I read some comments that it's good for accuracy that the barrel hood touches the breechface when the gun is in battery and I also read other guys saying that it's good to have a clearance of about .003" between the barrel hood and the breechface.
I also read somewhere else not in this forum that if there's contact between the barrel hood and the breechface the barrel hood may eventually break up.
So now I'm a bit confused. What do you guys think about it?
FWIW, when in the battery position, a mid-spec USGI 1911A1 slide forces the barrel fully forward against the slide stop pin by contact between the breech face guide blocks in the slide and the two aft edges of the chamber. This mid- spec gun will have a 0.006 inch gap between the barrel hood and breech face, and the total fore-aft play (endshake) between the barrel and slide will be about 0.013 inch.
When a 1911 is accurized, one of the many possible barrel-fitting steps is to reduce endshake as much as possible without jeopardizing reliability. For a carry gun, reliability is crucial, and the 0.003 inch gap you mentioned helps attain flawless reliability. For a target gun, accuracy is crucial and a 0.000 inch gap may help attain utmost accuracy.
Never heard of barrel hood breakup due to breech face contact.
Don't be confused - the differences are merely due to what the gun's going to be used for and the personal preferences of the individual pistolsmith. But, that's just what I think about it. Cheers
Thank you
I was asking about the hood breaking off because I read it on an old barrel fitting leaflet from FAC.
The barrel hood will touch the breechface as the slide moves forward to cam the barrel upward into vertical engagement. If the breechface presses tightly on the hood with the slide in full battery, it forces the barrel as far forward as it will go, placing the locking lug's horizontal engagement surfaces into contact. That eliminates than end-play between barrel and slide.
.003 inch of "clearance" doesn't mean that the breechface doesn't touch the hood with the slide static and in-battery. It only means that you can slip a .003 feeler gauge between them if the barrel is as far forward as it will go.
Zero clearance fit is part of accuracy enhancement that works to insure that the barrel goes to battery as close to exactly the same way each time. Unnecessary and even undesireable in a carry gun. I like to see .003, and won't get upset by .005 inch.
It allows for a little fouling and dirt to get between the two parts without compromising easy return to battery. Bullseye smiths generally prefer to have no clearance. Zero clearance is a little easier on the lugs, but .003 won't make enough of a difference to worry about.
The barrel hood doesn't undergo any impact stress during firing, and doesn't suffer any more impact that necessary to push the barrel forward when the slide strikes it. When the gun is feeding ammunition from the magazine, the slide is being slowed by the feeding round, and is moving pretty slow by the time it hits the hood... so it's a non-issue.
Breaking or cracking a barrel hood is something that I've never seen in nearly 44 years.
Not saying that it's never happened, or that it can't... just that I've never seen it. I'd also have to say that if it does happen, there's some reason other than the slide hitting it.
Never seen one break, I like to fit close enough that if you shoot 50 rounds or so, the hood keeps the breachface clean of fouling powder residue in the area it fits up to, in other words, close, but not touching . I used to shoot about 30 or 40 different guns a day. In this daily process I had to sandbag shoot for a test target almost every gun. I have shot old rattle trap guns with a lot of clearance in the hood area, that at 20 yds. would almost one hole. Go figure.
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I have shot old rattle trap guns with a lot of clearance in the hood area,
that at 20 yds. would almost one hole. Go figure.
Stranger things have happened. I saw a 1918 "Black Army" Colt... so loose that if you shook it hard, it'd field-strip itself... outshoot a new Colt Gold Cup from the bags at 50 yards... and both guns were shot by the same man.
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The barrel hood will touch the breechface as the slide moves forward to cam
the barrel upward into vertical engagement.
I think whether it will (or not) depends on the gun.
For a USGI (not National Match) M1911A1 built to 1970's era US Army (Rock Island Arsenal) specs, the barrel hood can never contact the breech face. The hood can be no longer than 0.154 inch and the space for the hood between the breech face guide blocks can be no shallower than 0.156 inch. So, unless one or both of these two dimensions on the parts are out of spec, the aft end of the hood can get no closer than 0.002 inch to the breech face. For mid-spec parts the gap will be 0.006 inch. Because the hood can never contact the breech face, the barrel is driven into battery by breech face guide block contact with the chamber edges outboard of the hood. [Ref: Blueprints in our Tech Issues section]
For USGI 1911's built to earlier (1928) and slightly different US Army (Springfield Armory) specs, the hood can indeed come into contact with the breechface - but only on some guns. However, for mid-spec parts the gap will be 0.00175 inch. [Ref: Blueprints from TheSight or M1911.com]
Can make no comment about any other 1911 - no idea what (if any) specs are used in their manufacture. That's all propietary information, no doubt.
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to 1970's era US Army (Rock Island Arsenal) specs, the barrel hood can
never contact the breech face.
