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ARctangent
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Posted: 5/21/2011 5:05:55 AM EST
[Last Edit: 5/21/2011 5:05:55 AM EST by Aimless]
Originally Posted By kitteh:
Just wondering: why the archaic sling loops, instead of QD sockets?


I myself have had the same frustrations about the lack of decent sling-mounting solutions for the Magpul PRS stocks that I own.
I also didn't want to destroy the value of my Magpul PRS stock by drilling big holes in it or otherwise butchering up my stock.
I just want an easy way to mount my sling, get it on and off fast, and use the original mounting bolts that came with the stock.
I also wanted a sling mount that would raise the sling a half-inch further away from the length-of-pull knob, so that the sling doesn't interfere and bind with the knob.

So I decided to do something about it:

This is a pic of my AR-10T with a pair of prototype QD sling mounts that I designed and machined myself.
I have been testing these for a while through several different hunting seasons and many range sessions.
The rifle had just barely gotten back from elk season, so it was kinda muddy at the time...



Anyway, they have held-up great, even without any hard-coat anodizing. No failures of any kind, even through lots of rough terrain, crappy weather, and several hundred (and I do mean hundred) miles hanging off my shoulder.
I have the utmost confidence in these QD sling loop mounts.

Introducing my prototypes:





The above two pics show that my prototypes are approximately four times the mass and strength over the original. They are made of 6061-T6 aircraft-grade aluminum (same as the original).

Here are my design efforts involved with the making of these sling mounts:

Here is a split-screen showing my production design solid model and drawing, with a completed production piece on it's machining fixture in the foreground:



On my computer is a split-screen of the production fixture solid-model, with sling loops attached to the machining fixture with mounting bolts.
In my hand is the complete machining fixture, a production QD sling loop, and the original mounted to the same fixture:



Analyzing the QD fastener dimensions in an optical comparator in order to accurately reverse-engineer the dimensions of the fastener and the ball-bearings in particular:



Pic of some drilled/tapped raw material on the machining jig and I am dial-indicating the jig with an Interapid .0005" indicator.



First-op done with a three-flute aluminum roughing endmill:



Finishing up the second-op:



center-drilling:



reaming after drilling slightly undersized:



At my fingertips and in my palm are some full-radius keyseat cutters I had custom-ground for me...precisely cuts the QD keyseat-groove.
$300 worth of custom-made cutter in this pic...spendy little bastards. I'll be pissed if I break one of these, I just know it.



Running the corner-round:



After the keyseats are cut and the parts are pretty much finished:



A little teaser for you guys...this tray of parts are going into the tumbler and will be back next week from the anodizers (type 2 mil-spec black hardcoat)







Also...I am just one guy, so I can't make very many.

I have already invested some money in patent attorney's fees and the usual crap that goes along with any endeavor like this.

Makes me wonder why anyone comes out with anything new to the market at all...royal ( and expensive) PITA to do so.

Anyway...there you go.

A solution does exist.

So what do you guys think? (I'm kinda beginning to think that I should quit while I'm behind...)
kwrangln
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Posted: 11/30/2009 3:39:53 PM EST
First off, I'm willing to bet that this thread gets locked down quick due to vendor rules on the site since it looks like you are setting up for production.

Second, I'd contact Magpul and say "Hey, I have something I think you'll be interested in". Sell em on the idea, and start selling them product if possible.

Good job on coming up with a solution and making it someday available to others.
J1911MCD
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Posted: 11/30/2009 5:08:07 PM EST
I have to say, you've done an impressive job.

My suspicion is that the QD swivels became popular well after the PRS was released. Now that they're the heat, mounts need to be made.

Cost point is everything and you're surely looking at a select market, but for those in that market, money is probably no object.

That said, I'm thinking about it.
ARctangent
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Posted: 2/4/2010 1:55:25 PM EST
[Last Edit: 2/4/2010 3:49:45 PM EST by ARctangent]
I will be having another meeting with my patent attorney on February 18th...
I will be receiving the first batch of completed second-gen QD sling loops from the anodizers tomorrow at 1:00PM PST.

I would appreciate some beta-testers...anybody up for it?

