1911Tuner says to use a Brownell 90 degree hammer hook file for cutting verticle faces on the upper lugs. But it won't fit! Neither will the lug file. Both will barely go between the lugs with the cutting surfaces up and down, but not to either side. Does anyone have an idea what will fit and stay square?
I haven't tried it, but how about Brownells' frame rail slot file? It is reversable -- on one side the sides cut and it's a safe edge, flip it over and the edge cuts and it has safe sides. I believe it's narrow enough to get in there.
Brownells square/safe sided hammer file works.
David... Just a smidgen. You shouldn't need to remove more than a couple thousandths from a given lug.
Johnny, is this the file?
http://www.brownells.com/aspx/NS/st...R+SQUARING+FILE
I don't have this one. Measurements *listed* were the reason that I said it "won't fit". Spacing between lugs on three barrels that I measured, runs around .177. Bar-Sto is .178, Storm Lake is .176, and Kart NM is .175. The lug file is really close at about .178. But that means it will have to cut going in.
Brownell shows a taper of the hammer hook file to be .180 to .185.
One barrel (Bar-Sto to Caspian, 10mm) needs .004 cut off lug one and two to contact all three. Wish it could have been ONE lug instead of two. The other (Kart NM to Caspian, 45) needs .002 off number one and .001 of number two.
Quote:
Brownell shows a taper of the hammer hook file to be .180 to .185.
Odd. Mine is an untapered pillar file...
David... If you can get the first and second lugs equalized... and you can get the third one to within a thousandth... let it go. The first two will set back and let the third one seat with use.
Johnny, I would have no hesitation seating one and two and leaving a thou on number three... in 45 ACP. I am fairly nervous with this 10mm build.
I plan to mark the lug faces with a marker, find a snug feeler guage to go between breech face and hood, and tap the barrel into the slide for markings for final fitting. Better ideas? I am getting enough variation in measurements to only trust them so far. I think slide lugs have some slight steps toward the bottom.
Yes, I totally failed to follow "good" instructions (I used everyone else's), and cut the hood first. EGW will weld it back for me though.
Quote:
Odd. Mine is an untapered pillar file...
David... If you can get the first and second lugs equalized... and you can get the third one to within a thousandth... let it go. The first two will set back and let the third one seat with use.
Be gentle when you tap it in. No need to force it all the way up.
Lug #3 has the least vertical engagement because of the tilt, so it won't make a big difference in the lock strength. Most of the Colt Delta Elites didn't have more than two bearing... and some of those were on 2 and 3. When it's time to seat'em... use downloaded ammo to heat the barrel up... about 3 mags full, rapid-fire... then use a magful of full-powered stuff while the barrel is hot. Should take care of it.
Unless you've got more than about .003 inch hood to breechface clearance, there's no need to weld it up. You'd have to use a sandbag rest... a good eye... and very high-quality ammo to see the difference in accuracy at 25 yards.
Thanks for the seating firing tip. That sounds like a good idea.
I've got a Delta that has probably had about 500+ full charge loads, including the original high pressure stuff. I've not checked lug contact on it. That should show something I suspect. I know that "number three" doesn't do a lot. But it could help a little. Like I say, after reading so many warnings, I'm a bit paranoid. Many WARNINGS! are for those who don't want to read, but...
I'm going to have more than .003" hood to breech clearance. I got a bit heavy handed before I realized that I was seating on the shoulders. Guess I worked too late that night. Some lessons come the hard way, but at least it is repairable at not great expense. The barrel to contacts at above the throat will be around .003, if that matters. I suppose that AND hood would be best. I want to minimize the slap for the obvious pressure reasons.
Interestingly, this guy will probably shoot it more off the bench than anything. He wants the best accuracy we can get with full charge loads. hmmm... His secondary use will be for hunting. He just wants the bullet to go precisely where he is aiming. And he is a pretty fair shot, though not a competitor. So I'm trying to comply with his desires.
With the setup shown below, even a flat jeweler's needle file (with the edges ground safe) can be used to trim the vertical lug edges. It has three benefits:
1. It does not rely on the horizontal/axial lug recess surface to provide a reference surface for the file, whose corners are supposedly square.
2. By guiding the file so it can't rotate or tilt when cutting, it positively prevents the file from miscutting the lug vertical surfaces. As long as the bore axis is held perpendicular to the drill press vise's jaw tops, the lugs cannot help but come out vertical.
3. No special file is required. It just needs to be thin enough to fit between the lugs, a suitably fine cut, and safe edges.
The file rests on a flat washer. Dry lube under it allows the washer to rotate along with the file during the cut, providing an arc to the file's motion - just like the lug it's cutting.
I don't cut lugs very often and don't have the steady, machine-like hand of 1911 Tuner, so this setup makes the operation fool-proof. For this fool, at least. Cheers
P.S.: The drill press vise must have a vertical jaw groove which is perpendicular to the jaw tops to secure the barrel without applying excessive jaw pressure
I think that I'm going to try that. -- Just happen to have a barrel to cut. I guess I'd better square off the jaw tops 1st.
The only problems that I see with this setup are various opportunities for misalignment. Is the barrel chamber end perfectly straight? Hardware store washers are not uniform, but uniform ones are available or can be made. The vice jaws would need to be very precisely aligned. The "V" needs to be precise to the faces and the tops in both directions.
