DPMS Type High profile rail height

[blue109]

nice job Odin!

[survivalshop]

 So if I'm reading your issue correctly , the Upper receiver has the bore for the Barrel / Extension , is higher then a std 308AR Upper ? Or is it just the rail height to Barrel center bore that higher & the rest is normal ?

   

    If its the the  Barrel center line .

   Higher or lower , that adaptor may work as far as lining up the Hand Guard rail heights , but what about the BCG bore in the Upper to the Receiver Extension on the Lower receiver . That Upper receiver on any 308AR lower will not line up as it should & the BCG will be no longer in a " line bore " from the Upper to Receiver Extension & it will bind or hit the Receiver Extension some where its not supposed to.

   How about the barrel center line to pivot pin & or Disassembly Pin ?

 

  Maybe I'm reading that solution wrong  <dontknow>

[guruofhotrod]

Interestingly enough I've assembled the components including the barrel (held in with the special Samson DPMS thread barrel nut) to check the fit of everything and the bolt lugs engage nice and smooth, lock in to battery just fine, I can rack the charging handle and it doesn't bind or misbehave - the bolt carrier runs the hammer back properly, doesn't bind in the receiver extension, the gas tube is aligned well, perhaps it's simply a matter of the rail and top portion of the upper being .020" too low - I'm  not sure how much room there is between the end of the charging handle (where it catches the bolt key) and the top of the bolt carrier?

The "tongue" above the charging handle measures .205" thick and I've come up with a measurement of 1.3005" for the barrel centerline to the top surface of the rail on the upper receiver. (Tom from Odin indicated that this is .018"-.020" lower than the high profile uppers that they designed their handguards around.) I'll measure the distance of the barrel centerline to the pivot pin center and post it up tomorrow but, I'm strongly suspecting the discrepancy is simply in the rail portion of the upper 

Edited March 9, 2015 by guruofhotrod

[FaRKle!]

How are the bore center lines of all the receivers compared to the bottom of each receiver?

[guruofhotrod]

I've only got one with me here at work (the one from arms unlimited) the measurement from the barrel centerline to pivot pin center is 1.006"

from barrel centerline to bottom surface is .7495" - I'll try to measure the ares tonight (I have to remove the Samson rail and the barrel first)

 

Thanks for the help in keeping me out of trouble <thumbsup>

[912dawg]

I've been trying to decide on a hand guard/forend for my SI-D build. I really like the look of the ODIN Works, but after reading this thread I'm a little worried. What I gathered was that the Odin didn't quite line up because of the specific upper it was being attached to. Is it safe to assume the Odin would line up correctly on an upper produced by a company like SI-D or Mega or Aero?

[guruofhotrod]

Should be no problem with SI or Mega, I would expect the Aero would also be good to go but, to be on the safe side I would give them a call 

and try to get Tom Hines on the phone to confirm that they have checked out a representative example of the brand of upper in question - the nice thing about the Odin is the way they offset the hole for the barrel nut in their adapter thus in theory being able to make an adapter to compensate for variations in rail height.

 

Edit: Just saw something very interesting, the Diamondback DB10 comes factory equipped with the Odin Keymod forearm and guess what?

There is the same rail mismatch between the upper and the handguard/forearm meet (visible at the 1:55 point in the video) I'm gonna have to give them (Odin) a call today and see what's going on with this

 

 

 

https://www.youtube.com/watch?v=CbaXLIhZLF4#t=72

Edited March 11, 2015 by guruofhotrod

[912dawg]

Guru,

Thanks for the info man! That makes me feel a lot better. It sucks that you had to go through all that, but I'm glad we were all able to learn from it.

