With all the guys jumping on the Caspian XR stripped-slide-and-frame deal, I thought I’d rummage through my old stuff on the XR in case anyone was interested. Back when Caspian offered the “XR Kits” as a special, I had done a bit of research and was ready to pull the trigger on one. Can’t remember what I bought instead of the kit. Probably something silly like food or electricity.
Anyway, I thought some of the new XR owners might find some value in what I had put together before.
Some history. Caspian first started offering the XR kit some time back, like in the early 2005 timeframe. Rumor was they were “over-runs” from the original Sig GSR 1911, and that Caspian put a ball-cut and an extra set of forward cocking serrations in to distinguish the “XR Kit” from the GSR. Caspian did, in fact, make the slide/frame combo for the original GSR (EGW made a bunch of the original pieces for the GSR, also, and that will become important later), and if you look at the XR compared to the original GSR, you can see the family resemblance.
Back in the day, the “kit” came like this:
Note that you got the frame, slide, ejector, firing pin, firing pin stop, grip safety, and the infamous “plate” for converting from Series 80 to Series 70. (More on that later.) Prices ran from about $550 at the beginning to about $450 at the “end,” when they were advertised as “slight cosmetic blems.” A pretty tempting deal.
So, enough of history. What are we getting? According to Gary at Caspian, we’re getting a stripped frame and slide, similar to this:
These sets are each, as we know, “seconds” or “cosmetically blemished” in some way. But for $100? This is a no-brainer (which is good for no-brainers like me).
“Dude! There’s a screw in my slide!”
One of the most visually unique features on a gun chock full of visually unique features is the “screw” at the left rear of the slide, also called the “manhole” by GSR owners. No, it doesn’t adjust the trigger pull, or lock the gun, a la S&W. The “screw” is simply a plug which holds in the firing pin plunger and spring of the Series 80 Firing Pin Safety. Sig, in fact, calls it the “Firing Pin Plunger Retainer.” Why it’s there takes a bit of ‘splainin’.
The XR kit (and GSR) is designed to incorporate the Series 80 Firing Pin Safety system. For a refresher, the “system” consists of four parts—two “levers” in the frame and a plunger and spring in the slide—that prevent the firing pin from moving forward unless the trigger is pulled.
Here’s an drawing of how the parts fit together:
And here’s what the actual parts look like:
Top to bottom that’s the Firing Pin Plunger Spring, Firing Pin Plunger (these fit into the slide), Plunger Lever, and Trigger Bar Lever (these fit in the receiver). The Firing Pin Plunger and spring fit in a hole in the slide, shown here:
But how do you keep that little bugger from falling out of there? When Colt introduced the Series 80, they modified the extractor to hold the small part in the slide. Note the cut-out on the Series 80 extractor:
Compared to a Series 70 Extractor:
But the XR (GSR) has an external extractor, so how do you hold the small part in? You drill a hole in the side of the slide and put a “plug” in to hold the Firing Pin Plunger and Spring. As you can see, on the XR, here’s no internal extractor cut machined into the slide:
The answer is the Firing Pin Plunger Retainer. Caspian provides a straight screw head, while Sig decided to go with a two-hole specialty head, hence the name “manhole cover.”
(At some point in the series, Sig switched from the Firing Pin Plunger Retainer to a more “standard” extractor-based retention system for the retaining Firing Pin Plunger, using basically a “stub” extractor to hold the plunger in, which is why some later Sig GSR’s look like they have both an internal and external extractor.)
So, what do you do with the Firing Pin Plunger Retainer? Well, that depends on whether you intend to build up as a Series 80 or Series 70. If you intend to build the weapon up as a Series 80, then the Retainer will hold the Firing Pin Plunger and spring in, and you won’t have to remove the Retainer unless you’re detail stripping the gun. If, instead, you intend to build the weapon up as a Series 70 gun, then you can get your Lock-Tite out and seal that mother for good. There is, however, a bit more to the Series 80/70 story other than locking down the manhole cover.
Recall the Series 80 firing pin block system consists of four part, of which two are in the frame. The Trigger Bar Lever and Plunger Lever sit in a milled slot next to the hammer and sear, and are held in by the hammer and sear pins. Here’s a picture of where the levers sit:
You can’t just leave out the Plunger Lever and Trigger Bar Lever. You have to fill that space next to the hammer and sear. Remember I said the XR kits used to come with a “plate” for converting from Series 80 to Series 70? Well, that “plate” sits down in that recess, held in by the hammer and sear pins. It is also the greatest source of frustration for the XR kit builders, as the plate provided by Caspian required a bunch of filing in most cases to make it fit. If you check the various 1911 forums, you’ll see quite a bit of heartburn over getting the plate to fit. Conversely, the 1911 Auto Frame Slot Blank offered by Brownells at just $5 seems to get universal acclaim for a drop-in fit. It looks like this:
And is available here.
