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Posted: 5/25/2022 2:40:32 PM EDT
[Last Edit: Blanco_Diablo]
It's been too long...thinking back, I've owned a 607 upper and a 607 lower with pinned stock in the past ..both at separate times and both sold because "I can get another anytime." Well now is finally the time. Just bought a pretty complete kit from a nice gentleman here on the site and will be doing it right. Everything will be here tomorrow but here are the pics I got from the seller.

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Now I've never installed a 607 stock myself. I know the NDS Lowers have a roll pin hole for the rod, but the rod is also threaded. Do I need to thread the back of my lower for that rod? Or is that just another mounting option?

I'll document my build here. Super excited to finally get started. Oh, by the way, primary arms has chrome BCGs (albeit with FA cuts) on sale for $100 right now...I picked up one for this and one for my XM177E1 project.
Link Posted: 5/25/2022 3:01:01 PM EDT
[Last Edit: 57Octane] [#1]
You’ll need to drill out the lower, tap it, and drill a cross pin for the rod. The hole in the NDS lowers are not for that but the pin size is the same. Probably going to have to open up the rod for the buffer detention spring as well.

I would not recommend trying to do it without a mill.

Also, the cross pin intersects the takedown pin spring hole. It’s what keeps the spring in place after the mod. I had to chop a few coils off of the spring to get it to fit as well.
Link Posted: 5/25/2022 4:25:37 PM EDT
[Last Edit: Blanco_Diablo] [#2]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 57Octane:
You’ll need to drill out the lower, tap it, and drill a cross pin for the rod. The hole in the NDS lowers are not for that but the pin size is the same. Probably going to have to open up the rod for the buffer detention spring as well.

I would not recommend trying to do it without a mill.

Also, the cross pin intersects the takedown pin spring hole. It’s what keeps the spring in place after the mod. I had to chop a few coils off of the spring to get it to fit as well.
View Quote

Yikes....I might have to see if John Thomas can do it when I send my barrel to him. I'm hoping he can chop the handguards down too.

ETA man I have been out of the retro game for too long...I remember now that the pin hole on the NDS lower is for the buffer tube and the 607s had two pins.
Link Posted: 5/25/2022 7:13:17 PM EDT
[#3]
Handguards are an easy chop - remove the heat shields (maybe not, if you're comfortable doing it all at once - I wasn't), measure from the end you're not cutting and add a bit just to be sure, sand/dremel to the fit you want. (I did it for my LaFrance clone - biggest issue was when my boss decided to "help" and shortened the (nicer) handguards too much.) Modify the heat shields to fit, reattach and celebrate the circumcision!
Link Posted: 5/26/2022 11:25:58 AM EDT
[#4]
I made a wooden jig for the hand guards that fit inside a miter box and used a hack saw to cut them. It was simple, a couple of screws and some markings on piece of wood. I used a dremel to trim the heat shields and remove the support ribs from the cut end. I had some pictures of a real one to tried to get as close as I could.

Link Posted: 5/27/2022 8:33:19 AM EDT
[Last Edit: swOHmatt] [#5]
The 607 cross pin does two functions.  It keeps the threaded rod from coming loose of the lower and it intercepts the hole for the rear takedown pin detent and spring.  Without a lower endplate there’s nothing to keep the takedown pin spring in place.  Placed far enough back to perform this secondary function it should not interfere with the buffer retaining pin and spring.  The stock rod threaded into the lower will intrude into the buffer retainer hole.  After Matt (607 stock) threads the lower and screws in the rod locating its final position with the cross pin, he then recuts with a mill the buffer retaining pin hole.  

Installation of the 607 stock isn’t difficult, but it does require a mill if you want to be sure it doesn’t all go pear shaped.

I threaded the rear takedown spring hole and screwed in a set screw.  I didn’t want to wrestle with holding that all in place as I tried to drive in the cross pin.  I positioned the set screw just deep enough to clear the cross pin.

https://www.ar15.com/forums/AR-15/Retro-Show-off-thread-/123-747212/?page=3#i8039492
Link Posted: 5/27/2022 9:17:07 AM EDT
[#6]
Thanks for the explanation! Yeah, sadly I don't have a mill. I think I have Matt's email so I'll see if he's still offering that service.

