1911 doesn't lock up all the way, help

[ar15barrels]

Ordered, will do. Going to wait until these get in.

Once you have the gauge pins, you are going to use them as "go" and "no-go" gauges to determine what size pin will let the barrel lock while the next larger will not.
Remove the link from the barrel so it won't affect your measurements.
Start with a 0.180" gauge pin and see if the barrel will lockup.
From there, go bigger if it will lockup or smaller until it finally locks up.
Your goal is to find the largest pin that will still let the barrel lockup and then the next larger pin that will not let the barrel lockup.
We will call the smaller one "go" and the bigger pin "no-go"

Once you know your starting NO-GO dimension, compare that to your actual slide stop pin diameter.
The difference between those two will be how much you need to remove from the underside of the barrel.

As you start cutting, you will keep gauging with larger and larger pins until you are getting the barrel to lockup on 0.001" smaller pin than your slide stop but NOT locking up on your slide stop.
When you get there, then you will want to stone the last bit until you get it to lockup on the slide stop.

As it starts to get close to lockup, you can reinstall the link and start looking at how much the link will trael past 90 degrees.
You want the angle of the cut to be right under 1 degree and once you pass 90 degrees with the link and the slide stop pin should trael around 0.045" to 0.060" beyond 90 degrees.
Do NOT thin out the back of the barrel feet where the slide stop pin rests to try to get the slide and frame to match.
You match up the frame and slide by blending them together after the barrel lockup is all set.
You only install the link to look at slide stop pin travel.
You remove the link before doing any gauging.
At the end, you will try different length links until you find the length that's just long enough to let the barrel lugs go fully into lockup without the link being tight.
The link should be loose while the barrel is locked to the slide stop.
If your link is too short, you will eventually break off the lower feet from the barrel.
The link has nothing to do with lockup.
The link is only there to pull the barrel DOWN and out of the slide as the barrel unlocks.

[Oldmandan]

I don’t see any pics of the barrel hood, what are your clearances on it?

Could be the angle of the pic, but your barrel looks tilted down in pic 3, and out of battery.

[BucDan]

I don't have it on the top of my head, but I wrote them down on my measurement sheet.

[ar15barrels]

So do you see how the slide stop travels behind the link pin by about 0.044"?
There should be about a 1degree angle there to get the barrel into a full tight lockup.
The end of that 0.044" long angle where the slide stop seats against the lugs should have a radius to match your slide stop pin.
Harder than getting the proper geometry there is getting it all square so that BOTH sides of the lug bear evenly on the slide stop.

That's the stuff that will be very hard to file/stone accurately but comes out perfectly when cut in an actual machine with the proper fixturing to set the geometry.

[ar15barrels]

Ordered, will do. Going to wait until these get in.

Did you get the pin set in yet and have a chance to play with them?
Isn't rice paper with cosmoline awesome?

[kendog4570]

...Isn't rice paper with cosmoline awesome?

I have a chicom .251/.500+ set that I have been using for over 15 years and the damn stuff is still on some of them.

[ar15barrels]

I have a chicom .251/.500+ set that I have been using for over 15 years and the damn stuff is still on some of them.

Same here.
I only unwrap the ones I actually need to use.
That happens only occasionally but those unused ones are very well preserved even 15-20 years later.

[BucDan]

I've been caught up with a new work project. Haven't had the chance to sit down and really look into it again. Hopefully this weekend. I do appreciate that every single one is wrapped nicely!

[BucDan]

Barrel hood to slide fitted.
Barrel top lugs to slide fitted.
Barrel bottom "feet" are fitted and slide closes.

I get binding when trying to rack the slide, barrel won't unlock, I have to apply pressure to the barrel by pushing it downward for it to unlock.

Now is this a barrel link situation? Shorter link? I'm using a Wilson #4 currently. I'm going to test the #3 from my other gun. I forgot to order a set.

Measurements all around the lugs and hood look good. I'm iffy on the feet, but it's locking up good, just not unlocking smoothly.

I've been thoroughly enjoying this process.

Part of me thinks I might have to do work on the barrel seating location of the frame because Para ramp frames don't have a strict dimension apparently. If that's the case, I'll stop here and wait until I get my FAL frame so Randall can work 2 guns while I'm there. It's my last SSE 1.0 frame, and it's a full length dust cover that I don't want to screw up.

[BucDan]

I did it! It fits good! Functions good! I gotta thank you guys for the tips and Randall for those measurements. I needed a #3 link to make it work.

