I have an STI slide and frame. The slide and frame are fit together. The barrel hood is fit.
So I cut the lower lugs using a wilson cutter (like I've done on 3 other gun builds) until the thumb safety will engage the slide. I used a 0.195 cutter.
I measured the center-to-center distance between the link pin and the slide stop pin and I got .273. According to what I've read, .273 corresponds to the #2 link.
I tried the #2 link and it is extemely tight and the slide stop pin will only actually go in when the pin is all the way back and it will not rotate around the lug.
So I tried a #3. It works great until I get the gun together and I can not get the slide to go all the way forward. It appears that the barrel is locked up all the way, but the slide is about a 1/4" out of battery.
Got any ideas what is going on?
Sounds like the lug feet on the barrel need a little smidge taken off.
If that's not it, Wilson has some links that are midway between the standard sizes.
Does the barrel/slide go to battery without a link with the slide stop pin installed, this will tell you if the lower legs are the problem. If so, then either adjust the upper barrel lug slots for lock up with your selected link or use a rat tail file and adjust the link.
I like a lot of lock up, even if the FP doesn't center on the primer. The slide should travel 0.10" back before the barrel drops, more if shooting hot loads and should feel a little draggy as the slide stop pin slides across the lower legs. For steel challenge guns (light loads) I adjust the link hole centers by egging the big hole since cyclic reliability is more important than lock up.
With the Roderus CD, Kuhnhausen's books, and countless videos at my side, I've just gone through this. I think I'm starting to understand how the slide, frame, and barrel interact and fit together because I'm starting to think of new ways of doing things. I found Brownell's to be very helpful too:
http://www.brownells.com/.aspx....art_III
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I measured the center-to-center distance between the link pin and the
slide stop pin and I got .273. According to what I've read, .273 corresponds
to the #2 link.
You can do that measurement (difficult to do accurately) but, the bottom line is how does the slide stop fit up against the lower lugs? I suggest this approach:
Install your "best guess" barrel link and link pin onto the barrel. Move the barrel link into the position it'll be in during lock up. (The slide stop hole is adjacent to the lower "blocking" surfaces of the lower lugs where they'll butt up against the slide stop pin, once the slide stop is inserted.) Take your slide stop and slide it through the barrel link pin and orient the slide stop just how it'll be in the frame (slide stop extention lever aft and barrel link centered on the pin section of the slide stop). Now, while holding it in this lockup position, attempt to move the slide stop pin up and down (against the horizontal barrel lug surface and then away from it). Unless the barrel link is too short, it will move a bit, due to clearances in the barrel link holes. Ideally, the slide stop pin should be able to touch the lockup up surface on the barrel lugs, but still have minimal clearance when you pull it down and away from the surface. If it's too tight and stays jamed against the barrel lug surface (feet) or if you can't get inserted into the barrel link, try a longer barrel link. (This assumes you've already cut the barrel lug surface correctly with your cutter.) If the slide stop pin never makes contact with the barrel lug surface, try a shorter barrel link. (Unless you need the longer one for better lockup, of course.) It's possible to increase lockup by installing a longer barrel link but, lockup being adequate, this is the correct barrel link length.
Also, if the slide stop pin is jammed tight against the barrel lug surface, it'll fail the link test described in the Wilson "Ultimate Series" video #1. (I'll try to find time to describe the test in a future post.)
Now, for the next check and adjustment, I'll quote from the Brownell's link, above:
Paint the sides of the lower lug feet with a marker and lay the link on the outside of the lugs using a link pin to hold it in place. With a scribe, rotate the link from its position of full lockup to the unlock position, at least a 45º arc. Then scribe that arc on the sides of the lower lug feet which will show where metal needs to be removed from the bottom of both feet of the barrel lug. This will allow the link to swing freely through its movement.
Finally, to close this post, I think PvtRyan may have had trouble with his barrel lugs dragging during lockup (requiring the lathe work) because he cut his frame slots .105" below the "deck" of his slide. The .105" dimension is for the slide stop "window." (Check the ordinance drawing carefully.) .100" is the nominal value to use for the slots.
This resulted in losing all of the .005" minimum clearance cited in the Brownell's guide, above. (If you cut your rails low, you increase lockup.) The lockup was too tight. Similarly, even if the slide slot is cut the correct level below the deck (it is referenced to the deck), less than nominal deck height (releative to the slide stop pin center) also results in tighter lockup--all else being equal, of course. I faced my deck at nominal minus .002" and my slots at .100" and it's working out quite well with my Fusion barrel.
Don't know if you ever came to the above conclusion, PvtRyan. Perhaps more "What I learned today." :)
Quote (calinb @ April 08 2010,20:57) With the Roderus CD, Kuhnhausen's books, and countless videos at my side, I've just gone through this. I think I'm starting to understand how the slide, frame, and barrel interact and fit together because I'm starting to think of new ways of doing things. I found Brownell's to be very helpful too:
http://www.brownells.com/.aspx....art_III
quote
I measured the center-to-center distance between the link pin and the
slide stop pin and I got .273. According to what I've read, .273 corresponds
to the #2 link.
