Clark Long Slide w/tuner

I had bought an old Clark Sr Long Slide that had been tuned up a few years ago. It wasn't shot after the tune-up and I'm the second owner. Could someone explain to me how to adjust the tuner that's on the rear sight and the BoMar rib that was installed on the gun during the tune-up? Also could someone explain the reason for the bump on the frame and corresponding notch on the bottom of the barrel? I'm assuming that this bump and notch are an attempt to help aline the barrel in lockup but I'm not sure.

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Thanks


Virgil

The tuners were used to compensate for using stock barrels that were welded up  for fitting for match quality pistol. The upper barrel lugs cannot be welded so the tuner applies pressure to top of the hood to provide close to center firing pin strike and help pistol lock up. A welded barrel can be fit deep into slide lugs but you can end up with a really long link. The bump as you called it on the feed ramp is used by Clark to make more reliable feeding if cartridge.  It does not assist in barrel alignment or lock up. Tuners are not necessary today with modern oversized match barrels. 
Jon

upper lugs may not be weldable ( ??) but other methods have been tried over the years... Can't remember exactly who did it but they would form a shim for the upper lugs and then simply force the barrel into battery. this would form the shim into the lug  and set it in place... Friend had one way back in the late 70s and it never came loose and he shot a lot.

seen upper lugs with  brazed shims back then too.

but as you note it's so much easier to simply buy a Kart and fit it these days

Thanks for the explanation Jon.

I was thinking that the "bump" was just busy work and really doesn't make any difference but wasn't sure. So if I understand it correctly, if I should replace this barrel with a modern match barrel I could loose the tuner and the "bump"  and consider them unnecessary ? If I replaced the barrel I would probably machine the cut-out for the "bump" just so that it's still an original frame from Clark and un-altered. The gun shoots jacketed bullets fine but doesn't like lead at all whether swaged or hard cast. I'm thinking it's because of the sewer like appearance of the inside of the barrel that is full of machining marks. Not at all smooth like a Kart or other modern match barrel.


Virgil

marvel sells a dot rail to replace your tuner rib in the same holes for 40.00

Hmmmm,  my late 70s long slide did not have the bump on the feed ramp... did have the tuner rib,  although I could never see why as the Clark 6" barrel had taller upper lugs.

I've tested it both with and without the tuner and see no real difference?

My Clark uses a welded up Colt barrel and has a tuner but no feed bump.  It shoots great.  I had a Clark 38 Special for years that had the feed bump but no tuner (not needed with that barrel I suppose).  As Jon has pointed out, in lockup the barrel bottoms against the tuner, not the upper lug bottoms.  Hence, with wear or whatever, this can be "tuned".  The tuner bottom is a rocker and the foot can be adjusted up or down by selectively loosening and tightening the two screws.  You can often adjust the tuner so tight the gun will not go into lockup.

I've rebarrelled the Clarks and left the bump. I just mill the barrel to match. 99% of pistols with tuners that were built with stock Colt barrels will have vertical play with barrel if you remove the tuner. As far as shimming goes it gives you less lug lock up and more recoil! The pistol will come out of battery sooner. I recently shot an old Shockey .45. With same load as my normal BE load the recoil was considerably more than my own pistol. I mean night and day difference. I'm not a fan of shimming. I understand why they did it back then, but it's really inferior to a modern barrel.
Jon

Another method used to get better lock-up was to drill and tap holes into the lug slot on the slide. Then set screws were installed and adjusted to get the proper lock-up.
 Not sure what you mean with the bump, are you referring to the felt bump just as the slide is locking-up that happens about 1/4" to 3/8" before completely closing?

Bump is raised portion on feed ramp in photo.

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Jon Eulette wrote:Bump is raised portion on feed ramp in photo.

This is correct and is protruding from the frame barrel bed with a cut-out on the ramp of the barrel to match the "bump or protrusion . On the frame it's probably 3/32 in width and height and maybe 5/32 of an inch long.


Virgil