[guruofhotrod]

Wasn't able to get Tom from Odin Works on the phone but, I sent an email out to him with the you tube link to the Diamondback promo vid

noting the 1:55 point where the upper receiver/handguard mismatch is noticable - I may give Diamondback Firearms a call monday for their

thoughts and possible solution - I can't imagine customers will just accept this on a $2600.00+ rifle

 

https://www.youtube.com/watch?v=CbaXLIhZLF4#t=72

[guruofhotrod]

Well, turned out ODIN seems to be kinda backed up in production and I really want to get this project wrapped up so, I was able to get a 

PDF of the blueprint of the adapter for the DPMS high pattern upper. With that I drew the part in Mastercam with the exception of moving 

the barrel nut threaded hole and gas tube hole up .020" then loaded up one of the Haas CNC Mills at work with the needed tooling and 

the program I generated and proceeded to cut a few adapters with the needed dimensions:

 

 

I still have to set up a fixture to properly locate the 6 #10-32 threaded holes to retain the handguard to the adapter (tried to drill/tap

them off of centerpunched locations in a rush yesterday and 4 of them had the drill "walk" on me resulting in improperly placed holes

seen in the pics but, most importantly the mismatch is resolved!  :banana: so, now I can finally get things completed! 

 

And, a couple pics of the engraving I did on the Ares 80% lower, I guess you could call it the "unofficial 308AR.com 308AR"

 

 

While I was at it, I didn't like the idea of using an open ended crowsfoot wrench to torque the barrel nut so, I drew up a nice boxed end crowsfoot wrench

in the "FLOW" waterjet program and cut one out of 1/2" 4340 plate

 

 

Edited April 11, 2015 by guruofhotrod

[blue109]

well that's handy!

[AngelDeVille]

I had the opposite problem with a DPMS upper that sat higher than my hand guard rail.

[survivalshop]

  Good job , but a lot of work for a hand guard that should fit from the Manufacturer . Sure is nice having a CNC around  <thumbsup>

[stingray230sx]

this is still an issue I guess......back in late 2013 I had built my first AR15 and was then looking into an AR10 to build, and I ran into all the differences / components etc.....in Jan/Feb 2014 I was starting to collect parts and 2 years ago most upper/lowers were backordered and when a SunDevil mfg set came up in their "devil coat" on a local social media gun site, offered by a local national guardsman / FFL holder seller, I kept my eyes out and ended up buying it for 550$,  then scoured the web trying to figure out exactly what height my upper "was" and "needed" in the form of a handguard.

SunDevil says their slick side upper uses the post 8/2009 "low" rail height at 1.253 so after searching I went with APEXMACHINE 15" rail for the post 2009 rail [ with the bore to rail measurement at 1.253] I actually wanted another rail, [Sampson I think, but it was 2 years ago, so not sure now] however it wasn't available in the "low" height so this is what I went with. I had already bought most everything else before the handguard so I was kinda chomping at the bit so to speak to get it done.

I had changed handguards twice on my AR15, ending up with a Diamondhead and I also wanted it for the SunDevil receiver but they indivated it would be a while, so I bought the APEX and I have the same issue as the OP, it is "NOT QUITE" and exact match, but I cant machine anything and was doing other things and didn't want to by several 200+ handguards just to get one to fit "exactly" so im living with it, a couple pics but with my crappy iphone4 so hopefully you guys can see the slight difference in the rail to guard height.

I want to build another with the Diamondhead guard for a 308 but most uppers I see are still backordered and are the DPMS "high" or pre 8/2009 height [APEX states the "high height is 1.313 at the center bore to rail]  Diamondhead says theirs is for the "low" height at 1.250 "range" lol.

still looking for an in stock upper/lower set and then I will have to choose I guess......

[guruofhotrod]

Doesn't the Apex have a separate top rail that you could remove? From the pics it appears that the rail on the handguard it the higher of the two.

Perhaps you could remove it and machine or have machined the amount of the mismatch from the bottom of the rail section so that when re-attached

the top surface will match the rail on the upper.

[stingray230sx]

Doesn't the Apex have a separate top rail that you could remove? From the pics it appears that the rail on the handguard it the higher of the two.

Perhaps you could remove it and machine or have machined the amount of the mismatch from the bottom of the rail section so that when re-attached

the top surface will match the rail on the upper.

yes, the top rail was an additional expense, and I have asked them about it but they defer to variances in the uppers mfg'd by different companies, I will have to look into local machine shops to see if I can have it done.....

