Requesting assistance with problem of reattaching Bomar extended rib with accuracy tuner

In 1986 Joe Chambers (C&C Customs, Seymour, Tenn.-now deceased) put an extended Bo-Mar extended rib with tuner, along with a National Match barrel, accuracy andtrigger job) on my Series 70 Colt 1911. Due to unfortunate circumstances I was never able to shoot the Bullseye game but have kept the pistol all these years. I decided to sell the pistol, so in preparation I removed the rib and tuner to clean the pistol. Now when I try to reinstall the rib (6 screws) the slide becomes “bound up” and locked in place. It seems the tuner is binding the chamber end of the barrel, but also the two front screws in alone also appear to bind the barrel. Has anyone experienced this and have some direction/help  you could offer? Thanks in advance for any help you could provide.

Sorry-5 screws

Check to see if the screws are in the proper location. The screws foreword of the ejection port are usually a bit shorter than the ones back near the firing pin.

You may have a longer screw in the wrong position.

That, and do the tuner screws last

I second DA/SA. You should have indexed what screw went where.  Try and try again until all good, then index and loctite them.  ANY screw protrusion in the slide has a chance of binding up, even if you think it is very minor.

OP,

Did you remove the tuner and the two screws that attach it?  If so, it will have to be adjusted to press on the hood by an appropriate amount.  It rocks back and forth  - too much pressure on the hood and the gun won't go properly into battery.  Too little, and the tuner does nothing.  I turn the front screw to provide the proper pressure on the hood in lock-up, then tighten the rear screw to hold the tuner in position.  Of course, be sure to use the correct screws so they don't extend too far and bind.  Hope that helps.

The tuner is used to "tune" the lockup.  It pivots like a seesaw, and it is entirely possible to set it so the gun will not go into lockup.  You need to re-tune it by loosening the front tuner screw and tightening the rear tuner screw until it will freely lock up.  Then sneak up on a proper lockup by gradually loosening the rear and tightening the front until it just barely goes into lockup.

Thanks to all who replied. Just got back in town and following the
recommendations was have all screws in place without binding the action. Now have to “retune” with Sharkdoctor and Dr. Don comments in mind. I must be honest to state that I do not fully understand the purpose or effect of the tuner in relation to a proper lockup. Do these maneuvers have direct or indirect effects on accuracy?

Greetings,

The forward "claw" of the tuner contacts the hood of the barrel. By adjusting the "tuner" up and down, the clearance between the slide stop pin, lower barrel lugs, and "tuner" become zero movement to allow consistent lockup.

Cheers,

Dave

fc60 wrote:Greetings,

The forward "claw" of the tuner contacts the hood of the barrel. By adjusting the "tuner" up and down, the clearance between the slide stop pin, lower barrel lugs, and "tuner" become zero movement to allow consistent lockup.

Cheers,

Dave

 Dave, does that mean the the upper barrel lugs don't lock into the slide lugs anymore? Does the barrel then contact the slide by the hood and push the slide back then the link pulls the barrel down? Kind of a unique system to get a pistol accurate again. Wouldn't it be cheaper to weld up the lower barrel lugs and re-cut them to force the barrel into the upper lugs.
 Stan

The front to back tolerance is still in play between the upper lugs, hood and slide.  The tuner pushes the barrel downward against the slide stop pin, which keeps the slide lugs from reaching the depth of the upper barrel lugs.  In a fully fit barrel the recesses of the top barrel lugs do this, but if those recesses are too deep in the barrel, rather than adding material or getting a new barrel, a tuner can be used to adjust the fit.  The tuner also allows further adjustment for wear, without having to replace the barrel.

I have found the tuner on my Curtis built gun to be very finicky if I don't keep that area clean.  It will start to raise the long line shots.  If I still don't pay attention, it will eventually lock the gun closed.

In theory, the tuner will allow the owner to adjust the lockup of the gun, without going to a gunsmith.  In practice the owner needs to learn what that lockup should really be. Just removing the play and creating a solid lockup isn't sufficient for optimum accuracy, although it will make a big difference for a loose gun.  Correct torque may still need to be found through testing, if one wants the tightest groups.

Ed Hall wrote:
 I have found the tuner on my Curtis built gun to be very finicky if I don't keep that area clean.  It will start to raise the long line shots.  If I still don't pay attention, it will eventually lock the gun closed.

 In theory, the tuner will allow the owner to adjust the lockup of the gun, without going to a gunsmith.  In practice the owner needs to learn what that lockup should really be. Just removing the play and creating a solid lockup isn't sufficient for optimum accuracy, although it will make a big difference for a loose gun.  Correct torque may still need to be found through testing, if one wants the tightest groups.

 Ed, I didn't know other gun makers used the tuner, I always thought it was the Jim Clark guns that used it. I do have a Clark Heavy Slide and now am interested in using the tuner to reduce recoil, like locking the upper lugs tighter. I have a feeling there's just so much that can be done with a tuner.
 I think I should have started a new post .
Stan

A big thanks to all who have responded to my request for help as well as providing detailed information on the purpose , function, and adjustment of the tuner. As a non gunsmith user I have learned a lot about my Bullseye 1911 Colt. By any chance would anyone know of an instructional aid ( perhaps even a video of some type) that demonstrates how all these components work together when the pistol is fired? Thanks again for all the help.

chopper wrote: Ed, I didn't know other gun makers used the tuner, I always thought it was the Jim Clark guns that used it. I do have a Clark Heavy Slide and now am interested in using the tuner to reduce recoil, like locking the upper lugs tighter. I have a feeling there's just so much that can be done with a tuner.
 I think I should have started a new post .
Stan

Hey Stan,

I'm not 100% positive my Curtis gun came from him with the tuner, but was told it did.  I got it second hand.  The tuner doesn't lock the upper lugs tighter.  (I'm not sure if that's what you meant.) Instead of tightening the mating of the upper lugs barrel/slide fit, it transfers the tightness to the tuner/barrel.  In a fully fit barrel example, the barrel is vertically locked between the upper lugs/slide and the lower lugs/stop pin.  With the tuner, the barrel is locked between the tuner and the lower lugs.  I don't see any recoil reduction from this.

To add to all of this, there is a relationship of many surfaces to a properly fit barrel, many of which cannot be addressed with the tuner.  These things include, but are not limited to:

- hood length
- hood width
- hood arc in relation to the lower lug flats
- fit of the upper locking lugs (only a portion of this fit is addressed by the tuner)
- positioning and radius of the rear feet of the lower lugs
- squareness and positioning of the slide stop pin holes in the frame

And to top that all off, when everything is fully locked into battery, the link should not be under any tension.  It should not be involved in the lockup - only in the unlocking.  And, if its timing is off, wear can result.

Also, once the tuner is properly set it is a good idea not to take it off.  You can clean it without removing it.  You can even take the rib off without removing it.  I have a Clark wadgun with tuner built for me in 1983, and the tuner has never been off of it.  Still shoots 2-2 1/2" at 50yds.

Ed, thank you much for a great explanation on these. I now understand how they could shoot high if adjust a little tight. Good info.
 Stan