It feels so good completing it!

[ar15barrels]

Barrel hood to slide fitted.
Barrel top lugs to slide fitted.
Barrel bottom "feet" are fitted and slide closes.

I get binding when trying to rack the slide, barrel won't unlock, I have to apply pressure to the barrel by pushing it downward for it to unlock.
up good, just not unlocking smoothly.

Is this with a link or without a link?
Because it's normal to have to unlock the barrel with your finger when you don't have a link.
The link is what pulls the barrel out of the slide so that the slide can move freely.
I think that too long of a link may limit the unlocking travel such that the barrel won't settle down on the frame seat where it belongs in order for the slide to clear the barrel's upper locking lugs.

Now is this a barrel link situation? Shorter link? I'm using a Wilson #4 currently. I'm going to test the #3 from my other gun. I forgot to order a set.

Measurements all around the lugs and hood look good. I'm iffy on the feet, but it's locking up good, just not unlocking smoothly.

Always start with a #3 as that's the standard length.

Run the shortest length link that will fit without binding as the barrel goes into full lockup.
You can sharpie or dykem the slide stop pin to see if the link is going tight at lockup or not.
You do not want the link in compression or in tension during lockup.
Compression will show sharpie or dykem wiping off the top of the slide stop while tension will show sharpie or dykem wiping off the bottom of the slide stop.
The slide stop should not have any tension or compression even when the link swings past 6:00 that 0.044" and bears on the lower feet.
There should only be compression on the slide stop pin from the lower barrel feet.
The link should be loose.
With the slide moved back 0.010" from full lockup, the slide stop should be free to pivot or a same-size gauge pin should be free to slide through the link.
By using a gauge pin the same size as your slide stop, you can slide the pin back and forth to feel if the slide stop pin is loaded by the link as the pin would not be free to slide.

[ar15barrels]

I did it! It fits good! Functions good! I gotta thank you guys for the tips and Randall for those measurements. I needed a #3 link to make it work.

It feels so good completing it!

What pin size ended up being your "GO" dimension before you started fitting your lower lug?

[ar15barrels]

I fitted a kart 9mm bull barrel into a para frame today.
After i got the hood cut and the barrel fitting into the front and rear of the slide, the barrel was tight on a 0.170" gauge pin.
The slide stop was 0.199".
This gave me a total cut depth of 0.029" that I needed to get a proper hard fit.
I stopped at 0.020" and re-gauged it and the pin diameters say I was right on track.
I finally stopped at 0.029" and the fit was perfect.
Here is the lower lugs after the final cut:



That's a single cut with a 0.200" diameter endmill done in the Weigand fixture, starting at 0.045" to the right of the link pin hole centerline moving to the link pin centerline at 1 degree angle and then around the corner 59 more degrees and then 0.215" towards the barrel where the endmill just barely touches the bottom of the barrel.

[eaglemike]

I fitted a kart 9mm bull barrel into a para frame today.
After i got the hood cut and the barrel fitting into the front and rear of the slide, the barrel was tight on a 0.170" gauge pin.
The slide stop was 0.199".
This gave me a total cut depth of 0.029" that I needed to get a proper hard fit.
I stopped at 0.020" and re-gauged it and the pin diameters say I was right on track.
I finally stopped at 0.029" and the fit was perfect.
Here is the lower lugs after the final cut:



That's a single cut with a 0.200" diameter endmill done in the Weigand fixture, starting at 0.045" to the right of the link pin hole centerline moving to the link pin centerline at 1 degree angle and then around the corner 59 more degrees and then 0.215" towards the barrel where the endmill just barely touches the bottom of the barrel.

That looks darn nice. It sure makes life better to have nice tools.

[BucDan]

What pin size ended up being your "GO" dimension before you started fitting your lower lug?

To be fair, I started filing before you told me about the gauges. It actually locks up on .184" so I used this number as my GO, .185" felt ok, but it is tight with a little thumb forcing action at .186" and tighter at .187". Slide pin from Wilson Combat is .1975". Mind you I'm using Harbor Freight calipers.

So I assume I already over filed quite a bit, but I can wiggle the gun on lockup and the barrel link seems to have some slack. After doing it the first time here, I'm curious on trying it again on another barrel since your lockup gauge is "much" smaller than my lockup.

That's one fancy setup, I used a round file and filed with finger weight in a diagonal direction, I'm actually looking to polish everything down.