spring and you can get enough spring into a small space. Takes a specially made guide rod and plug, though.


log man
29th October 2008

Ahh... not shortening the abutment will not shorten the space the recoil spring compresses into that's the slide's job. It will only reduce the slide travel and increase the in battery recoil spring tension by about 8.ozs, a good thing.


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