I will be sending out 10 pairs of these sling loops this weekend to the first ten people who email me (arctangent@ar15.com) with their mailing info.
I request that reviewers post their reviews (whether good or bad) to this thread by February 20th.

These sling loops are made from aerospace quality 6061 T6 aluminum.
This is quality US-made aluminum with certified inspection report available from SAPA Industrial Extrusions out of Spanish Fork, Utah...NOT some cheap-assed Chinese mystery-metal.
All threads are form-tapped for maximum strength.
The swivel socket features are machined directly into the sling loop, so there is no glued-in flush-cup to slip out when the glue eventually breaks down.
The swivel sockets now feature a swivel rotation-limiting design
100% US made.

Note: I cannot be held responsible for overtightened (stripped) threads, cross-threading, or failure to use lock-tight (red) during installation.

By the way...while I was visiting the anodizers today, one of the ball-bearings in my VLTOR heavy-duty sling swivels fell out, yet my QD sling loop prototypes are just fine.
Therefore my sling loops have lasted longer than the swivels themselves...
gwhipp
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Posted: 2/4/2010 4:19:36 PM EST
I would defiantly be interested in testing a QD mount for the PRS. Where do I sign up?
JTrusty
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Posted: 2/4/2010 6:35:11 PM EST
Email inbound.
Jason G Trusty
GEAR SECTOR™
www.gearsector.com
1-877-556-GEAR ( Toll Free )
1-219-406-5795 ( Direct )
DasRonin
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Posted: 2/4/2010 6:45:24 PM EST
IM sent
Isaiah 57:20
Dear Santa: since you failed to give me an 18inch LaRue OBR, could you drop one off for my birthday?

Remember...karma is justice without the satisfaction.
MudBug
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Posted: 2/4/2010 7:35:40 PM EST
[Last Edit: 2/4/2010 7:37:16 PM EST by MudBug]
email sent

I've been trying to find a way to attach my TAB Gear Sling to my Grendel I use in Practical Precision matches and was just about to give in and drill a hole.
"War is less costly than servitude. The choice is always between Verdun and Dachau." -Jean Dutourd

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ARctangent
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Posted: 2/4/2010 9:02:24 PM EST
Originally Posted By MudBug:
email sent

I've been trying to find a way to attach my TAB Gear Sling to my Grendel I use in Practical Precision matches and was just about to give in and drill a hole.


What sort of attachment points do you have on the TAB gear sling?
kingston
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Posted: 2/5/2010 4:54:42 AM EST
Email Sent.

I was going to order a new set of quick swivels. Please specify which you would prefer I used in the testing.
MudBug
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Posted: 2/5/2010 7:15:47 AM EST
[Last Edit: 2/5/2010 7:38:25 AM EST by MudBug]
Originally Posted By ARctangent:
Originally Posted By MudBug:
email sent

I've been trying to find a way to attach my TAB Gear Sling to my Grendel I use in Practical Precision matches and was just about to give in and drill a hole.


What sort of attachment points do you have on the TAB gear sling?


The the same as what you have in those pics. I got the sling and installed Flush cups in the stock on my Rem 700. I want to use the same sling with my grendel, I have a way to attach the Tab sling up front on my grendel, but no way to attach the sling in the back.


It's basically this sling

"War is less costly than servitude. The choice is always between Verdun and Dachau." -Jean Dutourd

www.450bushmaster.net
ARctangent
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Posted: 2/5/2010 8:08:58 AM EST
[Last Edit: 2/5/2010 8:09:33 AM EST by ARctangent]
Originally Posted By MudBug:
Originally Posted By ARctangent:
Originally Posted By MudBug:
email sent

I've been trying to find a way to attach my TAB Gear Sling to my Grendel I use in Practical Precision matches and was just about to give in and drill a hole.


What sort of attachment points do you have on the TAB gear sling?


The the same as what you have in those pics. I got the sling and installed Flush cups in the stock on my Rem 700. I want to use the same sling with my grendel, I have a way to attach the Tab sling up front on my grendel, but no way to attach the sling in the back.