In the meantime, I need to figure out which bolt release I want to use I'm leaning towards the transitional one. And yes, they're both original. I have some original deep dimpled takedown/pivot pins I'll be using, just need another dimpled selector. My original 3 pos one is on my 601.

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Link Posted: 5/27/2022 3:52:45 PM EDT
[#7]
Ok so I just got everything in my hands. It looks like the stock rod is threaded, but still meant to be pinned. My question is...do I need to deepen the pocket on the lower so it sits flush before pinning? Or will the rod go farther into the stock once it's fixed to the lower? Right now, I can't unlock the stock to extend it because I have no way to hold the rod steady, so it's just spinning with the locking sleeve when I change the lever from open to locked.

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Also just got my echo arms chrome BCGs from Primary arms. Absolutely insane how quickly they shipped..I ordered Wednesday! Only $100 so I got one for this project and one for my XM177 project

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Link Posted: 5/27/2022 4:06:08 PM EDT
[#8]
You need to deepen that hole all the way through the other side and thread it with the appropriate tap before you even think about drilling a cross pin.

Refer to this: 607 Receiver Stub
Link Posted: 5/27/2022 4:27:24 PM EDT
[#9]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 57Octane:
You need to deepen that hole all the way through the other side and thread it with the appropriate tap before you even think about drilling a cross pin.

Refer to this: 607 Receiver Stub
View Quote

Even though the rod is smaller in diameter than the recess in the receiver? I'd have to drill and tap at a smaller diameter than the current hole, so threads would only behind where I start drilling to deepen the hole. Is that correct?
Link Posted: 5/27/2022 4:56:38 PM EDT
[#10]
Yes, that’s correct.

The only way to have it threaded fully would be to start with a raw forging. It’s just a concession that has to be made when working with an off the shelf lower.

I would also recommend not trying to do this with a power drill and probably not with a drill press either.
Link Posted: 5/27/2022 5:44:01 PM EDT
[#11]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 57Octane:
Yes, that’s correct.

The only way to have it threaded fully would be to start with a raw forging. It’s just a concession that has to be made when working with an off the shelf lower.

I would also recommend not trying to do this with a power drill and probably not with a drill press either.
View Quote

Yeeeah I think I'm going to see if John Thomas can take care of it for me. I would just hate to mess it up.
Link Posted: 5/27/2022 7:46:54 PM EDT
[#12]
Ok spoke to JT and the barrel work and all that is no problem but no go on the 607 stock mounting soooo...what are my options? Is there anyone out there that does the work?
Link Posted: 5/27/2022 8:45:56 PM EDT
[#13]
You could probably drill the hole with a drill press if you can securely clamp it and get it square in both directions.  You’ll drill all the way into the firing control pocket, then tap the hole.  I’d then play around with how deep the rod will thread.  Work it until it functions properly.  Then you drill for the cross pin.  Another solid fixture will be needed since you’re not drilling a flat surface.  Start the hole with a drill point so it won’t wonder, then finish with a regular drill bit.  Finally you machine the buffer retainer hole.  It’s something like 6° off square so the mill will clear the top of the extension hole.  

Good news?  There are lots of lower fixtures available.  It isn’t difficult, you just need to go slow and use the proper tools.  The mill may be a problem but most machinists are gun guys and would probably be glad to help.

Matt can’t do it since he’s not an FFL and you’ve got a finished lower.  Don’t get discouraged.  You’ll get there and once finished will be glad you worked through it all.  

Here’s an install with a 607 using an interference fit rod. He drilled the hole in a vise and plain old drill.  https://www.ar15.com/forums/ar-15/How-To-Install-A-607-Stock----Pics-/123-420062/  

https://www.mcmaster.com/starter-drills/high-speed-steel-drill-point-countersinks-for-lathe-centers/
Link Posted: 5/27/2022 8:51:49 PM EDT
[#14]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 57Octane:
You need to deepen that hole all the way through the other side and thread it with the appropriate tap before you even think about drilling a cross pin.

Refer to this: 607 Receiver Stub
View Quote


That link BTW was an absolute gold mine of authentic info.
Link Posted: 5/28/2022 10:15:39 PM EDT
[#15]
Ok so it's definitely seeming like the stock mounting is going to have to be done by myself. I do have a drill press and vise I can use, so that helps. But I really want to get all this right. I'm an aircraft electrician and an amateur blacksmith, but not much of a machinist so please excuse my dumb questions

I measured the threaded portion of the rod. Excuse me if I'm wrong, I had to Google these terms, but from my measurements the crest of the thread measures at .432" and the root measures .410". I'm not sure what the thread pitch is yet. My questions are: a. How do I figure out the thread pitch to tap the hole at? And b. What diameter hole do I need to drill to make sure I can still tap it for the threaded rod? It'd be pretty easy if it was a plain rod like in the linked 607 mounting thread, but the diameter of the threaded rod is a good bit smaller than the recess in the receiver.
Link Posted: 5/28/2022 10:38:14 PM EDT
[Last Edit: m1sniper] [#16]
Take the stock to your local hardware store and test fit nuts onto the rod. Once you find the correct size, note what size it is, then google "correct drill bit to use for a ?? size tap."
The tap you need will obviously be the same diameter and thread pitch as the nut you pick up that fits the rod.

https://www.bing.com/search?q=drill+bit+tap+size+conversion+chart&form=ANSPH1&refig=4b74f31ae12e44c4a8bfdfa7a5e3061a&pc=U531&sp=1&qs=NM&pq=conversion+chart+drill+bit+and+tap&sk=PRES1&sc=2-34&cvid=4b74f31ae12e44c4a8bfdfa7a5e3061a


PS, if you have or can borrow one of those 80% jigs from someone, it makes it a whole lot easier to drill that hole with a drill press. It's how I did mine years ago.
Link Posted: 5/29/2022 1:29:01 PM EDT
[#17]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Blanco_Diablo:
Ok so it's definitely seeming like the stock mounting is going to have to be done by myself. I do have a drill press and vise I can use, so that helps. But I really want to get all this right. I'm an aircraft electrician and an amateur blacksmith, but not much of a machinist so please excuse my dumb questions

I measured the threaded portion of the rod. Excuse me if I'm wrong, I had to Google these terms, but from my measurements the crest of the thread measures at .432" and the root measures .410". I'm not sure what the thread pitch is yet. My questions are: a. How do I figure out the thread pitch to tap the hole at? And b. What diameter hole do I need to drill to make sure I can still tap it for the threaded rod? It'd be pretty easy if it was a plain rod like in the linked 607 mounting thread, but the diameter of the threaded rod is a good bit smaller than the recess in the receiver.
View Quote



7/16" diameter either 7/16 - 14 unc or 7/16 - 20 unf  

use a rule and measure the number of threads per inch then check with a nut as suggested by m1

These are handy  thread pitch gauge
Link Posted: 5/29/2022 2:36:40 PM EDT
[#18]
If you are not confident in your abilities start calling some local machine shops, or ask around at work. Lots of aerospace/machinists have mills in their garage.  

If you stay there while they drill it and the firearm doesn’t stay overnight you don’t need a shop with an FFL.
Link Posted: 5/31/2022 8:45:33 AM EDT
[#19]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 44Echo10:



7/16" diameter either 7/16 - 14 unc or 7/16 - 20 unf  

use a rule and measure the number of threads per inch then check with a nut as suggested by m1

These are handy  thread pitch gauge
View Quote

So 7/16" would be the diameter of the bit I'd need to use to drill the hole prior to tapping it? Or just the diameter of the tap I'd need to use?
Link Posted: 5/31/2022 9:08:47 AM EDT
[#20]
7/16 is the size of the tap. The hole will be smaller. Probably... 25/64 if I remember right.

