I moved on to the next step of my first barrel fitting project - fitting the hood.
I measured everything very carefully and set to work with the file. I took measurements and checked for square every so often, and was doing a fine job if I say so myself.
I fit the sides of the hood so that the hood would just fit, then I started trimming the hood length. The length I was aiming for was 1.319" - the hood started at 1.329".
I got down to 1.320" and switched to a stone. Nothing. The barrel wouldn't move up at all. Maybe my measurement was off? I took the hood to 1.319" - perfectly square. Still, no movement up.
Maybe the lugs? I dykem'd the lugs and checked - Nope.
I took a little more off the hood, still nothing. I measured again - 1.318".
I must be close. So I stoned, fit, stoned, fit. What was going on?
Then it hit me. I dykem'd the barrel hood and saw. The barrel hood recess in the slide was not perfectly smooth. The sides of the hood were binding. I hit the slide recess with a few passes of a stone and dressed the sides of the hood up.
The barrel hood slid neatly up into place - no side to side movement at all.
Problem - I now had a gap between the barrel hood and breech face. I had been hoping for a perfect NM fit. I measured it, .0025" gap.
Well, I guess I'm going for a good ordnance spec fit now.
Lesson #1, trust your instruments. I should have stopped at 1.320" and checked everything twice before taking off more metal.
Lesson #2, get a barrel stoning fixture. Man, did that take a lot of time.
You'd need an extremely accurate pistol and carefully handloaded ammunition and a machine rest to see the difference in group size between a "perfet" match fit and .0025 inch of clearance between the hood and the breechface.
Don't sweat the small things. If the barrel is well-fitted otherwise, it'll be more accurate than all except a Distinguished Expert can appreciate.
When the barrel is in the slide, does the 0.0025" hood-breech face gap change when the barrel is forced fore and aft?
You may have gotten lucky if the breech face guide blocks in the slide and the chamber face are such that there's no (or less) fore-aft play. But, even if all the fore-aft play you have is 0.0025" - that's pretty good too, like Tuner said.
After all, you really weren't building a bench rest 1911, were you?
Fitting a match barrel The Jack Fuselier Way
"First let's clear up a common misconception about the space between the hood and the breech".
"#1 The clearance between the hood end and breech is irrelevant, as long as it is enough to function with fouling present."
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Fitting a match barrel the Jack Fuselier way ..."#1 The clearance between
the hood end and breech is irrelevant, as long as it is enough to function
with fouling present."
But even if the slide drove the barrel into battery by hood/breechface contact (instead of chamber face/breechface guide block contact) I'd think the hood would just scrape off any fouling on its way up the breechface.
I think.
Don't forget the role of the lugs atop the barrel, matey, and then there's that pesky slidestop.
All you want to do is see to it that the barrel goes to the same place in relation to the slide and frame for each firing. The hood can limit side to side movement at the top of the chamber, but only such movement as is allowed by the stacked clearances of slidestop pin, link, link pin, barrel foot lug. Minimize those and have a snug slide fit of the hood at it's sides and you're good to go. Cut the foot lugs for a camming rise to battery and worry less over the rest.
When you are getting the barrel lugs up into their notches nicely there's a liklihood that you'll find that your hood to breech clearance has all but disapeared, and that, or those, fitting are the money ball - the one that counts.
BTW, the words above are not my words but Jack Fuselier's taken from one of the technical articles kept just outside this forum.
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BTW, the words above are not my words but Jack Fuselier's
Here are a few more of his words..
While in battery before firing the barrel is forced back against the breech by the recoil spring, and the slide is forced forward.
I'm sure Jack is a fine smith... and I find much that he says to agree with completely... but he's gonna hafta explain that one.
The recoil spring has no direct bearing on the barrel what-so-ever when the gun is in battery. When the gun is assembled, the recoil spring is captive between the plug and the guide rod flange... and the guide rod flange doesn't touch the barrel. It bears against the impact abutment.
He also states that the barrel doesn't move backward while the slug is in it... which is categorically wrong. Once any slack is taken out of the lugs... if the slide is moving, the barrel is moving... and the assembly is moving while the bullet is present. If the hood is closely fitted to the breechface... and it doesn't have to be tight... there is no slack in the lugs because the slide forces the barrel forward as far as the lugs will allow.
He and Kuhnhausen must've been poker buddies.
OOH! OOH! I found more!
Headspace with any particular barrel can be changed only by changing the
chamber depth.
Betcha I can change the headspace without a chamber reamer. All ya gotta do is take a pillar file and start cuttin' on the front faces of the barrel lugs. For every thousandth of an inch you cut... headspace increases a thousandth of an inch.
I'm gonna go put my fireproof suit on now...
Tuner - you made me take one apart again to prove you to be right (of course) the guide rod flange does indeed seat against the frame, not the bbl, as when installing slide to frame. Once again, thanks.
Which all is why I restricted the quotation as I did, but then Neimi quoted ME using the words of HIM so I made sure he knew where it came from.
My only hope was to move Neimi's attention from the hood fit he seemed to feel he'd made too large. Having engineers in my family has made me too familiar with a tendency to micro-focus on a single aspect of a problem particularly when attention is forced to an area by concern that an error had been made, and I wanted him to know that he's still OK.
Quote:
BTW, the words above are not my words but Jack Fuselier's taken from one of
the technical articles kept just outside this forum.
Sorry, Hill. Neglected to include the source of the quote in my original post. Just edited it to include the source.
Quote:
Which all is why I restricted the quotation as I did, but then Neimi quoted
ME using the words of HIM so I made sure he knew where it came from.
Did a sloppy job quoting your quote. See my previous post. And you can quote me on that!
Quote:
My only hope was to move Neimi's attention from the hood fit he seemed to
feel he'd made too large.
It was the OP (Tom in Ohio) who was concerned about the gap, not Mrs. Niemi's little boy.