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Old April 29, 2021, 11:38 AM   #1
45flaco
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Convert Para LDA frame casting to single action

Hey guys. Going to pick up one of the LDA frame castings from Sarco.
Mainly as machining practice, but I do want to end up with a functional 1911.
Obviously I don't want the weird proprietary swivel trigger.
Looking at the castings, they seem to be pretty similar other than width to a real 1911 frame casting, which Ive finished before.

Assuming Id just drill and ream the holes in the standard SA locations, do the finish milling and filing, cut new trigger slot, weld up old one, use standard parts except the widebody specific trigger and mag release?
Anything else I'm forgetting?

And before someone says "just buy a gun", I'm doing this as practice. I like making things.
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Old April 29, 2021, 01:29 PM   #2
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I have often wondered how difficult this would be. I think with a decent milling machine it should be easy -- but I don't have a milling machine.

The LDAs don't have a disconnector, IIRC, so you will also have to drill that out. And I believe you'll also have to machine the trigger track. Do you have a set of blueprints to locate the holes and the trigger slot? The SA Paras take all standard fire control parts (except for the double-wide trigger bow and the magazine catch), so standard blueprints will get you most of what you need.

Please post either progress reports or an after action report. I'd be very interested to see how it turns out.
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Old April 29, 2021, 04:45 PM   #3
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It's been a couple of years since I've handled a LDA, but this doesn't sound like a project I would take on (and I'm a gunsmith by trade!). Filling the trigger pivot recess just sounds like a pain, and cutting out a trigger and trigger bar channel sounds very ambitious to me. And I have the machinery to do it if I were to choose to! Filling in the trigger recess with weld will warp the frame and require straightening, filling it with a pinned block will look hokey. You're only saving $30 for the LDA frame over a standard frame, so I say spend the money and save yourself the headaches. My advice would be to buy a Para style single action hi-cap frame (I don't care whose). I have built several hi-cap 1911s (couple of Para frames, a Caspian frame, RIA frame, Springfield frame), and while they are fun, they are very heavy loaded and no fun to carry. My Para P12 is one of my favorites, it's compact but still heavy. Don't get me wrong, I understand you want a cool project, just I would start somewhere other than a LDA frame unless you are going to build a LDA.

My last hi-cap 1911 started out as a semi-finished Springfield hi-cap single-action frame (I don't recommend this one, it's not standard Para format). I picked up the frame in trade, a slide on eBay, a ramped barrel in trade, fire control parts were take-off stuff from customers' guns, got Novak sights, bought the small parts here and there, bought a couple of purple-heart wood slabs from a knife-making supplier, you know the runaround. Took about a year, and when I finally got all the parts collected I started assembling the gun, fit the parts, mill the slide for sights, make and checker the grips, and test the whole thing (feeding, trigger, barrel lockup, feeding, firing, etc), finish it, all before you ever get to go out and show it off. That's a lot of work! I would almost say buy a factory hi-cap pistol and build it up to your own specs, but you want a project. Just don't overcomplicate it.
Quote:
LDAs don't have a disconnector, IIRC
They do, it's part of the trigger group, not a frame-mounted part.
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Old April 29, 2021, 05:25 PM   #4
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Quote:
Originally Posted by Scorch
Quote:
LDAs don't have a disconnector, IIRC
They do, it's part of the trigger group, not a frame-mounted part.
Correct. That's what I meant, but I tried to keep it short. I guess I overachieved.

And if using a Para slide -- the LDA slides don't have the recess for the disconnector to rise up into. That's a fairly easy fix -- but it requires making a cut.
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Old April 30, 2021, 01:04 PM   #5
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My problem was finding a steel Single action, double stack frame. All the single actions I saw were either aluminum, which I dont mess with, or single stack.
Figure if nothing else, its a learning experience.
For the trigger puvot recess, I was actually going to just put a piece of steel in there, tack it at opposite corners, let cool, do the remaining corners, file/machine as necessary. Ive patched a fair amount of things, so Im not super worried about that part.
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Old April 30, 2021, 01:07 PM   #6
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I have all the equipment to finish a standard 1911 frame, should still jave the blueprints somewhere. The obly part I'm not prepared for is the interior work, for the trigger bar channel. I cannot find a blueprint that gives it's location in reference to the top deck.
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Old April 30, 2021, 01:09 PM   #7
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Also, I'm not sure what to use to cut that. Probably some sort of long woodruff cutter.
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Old April 30, 2021, 01:27 PM   #8
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Aren't virtually all of the frame dimensions relative to the slide stop pin hole?
I think all dimensions are in Vol. II of the Kuhnhausen sop manual.
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Old April 30, 2021, 01:31 PM   #9
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Quote:
Originally Posted by 45flaco
For the trigger puvot recess, I was actually going to just put a piece of steel in there, tack it at opposite corners, let cool, do the remaining corners, file/machine as necessary. Ive patched a fair amount of things, so Im not super worried about that part.
Is it necessary to fill the pivot recess at all? Or couldn't you fill it with J-B Weld, and not have to use any heat?

