Barrel fitting question for everyone who has fit a barrel

[trotterlg]

How much did you have to grind off or shim up the hinge to get the barrel to fit properly?  Only when fitting a new barrel, not one that had previously been fit hacked up by someone else.  I have a thought in my little pea brain and need some numbers.  Larry

[Smokin Joe]

The last 2 times were .002 and .003.

I used a cheap feeler gauge, annealed it and JB Welded it before grinding.

[Brett]

I lucked out on the first one.  It fit and functioned perfectly without having to do any modifications.
The second one was too tight and would not close on my frame.  About a dozen careful licks to the bearing surface of the underlug with a round file took care of it.  I blackened the radius with a felt tip marker and took a few careful strokes, just enough to evenly remove the black marker.  Then I would wipe it down with gun cleaner to remove any filings and check the fit to my frame.  I repeated this process several times until the gun would lock up dependably with a moderate amount of force.  The key to successful fitting is to go s l o w and check the fit often.       

[Brett]

Oh, just a reminder. You want to make all the modifications to your barrel not your frame.  Any changes to your frame would effect the fit of any barrels currently fit to that frame. 

[trotterlg]

This is my thought:  If you took a 10mm metric sholder bolt 30mm long, offset it .018 inches and then turned it to .375 in the middle where the hinge rides, you could then ream the pin hole in the frame to 10MM and have + or - .009 inch of adjustment for barel fitting without ever having to shim or file a barrel.  Depending on what position you locked in the hinge bolt would give you an infinant range of adjustment for lockup.  Larry

[quickdtoo]

I've used shims from .004" to .012" on unmodified barrels, .0018" and .026" on a couple that had been "modified" since they left H&R. On the factory fitted 45 Colt carbine barrel, I removed about .003"-.004" from the chamber face of the barrel to fit it to its own frame, all excess headspace, it was fitted to the same frame as the .444 accessory barrel.

Tim

[trotterlg]

I have a spare shotgun frame sitting here, I think I may pick up a 10mm drill and a 10mm sholder bolt ahd have a go at it, looks like .009 inch plus or minus would cover most fittings.  Larry

[MSP Ret]

Larry, good idea but I have a question, if you did that as you rotated the bolt to change the distance from the bolt bearing surface to the breech face wouldn't you also be changing the height of the bolt/bearing surface? Wouldn't that change the fit also?....<><....:?

[wtroger]

Larry what I have found is that the cut in the barrel lug is not always (very rarely) straight the last one I fitted need .004 on one side and only .001 on the other. But what I have seen is .004-.005 is what it usually takes

[trotterlg]

It wouuld change the heigth, a maximum of .009 inch, you could choose to either raise or lower the barrel pivot, most of the time it would be by about .005 inches, I doubt this would be a problem.  Larry

[PHATINJUN]

Very interesting Larry please keep us posted and if you could on your progress...pictures if you don't mind. You are a real asset here for handi innovations thanks .Kurt