It's basically this sling

http://www.riflesonly.com/images/products/TAB/sling_unbuckle_600.jpg


Awesome!
My QD sling loops would work perfectly for that application.
MudBug
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Posted: 2/5/2010 8:32:15 AM EST
Originally Posted By ARctangent:
Originally Posted By MudBug:
Originally Posted By ARctangent:
Originally Posted By MudBug:
email sent

I've been trying to find a way to attach my TAB Gear Sling to my Grendel I use in Practical Precision matches and was just about to give in and drill a hole.


What sort of attachment points do you have on the TAB gear sling?


The the same as what you have in those pics. I got the sling and installed Flush cups in the stock on my Rem 700. I want to use the same sling with my grendel, I have a way to attach the Tab sling up front on my grendel, but no way to attach the sling in the back.


It's basically this sling

http://www.riflesonly.com/images/products/TAB/sling_unbuckle_600.jpg


Awesome!
My QD sling loops would work perfectly for that application.




I agree, and I would happily post my review over at Snipers Hide also where I bet lots of people would be interested.
"War is less costly than servitude. The choice is always between Verdun and Dachau." -Jean Dutourd

www.450bushmaster.net
ARctangent
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Posted: 2/5/2010 12:19:02 PM EST
[Last Edit: 2/7/2010 3:05:38 PM EST by ARctangent]
Here is a look at the 1st and 2nd Op Jig design:



And the 3rd Op Jig design:



one of my 3rd op jigs in action:





Here is a view of the 50-piece model I designed to machine the QD sling loops with:



Here is a look at one of the 50-piece final op jigs in action:







Here is a pic from the batch I picked up from the anodizers about an hour ago.



These will get mailed out to my beta testers first thing in the morning.

Thanks guys!
Go4broke
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Posted: 2/5/2010 3:00:17 PM EST
Very Nice...need something like this for Magpuls MOE handguard.
kingston
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Posted: 2/5/2010 5:44:26 PM EST

I agree, and I would happily post my review over at Snipers Hide also where I bet lots of people would be interested.


Me too. Someone should start a thread over there...
kingston
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Posted: 2/6/2010 11:21:00 AM EST
[Last Edit: 2/6/2010 11:38:19 AM EST by kingston]
ARctangent,

I just got back from an event where we were talking about your PRSQD Sling Attachment Point (PRSQDSAP) for short- kind of for short- and everyone was excited to see it. For instance shooting from a bench, I always prefer to remove a sling on any rifle. However with the PRS and a 2 point sling, there are any number of ways to remove the sling from the front stock, but that leaves you with the sling dangling from the butt stock. Sure one could use the PRS's picatinny rail to add a sling attachment point, but at the least ergonomic point on the butt stock. Well we are excited to try this out, I'm sure it will work great. Have you thought of making a similar attachment that could be bolted to the free floated tubular front hand guards often found on precision AR's. I'm thinking of free float hand guards like the Hogue, and others. Many of us who use our ARs as precision rifles, hunting p-dogs, chucks and the like, need a sling to hump these heaviest of ARs around.

Oh, yea I was just assuming that I was on the list, could you please confirm.

Thanks!

ARctangent
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Posted: 2/6/2010 12:25:10 PM EST
[Last Edit: 2/8/2010 8:37:57 AM EST by ARctangent]
Originally Posted By kingston:
ARctangent,

I just got back from an event where we were talking about your PRSQD Sling Attachment Point (PRSQDSAP) for short- kind of for short- and everyone was excited to see it. For instance shooting from a bench, I always prefer to remove a sling on any rifle. However with the PRS and a 2 point sling, there are any number of ways to remove the sling from the front stock, but that leaves you with the sling dangling from the butt stock. Sure one could use the PRS's picatinny rail to add a sling attachment point, but at the least ergonomic point on the butt stock. Well we are excited to try this out, I'm sure it will work great. Have you thought of making a similar attachment that could be bolted to the free floated tubular front hand guards often found on precision AR's. I'm thinking of free float hand guards like the Hogue, and others. Many of us who use our ARs as precision rifles, hunting p-dogs, chucks and the like, need a sling to hump these heaviest of ARs around.

Oh, yea I was just assuming that I was on the list, could you please confirm.

Thanks!



Yes, you are confirmed. Package was sent with two of the QDSL's inside.
Everything went out this morning via USPS first class mail.

Confirming beta-testers:
DasRonin
kingston
JTrusty at Gear Sector
Mudbug
Matt F
GWhipp

Still waiting for a mailing address from PhillipW.

Willing to give a set for testing and evaluation to:

justpete
eracer

If they would shoot me an email with a mailing address and be willing to post a review.

Edit:
justpete and PhillipW now confirmed as of this morning.
ARctangent
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Posted: 2/7/2010 2:04:26 PM EST
[Last Edit: 2/7/2010 2:41:38 PM EST by ARctangent]
Originally Posted By kingston:
Email Sent.

I was going to order a new set of quick swivels. Please specify which you would prefer I used in the testing.


This is a good question and deserves further explanation.

Any (heavy duty) push-button sling swivel with a 3/8" diameter shank will work.
When I initially started this project, I bought five different brands of HD push-button swivels and mic'd then all.
They're all pretty close to .3730" diameter with a tolerance variation around +/- .0005" from nominal.
Wanting the maximum shank and ball-bearing engagement as possible, I sent a few of my prototypes in to the anodizer's.
I wanted to get an idea of precisely how much build-up would occur...the anodizer's advice was correct in that he predicted a build-up of .002" (per side) with a total of .004".
That being the case, I then used a .379" oversized reamer for my socket holes, with a .0004" total anodizing build-up leaves the final dimension at .375".
Which means that the largest QD swivel (.3735" shank diameter) will fit with .00075" clearance (all around), and an nominal sized one (.3730") will fit with a .001" clearance.
Being that the tolerances were so tight, I designed the QD socket feature with a through-hole such that any debri (sand, dirt, and such) can simply be blown-out and not allowed to accumulate.

Here is a pic of one of the VLTOR heavy duty sling swivels with a 3/8" shank diameter (actually .3730" mic'd):



Now, the rotation limiting design feature within the socket hole...
It is designed in such a manner that if you insert your QD swivel such that the loop ring is coplanar with your rifle bore axis (i.e. "horizontal" ) you'll have a rotation limit approximately +/- 30 degrees from the "horizontal"



Counterclockwise limit from horizontal:



Clockwise limit from horizontal:



Conversely, if you insert your QD swivel perpendicular to you rifle bore centerline, it will result in a rotational limit +/- 30-degrees from the "vertical":



Counterclockwise limit from "vertical":



Clockwise limit from "vertical":



In addition, this is a Blue Force Gear Female Fastex Adapter with a heavy-duty push-button swivel:



It mic's right on at the .3730" nominal dimension that best fits my QD sling loops:



It drops right in:



So now the Magpul PRS stock can be used directly with a number of Blue Force Gear series of single-point slings, including the SOC-C Sling, the Vest/LCE strap, and the UDC sling.

http://www.operationparts.com/PhotoGallery.asp?ProductCode=CONPAK-OD

http://www.operationparts.com/PhotoGallery.asp?ProductCode=SOC-C-V-CB

http://www.operationparts.com/BLUE_FORCE_UDC_ONE_POINT_SLING_PUSH_BUTTON_BLACK_p/udc-pb-bk.htm

I am not a high-speed-low-drag guy (more of a mechanical engineering geek) but you could conceivably even use a single-point sling in conjunction with a two-point sling...

Allowing you to carry or rest the rifle on the single-point sling, yet allows you to instantly disengage the fastex buckle and go to your two-point or sling:



Combined with any number of pic-rail QD swivel adaptors up front (in this case a daniel defense version) any number of two-point slings can be used, pictured is a Turner Saddlery all-weather national match sling:



But ANY two point sling with HD sling swivel adapters can now be used in conjuction with the Magpul PRS stock, such as the Larry Vickers Combat Applications sling with two HD QD sling swivels on the ends::

http://www.operationparts.com/PhotoGallery.asp?ProductCode=VCAS-PB-FG

Or the TAB gear sling with the heavy-duty QD sling swivels (my personal favorite sling...LOVE TAB gear stuff from Rifles Only!):

http://www.riflesonly.com/store/TAB/sling_big.html






edwin907
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Posted: 2/7/2010 2:57:39 PM EST
Originally Posted By ARctangent:

Yes, you are confirmed. Package was sent with two of the QDSL's inside.
Everything went out this morning via USPS first class mail.

Confirming beta-testers:


If you are willing to sell these, I'd certainly like to get a pair of them for my stock.

MudBug
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Posted: 2/7/2010 3:02:51 PM EST
I'm so glad you mentioned the Rotation limiting design. I thought for sure that would be the first change I was gonna suggest since it's often left out of QD mounts. Nice job of thinking the whole thing through.
"War is less costly than servitude. The choice is always between Verdun and Dachau." -Jean Dutourd

www.450bushmaster.net
ARctangent
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Posted: 2/7/2010 3:53:03 PM EST
[Last Edit: 2/7/2010 4:38:01 PM EST by ARctangent]
Originally Posted By MudBug:
I'm so glad you mentioned the Rotation limiting design. I thought for sure that would be the first change I was gonna suggest since it's often left out of QD mounts. Nice job of thinking the whole thing through.


Thanks!
I tried to come up with the best design possible...
You'll be receiving your set by the middle/end of the week.

My hope is that:

People who were on the fence about buying a Magpul PRS stock (because of the severely limited sling options) will be prompted to buy them up (lets face it, it is quite possibly the best stock ever designed for scoped AR's).
I foresee a lot of single and two-point slings being sold along with heavy duty QD swivels when news of my parts catches on...

Though it happens all the time, hopefully somebody won't rip off my design and I'll be able to make a few bucks...hell I'd be happy just to break even at this point.
ARctangent
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Posted: 2/8/2010 9:11:15 AM EST
Originally Posted By edwin907:
Originally Posted By ARctangent:

Yes, you are confirmed. Package was sent with two of the QDSL's inside.
Everything went out this morning via USPS first class mail.

Confirming beta-testers:


If you are willing to sell these, I'd certainly like to get a pair of them for my stock.



Willing to be a beta-tester?
One last set available.
ukdaver28
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Posted: 2/8/2010 10:15:47 AM EST
Originally Posted By ARctangent:
Originally Posted By edwin907:
Originally Posted By ARctangent:

Yes, you are confirmed. Package was sent with two of the QDSL's inside.
Everything went out this morning via USPS first class mail.

Confirming beta-testers:


If you are willing to sell these, I'd certainly like to get a pair of them for my stock.



Willing to be a beta-tester?
One last set available.


I am so willing to help you out.... Dam I wish Io had seen this product sooner..... I just bought a UBR cause my PRS did not have flush cups....

Please contact me ASAP and GREAT job love stuff like this.



ARctangent
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Posted: 2/8/2010 10:24:20 AM EST
Originally Posted By ukdaver28:
Originally Posted By ARctangent:
Originally Posted By edwin907:
Originally Posted By ARctangent:

Yes, you are confirmed. Package was sent with two of the QDSL's inside.
Everything went out this morning via USPS first class mail.

Confirming beta-testers:


If you are willing to sell these, I'd certainly like to get a pair of them for my stock.



Willing to be a beta-tester?
One last set available.


I am so willing to help you out.... Dam I wish Io had seen this product sooner..... I just bought a UBR cause my PRS did not have flush cups....

Please contact me ASAP and GREAT job love stuff like this.





IM sent.
kingston
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Posted: 2/8/2010 10:41:01 AM EST
[Last Edit: 2/8/2010 10:59:22 AM EST by kingston]
Got my beta set today in the Mail. They look great. The first thing that I noticed was the swivel stop limit milled into the bearing races. Unfortunately the two QD Sling Swivels that I have are too big and will not fit. I just place a large order with a bunch of swivels and slings. I will post pics when they arrive. Just FYI, the two that I have are not marked, but came with my Beretta Xtema II shotguns, these are the ones that do not fit. These measure .3740 and the mount measures .3750 on my Mituoyo CD-S6"CT calipers.

ARctangent, check your PMs and Email...
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