So, if you decide to build up as a Series 70, Lock-Tite and Brownell’s Frame Slot Blank. If you decide to build up as a Series 80, then you’ll need to get the Firing Pin Plunger Spring, Firing Pin Plunger, Plunger Lever, and Trigger Bar Lever. You can get them all from Brownells, and if you go this route, I recommend the Cylinder & Slide Series 80 Trigger Pull Reduction Kit It contains the Hammer Pin, Sear Pin, Trigger Lever, Plunger Lever, and Firing Pin Plunger, all yummy Titanium-nitrided and moly-disulfide coated.
Remember, too, that if you go Series 80, you’ll also need a Series 80-specific Firing Pin Stop, as you need the lower right corner notched to clear the flippers, levers, gee-gaws and doo-dads.
As well as a Series 80-specific Grip Safety (thinner tab to miss the aforementioned levers and gee-gaws).
Crap, this is getting longer than either you or I wanted it to get. Let’s see, what else is important…
Caspian cuts all their slides (including the XR) for a .38Super firing pin, to prevent “primer flow.” You’ll need a .38Super pin for this project.
Storm Lake Machine makes the OEM barrel for the Sig GSR, and for the XR kits. Caspian has them for $75 on their website, stating “These come from a limited production run designed explicitly for the XR kits and will not fit all standard 1911 models.” Look here to find them.
Remember I mentioned Evolution Gun Works (EGW)? Well, they were players on the original GSR as well. They supplied the sear, bushing, and some other small parts. They are also selling the Storm Lake barrels, complete with bushing they designed for the GSR project, on their website for $120. EGW is also a good source for the external extractor. You get the “normal” one for $24 or the “heavy duty” ones for $40. You can also get the extractor pin and spring there.
OK, this is all I can dig up from my notes, and it's more than anyone wanted, but once I get blabbin'...
I'm no expert or gunsmith. There are plenty of them on the forum, and you should seek/heed thier counsel, but I've built up a couple of 1911's, and I've had this project in the hopper for a while. Glad I can move it to the front of the que, and share what notes I had on the project.
Anyway, I thought some of the new XR owners might find some value in what I had put together before.
Some history. Caspian first started offering the XR kit some time back, like in the early 2005 timeframe. Rumor was they were “over-runs” from the original Sig GSR 1911, and that Caspian put a ball-cut and an extra set of forward cocking serrations in to distinguish the “XR Kit” from the GSR. Caspian did, in fact, make the slide/frame combo for the original GSR (EGW made a bunch of the original pieces for the GSR, also, and that will become important later), and if you look at the XR compared to the original GSR, you can see the family resemblance.
Back in the day, the “kit” came like this:
Note that you got the frame, slide, ejector, firing pin, firing pin stop, grip safety, and the infamous “plate” for converting from Series 80 to Series 70. (More on that later.) Prices ran from about $550 at the beginning to about $450 at the “end,” when they were advertised as “slight cosmetic blems.” A pretty tempting deal.
So, enough of history. What are we getting? According to Gary at Caspian, we’re getting a stripped frame and slide, similar to this:
These sets are each, as we know, “seconds” or “cosmetically blemished” in some way. But for $100? This is a no-brainer (which is good for no-brainers like me).
“Dude! There’s a screw in my slide!”
One of the most visually unique features on a gun chock full of visually unique features is the “screw” at the left rear of the slide, also called the “manhole” by GSR owners. No, it doesn’t adjust the trigger pull, or lock the gun, a la S&W. The “screw” is simply a plug which holds in the firing pin plunger and spring of the Series 80 Firing Pin Safety. Sig, in fact, calls it the “Firing Pin Plunger Retainer.” Why it’s there takes a bit of ‘splainin’.
The XR kit (and GSR) is designed to incorporate the Series 80 Firing Pin Safety system. For a refresher, the “system” consists of four parts—two “levers” in the frame and a plunger and spring in the slide—that prevent the firing pin from moving forward unless the trigger is pulled.
