Barrel hits slide in linkdown.


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1911fun
March 14, 2013, 02:08 AM
Hello all, new member here. I have installed a .460 Rowland kit from Clark Custom on a Kimber Stainless II. The kit dropped in o.k. I've shot it a bit and it runs fine. As my interest in working on the pistol has grown I've read many threads here on upper lug engagement, lower lugs, barrel links etc. With more thorough inspection and beginning to learn what to look for, I think I have a problem. I performed a check to see if the barrel stops on the VIS when the gun cycles. Slide .250 back from battery, barrel pushed back firmly, slide stop inserted but hanging vertically. The slide stop does not swing free. Marked the VIS with sharpie, put gun in same condition and gave the muzzle a couple raps with a plastic mallet. The VIS showed contact had been made with the rear of the lower lug. What I stumbled on today (boring day off, why not take guns apart) is that it appears the O.D. of the chamber has been stopping on the I.D. of the slide in link down. The .460 kit barrel's chamber is slightly larger in O.D. than the barrel that came with the gun. Another test with marker confirmed this contact. So to me, rearward movement of the barrel is almost stopped by the VIS but downward movement is being stopped by the I.D. of the slide against the chamber instead of the saddle or bed in the frame. The pin wont swing free in the test because it is in a bind with the link which is under tension because the slide/chamber contact wont let the barrel drop and send the pin around the corner on the lower lugs. Thats how it works out in my head anyway. I assume it is a no-no to remove metal off the chamber. My questions are, has anyone here ever seen this condition? Is it ok to relive the I.D. of the slide a little bit just above the rail groove to allow the barrel to drop down lower? Is there another problem I am missing or a better cure I have not thought of. Thanks in advance for your time and expertise and apologies for any misnaming of parts or technical terms. Like I said before, new guy here.

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rcmodel
March 14, 2013, 12:23 PM
A belt sander is your friend.

Take it off the barrel chamber area until you have proper clearence.

rc

1911fun
March 14, 2013, 10:25 PM
Thanks RC. Still sounds risky to me. How much is safe to take off the chamber?

1911Tuner
March 15, 2013, 06:38 AM
Are you sure that the barrel's vertical drop is being stopped by the slide...or by the frame bed?

mookiie
March 15, 2013, 11:03 AM
Sorry, a little off topic, but does anyone have a link that might explain exactly what you are talking about?

1911Tuner
March 15, 2013, 11:21 AM
No links, Mookie...but I can offer a basic explanation.

When the slide recoils, it grabs the barrel by the upper lugs and drags it backward. Linkdown starts at about .110 inch back, give or take. At .250 inch, linkdown is complete and the barrel is on the frame bed.

During the linkdown phase, the barrel strikes the Vertical Impact Surface in the frame, stopping its rearward travel. At this point, the upper lugs are fully clear of the slide, and the slide continues rearward. At the time that the barrel strikes the VIS, there should be about .003 inch of clearance between the bottom of the barrel and the bed, and the barrel completes the drop under gravity.

If the barrel's rearward movement is stopped by the link...or if the barrel hits the barrel bed before it hits the vertical impact surface, or even at the same time...the link is under tensile stress, and can stretch...break...or it can pull the lower lug off the barrel.

In rare instances due to dimensional problems, the barrel can contact the inside of the slide before it stops against the VIS, with the end result the same as stopping on the link or hitting the frame bed before stopping on the VIS.

1911fun
March 15, 2013, 01:58 PM
Hi everyone. Yes Tuner the barrel is stopping vertical drop on the slide rather than the bed. O.D. of the original barrels chamber is .688", O.D. of the replacement barrels chamber is .695". Using marker to see contact, I unlock the action and push down on the barrel hood. I get two stripes on the inner radius of the slide about .075" above the rail grooves on both sides and no marks on the bed. I'm sure a picture would be worth a thousand words right now but I do not have that capability. Thank you for bearing with me.

mookiie
March 15, 2013, 02:24 PM
1911Turner, thanks for that information, now this thread makes sense too me! Thanks again guys!

1911Tuner
March 15, 2013, 04:21 PM
With only .0035 per side, I think I'd just make straight cuts with a smooth mill file instead of trying to reduce the diameter .007 inch.

I don't see .007 inch keeping the barrel off the frame bed unless there's an issue inside the slide.

Mookie...Glad to help.

1911fun
March 15, 2013, 08:27 PM
I have the barrel fitting nicely now. Thanks everyone.

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