Quote:
I have all the equipment to finish a standard 1911 frame, should still jave the blueprints somewhere. The obly part I'm not prepared for is the interior work, for the trigger bar channel. I cannot find a blueprint that gives it's location in reference to the top deck.
Send me a PM with your e-mail address and I'll send you a print.
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Old April 30, 2021, 01:58 PM   #10
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Quote:
Originally Posted by Aguila Blanca View Post
Is it necessary to fill the pivot recess at all? Or couldn't you fill it with J-B Weld, and not have to use any heat?


Send me a PM with your e-mail address and I'll send you a print.
So I dont think its actually necessary to fill that gap. With where it is, I dont think anything will get in there. And even if it does, I dont see it mattering much. I was just figuring on doing it as part of the machining and welding practice.
I dont actually have like super high expectations for this project, I just like having a few projects lying around to work on when I have free time.
But I'll give the JB weld a try. If it works, nothing more needed. If it doesnt, I'll go through with the weld.
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Old April 30, 2021, 02:04 PM   #11
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I know JB weld contains small amounts of steel, can it be blued?
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Old April 30, 2021, 07:52 PM   #12
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Quote:
Originally Posted by 45flaco
I know JB weld contains small amounts of steel, can it be blued?
I doubt it. But it's going to be mostly (or all) hidden once the trigger is installed, so nobody but you will even know.

I'll have to drag out my P12.45 and take a look at how big that aperture is and exactly where it's located.
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Old May 1, 2021, 03:11 AM   #13
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Quote:
My problem was finding a steel Single action, double stack frame.
https://www.caspianarms.com/receiver...ver-kit-carbon
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Old May 1, 2021, 08:02 AM   #14
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The Caspian high-cap frame was dimensioned specifically for .38 Super, so in any larger caliber, the capacity is more mid-cap; only ten rounds in .45, IIRC?
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Old May 1, 2021, 12:03 PM   #15
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The other problem with the Caspian double stack is that it only takes Caspian magazines.
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Old May 1, 2021, 03:16 PM   #16
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All true, but they're available.
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Old May 1, 2021, 05:11 PM   #17
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Pro-Mag, or one of the other marginal brands did make mags for Caspian hi-caps, but don't know if they're still available.
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Old May 1, 2021, 10:24 PM   #18
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Yeah, I took a look at caspian, and in addition to proprietary mags and being 9mm/38 frames, they're also entirely finished.
I dont actually need another 1911, I just thought it would be a fun project to buy something for machining practice.
Since Ive already done an 80%, I figured it would be a learning experience to go another step back to a casting. Just for giggles. If this works, I'll cast one myself from brass, lol. Then machine that.
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Old May 1, 2021, 10:26 PM   #19
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Quote:
Originally Posted by RickB View Post
Aren't virtually all of the frame dimensions relative to the slide stop pin hole?
I think all dimensions are in Vol. II of the Kuhnhausen sop manual.
So, a lot of the directions are based off the slide stop hole, but I recall most of the vertical dimensions being off of the top deck. Or at least thats what I measured them off of, lol. But yes, the trigger and hammer pins I think I measured from the slide stop hole for horizontal fistance.
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Old May 1, 2021, 11:04 PM   #20
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So, a lot of the directions are based off the slide stop hole, but I recall most of the vertical dimensions being off of the top deck. Or at least thats what I measured them off of, lol. But yes, the trigger and hammer pins I think I measured from the slide stop hole for horizontal fistance.
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Old May 1, 2021, 11:47 PM   #21
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Quote:
Originally Posted by 45flaco
So, a lot of the directions are based off the slide stop hole, but I recall most of the vertical dimensions being off of the top deck. Or at least thats what I measured them off of, lol. But yes, the trigger and hammer pins I think I measured from the slide stop hole for horizontal fistance.
The top deck is located relative to the slide stop pin hole center. That is THE reference point for the M1911 frame.
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Old May 2, 2021, 12:16 PM   #22
45flaco
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Quote:
Originally Posted by Aguila Blanca View Post
The top deck is located relative to the slide stop pin hole center. That is THE reference point for the M1911 frame.
Good to know. My last one I just reverse engineered off my existing 1911, but I have a set of actual blueprints now, thanks to you.
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Old May 2, 2021, 12:28 PM   #23
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Good to know. My last one I just reverse engineered off my existing 1911, but I have a set of actual blueprints now, thanks to you.
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Old May 3, 2021, 11:18 AM   #24
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So looking at the blueprints, I'm trying to figure out how to machine the slot for the trigger bars, inside the Mag well. The front cut for the trigger, in the trigger guard, should be no issue. But the cut for the trigger bars, I cant figure out how to cut. I'll have to look at my standard 1911 and see how they did it. Any advice?
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