Checkering on a Colt...

[krs]

I want to checker the front of the grip on one of my Colt 1991a1 pistols but the steel is kind of thin at .080". It does seem to be consistent thickness up and down but I realized that I don't know how deep checkering would go. I'd hate to find that I'd cut all the way through.

I have checkering files from Brownell's, both 20 and 24 lpi versions.

Does anyone know if there is a risk of going through the front strap on one of these pistols?

I make the thickness of the same location on a 1974 Series 70 Government model to be almost .015" thicker than it is on the later gun.

 

[rcmodel]

Checkering depth depends on the LPI.

20 LPI = .050" line spacing.
24 LPI = .042" line spacing.

Assuming the diamonds are as deep as they are wide, that is the maximum amount of depth. But there is some error in figuring it this way.
In actual practice 20 LPI will be about .035" deep, and 24 lpi about .030".

But still, the finer the LPI, the less depth there needs to be.

rcmodel

 

[krs]

That makes sense, and it means that unless I screw it up there should be approximately .050" of wall thickness left.

It starts to make sense why George at EGW offers a checkered insert meant to be welded into the frontstrap after milling out a recess, or an opening, to accept it.

 

[rcmodel]

Actually, the EGW insert is more to insure you get good checkering without a ruined frame.
Or to repair frames that are already ruined.

More 1911 frames have probably been screwed up with botched DIY checkering jobs then any other cause.

It isn't nearly as easy to do a presentable job as it might seem!

rcmodel

 

[krs]

Yessir! I've been practicing for some time, first on steel tube, then onto serrated mainspring housings, and finally on a RIA frame that turned out pretty good, IMO, although I know there's a mistake.

Even with some checkering under my belt doing it on a colt frame has me spooked and I might hold off until I can build up some more practice.

I'm wondering now about whether .050" is enough steel to keep the frame in dimension when it's in use.