Tuning a Clark Custom Bomar rear sight on 38 wadcutter

I've seen this topic before on this forum but am trying to understand the tuning technique. Perhaps some of your have seen on the old Clark Customs, two hex screws on the rear sight just behind the ejection port.

I was told by Logan Clark to "turn rear screw until there's some resistance. Rack slide so it’s forward and turn front screw until barrel doesn’t move. Then turn ¼ turn back and it’s tuned."


Sounds pretty straight forward but the slide seems to move whether the front screw is tight or not. I don't see it effecting movement.


The gun seems to shoot quite accurately, at least at 25 yards, whether the sight is tuned or not.


I'm thinking of dispensing with the stock sight and putting a red dot on it. I'd add an adapter on the GI cut on the slide. I don't want to drill on the slide and adulterate it anymore than I have to.

Does it have mini-rib or full length rib? If mini-rib it's non-adjustable (not a tuner). They make full length rails with tuner cutout.
Because you didn't want to drill more holes I'm assuming its the mini-rib.
Jon

Appreciate the response.

It's the mini rib or half rib. It begins at the end of the ejection port. I also have the full ribbed version that runs the length of the slide on a Clark .45. It has exactly the same setup behind the ejection port with the two screws. 

So you're saying it's not a tuner, rather a way to affix the rear sight?

It has no tuner! The barrel hood rest against bottom of the rib. They welded up barrel and fit to the mini-rib. So not adjustable. Here's 2 of my .38's with my own mounts.
Jon

By the way, if you remove mini-rib the barrel will be loose in slide. It is the vertical lockup!
Jon

I guess that's a good reason not to take it off!

Can you send me a pic of the top view and side view of that rib?
joneulette@hotmail.com

It looks different than typical mini-rib.
Jon

You mentioned slide fit being loose.  Is the slide to frame loose without the barrel installed. if so, then that needs it's own attention separate from barrel lockup.

The fit to the frame is fine, with or without the barrel. 

What I meant to say was that I could not discern any difference between the slide's functioning, racking the slide back and forth, whether the screws on the tuner were tightened down, or not. 

The slide seemed to function in the same manner--which seemed fine. It was my impression from Mr. Clark's comments that the barrel wouldn't move if the tuner screw was cinched down. It doesn't seem to matter how tight the screw is set.

Possibly barrel was fit to slide not tuner. What barrel is it; Colt, etc. Loosen rear screw tighten front.
Jon

There's no marking or logo I can make out on the barrel. I did tighten up the front, we'll see what happens. Right now it seems to group pretty well. I can get 1.5" at best or so off the bench at 25 yards, but because there's no ransom rest, with iron sights it's impossible, at least for me see how much better better than that I'd get with a "tuned" gun.

Tuner is really a poor choice of wording. They were made to compensate for stock barrels that were welded up and refit. Tuners are not needed with newer barrels. When I fit new barrels to older guns the tuner is left on but has no function other than looks.
Jon

Thanks Jon, that's interesting to find out. You're saying though that if the site is replaced it will in fact not lockup? I guess that means there's no way then to even put a red dot on it without doing a bunch or work on the gun?

Greetings,

You can remove a "Tuner" rib, or half rib, leaving the "Tuner" in place.

Ever wonder why so many Bo-Mar ribs show up on eBay with the "Tuner" missing?

One of my life long projects is to machine a handful of "Tuners" to replace those that went Walk-About.

Cheers,

Dave

Hi Dave,

Thanks for your comment. I thought the whole rear sight, tuner and all come off in one piece--that it's part of the rear sight. I didn't realize there were two separate components.

Greetings,

From Gil Hebard Guns, Catalog 24, page 30...

Cheers,

Dave

I have 5 mini-ribs that do not have the tuner. But they do stop barrel from going completely into full lock up vertically (not 100% into slide lugs). They center the firing pin strike on the primer. I had forgotten about these Dave because I hadn't seen one in many years. I've seen full ribs cut down to mini-ribs and have done that myself.
Jon

I wish i would of been able to collect all those Hebard catalogs

Greetings Jon,

I have most all of the Hebard catalogs. The Mini-Rib with Tuner came after the Half-Rib that was a hard barrel fit.

Some benefits would be that the Tuner is adjustable for wear while the Half-Rib was not. Also, the Half-Rib required milling a flat on the top of the slide.

I machined a Half-Rib with a Weaver scope mount for a fellow shooter. What a lot of work to get the rib to match the barrel !!! Luckily, my mill repeats fairly well and I was able to "sneak up" on the final fit.

Cheers,

Dave

Hi Jon an Dave, 

Thanks for your advice. The takeaway, as I gather, is that  I can play the tuner and see if it impacts the grouping.

However, I will not be able to add a red dot to this by removing the tuner/sight because the gun will not function properly without it.

That's pretty much all I need to know.

with warm aloha

Rob

Greetings Rob,

There is no "playing" of the Tuner. There is only one correct setting.

Regarding a Red Dot, you could buy a Clark scope mount with the Tuner cutout.

The next can of worms would be to verify the the existing holes of your Mini-Rib line up with the holes in the scope rail. Someone would still have to drill two holes between the ejection port and front of the slide.

You could also compare the hole pattern of your slide with someone that already has a Clark scope rail. Sometimes you get lucky as the holes "might" be in the right place.

Ask around the local shooting club to see if there are any Tool Makers or Precision Machinists that would be willing to help you out.

Cheers,

Dave

Thanks for your patience Dave. I still am a bit unclear about the actual procedure of tuning it, now that I've "de-tuned" it. How does one determine the "correct" setting.

  mahalo

Greetings,

Going from memory and a telephone tutorial from Jack Maple...

Clean the tuner, barrel, everything.

Screw down the front screw of the tuner so the barrel will not return to battery.

Slowly back off the front screw until the barrel moves forward into battery.

Tighten the rear screw until you feel it snug up.

Disassemble the pistol and apply marking dye to the top of the barrel hood (where it contacts the Tuner) and the lower locking lugs.

Assemble the pistol without the recoil spring and cycle it a few times.

Take the pistol apart and examine the wear pattern on the hood and lower lugs. The lower lugs should show burnish marks where the slide stop pin engages.

Fine tune the setup by alternately tightening and loosing the two Tuner screws.

The pistol should lock up without binding and no vertical movement of the barrel.

Once you have mastered the above, tear it all down again. This time you will clean the tapped holes and screws with degreaser and apply some Blue LocTite to the threads.

Reassemble as above.

Take your time. If you have to do it more than once, no worries.

Cheers,

Dave

Aloha Dave,

Thanks very much for your efforts to help me. I can see this is a serious endeavor!

This is by far the most detailed description I've received.  Indeed I will take my time on this one.

mahalo!

Rob

Greetings Rob,

"Aloha?" Are you located in Hawaii?

Ed Masaki is on one of the islands. Might be worth introducing yourself to him. Very talented Pistol Smith. I do not recall what he charges for Free Advice.

Search the forum for "Masaki" and you might find his contact info.

Cheers,

Dave