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Discussion Starter #1
Ive just put together a caspian pistol that ive been working on!!! When i put the frame,slide and Barrel together they lock up fine and require a little force to lock up all the way , the pistol is almost impossible to cycle with the bare force of my hand because it locks up and the barrel acts like it does not want to unlock and requires a gentle slap to the front of the slide with the palm of my hand in order to unlock it out of battery.:confused: Ps. The slide to frame fit is not too tight to be of any problem . Any help or advice would be appreciated!
 

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Assuming the barrel was fit correctly to the slide, the tightness you feel is probably caused by the way the barrel is wedged between the upper slide lugs and the slide stop pin.

If you used a Wilson or Brownells lug cutter to cut the bottom lugs of your barrel, you probably used the .195" cutter to do it. However, the slide stop cross pin is probably .200" in diameter. So, you wound up with a .005" interference fit, unless you finished the bottom barrel lugs further by hand after you got done with the lug cutter.

Almost everyone leaves at least a slight bit of interference in this area, but how much is too much? Different for lots of people. I'm sure some people will tell you to just cycle it a bunch until it loosens up. But if it's so tight that it concerns you, you can take a fine, round file (no dremels, please) and remove .001" or so from the barrel lugs, and see what happens. Make sure you cut both sides evenly, you don't want one lug higher than the other. Don't cut rearward, because if you do you'll move the rear of the slide forward in battery.
 

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Wondering . . . before he takes off the .001, would it be a good idea for him to first "smoke up" the front of the feet with a magic marker and cycle the gun to see where metal needs to be removed?

Best,
Jon
 

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New build

I would recommend using smoke or magic marker like Big Jon advises. Also, measure the distance inside the slide from the breech face to the locking lug recess, then measure your barrel from the top lug to the end of the hood extension. If the barrel is just a bit too long at the hood extension, it will not unlock properly.
 

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Also, measure the distance inside the slide from the breech face to the locking lug recess, then measure your barrel from the top lug to the end of the hood extension. If the barrel is just a bit too long at the hood extension, it will not unlock properly.
Ah! Good point, Rich. Sounds like it's the feet, but you're right . . . it might just not be. Better to cover the bases.

Best,
Jon


P.S. - 45man, why don't you start with the top interface and make sure everything's fine there. Then, address the feet. Hopefully that'll solve it, but it may not. If it doesn't, then you may start having to look at link lengths, holes, etc. Correct me if my advice is wrong there, guys.
 

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Wondering . . . before he takes off the .001, would it be a good idea for him to first "smoke up" the front of the feet with a magic marker and cycle the gun to see where metal needs to be removed?

Best,
Jon
In this case, that won't really tell us anything. Whether the bottom lugs are .005" too high, or only .001" too high, any marks on them will still get rubbed off as the barrel goes into battery.

But Jon is right, you probably ought to at least try to verify that this is the problem before removing metal. The best way is to substitute smaller pins for the slide stop pin, and seeing if the lockup becomes easier as the pin diameter decreases. If you have a set of gage pins, which you probably don't, you can simply put the appropriate size gage pin in place of the slide stop, and start working down in diameter until the lockup becomes easy. If you don't have gage pins, you can use the shank end of a drill bit as a substitute. A 3/16" bit is .188". In numbered bit sizes, a #10 bit equals .194", a #9 = .196" (about the same as a lug cutter, and should result in a very easy lockup). A #8 bit is .199", and a #7 =.201" (a touch larger than your slide stop pin, and more than likely won't go into the holes in the frame). If you use this method, please make sure not to put the cutting part of the drill bit in the holes, as you don't want to alter the holes in the frame. If the lockup is much easier with pins smaller than your slide stop pin, then it's a pretty good indication that the lower barrel lugs just need to be dressed until you get the fit you're looking for.

A long hood CAN make the lockup very tight. But the hood is fit first when installing a barrel, and if it were left long, it would be very difficult to get the upper barrel lugs to enter they slide lugs. It would have been pretty obvious during that part of the process, and I'm reasonably confident that 45man#1 would have caught it at that time.

One other thing to check is to make sure that the slide stop pin clears the forward edge of the lower barrel lugs as the barrel links up and down. Most of the time, after cutting the barrel feet, a radius also has to be applied to the forward edge of the lower barrel lugs so that the pin doesn't hang up as the barrel links down.

Art Lundwall
 

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Discussion Starter #7
Thanks to everyone for all the great feedback! im pretty sure its the lower lugs.
 
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