Barrel Clinic-2

[1911Tuner]

I just had a thought...maybe I oughta call these threads: "Barrel Misfit." :D

Onward...

Having learned my lesson on Pistol #1, and being symbolically spanked for my negligence, he went on to explain that not all pistols are created equal...not even the ones that are within spec...and that even though the first gun would probably be marvelously accurate, it wouldn't be well-suited for anything other than target-grade ammunition...or "Softball" loaded to low pressures and velocities...200-grains at 650 fps...unless I wanted to refit another barrel in a few thousand rounds. I didn't.

He instructed me to fit #2 by the same methods that I had used on #1. I complied, but verified that the vertical lug engagement was good this time. Seems like it had .048 inch...It's been a long time...but it was a lot better than the first one, and Henry said that it passed muster.
O happy day! ...or so I thought. He played me like a cheap fiddle.

Yadda yadda yadda...mumble grumble...Done! I handed it over and he said: "Good job." But the twitch in his eye told me that I hadn't heard the other side just yet, and I waited for what I knew was comin'.

He handed pistol # 2 back to me, grinned, and asked me what was wrong with it. I performed the checks that had failed #1 again... and it looked good. I didn't know. I had again followed his instructions to the letter. He grinned and opened a box containing a set of three adjustable gauges... took the pistol apart, and slipped gauge #1 into the slide. He wrote the numbers down and repeated the process with the next two gauges. Then he measured the distance from the hood face to the front faces of each barrel lug...handed the figures to me...and asked me if anything concerned me about those figures. I studied on it for about 10 minutes, and the problem jumped out at me.

What was wrong? What to do?? Was I cut out for this??? Can I go home now???? Since it was late, I'd have to wait until the following weekend to correct the problems...and it would take Saturday and Sunday.

Diagnosis and correction, please.

Stans...if you nail it on the first reply, I'm keepin' the Rand. :p

Please note:

This saga isn't exactly chronologically correct. I got a little ahead of myself whilst writin' it up on the notepad. Both guns were done one Saturday, but the fix on both wasn't until the following weekend. The man made me fret over it for a whole week. A real sadist...

[1911Tuner]

Awwwww...C'mon now! I gave ya'll the big clews with gauging the slide and measuring the barrel thrust face locations. Kart Easy-Fitters, pay attention.

[gottripletsNC]

ok here's a question cuz I SURE don't know the answer...

after all this fitting, and filing and cutting on the barrel lugs etc. how did the ammo fit in the chamber, did you make the head space to tight and actually shorten the chamber itself?

[SAWBONES]

By your description of the manner in which the defect was demonstrated, I'll guess that only the front face of the front barrel lug was properly matched to its lug recess within the slide, such that it was bearing the bulk of the initial force in recoil, and that the others were slightly too far rearward of the ideal position within their respective lug recesses to offer much support .

[stans]

I'm gonna guess that you the barrel set up so that the slide was bearing on only one of the radial lugs and it probably wasn't lug number one.

[1911Tuner]

ok here's a question cuz I SURE don't know the answer...

after all this fitting, and filing and cutting on the barrel lugs etc. how did the ammo fit in the chamber, did you make the head space to tight and actually shorten the chamber itself?


Sawbones...Almost.

Stans...I'm keepin' the Rand. :p

Gottriplets,

Headspace is defined in two ways, neither of which are determined by the
hood length. The hood can be completely removed, and the headspace
will be unchanged.

Static Headspace is defined as the distance from the breechface to the chamber shoulder and is what it is. It is only changed by the deformation (setback) of the locking lugs as the gun is fired.

Working Headspace is variable, and is determined by the difference between the length of a given cartridge case and the static headspace.

Excessive headspace can be dangrous or only a nuisance. If the chamber is reamed too deep, it only causes erratic ignition and accuracy issues. if it's caused by lug setback, it allows the case to back out of the chamber when the slide moves and the locking lugs are still engaged under pressure, resulting in lost case head support. In the 1911, the case failure usually occurs at the bottom, where the barrel ramp (throat) exposes the head first.

Anyway...Stans has homed in on the problem. One lug bearing the brunt, and it's not the most supported one...that being the first lug. Question is...
How is that corrected? Another clew: Sometimes it can't BE corrected AND
maintain safe headspace because....?

Bottom line: Until you gauge the slide lug thrust face locations and the barrel lug thrust face locations...you don't know what kind of barrel fit that you have. This is the drawback to the Kart Easy-Fit system. It's designed around the assumption that the slide is cut to mid-spec...and sometimes that just ain't the way it goes down. The barrel in question usually allows enough leeway to correct the problem by equalizing at least two lugs and maintain safe headspace...but not in all cases.

Good show, gentlemen!

[gottripletsNC]

told ya I didn't know the answer....

see when it comes to the barrel fit clinic, my expertise is knowing how to ship it to someone who knows how to work on em...

[1911Tuner]

told ya I didn't know the answer....

see when it comes to the barrel fit clinic, my expertise is knowing how to ship it to someone who knows how to work on em...


It matters not, young grasshopper. You have learned and progressed. You are now equipped to spring upon the wannabes
armed with knowledge...and shoot'em down with aplomb.
(Betcha didn't know that an old redneck pistolwrench could talk that fancy.)

Since "Stans the Ringer" has already rung my bell on this second part, I'll go ahead and post the last chapter of this trilogy into madness today.

Note that the "Fit Down" system does work well, and you can usually equalize at least two lugs without getting into headspace problems unless the slide thrust faces are so far outta whack that you don't have enough leeway to work with...but that takes a lot. The 1911 allows a generous headspace tolerance, and lug equalization is a part of why that is. The Kart barrel's chamber depth is held to a minimum while still providing enough, and in mid-spec slides that lock on the first lug, the static headspace usually doesn't exceed .903 inch. If you have to face a lug even as much as .010 inch, you're still at about average for an entry-level production gun...and you'll have a stronger lockup to boot, assuming full depth in the vertical plane, and
with less fore and aft play. Few production guns have more than one lug in the game...and it's only occasionally the first one. The Kart is actually a very good system,and having a go at fittin one will teach you a lot...but it's not the end-all/be-all solution for all guns.

I finally got around to trying the Kart Easy-Fit in two guns this year, and got very good results. Two lugs in one and three in the other, with headspace not exceeding .905 in either. Both are fully up to the task of carry and fairly hard use...and both provided a marked accuracy increase over the stock barrels...but neither one would be a threat in serious Bullseye competition.
A third gun wouldn't work with the system, and I had to resort to a full hard-fit Kart...and I didn't fit for the nth degree of accuracy with that one. Strength, durability, and reliability was my main concern.

Stay tuned for Part 3.