[st.attila]

I have the exact condition described in the original post.  Using my digital calipers (purchased in 1989 and not recalibrated since), I measured .022 inches proud of my DPMS A3 High Profile receiver manufactured in 2008.

 

I e-mailed Odin Works on July 22, 2018.  Not receiving a response, I followed up with a call on July 27 in which I spoke with Mitch in customer service and he said my e-mail was forwarded to production for investigation.  I intentionally didn't mention that I had already come across this post.

 

I called on August 10 and spoke with Mitch again.  He offered up a long list of possible reasons why there might be an issue.  He offered to measure my adapter to determine if it was manufactured correctly.  If I understood him correctly, he also offered to measure my upper receiver to determine if my receiver bore was non-standard.  I declined.  I told him that I believed his adapter was manufactured to Odin Works' engineering specifications.

 

I then decided to mention this thread and Tom Hines.  He told me he would ask Tom on Monday (8/13) if he remembered this inquiry.  I have yet to receive a response.

 

I'm not sure if Odin Works will make any attempt to address this issue.  I'm getting impatient to correct the issue.  I used to be able to use the most forward picatinny rail slot for my scope prior to the change in forend.

Edited August 16, 2018 by st.attila

[st.attila]

I thought I would post an update, but there is not much to report.

I called back on August 27, and left voicemail for Mitch.

I called back on August 28, and left voicemail for Mitch again.  This time he returned my call.  When I asked if he spoke with Tom, he said yes and that Tom remembered the interaction with guruofhotrod.  He went on to say there was nothing they could do for me since my receiver rail was was above my handguard rail and the 2.06 adapter was high as they could move the bore line.  I had to remind him that it was my handguard rail that was above my receiver rail using the 2.06 adapter and mentioned he could refresh his memory by looking at the photos I had provided in my initial e-mail.  We continued to talk and I could tell that Mitch just wanted me to go away.  I kept insisting that I was not satisfied and requested the adapter engineering drawing to make my own adapter.  He said creating unique adapters was not something they could do.  I mentioned that guruofhotrod and myself must be their only customers with high expectations because our DPMS receivers were made several years apart and suffered the same condition.  Mitch told me he would see would they could do and he would get back with me.

I called back on September 15 and spoke with Mitch again.  This time he told me Engineering was evaluating what they could do for me.  I pressed for the previously requested adapter drawing, but Mitch told me they would figure out how to satisfy me.  Well, it's September 26 and I have yet to hear from Mitch or anyone else at Odin Works.

Let me add that all conversations between Mitch and I have been cordial.  We just see the situation from different perspectives.  BTW, I haven't given up yet.

[st.attila]

I'm not Paul Harvey.  You know what the news is -- in a minute, you're going to hear [read] the rest of the story.

I called again on November 30, 2018 and spoke with Mitch yet again.  He noted this time I'm now 1 of 3 that has reported this issue.  The last being a call from a Kentucky gun shop working on a customers gun.  Mitch stated that the shop milled the Picatinny rail.  He restated again that he was going to request the engineering drawing for me.

On February 9, 2019, Mitch stated that he was going to request the engineering drawing for me, again.

On March 29, Aaron answered the customer service line.  He remembered Mitch conveying a customer that had my issue.  Aaron and I had a good conversation and he stated he had an early DPMS LR-308 and understood how in the early days how the large platform AR was not standardized, even by DPMS.  He stated he would get me the engineering drawing or have one made and that he would also call me the following week.

On June 11, I called Aaron, but he was out to lunch and I left a message for him.

On June 28, Aaron told me that they were going to make a batch of adapters in 2-3 weeks and they would try to make me one.

On August 15, Aaron called me.  He had made me 2, 2.04 adapters and asked if I still wanted one.  I said yes of course.  I paid him for both, $10 each and $4.35 for shipping.

On August 17 they arrived USPS mail.  I opted to prep and paint one adapter.

On August 18 I installed the painted adapter and as expected, the upper receiver and forend rail align perfectly.  I sent Aaron a note of the outcome and thanked him for providing good customer service.

On August 19 Aaron responded to my note.

I'm not Paul Harvey...and now you know -- the rest of the story.