For a final decking height I have been using the dimensions 0.350 off the top of a 0.200 pin inserted into the slide stop hole, ( basically 0.450 from CL) but last one very tight, had to go to a #1 link. Most of the cs and ss 80% frames seem to have 5 or 10 thou extra for decking.
Is there a slide fitment work sheet or other trick that takes the barrel engagement into consideration prior to decking the frame?
When I did my stealth arms 80%, I had to remove a few thousandths off the top of the frame for the slide to fit. I used a black sharpie to mark the area and pushed it into place which removed the marker. I then used a file to carefully and slowly remove material and finished with some 220 grit lapping compound which gave me a perfect fit. Post up some pictures so we have a better understanding of what you’re trying to accomplish.
So I am talking before I cut the rails, determining where to cut the deck and rails in relation to slide stop or other reference, not fitting the slide after… Not sure a picture will help. The Matrix jig puts it at +/- .450 from the center of the slide stop pin, but like I said last one kinda tight. If I could determine this before decking, I could set the deck and rails [edit talking 2 or 3 thou] higher rather than going to a smaller link
This all depends a bit on what slide you buy and how you cut the bottom lugs. For example, if you use a .195" lug cutter, you’ll have a different result than if you used a .197".
P.S. Needing a very short link could be an indication of too little barrel top lug engagement with the slide. Lots of folks try to get .042" or a bit more.
I measure the barrel down/barrel up and subtract the feeler gauge between the barrel and lugs, got plenty. .050+ The top engagement is slammed tight with a #3 link, slide needs tapping with rubber mallet to go into battery. #2 link slide needs just a little nudge. #1 goes into battery smoothly.
I cut the lugs to match the slide stop pin and link, but do it out of the frame with files.
This isn’t a match barrel or slide so I don’t intend to custom fit the barrel, but like I originally posted, need a way to measure link and slide engagement before I cut the frame next time
@albroswift As discussed above, the idea is to shoot for the spec. Unless you are certain you will never have to replace any parts in your pistol.
Since you mentioned that you had to use a #1 link on the last one I assume you didn’t have to use #1 link on previous builds. So which part or parts was/were out of spec?
@Mosinvirus I assume the Sarco barrel and slide are on the tight side.
So the spec I use is .450 off the CL of the slide stop, and as I am matching the frame to the slide, don’t intend to replace slide/ barrel, I would like to be able to determine this prior to decking. Other option is to put the #3 link in and fit the barrel, but that is .010 to remove between the top of the barrel lugs and the slide. I could see doing the work on a match barrel but not so much on a drop in build.
Anyway, piece is finished.
Just plain awesome!
Understood. Yes, you can stack the parts and measure everything out and know ahead of time what the barrel will want, but I still don’t think that is the way to go.
I believe Jack Weigand explains some measurements when showing how to use his colt barrel fitting fixture. There is also a known amount of link travel past the center line when in lock up. So technically you could measure everything out ahead of time and cut the rails on the frame higher.
However, have you considered the effect of that on other parts in the gun? Disconnector protrusion and amount of its travel down to disconnect when slide cycles for example? If you position the rails higher, you would probably want to position the sear, disco and hammer higher, but then you will also need to position the trigger and sear spring higher…
Also, with a shorter link, have you verified VIS contact?
Thought of that, disconnector length and all. Maybe just stick to spec.
Yes, getting good vis contact. Issue was top of barrel shoved up too tight
Thanks for letting me bounce this off your head.
No reason not to try a little radial? lug / slide fitting, any suggestions for me there?
Yes, unfortunately some parts combinations are just not great, and do get into conflicts.
Can you elaborate on what you are trying to solve?
Just to make a #3 work, really nothing to solve other then that. I have heard that with match barrels some fitting of the lugs to the slide is required, that sort of stuff. Maybe just leave it alone and use the #1.
Well, if you already fitted a #1 link to the barrel and the bottom lug is already shaped for #1 link, you would have to weld up the bottom lug and recut once the reason for the barrel sitting so low is identified.
What I am more interested in is why the barrel is sitting low, or if the link pin hole in the bottom lug is simply placed too low…
Can we see a picture of your bottom lug?
Checked engagement, .042+/-
(Barrel down, .163 barrel up .112 barly get a 0.010 feeler between the barrel and slide when down.)
Checked deck height, .355 off a pin that measures 0.196 so pretty close on that.
As far as welding the lugs, its a Sarco 49 dollar barrel so may just get another one and fit the upper lugs with the #3 link.
Update, ordered another ($49.95) Sarco barrel, good lock up and unlock with #3 link hardly any fitting. I think my inexperience caused me to fit the lower lugs before I realized the first barrel was out of spec, should have played with the upper engagement first.