For example if your threads are 1/2 x 20, you drill a 15/32 hole and the tap cuts the 1/2 part.  



Link Posted: 5/31/2022 9:58:03 AM EDT
[#21]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 57Octane:
7/16 is the size of the tap. The hole will be smaller. Probably... 25/64 if I remember right.

For example if your threads are 1/2 x 20, you drill a 15/32 hole and the tap cuts the 1/2 part.  



View Quote

Got ya. Just googled it and it looks like if it's 7/16-14NC then it's 23/64“ but if it's 7/16-20NF then it's 25/64". Thanks!
Link Posted: 6/3/2022 1:29:43 PM EDT
[#22]
Just wanted to put a shameless plug for John Thomas out there...dude is amazing. I totally crapped the bed on shipping my 607 stuff to him for work (barrel chop, FSB smoothing and bayo lug removal, install handguard caps, parkerize moderator). Forgot the front handguard cap, the money order, and the note for requested work. John still had the work done the day he got it and send back out to me same day. Meanwhile I just waited almost 8 months for my simple FAL build . Can't wait to send him my XM177E1 stuff too.

I'll update again when I get the barrel back and upper built. Stopping by the hardware store today...I may do the stock install myself. I'm pretty sure I can pull it off.
Link Posted: 6/9/2022 11:47:58 AM EDT
[#23]
Can JT install these stocks?

Link Posted: 6/9/2022 12:29:13 PM EDT
[#24]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By techno_000:
Can JT install these stocks?

View Quote

I asked, he said he doesn't do that work unfortunately.

I did just get my barrel back from him and it looks awesome. I'll post pics when I get the upper together
Link Posted: 6/10/2022 5:00:25 PM EDT
[Last Edit: Blanco_Diablo] [#25]
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I don't know why, but I had so many issues putting this upper together. I've barreled countless receivers but I could not get the barrel nut to line up, cracked the rearmost tooth of the HG getting it mounted ..just problems. But it's together! Now I need to mount the stock....but.  

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Won't fit in my drill press

ETA: I know my drill press is rusty. My brother left it in his shed for a while
Link Posted: 6/10/2022 5:14:45 PM EDT
[#26]
Paging Doctor Emel...
Link Posted: 6/10/2022 5:15:48 PM EDT
[#27]
Link Posted: 6/11/2022 10:07:00 AM EDT
[#28]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Blanco_Diablo:
cracked the rearmost tooth of the HG getting it mounted
View Quote View All Quotes
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Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Blanco_Diablo:
cracked the rearmost tooth of the HG getting it mounted

That was actually something the Army documented and complained about during testing. S'why they went to the short rounds.

Won't fit in my drill press

I have that same cooler.

Seriously though, that set up look really sketch. I would want to clamp onto the lower more than that. It doesn't scream "solid" to me. I'd strip it too. All the aluminum chips are probably bad for the action.

As far as drills, I'd start small and work my way up. Hit it with a center drill and then use progressively larger bits until you get to the final size. It's slower but, you're moving less material at a time and can probably keep it more stable.

To echo the above, you can get stubby drills. Probably have them on amazon.
Link Posted: 6/11/2022 1:24:26 PM EDT
[#29]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 57Octane:

That was actually something the Army documented and complained about during testing. S'why they went to the short rounds.


I have that same cooler.

Seriously though, that set up look really sketch. I would want to clamp onto the lower more than that. It doesn't scream "solid" to me. I'd strip it too. All the aluminum chips are probably bad for the action.

As far as drills, I'd start small and work my way up. Hit it with a center drill and then use progressively larger bits until you get to the final size. It's slower but, you're moving less material at a time and can probably keep it more stable.

To echo the above, you can get stubby drills. Probably have them on amazon.
View Quote

Haha! Yeah this was just a mock up to see if it'd even fit. I'll have to look for some stubby bits. I reached out to unclemoak's company to see if they can do the work. If not, I'll try to tackle it myself.
Link Posted: 6/20/2022 11:38:32 AM EDT
[Last Edit: Blanco_Diablo] [#30]
Alright well...I tried.

I drilled and tapped the hole, I *thought* everything was straight, checked level constantly. It must have just moved ever so slightly and caused the drill bit to go in at an slight angle. That angle is *just* enough to cause the locking rod to press upwards against the buffer tube when everything is installed. Tried to get the stock on and there's no way, just too much friction. Sigh! Well, luckily I have a second partial fence lower, so I went ahead and swapped my XM177E1 stock and such to this lower and it's like it never happened. I'll be sending the 607 stock and my undrilled lower to unclemoak shortly. Oh well!

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ETA: Is there anywhere that sells DOD acceptance stamps anymore?
Link Posted: 6/20/2022 2:26:00 PM EDT
[#31]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Blanco_Diablo:
Alright well...I tried.

I drilled and tapped the hole, I *thought* everything was straight, checked level constantly. It must have just moved ever so slightly and caused the drill bit to go in at an slight angle. That angle is *just* enough to cause the locking rod to press upwards against the buffer tube when everything is installed. Tried to get the stock on and there's no way, just too much friction. Sigh! Well, luckily I have a second partial fence lower, so I went ahead and swapped my XM177E1 stock and such to this lower and it's like it never happened. I'll be sending the 607 stock and my undrilled lower to unclemoak shortly. Oh well!

https://www.ar15.com/media/mediaFiles/68140/signal-2022-06-17-12-22-01-439_jpg-2424781.JPG

ETA: Is there anywhere that sells DOD acceptance stamps anymore?
View Quote


I have to give you credit for trying because I'd have a really hard time messing with a NDS Lower right now knowing it can't be replaced.
Link Posted: 6/21/2022 9:12:44 AM EDT
[Last Edit: Blanco_Diablo] [#32]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By HipSh0T:


I have to give you credit for trying because I'd have a really hard time messing with a NDS Lower right now knowing it can't be replaced.
View Quote

Haha! Believe me, I thought of that. But then I figured there's no way that I can screw it up so bad as to make it unusable. Now that the CAR stock is on there, it's like it never happened. If I only had the one lower, I wouldn't have even tried it.
Link Posted: 6/24/2022 5:13:14 PM EDT
[#33]
Okay, the lower and stock are all ready to go to unclemoak. I'll update again when it gets back to me! In the meantime, my form 1 for the XM177E1 was submitted
Link Posted: 8/2/2022 8:24:04 PM EDT
[#34]
Still waiting to get the 607 stock and lower back...but just got the approved form 1 for my XM177E1 back today!

Attachment Attached File


This is easily one of the coolest, most handy AR platform guns out there.
Link Posted: 8/3/2022 10:29:49 AM EDT
[#35]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Blanco_Diablo:
Still waiting to get the 607 stock and lower back...but just got the approved form 1 for my XM177E1 back today!

https://www.ar15.com/media/mediaFiles/68140/20220802_155557_jpg-2474833.JPG

This is easily one of the coolest, most handy AR platform guns out there.
View Quote
Definitely the best looking AR variant.
Link Posted: 8/3/2022 11:06:29 AM EDT
[#36]
Too cool for school, and I like the CAR stock.
Link Posted: 8/3/2022 1:55:41 PM EDT
[#37]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Superluckycat:
Definitely the best looking AR variant.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Superluckycat:
Originally Posted By Blanco_Diablo:
Still waiting to get the 607 stock and lower back...but just got the approved form 1 for my XM177E1 back today!

https://www.ar15.com/media/mediaFiles/68140/20220802_155557_jpg-2474833.JPG

This is easily one of the coolest, most handy AR platform guns out there.
Definitely the best looking AR variant.


It's a coinflip between XM177E1 and Mk18 Mod 0 for me.
Link Posted: 8/3/2022 2:22:42 PM EDT
[#38]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By HipSh0T:


It's a coinflip between XM177E1 and Mk18 Mod 0 for me.
View Quote

That is hard..

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Especially when you include the latest gen..

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