But it should. The problem with the barrel moving forward from contact between the barrel face and the breechface guides is the extractor knockin' a ding in the right side of the barrel ramp... and even though the print specs suggests that's where the contact is... I've seen very few gun that actually did it unless the hood is far too short. Maybe... one in a hundred. Maybe.
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But it should. ...I've seen very few gun that actually did it unless the
hood is far too short.
Well, just between you, me and the lampost, I think the hood should contact the breech also.
But then you've seen almost infinitely more 1911's than I have while my primary source of 1911 info is the blueprints.
["almost infintely"? That must work out to lots, lots, lots, LOTS, LOTS more]
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That must work out to lots
I've had my hands in a bunch of'em, for sure. Every one that has had contact between the right side of the barrel face and the guide block has suffered some damage from the extractor. Many can be clearanced by taking a little off the extractor nose and the peened area in the barrel... some can't. In about 98% of those that do contact there, the hood length is badly out of spec.
The idea of the hood breaking up if it contacts the breech probably comes from the days of accurizing by welding up and working back barrel hoods to get a nice fit. Lousy porous weld with a too hot flame probably WOULD crack or crumble away it it hit anything with much force.
Seems like a remember some magazine article caution about that. Maybe it was in the old NRA pamphlet on "How to accurize your 1911 at home" or something like that.
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The idea of the hood breaking up if it contacts the breech probably comes
from the days of accurizing by welding up and working back barrel hoods to get
a nice fit.
Very likely. It also may stem from the belief that the barrel recoils and drives the slide.
I heard a guy explaining it to another customer in a gunshop in his version of how the locked breech/recoil operated pistol functions. Said there was a lotta recoil force absorbed by the barrel hood. I tried... but I couldn't help myself. I asked: "How ya figure?"
He explained in depth about the locking lugs, and said that the hood was actually the "Fourth Lug" because it hit the breechface as the barrel recoiled and pushed on the slide... and added, a trifle condescendingly: "Everybody knows that."
I let it go...
Hill, I bet you are right on the weld busting. Man I'm glad I passed through all that stuff. Hopefully never to return to torching, and torchering myself in the process.
I remember torches. Bad JuJu. Tig is better. Not as harsh. Welding and refitting is still a viable option for original, semi-collectible guns that are moderately shootable, but need a little better barrel fit. I have a 1925 refinished, but mechanically in near new condition Commercial Colt Government Model. I plan to tig the hood and refit sometime soon... as soon as I can find A Round Tuit, that is...
I was kinda' surprised while looking through the Jim Clark website that they still use welded hoods in their builds. Tig welded, for sure, but still it was a surprise that any builder would still use such methods in this day of CNC everything. They even have a picture of a barrel hood with a nice neat bead on it, ready for hand fitting. Guess they fit a new barrel if a customer really wants one or if something's beyond fixing with the original. It's kinda' like looking back over thirty years.
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I was kinda' surprised while looking through the Jim Clark website that
they still use welded hoods in their builds.
Not really an issue unless the smith fits the hood to "wedge" the barrel into battery and hold the barrel hard forward against the lugs the way some prefer. As long as there's even a thousandth of an inch clearance between the breechface and the hood with the barrel as far forward as it'll go... there's not a lot of stress on the hood.
Yes, and Amen to what tuner said. Tig is the way. Handy to fix the top of feed ramps especially. You know the ones Tuner, Hill that some guy thought it would feed better by rolling over the top towards the throat to make it even with the bll. Naw, a butcher job. I hate them. I have also fixed butchered beavertail jobs, Tangs were too short etc. Endless value to a steady hand and a Tig.
I found that leaflet but it ended up being for a Star.
I guess I can publish that brochure online so here it is:
PICTURE 404
PICTURE 404
"If the hood touches the breechface, it will eventually set up a stress fracture..."
That probably comes from a basic misunderstanding of the how the gun functions. As noted... Many people are under the mistaken impression that the barrel recoils and drives the slide backward. And, yes. There are manufacturers who don't fully understand how the gun that they build functions. Even Jerry Kuhnhausen... bless his heart and may he rest in peace... refers to the barrel face as a recoil face in one of his illustrations... when it's no such thing. Recoil drives the slide backward while the bullet exerts a hard forward drag on the barrel... trying to separate barrel and slide... not hammer them together.
If a barrel hood stress fractures because of light contact with the slide, the barrel is likely about as brittle as glass.
I used to do this when I welded up the hood, lugs and two small dits on the rear bll locking cuts. It can be done, but I have never welded stainless. So TUNER where are you with the stainless wire?
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Do you guys have an opinion as to tig welding stainless steel barrel hood
on all sides to tighten up a loose fit- can it be done?
Ummmmm, in reading through this thread I'd guess that yes, it can be done.