After many months, SC-DGR... - XDTalk Forums - Your HS2000/SA-XD Information Source!

**Hooz** · 02-09-2007, 12:57 PM

I haven't posted here in for a few months, but many of you will remember that I was working with Don on developing a one-piece guide rod for the XD Sub Compacts. While I haven't been very active on the forums for a while, work on the SC-DGR has been happening in the background. Let me take a minute to get everyone up-to-speed.

Don sent me a drawing of an SC-DGR rod that he had designed and a custom brass bushing. I asked my Dad (a tool-and-die guy) to make me a few prototype rods based on Don's design, and I was off to the races!

I started the whole process by using a cut-down, round wire 1911 spring like the ones currently used with the Service Model DGR. In order to fit the "stacked height" limitations of the SC, I had to cut some coils off of the spring. Once I cut enough coils to make the spring fit, it was then too short and, consequently, didn't have enough force to hold the slide in battery. So, I started looking for alternative springs.

I found an alternative to the round wire 1911 springs from ISMI. ISMI makes an 18# flat wire spring for the compact Glock models, and after an email exchange with ISMI, I was confident that a cut-down flat wire spring would be just the thing for the SC-DGR. I ordered a few springs, received them, measured them, did the calculations and cut them. By my calculations, I would be able to fit 20 coils and still fall within the "stacked height" requirements.

The ID of the flat wire spring was smaller than the round wire springs I'd been trying. In order to use the ISMI springs, I redesigned the rod, and Don made me a few brass bushings to accomodate the new rod diameter.

Here is the (cut) ISMI spring compared to an uncut ISMI spring:

And the same (cut) spring compared to a standard Service Model (4") round wire spring:

Here is the (cut) ISMI spring with the redesigned rod and bushing:

And my XD-9SC slide:

After some test fitting, more cutting and more test fitting, I found that I could only go up to a maximum of 17.5 coils with the ISMI spring. Any more and I couldn't lock my slide open as the spring was compressing solid and not allowing the slide to go back far enough to engage the locking lever.

Here is what I ended-up with:

Looks pretty cool, eh? Well...

I did run some rounds through the gun with the SC-DGR, but I experienced quite a few issues. As the spring "settled", the gun refused to go all the way into battery, and if it did, a light push on the front of the slide was all it took to knock it out of battery.

Unfortunately, 17.5 coils isn't enough to reliably return the gun to full battery and hold it there. Without a custom spring built specifically for this application, I really don't think that an SC-DGR is a realistic possibility. I've tried about every spring I could get my hands on and multiple rod/bushing designs, but the simple fact is that (to my knowledge) there just isn't a spring on the market that will work.

After all the time (and money) I've invested in this thing, I am sorry to say that I really don't think an SC-DGR is possible.

**Old School** · 02-09-2007, 01:01 PM

The effort was a good one and we all appreciate your insight. It may just be that the XDSC setup is the best setup for that little gun. There is nothing wrong with that.

OS

**Hooz** · 02-09-2007, 01:04 PM

Yeah... But it looks really cool anyway

Maybe if I thinned the head of the rod and the flange of the bushing I could fit another coil in there. But then I'd be worried about the reliability of those parts. I'd hate for the rod to break when firing the gun, or for the spring to come flying out the front due to a weak/broken bushing. And I'm not even sure that one more coil would be enough.

20 coils put enough pressure to hold the gun in battery, but the slide wouldn't go all the way back. I guess it's a pretty fine line when 2 coils makes it or breaks it for you.

**PackerfanXD** · 02-09-2007, 01:07 PM

Thanks for all the time and effort, Hooz! It is disappointing, though...

**Old School** · 02-09-2007, 01:20 PM

Quote:

Originally Posted by Hooz

Yeah... But it looks really cool anyway

Maybe if I thinned the head of the rod and the flange of the bushing I could fit another coil in there. But then I'd be worried about the reliability of those parts. I'd hate for the rod to break when firing the gun, or for the spring to come flying out the front due to a weak/broken bushing. And I'm not even sure that one more coil would be enough.

20 coils put enough pressure to hold the gun in battery, but the slide wouldn't go all the way back. I guess it's a pretty fine line when 2 coils makes it or breaks it for you.

Considering the amount of work thus far, unless ISMI makes a custom spring for this setup, the individual will need to cut coils. Not a perfect scenario and I would much rather trust the stock setup over this one. Just my opinion, of course.