I like the idea of a fixture instead of relying on my eyes and hands. But the machinist vices I have all have too much play for the tops of the jaws to align well enough with consistency. I have one possible exception in my milling machine vice. It *might* work.
I think you are on to a great idea. Some testing of setups is in order here.
Good idea, NIEMI. I'm just about sure that vise and washer will get the barrel lugs as square as the lugs in the slide. Last barrel I fitted, the slide lugs were cut off center and a little out of square.
Whatever the uncertainties in this setup might be, I figured they were lots, lots less than my most carefully held file. I guess it's the "lesser of two evils", so to speak. Maybe not perfect - but perfecter than me! Cheers
Quote:
Odd. Mine is an untapered pillar file...
David... If you can get the first and second lugs equalized... and you can get the third one to within a thousandth... let it go. The first two will set back and let the third one seat with use.
Mine fits also... it is square, untapered, 2 safe sides.
Another related question - at what point is so much barrel /slide lug slop introduced that it is not worth equalizing the lugs? How much fore/aft movement is too much, or is there such a thing? Asked another way, is it possible that at some point the 'running start' and attendent battering of the lugs would tend to nullify the additional strength of equalized lugs? Or does this ever happen with quality parts?
Is it a good idea to use hard barrel hood/slide contact to limit the play created by equalizing? I wouldn't think so.
Well, turns out to be several questions. The reason I ask is that I have an old useless GI slide that looks like the lugs have had steps cut into them from, I'm speculating, this sort of battering.
Niemi, that is a very clever setup!
Quote:
Another related question - at what point is so much barrel /slide lug slop
introduced that it is not worth equalizing the lugs?
That's the 64-dollar question...
As a few have noted... sometimes the slide lugs aren't dead square. Sometimes the face of a given lug isn't dead flat. Some are uneven. Measure the distance from the rear face of the lug to the front of the slide on three points, and you may get two or three different measurements. It's usually better to fit the barrel lugs to get close.... within .001 inch... and let the gun finish the job by shooting it to seat the lugs.
That's the way it was done in the early days... with high-pressure proof loads.
Trouble is, that the new slides and barrels are made of harder stuff. They don't seat as readily as they did. If one of the two forward lugs is bearing the brunt, you can crack or shear a lug during the process. So, you fit to the most supported lug... #1... and let that one seat to bring one or both of the other ones in.
Trouble is... that as the lug sets back, headspace grows. As the lug seats and headspace grows... so does endshake. A little endshake isn't an altogether bad thing, but there's a limit. Too much endshake, and the barrel and slide lugs slam into one another when the gun fires, and the lugs get slap-seated with impact stress.
So... We fit to seat on the first and most supported lug. If we're careful... and a little lucky... we also get one of the others to bear...hopefully #2. This, before we do the final fit of hood to breechface and controlling fore and aft play so that when that final .001 inch of lug equalization occurs, .001 inch of additional endshake is all that we get. If two lugs are bearing equally, that additional .001 will be slow in coming, and in some guns that are fired mainly with lead bullets or especially lightly-loaded target grade ammo... most especially if the gun is never allowed to get very hot... it may never come.
As a rule, .003-.005 inch of endshake is a non-issue except in the most accurate of bullseye guns. .003-.005 inch of hood to breechface clearance is also nothing to be too concerned about... nor is .003-.005 inch of static headspace over minimum. Unless all brass is of equal length, working headspace will vary from shot to shot anyway.
What you don't want is to lose any more case head support than absolutely necessary... which occurs when you remove material from the front faces of the barrel lugs during the fitting/equalization of the lugs... because that increases headspace in the ka-boom direction. So keep it at a minimum.
THAT's what I call an expert answer!
Is endshake the actual measurable fore/aft movement of the barrel when in the slide (my guess)... or is it the theoretical fore/aft movement possible between the slide and barrel lugs, and which can be attenuated somewhat, if temporarily, by hood fitting?
Would using a lathe w/ a very sharp bit be be better for lug trimming than a file? (I have a small, hobby lathe, which is quite accruate, and a .0005" cut is possible)
As Niemi notes (he's a smart guy), holding a file at exactly 90 is iffy at best for me.
Quote:
Is endshake the actual measurable fore/aft movement of the barrel when in
the slide (my guess)... or is it the theoretical fore/aft movement possible
between the slide and barrel lugs
Both. The lugs are the limiting factor of fore and aft movement... endshake... unless and until the hood to breechface fit stops aft movement. Even if the hood is completely removed, the lugs will limit the travel.
Quote:
which can be attenuated somewhat, if temporarily, by hood fitting?
Yes. By fitting the hood closely to the breechface, the barrel is pressed as far forward into the slide as it can go... limited by horizontal lug engagement. The face of the hood against the breechface stops rearward travel.
However... Some slide/barrel combinations allow the barrel to be pressed forward by the breechface bearing on the chamber face, below the hood. I don't like to see that condition, and much prefer that the hood time the barrel into the slide and leave a little clearance between chamber face and breechface. It doesn't have to be very much... about .003-.005 inch will do.
I also don't like to have zero clearance after the hood is fitted... on a carry or duty gun... and I usually take about .003 inch off the hood face if the barrel lugs are being positively pressed against the slide lugs. For guns intended purely for target or range work... zero clearance is fine, and often enhances accuracy a little, all else being correctly fitted.