You can do that measurement (difficult to do accurately) but, the bottom line is how does the slide stop fit up against the lower lugs? I suggest this approach:
Install your "best guess" barrel link and link pin onto the barrel. Move the barrel link into the position it'll be in during lock up. (The slide stop hole is adjacent to the lower "blocking" surfaces of the lower lugs where they'll butt up against the slide stop pin, once the slide stop is inserted.) Take your slide stop and slide it through the barrel link pin and orient the slide stop just how it'll be in the frame (slide stop extention lever aft and barrel link centered on the pin section of the slide stop). Now, while holding it in this lockup position, attempt to move the slide stop pin up and down (against the horizontal barrel lug surface and then away from it). Unless the barrel link is too short, it will move a bit, due to clearances in the barrel link holes. Ideally, the slide stop pin should be able to touch the lockup up surface on the barrel lugs, but still have minimal clearance when you pull it down and away from the surface. If it's too tight and stays jamed against the barrel lug surface (feet) or if you can't get inserted into the barrel link, try a longer barrel link. (This assumes you've already cut the barrel lug surface correctly with your cutter.) If the slide stop pin never makes contact with the barrel lug surface, try a shorter barrel link. (Unless you need the longer one for better lockup, of course.) It's possible to increase lockup by installing a longer barrel link but, lockup being adequate, this is the correct barrel link length.
Also, if the slide stop pin is jammed tight against the barrel lug surface, it'll fail the link test described in the Wilson "Ultimate Series" video #1. (I'll try to find time to describe the test in a future post.)
Now, for the next check and adjustment, I'll quote from the Brownell's link, above:
Paint the sides of the lower lug feet with a marker and lay the link on the outside of the lugs using a link pin to hold it in place. With a scribe, rotate the link from its position of full lockup to the unlock position, at least a 45º arc. Then scribe that arc on the sides of the lower lug feet which will show where metal needs to be removed from the bottom of both feet of the barrel lug. This will allow the link to swing freely through its movement.
Finally, to close this post, I think PvtRyan may have had trouble with his barrel lugs dragging during lockup (requiring the lathe work) because he cut his frame slots .105" below the "deck" of his frame. The .105" dimension is for the slide stop "window." (Check the ordinance drawing carefully.) .100" is the nominal value to use for the slots.
This resulted in losing all of the .005" minimum clearance cited in the Brownell's guide, above. (If you cut your rails low, you increase lockup.) The lockup was too tight. Similarly, even if the frame slots are cut the correct level below the deck (it is referenced to the deck), less than nominal deck height (should be referenced to the slide stop pin center) also results in tighter lockup--all else being equal, of course. I milled my deck at nominal minus .002" and my slots at .100" and it's working out quite well with my Fusion barrel.
I don't know if you ever came to the above conclusion, PvtRyan. Perhaps more "What I learned today." :)
Or maybe I'm just learning today.
I'm not really an authority on the M1911 but it is my understanding that if you are using the barrel lugs to push the barrel into the slide, then the link doesn't have to be a tight fit anywhere. It is only in use when the gun is fired to pull the barrel down out of engagement with the slide. It does not have to be a tight fit when going into battery; the barrel lugs perform that function.
I'm not an authority either and I certainly don't have a great deal of confidence in my assertions. I've not even installed the fire group parts yet but I have spent countless hours studying and thinking about slide and barrel fit, and milling, filing, stoning, etc.
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if you are using the barrel lugs to push the barrel into the slide, then
the link doesn't have to be a tight fit anywhere.
If you cut the barrel lugs long enough to push the barrel into lockup, great, but for them to do the job, the link length must be correct too. Here are the three other possibilities, the way I see things:
1. Link is very short: You won't even be able to get the slide stop pin past both the link and the barrel lugs, because the barrel lug "lock up surfaces," which you carefully custom cut, will cover part of the hole in the link for the slide stop pin.
2. Link is just a little bit short: You'll be able to insert the slide stop pin all the way through the pistol but there won't be enough clearance between the slide stop pin and your custom cut lug "lock up surfaces." The slide stop pin will bind on the lugs as it slides over them when the slide cycles, because the too-short link is pulling the slide stop pin up hard against the lug surfaces. The first video in the AGI "Ultimate 1911" series, "The Reliable Combat .45--Building a Single Stack" describes the "slide stop test" that should detect this problem.
3. Link is just a little bit too long. You might not have problems, but the lugs are no longer pushing the barrel up into lock. Rather, the link is pushing the barrel into lock first. This sort of defeats the purpose of custom cutting the lugs to push the barrel up into lock.
4. The link is very long. Depending on how the locking lugs of the barrel and slide fit together, the lockup can be too strong. This can cause the lugs to drag or it can result in drag from insufficient clearance between the barrel hood and the slide. (Brownell's says you should have at least .005” clearance between the top of the barrel and the slide upper lugs.) The "pencil test" from the AGI video might help here. There also comes a point when a link is so long that barrel position with respect to the slide and/or the frame can become a problem at link-up and/or link-down..
If you select the link length just right, there will be enough clearance for the slide stop pin to glide over the lugs without binding during cycling, yet also not push the barrel into lock up before the lugs can do the job you customized them to do and cam the barrel up into lockup as intended.
Again, please keep in mind that, until two months ago, I didn't even know what a lug cutter is!
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I tried the #2 link and it is extemely tight and the slide stop pin will
only actually go in when the pin is all the way back and it will not rotate
around the lug.
Read the Brownell's page, D. If you measured correctly, #2 is the right link length and you simply need to file and/or stone back the front rounded section of the lugs (not the level section or the "backstop" that stops the motion of the barrel with respect to the slide stop pin) so the slidestop pin can rotate over the front part of the lug.
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So I tried a #3. It works great until I get the gun together and I can
not get the slide to go all the way forward. It appears that the slide is
locked up all the way, but the slide is about a 1/4" out of battery.
It sounds like your barrel is locking up early, which happens before the slide is as far forward as normal, which is consistent with too much link length (though one size long in link length doesn't usually make a huge difference). Check your #2 with the method I describe in my first post. If you need to file some metal off the front of the lugs, as described in the Brownell's guide, it's normal to need to adjust it.