[gary gruber]

i am having difficulty fitting a new Kart barrel in a new 1911 i am building. i am using an older kart drop in barrel that i have in my Kimber custom as a reference.

here's the problem. the older barrel locks up perfectly in the new slide (a Baer). i have measured all of the critical dimensions of the upper locking lugs between the old and new barrel and everything appears to mike to within a few thou of one another.

the new barrel is a 'gunsmith' fit. this is my first attempt of not using a drop-in, and i am having a very hard time.

i have 100% lock up for both lugs. the issue is firing pin alignment. i can't see more than a small half moon with a piece of brass inserted into the chamber -- which is headspaced properly.

the older barrel aligns perfectly. i have filed quite a bit from the rear most locking lug in an attempt to get the barrel 'up' for the firing pin hole to center, but try as i may, i cannot get it to center. i had to remove quite a bit of material to get even a modest lock up value, and am sure i have probably ruined this brand new barrel in an attempt to get the firing pin hole centered.

what i can't figure out is what i did wrong. i have measured and re-measured both of the lugs on both of the barrels.

i have measured the overal height of the barrel in front of the lugs. i have measured the depth of the lugs. the only major difference i can find is that the older barrel is about 5 thou smaller

behind the first locking lug --measured an inch in front of the beginning of the chamber. aside from this small difference, i cannot account for why i can't get the firing pin hole centered.

it would be a shame to trash the barrel since it is locking up so beautifully.

 

[BBBBill]

...i am using an older kart drop in barrel that i have in my Kimber custom as a reference.
...i have measured all of the critical dimensions of the upper locking lugs between the old and new barrel and everything appears to mike to within a few thou of one another...
...the older barrel aligns perfectly. i have filed quite a bit from the rear most locking lug in an attempt to get the barrel 'up' for the firing pin hole to center, but try as i may, i cannot get it to center...
... the only major difference i can find is that the older barrel is about 5 thou smaller behind the first locking lug ...

I focused on the above parts of your post that I quoted for my comments/questions as these are the things that get my mental gears turning.
1. The other barrel is a drop in and in a different brand of slide although you did state that it fit the Baer slide properly for firing pin centering. What about the other dimensions?
2. A few thousandths is a huge amount when you are fitting a match barrel.
3.What are you using for a fitting bushing? Is the bushing binding?
4. Clarify what you mean by smaller behind the first locking lug. The mental picture is a little fuzzy as to exactly where/what you are measuring.
I'm sure Bob Brown or one of the other resident pros will chime in here with more expert guidance.

 

[gary gruber]

I focused on the above parts of your post that I quoted for my comments/questions as these are the things that get my mental gears turning.
1. The other barrel is a drop in and in a different brand of slide although you did state that it fit the Baer slide properly for firing pin centering. What about the other dimensions?
2. A few thousandths is a huge amount when you are fitting a match barrel.
3.What are you using for a fitting bushing? Is the bushing binding?
4. Clarify what you mean by smaller behind the first locking lug. The mental picture is a little fuzzy as to exactly where/what you are measuring.
I'm sure Bob Brown or one of the other resident pros will chime in here with more expert guidance.

thanks for your help.

i am using a very loose barrel bushing -- one i have specifically oversized for barrel fitting -- no springing or binding. the diameter of the older barrel -- the one that fits, locks up and aligns properly is 5-6 thou greater than the new barrel. i measured this about one half inch behind the first locking lug.

 

[damien]

Have you test fired yet or cut the bottom lug? I think you should be okay, the centered firing pin hole is helpful but not mandatory. It sounds like it is only slightly off center and should reliably ignite. The barrel fit sounds like when you weld up a factory barrel and refit it. The top lugs jammed up all the way into the slide lugs and lockup was controlled by the bottom lug. I've seen a few guns refit this way reliably fire with a very offset primer strike. The 45 large primer is pretty forgiving. In the rare case the firing pin hit is too off center, Clark sells an offset firing pin bushing for the breech face. I think they are the only outfit still refitting good factory barrels. Anyway, getting back to your new barrel, seems a little strange though, since you filed on the rear lug all the way and it still won't center the firing pin. I think you are getting more lockup on the front lug and its keeping the barrel from going all the way up for the rear lug to engage. Use another barrel bushing but one that is loose on both the outer and inner diameter and recheck the lug engagement. Did you coat the lugs with Dychem or Permanent Marker? If you are getting more lockup on the front lug, you're done with fitting the top lugs, don't file on the front lug at all. Just fit the bottom lug like a welded up barrel.

 

[Bodeen]

You need to find out exactly where the contact is at this point. Mark the barrel lugs with dykem or marker, assemble and tap the barrel feet with a softface mallet, disassemble and look for the shiny spots. It is not unusual to have to remove steel from the rear barrel lug at 3 and or 9 o'clock postions.

 

[gary gruber]

You need to find out exactly where the contact is at this point. Mark the barrel lugs with dykem or marker, assemble and tap the barrel feet with a softface mallet, disassemble and look for the shiny spots. It is not unusual to have to remove steel from the rear barrel lug at 3 and or 9 o'clock postions.

i figured it out last night. i just had to remove more metal. a lot more metal. since this was the first full bore 'gunsmith' barrel i had worked with, i was expecting to take a few file strokes here and there. when i measured my lug lockup last night and found it was only at 15 thou -- and 45 thou is the minimum required, i realized i had a long way to go.

i slowly worked the metal off the rear lug recess -- and the front lug recess until i managed to get .046 lockup. i am away from home and don't have any modeling clay to work with. when i get home this weekend i will pack the slide lug recesses with clay and measure the concentricity of my barrel lugs.

i'm real close. i have a nearly centered firing pin hole now, just a very small amount left.

wow is all i can say with regards to the amount of metal i had to remove. somehow i can understand why the barrel only cost me $96. I am wondering if the $200 Wilson barrel is actually a better barrel than the Kart -- or if they have just done more of the fitting work required on the upper lugs.

i now have a good solid lockup on both lugs. after i measure the clay imprint, i will be able to work towards getting 100% lockup. i would like to get as close to 55 thou as i can, but it is feeling very, very solid at 0.046.

thanks for your help and advice. what i have learned from all of this is just how much work is required for a good custom fit of a barrel -- and i haven't gotten to the bottom lugs and link pin yet.

 

[rimfire22]

thanks for your help.

i am using a very loose barrel bushing -- one i have specifically oversized for barrel fitting -- no springing or binding. the diameter of the older barrel -- the one that fits, locks up and aligns properly is 5-6 thou greater than the new barrel. i measured this about one half inch behind the first locking lug.

gary gruber,

I've never tried this project myself but based on your info you might consider looking into the link as well. I know there's different sizes that have an impact on this issue.

rimfire,22

 

[gary gruber]

gary gruber,

I've never tried this project myself but based on your info you might consider looking into the link as well. I know there's different sizes that have an impact on this issue.

rimfire,22

absolutely correct. i expect that i will be using at least a #4 link. that means i will have to be extra careful with the lower lugs. there's plenty of meat on them now -- but i only ordered the .195 cutter from Brownells and i am seriously thinking of going back and getting the .186 cutter as well.