Don · 02-09-2007, 03:43 PM

Thanks for the efforts!

slugger6 · 02-09-2007, 03:48 PM

Hooz - Thanks for the informative post and all the hard work. Too bad it wasn't meant to be.

hk-sigman · 02-23-2007, 07:11 PM

I think that it would still be possible with the proper spring. You should try the spring from a S&W CS9 Chiefs Special. Or maybe even the CS40 Chiefs Special for a heavier spring.

Don · 02-23-2007, 08:08 PM

Part of the spring problem is that when the slide is closed the installed spring needs to have about 6 lbs force (can be less but gets iffy) and then have the full force at near the stack height. I can play with math and come up with a spring, but I suspect it will have a very short life. I need to fab up yet another prototype to send out, but I also think I may need to look at a smaller rod and dual springs to do the deed without the short fatigue life. KelTec goes this route and even though they are not not needing to cock a striker it may be possible to meet the specs with dual springs on a plain rod. As in valve springs for some engines it would be right hand wind on one and left hand wind on the other to avoid coil interference (the factory assembly avoids this coil interference by the tube between the springs).
The factory did a good job on the spring rate for the sub in my opinion. At best an aftermarket spring will mimic the factory feel. I have heard of factory assemblies coming apart on Service models, it has not appeared yet on the Subcompact models that I remember (have I missed something?).

**Hooz** · 02-23-2007, 08:49 PM

You know I'm always up for beta testing

I think the majority of the people interested in the SC-DGR are in it for the reliability more than changing the effects of recoil. I'm now on my second recoil assembly due to the weld coming apart (after about 3500 rounds), many other people have had a lot worse luck than that. It's all about peace of mind.

02-09-2007, 12:57 PM	#1
Hooz XDTalk 1K Member Join Date: Feb 2006 Location: Hilliard, OH Posts: 1,794	After many months, SC-DGR... I haven't posted here in for a few months, but many of you will remember that I was working with Don on developing a one-piece guide rod for the XD Sub Compacts. While I haven't been very active on the forums for a while, work on the SC-DGR has been happening in the background. Let me take a minute to get everyone up-to-speed. Don sent me a drawing of an SC-DGR rod that he had designed and a custom brass bushing. I asked my Dad (a tool-and-die guy) to make me a few prototype rods based on Don's design, and I was off to the races! I started the whole process by using a cut-down, round wire 1911 spring like the ones currently used with the Service Model DGR. In order to fit the "stacked height" limitations of the SC, I had to cut some coils off of the spring. Once I cut enough coils to make the spring fit, it was then too short and, consequently, didn't have enough force to hold the slide in battery. So, I started looking for alternative springs. I found an alternative to the round wire 1911 springs from ISMI. ISMI makes an 18# flat wire spring for the compact Glock models, and after an email exchange with ISMI, I was confident that a cut-down flat wire spring would be just the thing for the SC-DGR. I ordered a few springs, received them, measured them, did the calculations and cut them. By my calculations, I would be able to fit 20 coils and still fall within the "stacked height" requirements. The ID of the flat wire spring was smaller than the round wire springs I'd been trying. In order to use the ISMI springs, I redesigned the rod, and Don made me a few brass bushings to accomodate the new rod diameter. Here is the (cut) ISMI spring compared to an uncut ISMI spring: And the same (cut) spring compared to a standard Service Model (4") round wire spring: Here is the (cut) ISMI spring with the redesigned rod and bushing: And my XD-9SC slide: After some test fitting, more cutting and more test fitting, I found that I could only go up to a maximum of 17.5 coils with the ISMI spring. Any more and I couldn't lock my slide open as the spring was compressing solid and not allowing the slide to go back far enough to engage the locking lever. Here is what I ended-up with: Looks pretty cool, eh? Well... I did run some rounds through the gun with the SC-DGR, but I experienced quite a few issues. As the spring "settled", the gun refused to go all the way into battery, and if it did, a light push on the front of the slide was all it took to knock it out of battery. Unfortunately, 17.5 coils isn't enough to reliably return the gun to full battery and hold it there. Without a custom spring built specifically for this application, I really don't think that an SC-DGR is a realistic possibility. I've tried about every spring I could get my hands on and multiple rod/bushing designs, but the simple fact is that (to my knowledge) there just isn't a spring on the market that will work. After all the time (and money) I've invested in this thing, I am sorry to say that I really don't think an SC-DGR is possible. __________________ XD-9 Tactical : XD-45 Tactical Member: IDPA, USPSA, ASSA, NRA, GOA Last edited by Hooz : 02-09-2007 at 04:14 PM.