Here’s an drawing of how the parts fit together:
And here’s what the actual parts look like:
Top to bottom that’s the Firing Pin Plunger Spring, Firing Pin Plunger (these fit into the slide), Plunger Lever, and Trigger Bar Lever (these fit in the receiver). The Firing Pin Plunger and spring fit in a hole in the slide, shown here:
But how do you keep that little bugger from falling out of there? When Colt introduced the Series 80, they modified the extractor to hold the small part in the slide. Note the cut-out on the Series 80 extractor:
Compared to a Series 70 Extractor:
But the XR (GSR) has an external extractor, so how do you hold the small part in? You drill a hole in the side of the slide and put a “plug” in to hold the Firing Pin Plunger and Spring. As you can see, on the XR, here’s no internal extractor cut machined into the slide:
The answer is the Firing Pin Plunger Retainer. Caspian provides a straight screw head, while Sig decided to go with a two-hole specialty head, hence the name “manhole cover.”
(At some point in the series, Sig switched from the Firing Pin Plunger Retainer to a more “standard” extractor-based retention system for the retaining Firing Pin Plunger, using basically a “stub” extractor to hold the plunger in, which is why some later Sig GSR’s look like they have both an internal and external extractor.)
So, what do you do with the Firing Pin Plunger Retainer? Well, that depends on whether you intend to build up as a Series 80 or Series 70. If you intend to build the weapon up as a Series 80, then the Retainer will hold the Firing Pin Plunger and spring in, and you won’t have to remove the Retainer unless you’re detail stripping the gun. If, instead, you intend to build the weapon up as a Series 70 gun, then you can get your Lock-Tite out and seal that mother for good. There is, however, a bit more to the Series 80/70 story other than locking down the manhole cover.
Recall the Series 80 firing pin block system consists of four part, of which two are in the frame. The Trigger Bar Lever and Plunger Lever sit in a milled slot next to the hammer and sear, and are held in by the hammer and sear pins. Here’s a picture of where the levers sit:
You can’t just leave out the Plunger Lever and Trigger Bar Lever. You have to fill that space next to the hammer and sear. Remember I said the XR kits used to come with a “plate” for converting from Series 80 to Series 70? Well, that “plate” sits down in that recess, held in by the hammer and sear pins. It is also the greatest source of frustration for the XR kit builders, as the plate provided by Caspian required a bunch of filing in most cases to make it fit. If you check the various 1911 forums, you’ll see quite a bit of heartburn over getting the plate to fit. Conversely, the 1911 Auto Frame Slot Blank offered by Brownells at just $5 seems to get universal acclaim for a drop-in fit. It looks like this:
And is available here.
So, if you decide to build up as a Series 70, Lock-Tite and Brownell’s Frame Slot Blank. If you decide to build up as a Series 80, then you’ll need to get the Firing Pin Plunger Spring, Firing Pin Plunger, Plunger Lever, and Trigger Bar Lever. You can get them all from Brownells, and if you go this route, I recommend the Cylinder & Slide Series 80 Trigger Pull Reduction Kit It contains the Hammer Pin, Sear Pin, Trigger Lever, Plunger Lever, and Firing Pin Plunger, all yummy Titanium-nitrided and moly-disulfide coated.
Remember, too, that if you go Series 80, you’ll also need a Series 80-specific Firing Pin Stop, as you need the lower right corner notched to clear the flippers, levers, gee-gaws and doo-dads.
As well as a Series 80-specific Grip Safety (thinner tab to miss the aforementioned levers and gee-gaws).
Crap, this is getting longer than either you or I wanted it to get. Let’s see, what else is important…
Caspian cuts all their slides (including the XR) for a .38Super firing pin, to prevent “primer flow.” You’ll need a .38Super pin for this project.
Storm Lake Machine makes the OEM barrel for the Sig GSR, and for the XR kits. Caspian has them for $75 on their website, stating “These come from a limited production run designed explicitly for the XR kits and will not fit all standard 1911 models.” Look here to find them.
Remember I mentioned Evolution Gun Works (EGW)? Well, they were players on the original GSR as well. They supplied the sear, bushing, and some other small parts. They are also selling the Storm Lake barrels, complete with bushing they designed for the GSR project, on their website for $120. EGW is also a good source for the external extractor. You get the “normal” one for $24 or the “heavy duty” ones for $40. You can also get the extractor pin and spring there.
OK, this is all I can dig up from my notes, and it's more than anyone wanted, but once I get blabbin'...
I'm no expert or gunsmith. There are plenty of them on the forum, and you should seek/heed thier counsel, but I've built up a couple of 1911's, and I've had this project in the hopper for a while. Glad I can move it to the front of the que, and share what notes I had on the project.
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