For the sake of brevity, this will be broken into two parts. The first one deals with the barrel striking the vertical impact surface before the lugs have gotten completely clear of the slide's.
This won't include a diagnostic or a tutorial on what to do should the gun fail. This is only to alert you to a possible problem that warrants further investigation by a qualified pistolsmith.
Possible causes are:
VIS located too far forward in the frame. Lower barrel lug located too far rearward or link pinhole mislocation. Link too long. Frame barrel bed badly machined...too high...and ties into Part 2.
Although, with enough practice, you'll be able to visually verify sufficient clearance, for now you'll need a gauge. The best one is a simple wire or "snap gauge" used to check spark plug gap. The one with the L-shaped wires on individual blades that open like a pocketknife is perfect. I haven't had to use one in years, but if memory serves, the smallest one is .016 inch, which is just about ideal. That may vary, depending on the manufacturer.
I suggest removing the recoil system for this to make the gun easier to manipulate.
It entails pulling the slide .250 inch out of battery, which would involve a vise and a dial indicator...but there's a workaround. Because you;'re testing how far the link (or cam) takes the barrel, it must be done vertically instead of horizontally, where gravity can give a false read.
Press the muzzle straight down on a tabletop until it hits a hard stop and hold it firmly. Lay the gauge on top of the barrel as well centered as you can and slip it between the top of the barrel and the underside of the first slide lug. That gap should be a minimum of .015 inch. Though hand-built, closely fitted pistols can get by with a little less, this is a one size fits all for any ordnance spec pistol.
If the gauge will enter the gap with a little resistance, you're golden. If not, the gun hasn't automatically failed the test. This only shows that there may be a problem that warrants further attention from someone who has the knowledge and equipment to make a more exact determination.
This test can be applied to any pistol that operates with the Colt-Browning tilting barrel locking system, whether or not it has a linked barrel. The barrel drop timing requirements are the same.
FYI, I've only seen a small handful of factory built pistols fail this test. The early Thompson Auto Ordnance guns were notorious for it, along with a few Norincos. In all but a very few, the location of the lower barrel lug was at fault. So, the chances that a given pistol will fail it are pretty slim.
This won't include a diagnostic or a tutorial on what to do should the gun fail. This is only to alert you to a possible problem that warrants further investigation by a qualified pistolsmith.
Possible causes are:
VIS located too far forward in the frame. Lower barrel lug located too far rearward or link pinhole mislocation. Link too long. Frame barrel bed badly machined...too high...and ties into Part 2.
Although, with enough practice, you'll be able to visually verify sufficient clearance, for now you'll need a gauge. The best one is a simple wire or "snap gauge" used to check spark plug gap. The one with the L-shaped wires on individual blades that open like a pocketknife is perfect. I haven't had to use one in years, but if memory serves, the smallest one is .016 inch, which is just about ideal. That may vary, depending on the manufacturer.
I suggest removing the recoil system for this to make the gun easier to manipulate.
It entails pulling the slide .250 inch out of battery, which would involve a vise and a dial indicator...but there's a workaround. Because you;'re testing how far the link (or cam) takes the barrel, it must be done vertically instead of horizontally, where gravity can give a false read.
Press the muzzle straight down on a tabletop until it hits a hard stop and hold it firmly. Lay the gauge on top of the barrel as well centered as you can and slip it between the top of the barrel and the underside of the first slide lug. That gap should be a minimum of .015 inch. Though hand-built, closely fitted pistols can get by with a little less, this is a one size fits all for any ordnance spec pistol.
If the gauge will enter the gap with a little resistance, you're golden. If not, the gun hasn't automatically failed the test. This only shows that there may be a problem that warrants further attention from someone who has the knowledge and equipment to make a more exact determination.
This test can be applied to any pistol that operates with the Colt-Browning tilting barrel locking system, whether or not it has a linked barrel. The barrel drop timing requirements are the same.
FYI, I've only seen a small handful of factory built pistols fail this test. The early Thompson Auto Ordnance guns were notorious for it, along with a few Norincos. In all but a very few, the location of the lower barrel lug was at fault. So, the chances that a given pistol will fail it are pretty slim.
Last edited: