Barrel Lug Fitting Dimensions (for oversize match barrels)

[Jediwarrior]

Hello.

I would like to share 15+ years of pistolsmithing experience.

Posted is a pic of the barrel lug dimensions that I came up with over the years. Note that this is similar to the Ed Brown dimensions.

Point A: The barrel does NOT touch the slide stop at this point, where the barrel is in the unlocked position.The link protrudes by 0.003 in. This will prevent ugly flat spots on both barrel and slide stop.

Point B: The slide stop makes contact about 0.025 in. ahead of point C.

Point C: The start of the 0.080 in. flat. This is 0.020 in. forward of the link pin hole centerline.

Point D: The end of the 0.080 in. flat.

The second pic shows the shiny flat spot on the bottom.

Comments are welcome.

[Jediwarrior]

More pictures.

[bonglee0507]

Is this better than jerry kuhnhausen?

Sent from my iPhone 5s using Tapatalk 2

[Jediwarrior]

Hello Bong,

Well, as the Jedimaster Brian Enos himself said barrel fitting is a bit of art and a bit of science.

My best description of Jerry's style of fitting the lower lug is "old school". During that time, they probably believed the longer the flat, the better for accuracy. Looking at the picture's in his first volume, the flat is about 0.250 in. long, and he overcuts the vertical stop point of the slide stop. Also, there is a sharp corner in the front, and he says to elongate the link hole slightly to allow the slide stop pin swing by.

The lug will also contact the slide stop pin at point A, which will cause peening and metal displacement which will eventually cause binding.

The biggest problem of overcutting the lug where the slide stop pin stops is that the link hole will have to be elongated, just like for the sharp corner in the front. This could cause timing problems which will cause premature wear on the upper locking lugs.

I have Ed Brown's manual and I read Schuemann's barrel fitting instructions. I believe in their principles of barrel fitting coz I know they work and will last a long time. I have NOT done anything like Jerry's instructions; and based on experience, his technique will cause more problems in the long run.

Edited December 2, 2013 by Jediwarrior

[bonglee0507]

so you installed my barrel based on schuemann/ed brown's instruction?

[ltdmstr]

Aren't those dimensions going to change depending on the link you use and fit of the slide, frame, barrel, etc.? Seems like you're taking a manufacturing approach and cutting everything the same instead of fitting to a particular combination of parts.

[Jediwarrior]

Hi Bong,

Yes, I did fit your barrel to Ed Brown and Schuemann instruction. The link I used was a Wilson #3.

[Jediwarrior]

Hi ltdmstr,

No, these dimensions I suggested will work for any link size that you use.

Although, I have never used a Wilson link #1 for any of my builds. I tell my staff that it would be better to err on having the barrel set too high and have to use a longer link, than to have it set too low. The high and low setting refers to the alignment of the firing pin hole to the center of the chamber/bore. Of course, we always strive to have perfect alignment.

That is why I have never used a #1 link.

[ltdmstr]

Aren't the A-B-C dimensions going to change depending on which link you use?

[Jediwarrior]

I see what you mean. A short link (Wilson #1) will have slightly different dimensions.

Point A will always have a clearance. Ideal minimum is 0.005 in. Material removed here will be a lot for #1 link.

Point B and C could move closer to the vertical centerline.

So length of flat (from point C to D) could be shorter to about 0.070 in.

I haven't fitted a barrel that used a #1 link, and I avoid this by setting the barrel higher so I could use a #2 link.

[ltdmstr]

The dimensions will vary with other links as well, not just a number one. Btw, over the years I'd say about 70% of barrels I've installed have used a number three link and most of the others used a number four. I have used a couple of twos and fives, but never a number one.

[Jediwarrior]

I would say 70% of my builds are #3 and #4.

20% are #5

2% are #2

8% are greater the #5. Ed Brown used to sell an extra long link that would be an equivalent to a Wilson # 6.

[bonglee0507]

I would say 70% of my builds are #3 and #4.

20% are #5

2% are #2

8% are greater the #5. Ed Brown used to sell an extra long link that would be an equivalent to a Wilson # 6.

did the slide overhung at the back?

[Jediwarrior]

Hi Bong,

Yes, about 99% of my builds, the slide will overhang at the back when fitting oversize match barrels such as KKM, Schuemann, Bar-Sto and others.

Overhang is usually about 0.050 in.

Very rare do I get a good match at the back, and it was probably due to the oversize specs on the frame.

I file down the back together with the extractor following closely the original contour.

That is why it is better to fit the barrel first, then machine the slide for the rear sight.

[kl7883]

Hello.

I would like to share 15+ years of pistolsmithing experience.

Posted is a pic of the barrel lug dimensions that I came up with over the years. Note that this is similar to the Ed Brown dimensions.

Point A: The barrel does NOT touch the slide stop at this point, where the barrel is in the unlocked position.The link protrudes by 0.003 in. This will prevent ugly flat spots on both barrel and slide stop.

Point B: The slide stop makes contact about 0.025 in. ahead of point C.

Point C: The start of the 0.080 in. flat. This is 0.020 in. forward of the link pin hole centerline.

Point D: The end of the 0.080 in. flat.

The second pic shows the shiny flat spot on the bottom.

Comments are welcome.

very intresting,thanks for sharing! just a question..........but would this drawing be accurate for a officer or commander barrel lugs as well?

[Jediwarrior]

Yes, it would.

Although at point A, there will be a huge clearance as the bottom lugs of the Commander and Officer's barrel are shortened at the front.

And, you might use a link #5 or greater for the Officer's.

[kl7883]

thank you for your response

[walnutty]

Thanks for the great pics and post. Makes barrel fitting more understandable by amateurs like me. I've been learning how to ream chambers, fit slide stops, thumb safeties, trigger groups, barrel bushings, dovetail sights, extractors, ejectors in the last couple of years. Barrel fitting is still one of those things I'm afraid to tackle.

Maybe one of these days. Info like this answers most of the question marks that I have.

May I ask what kind of lug cutter you use?

Edited December 31, 2013 by walnutty

[Jediwarrior]

Tom Wilson from Brownells.

I did see another brand where the cutting surfaces were continuous, unlike the Tom Wilson which is serrated. This newer brand gave a much smoother finish than the Wilson.

Another trick I do is to apply tape on the locking groove on the barrel (where it contacts the slide) if I use a slide stop with a pin diameter of 0.200 in. Since the cutter dia. is only 0.196 to 0.195, the tape makes up for the difference, and fitting is much faster as I remove less material on the lug by hand.

[kl7883]

Tom Wilson from Brownells.

I did see another brand where the cutting surfaces were continuous, unlike the Tom Wilson which is serrated. This newer brand gave a much smoother finish than the Wilson.

Another trick I do is to apply tape on the locking groove on the barrel (where it contacts the slide) if I use a slide stop with a pin diameter of 0.200 in. Since the cutter dia. is only 0.196 to 0.195, the tape makes up for the difference, and fitting is much faster as I remove less material on the lug by hand.

what kind of tape do you use? like a regular scotch tape?

[ltdmstr]

why not use a 5mm end mill? measures .197".

[stardust tommy]

used the cutters from Chambers Custom, they are great and verry sharp! verry easy to overcut the legs !

I

[Jediwarrior]

Hi ltdmstr, I use masking tape, cut into strips. Thickness is 0.002 in., but it does compress, so depending on the build, I sometimes use 2 strips.

Of course, you remove them for the final hand fitting.

Hi Tommy, thanks for sharing! I may buy these to replace what I have. Anything that speeds up quality work is definitely appreciated.

[Jediwarrior]

Hello ltdmstr, regarding the 5mm end mill, how will you support it at the other end once you insert it in the frame?

The $300+ Weigand barrel fitting fixture uses one, but I prefer to do it the old way.

[ltdmstr]

Jedi,

I've used the WIlson cutter as well as standard end mill with the barrel clamped in blocks. Now I use the Weigand fixture. It's not cheap. But for someone who does this on a regular basis, it's a good investment.