New to AR-10's: compatibility question

[mekrebs]

Is a BCA DPMS upper compatible with a Noreen DPMS lower?

[98Z5V]

We might never know, unless you try it.  Never seen that combo here before.  It's a risk, but worth trying -maybe.  

Common rule is stick with uppers and lowers from the same manufacturer - then you can blame the manufacturer when things don't go as planned.  

There's no guarantee of compatibility in the Large Frame ARs.  

[mekrebs]

Thanks but already committed.

 They are both supposed to be DPMS Gen. 1 but I'm not sure about the high versus low factor. Or if it even is a factor.

[98Z5V]

Be interesting to see if they fit.  Hope this works - make sure to keep this thread updated, both good and bad.   This is the only way we learn, here.   

[mekrebs]

It's a good omen that there are 6 reviews on the Noreen web site that state BCA uppers work well with this lower

https://onlylongrange.com/100-308-multi-cal-billet-lower-receiver-black-anodized-dpms-pattern/#write_review

[98Z5V]

Worth the risk then.  Go for it.  

[mekrebs]

It's a good omen that there are 6 reviews on the Noreen web site that state BCA uppers work well with this lower

https://onlylongrange.com/100-308-multi-cal-billet-lower-receiver-black-anodized-dpms-pattern/#write_review

 

For the record, here's the BCA upper: https://www.bearcreekarsenal.com/308-22-bn-light-weight-barrel-1-10-twist-rifle-15-mlok-forged-upper.html

"DPMS Gen1 Low Profile model."

[98Z5V]

Let us know how it turns out.  Budget guns have budget problems, most likely in recoil systems and gas systems.  Since you're building it yourself, you can probably avoid those pitfalls, so I'll watch this one, and see how it turns out.  

[mekrebs]

I hope you will keep advising me too. Thanks.  Looking forward to working out The inevitable bugs,with your help.  

[shooterrex]

BCA Creedmoor upper fit an AERO lower just fine for me.

Aero is DPMS pattern.

Edited December 29, 2022 by shooterrex

[mekrebs]

Aereo is what generation DPMS?

[mekrebs]

What is the functional difference between DPMS gen 1 and 2?

[98Z5V]

6 hours ago, mekrebs said:

Aereo is what generation DPMS?

Aero M5 receivers are compatible with DPMS LR-308 patterns, and they're the High Profile, not the Low Profile.  DPMS changed the top pic rail height around 2012-ish, and made it about 0.060" lower.  Here's info on that:

5 hours ago, mekrebs said:

What is the functional difference between DPMS gen 1 and 2?

There isn't a Gen 1 DPMS.  There's the LR-308, which is the original version.  Then, there's the DPMS G II pattern, and that shrinks the receivers to almost AR15-size, and you're supposed to be able to use any AR15 rail on them.  

DPMS G II info:

https://www.americanrifleman.org/content/review-dpms-gii-ar-308/

[mekrebs]

I think I understand the difference in heights of the pic rail between type 1 and 2 but what does that have to do with the lower?  It seems to me that the rail height is an issue with the upper and has nothing to do with the lower. Am I wrong?

 

[98Z5V]

1 hour ago, mekrebs said:

I think I understand the difference in heights of the pic rail between type 1 and 2 but what does that have to do with the lower?  It seems to me that the rail height is an issue with the upper and has nothing to do with the lower. Am I wrong?

 

You were asking about DPMS Gen 1 and Gen 2 - which don't exist.  There is no "Gen 1" or "Gen 2" DPMS guns.  There aren't any DPMS gun anymore, newly produced.  Palmetto State Armory (PSA) bought the brand, when Remington went under, so all the "new" DPMS guns are PSA PA-10 Gen 3 guns.  Which will have problems, straight from the factory.

So, going back, you were asking Gen 1, Gen 2, no such animal, ever.  There's a DPMS LR-308 pattern, and there's a DPMS G II pattern.  That's it.  The G II pattern is smaller than typical Large Frame receivers, because they "Shrunk" the receivers to make it more AR15-like.  They changed the BCG dimensions, the barrel extensions dimensions, the upper incorporates a steel "addition" that's pinned in place to take the place of M4 feedramps -the G II is a completely different gun, the company is gone, there is very little aftermarket support for it - because they went under at a time that the aftermarket wasn't supporting it.  It's timing.  Bad timing. Not enough of them went out the door, in order to support aftermarket support, before Remington went under, for good.