02-09-2007, 01:01 PM	#2
Old School XDTalk 5K Member Join Date: Dec 2003 Location: Illinois Posts: 7,497	The effort was a good one and we all appreciate your insight. It may just be that the XDSC setup is the best setup for that little gun. There is nothing wrong with that. OS __________________ Visit www.pistolgear.com for all of your XD needs!

02-09-2007, 01:04 PM	#3
Hooz XDTalk 1K Member Join Date: Feb 2006 Location: Hilliard, OH Posts: 1,794	Yeah... But it looks really cool anyway Maybe if I thinned the head of the rod and the flange of the bushing I could fit another coil in there. But then I'd be worried about the reliability of those parts. I'd hate for the rod to break when firing the gun, or for the spring to come flying out the front due to a weak/broken bushing. And I'm not even sure that one more coil would be enough. 20 coils put enough pressure to hold the gun in battery, but the slide wouldn't go all the way back. I guess it's a pretty fine line when 2 coils makes it or breaks it for you. __________________ XD-9 Tactical : XD-45 Tactical Member: IDPA, USPSA, ASSA, NRA, GOA Last edited by Hooz : 02-09-2007 at 01:07 PM.

02-09-2007, 01:07 PM	#4
PackerfanXD XDTalk 5K Member Join Date: Feb 2006 Location: Ground zero of the invasion Posts: 6,254	Thanks for all the time and effort, Hooz! It is disappointing, though... __________________ The wealthiest nation in the world with the mightiest army man has ever assembled could not stop them. Mexican 300 http://www.break.com/index/mexican-300.html No more anchor babies! Free Ramos and Campion

02-09-2007, 03:43 PM	#6
Don XDTalk 4K Member Join Date: Mar 2001 Location: Pullman, WA Posts: 4,138	Thanks for the efforts! __________________ Don geek with guns Why don\'t you all f-f-f-fade away.... FAQ - Don\'s Guide Rod

02-09-2007, 03:48 PM	#7
slugger6 XDTalk 10K Member Join Date: Dec 2006 Location: Ohio Posts: 17,649	Hooz - Thanks for the informative post and all the hard work. Too bad it wasn't meant to be.

02-23-2007, 07:11 PM	#8
hk-sigman XDTalk Newbie Join Date: Feb 2007 Posts: 12	I think that it would still be possible with the proper spring. You should try the spring from a S&W CS9 Chiefs Special. Or maybe even the CS40 Chiefs Special for a heavier spring.

02-23-2007, 08:08 PM	#9
Don XDTalk 4K Member Join Date: Mar 2001 Location: Pullman, WA Posts: 4,138	Part of the spring problem is that when the slide is closed the installed spring needs to have about 6 lbs force (can be less but gets iffy) and then have the full force at near the stack height. I can play with math and come up with a spring, but I suspect it will have a *very* short life. I need to fab up yet another prototype to send out, but I also think I may need to look at a smaller rod and dual springs to do the deed without the short fatigue life. KelTec goes this route and even though they are not not needing to cock a striker it may be possible to meet the specs with dual springs on a plain rod. As in valve springs for some engines it would be right hand wind on one and left hand wind on the other to avoid coil interference (the factory assembly avoids this coil interference by the tube between the springs). The factory did a good job on the spring rate for the sub in my opinion. At best an aftermarket spring will mimic the factory feel. I have heard of factory assemblies coming apart on Service models, it has not appeared yet on the Subcompact models that I remember (have I missed something?). __________________ Don geek with guns Why don\'t you all f-f-f-fade away.... FAQ - Don\'s Guide Rod

02-23-2007, 08:49 PM	#10
Hooz XDTalk 1K Member Join Date: Feb 2006 Location: Hilliard, OH Posts: 1,794	You know I'm always up for beta testing I think the majority of the people interested in the SC-DGR are in it for the reliability more than changing the effects of recoil. I'm now on my second recoil assembly due to the weld coming apart (after about 3500 rounds), many other people have had a lot worse luck than that. It's all about peace of mind. __________________ XD-9 Tactical : XD-45 Tactical Member: IDPA, USPSA, ASSA, NRA, GOA

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