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Old May 26, 2012, 12:35 PM   #1
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Join Date: November 13, 2006
Posts: 5,246
1911 timing/linkdown/slide-bbl clearance

Bought a ATI Philipine 1911 clone for darn good son-in-law.
Its pretty OK,I have replaced most internal parts.Its unfired.

Drawing the slide back till the bbl lug contacts the frame bridge,I see no clearance barrel to slide.There are light drag marks on the barrel as seen in the ejection port.On other 1911's I have seen what happens when the locking lugs do not fully disengage in firing.We don't want that.

I tried a new GI barrel just to see how it would act.Same problem,but a little more so.

My conclusion,some steel needs to come off the bridge,rather than the barrel lug.

IIRC,the spec per Kunhausen/Scheuman is a .012 feeler gage to pass at the forward lug with spring preload up on the bbl.

My plan:

Measure actual linkdown travel with depth mic,from there figure the unlocked angle of the barrel.My eyeball tells me it will be about one degree. As the barrel underlug is square to the barrel,it makes sense to me the face of the bridge where the lug contacts can be drafted (angled) some,so I should get full prussian blue transfer.I understand the hard contact needs to be close to the barrel or the lug may break off.

There is a mill technique of making a single tooth broach,you put it in the Bridgeport collet and just stroke the quill up and down,no motor.You cut one chip per stroke.I have made square corners,keyways,etc this way.I think that is how I will cut the bridge face back,initially.I can get square corners that way,no cutter radius.
I should be able to take about .008 off and still have my chips cut free as the draft angle runs out.

I do not think taking .008 will get me the full .012 spec,but if I have some running clearance,it beats no running clearance.

As I am a 1911 rookie,I would just like feedback as to if my plan seems sound.Thanks.
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