I hope that makes more sense.  All that DPMS G II shiit is in the article that I linked above.  You need to read that linked article, to understand the differences.  It's just that easy, really.  Read the article I linked above.

Edited December 30, 2022 by 98Z5V

[98Z5V]

Post a pic of your gun.  That will solve everything.  

[mekrebs]

I'm on my way to my FFL to pick up my lower.  I already have my complete upper.  So now I can put the 2 pieces together and check alignment.  I'll post pictures.  I also plan to keep a pictorial build diary for a cheap 308 AR so I can share what I learn (via PDF). 

I also bought an Aero m5 lower to compare.  Wgat else might be helpful?

 

BVTW:  I assume you're probably aware of it but Brownells put this out describing the differences between an "Ar10"v vs. DPMS:

https://m.facebook.com/watch/?v=494987281552476&paipv=0&eav=AfYYto5sa0DmApIqlx9m04U-5FJmgQ3qpkLxY7XGcQvoU8iDUY9qDIgIxCzdSeBfk6o&_rdr

[mekrebs]

So far so good.   The 308 Noreen lower fits well with the BCA upper  See pics of both sides an d tell me what you think please.

There's more thickness on the upper than the lower.  Is that to be expected?  But regardless, the pin alignment looks spot on  

And Thanks!

 

Mark

[mekrebs]

I just got done reading this thread: https://forum.308ar.com/topic/25314-noob-308-build-almost-finished/

I bought a 308 buffer ( 3.4 oz and 2.5") and spring from MAS Defense but forgot to get a tube because I thought I already had one.  Well damn I dont.  Back to the store. Am I right that any decent milspec buffer tube should work?  How's the buffer specs sound?

Thanks 

Mark

 

 

[mekrebs]

PS:  I'm basing my statement anbpout buffer tubes on this compatability guide: https://www.primaryarms.com/blog/are-ar10-and-ar15-parts-interchangeable

 

[shooterrex]

That buffer is to light. Your buffer needs to be in the five and a half ounce range.

This buffer,spring,and tube is what the guy that designed the original AR10's came up with. It works.

https://www.armalite.com/SACItem.aspx?Item=AR10REKIT01&ReturnURL=/Armalite/Product-Category/AR10-Parts-Accessories&Category=4eeff98b-d9a6-40fd-be6b-ab2e44ec1080

[mekrebs]

Thanks. I already have some extra tungsten weights

[shooterrex]

Without a stainless buffer body you will still be a little light. You also have no idea whose " milspec 308" spring you are using.

Large frame guns are not milspec anything. They are a whole different animal.

Your bolt carrier group is longer and heavier. You need the proper spring and weight buffer to handle the extra mass.

[98Z5V]

3 hours ago, mekrebs said:

Thanks. I already have some extra tungsten weights

Keep that aluminum-bodied 2.500" buffer - it only fits 2 weights, and they're both tungsten.  That's the only way it makes it to 3.8oz in the first place.  You won't gain anything replacing one of the buffer's tungsten weights with one of the ones you have on hand. 

You can buy a cheap, stainless-bodied buffer from DSG Arms, and it comes with steel weights, weighs 3.8oz.  Swap the tungsten weights into it, and it give you 5.15oz.  That's running in my .260 Rem right now, and still works.  It's at the bottom end of what I'm comfortable with, but it runs. 

Here's the DSG buffer you'd need, and it's $22:

https://dsgarms.com/lower-receiver-parts-dsg-4201-0021

[98Z5V]

5 hours ago, mekrebs said:

PS:  I'm basing my statement anbpout buffer tubes on this compatability guide: https://www.primaryarms.com/blog/are-ar10-and-ar15-parts-interchangeable

 

There are some huge problems and outright errors in that PA article.  There's also alot of information that's pretty good.  I can't overlook the mistakes in the article, though.  I would not use that as a reference, and stand behind what's written in that.

Read this when you have the time.  It breaks it down over months of information-publishing, and after years of experimentation: