Ruger Bisely Blackhawk Line Bore Build

[was1911]

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[dougader]

Lee has posted a few builds here. I'm not sure if they would fall in the same exact build you are asking about.

I think the "Seyfried" build would be the closest:

www.singleactions.com/SeyfriedsBuffaloSeville.html

[cmh]

I think and I emphasize the word "think" alot if not most of these cylinder conversions are probably line bored........... they sure seem to shoot that way

[Paden]

I believe line boring is pretty much standard operating procedure for guys doing custom builds/conversions, no?

[steve]

I think Lee does it a bit different than lineboring. If I remember right, Lee indexes the clyinder and center punches a mark as opposed to drilling the pilot hole with the cylinder still in the frame..........if that makes any sense?? I would love to see a step by step line bore build or any kind of gunsmithing for that matter!!! I love those kind of threads!!

[Lee Martin]

You're correct Steve. We used to do traditional line-boring but switched to line-indexing in the late 90's. There are advantages with the latter but it would take paragraphs to explain. Eventually I may do an article comparing both methodologies.

I will say this....we check bore-to-barrel alignment on every hole we cut and our process is deadly accurate. 0.0000" - 0.0005" isn't uncommon.

-Lee
www.singleactions.com
"Building carpal tunnel one round at a time"

[cmh]

Darn............. I knew what line boring was but line indexing........... I "THINK" I am gonna read that article

[dougader]

That's what I was thinking, too. I tried to search for an email where you discussed it before... even read the whole 44 Special conversion thread at Ruger forum looking for it, lol.... but there was just a couple words there...

[Lee Martin]

Until I do a compare-and-contrast article on the two let me provide more on our process. Years ago we started with common line-boring and it worked fine. It yields excellent alignment and is a great marketing tool (folks love buzzwords and few top "line-bored"). Until you actually do it though it's hard to understand the benefits and limitations. Yes, you lock the cylinder in the frame with a jig so it doesn't move. Yes, you drill through a frame mounted spud and it starts the pilot hole ("starts" being the key word). Outside of the jig however the cylinder still experiences a degree of "miss". An oversized matched-to-frame bolt cannot eliminate all lateral movement. They remove perceivable play but it's still there albeit it small (incidentally a little play can be a good thing). The same holds for basepins. But once that pilot hole is drilled you have to revert to what I call line-indexing. Or put another way you're at the mercy of centering devices.

We indicate the bore centerlines off the frame as well. To that end our starting point is the same as line-boring. The difference is we prefer to re-indicate that axis using a centering gauge. For those not familiar with the instrument, the high-end versions are accurate to 0.0001" (yep, that's one ten-thousandth). The initial hole is then drilled front to back. With line-boring you only drill half way, or a little there past, and remove the cylinder from the gun. That pilot then has to be re-indicated to complete the bore (a co-axial centering gauge accomplishes this). The next pass on each hole is re-indicated, drilled, and so goes the process. Chambering involves flipping the cylinder, indicating to the bore, and chambering.







The machine's rigidity is also critical. We use a large 3-jaw Hartford Super Space on a Bridgeport. This greatly reduces vibration during the cut. And while Hartford spacers are accurate to seconds of a degree we still use axial centering devices on every pass. Moving the head 60 degrees from the prior index isn't good enough.

There's a lot at play here and hopefully I can document it all one day. Until that time I'll part with this. The methods I've outlined increase accuracy potential, they don't guarantee it. I've seen quite a few factory revolvers with 0.005" or more run-out that print like a demon. Conversely I've heard of line-bored guns that didn't live-up to the marketing. And if the other key variables are amiss it's a complete crapshoot (forcing cone, throats, barrel spec and concentricity, bullet quality, and most important of all the shooter).

-Lee
www.singleactions.com
"Building carpal tunnel one round at a time"

[cmh]

Hello Lee, thanks for taking the time to type all that out. It makes alot of sense and is easy to see why the tolerances would be so much closer............ your removing the variables Regards Sir

[contender]

Excellent info here. Truly good machine work by those who understand machining.

[bradshaw]

Except for cowhide belts spinning from ceiling shafts to power the machine tools, Sam Colt could have walked into the Dan Wesson factory and felt right to home. Continues to amaze me how Colt, Smith & Wesson, Sharps, Winchester, Singer with his sewing machine, etc., produced such brilliant work in the 1800s. Rather doubt the near-ZERO chamber offset of Dan Wesson and many S&W revolvers was achieved with line-boring----and swing-out cylinders, no less. When S&W set back the barrel on a M-19 for me, they replaced the cylinder. Chamber-to-bore offset averaged .002-inch. Among the intricacies of the dead-simple revolver, the chamber in line with the barrel is positioned by the notch on the other side of the cylinder.

Guys like Lee Martin senior and junior properly carry alignment to an extreme, with predictable results.
David Bradshaw

[cj3a]

Was1911 please do. Your last post was excellent