Receiver Compatability

[D.R.D.]

This may have been addressed before, but I cannot seem to find the thread about it.

I've got one of the last generation SI Defense upper receivers (DPMS High pattern), before they transitioned into Falkor Defense.

I cannot find any SI lowers available to match it, nor does Flakor offer the lowers only on their site, only matched sets.

What other lowers has anyone used that will run reliably with the SI upper?  I though I recalled reading about feeding issues with certain mags.  Anyone have any ideas?

Thanks!

[98Z5V]

This just came up in the last couple weeks - it's really the only one we've dealt with so far. 

 

[survivalshop]

52 minutes ago, D.R.D. said:

This may have been addressed before, but I cannot seem to find the thread about it.

I've got one of the last generation SI Defense upper receivers (DPMS High pattern), before they transitioned into Falkor Defense.

I cannot find any SI lowers available to match it, nor does Flakor offer the lowers only on their site, only matched sets.

What other lowers has anyone used that will run reliably with the SI upper?  I though I recalled reading about feeding issues with certain mags.  Anyone have any ideas?

Thanks!

  I had a GenII SI Defense on an Early Billet CMMG Lower & it had issues with the original LR PMags , but would work fine with any Metal Mag brand & Lancer L 7 mags . The Upper also worked on my DPMS Lower , with all mags . The early CMMG was designed & made long before Magpul came out with their LR PMags. The Gen 3 LR PMags worked fine in this rifle . Magpul made some changes to the new Gen 3 .

[D.R.D.]

Has anyone you know of had success mixing and matching with an Aero M5?  (Please don't tell me I'm invoking the "rule" ;-)

 

[98Z5V]

4 minutes ago, D.R.D. said:

Has anyone you know of had success mixing and matching with an Aero M5?  (Please don't tell me I'm invoking the "rule" ;-)

 

Well, in the thread I linked, that was on a DPMS (actual) lower receiver.  Aero is DPMS-based.  I'd risk it. 

[D.R.D.]

Good to know.  This will be for a 6.5CM build

[EngrBob]

I used an Aero M5 upper with a Blitzkreig 80% lower on my .338 Federal build.  Fits and works perfectly.  Keep in mind that an Aero M5 upper is a DPMS high profile so you need to consider that when choosing a handguard.

[D.R.D.]

I already have the upper.  It's SI Defense (also DPMS high).  A compatible lower is what I'm looking for

[survivalshop]

1 hour ago, D.R.D. said:

I already have the upper.  It's SI Defense (also DPMS high).  A compatible lower is what I'm looking for

 Areo has a complete Lower on sale today https://aeroprecisionusa.com/m5-b5-bravo-complete-lower-black.html?sc_src=email_1858300&sc_lid=116340024&sc_uid=6WmFcKFmPv&sc_llid=21183&utm_source=Emarsys&utm_medium=email&utm_campaign=Weekly+Special+-+M5+(.308)+B5+BRAVO+Complete+Lower+Receiver+07.17.172017-07-17+18%3A04%3A00&sc_eh=dccc4f5c6385104f1

[D.R.D.]

Good deal...I only need the receiver, though.  I'm thinking of a PRS stock and trigger tech 2-stage for it.

BTW, anyone know what the best buffer weight is for a 6.5CM out of a 24" barrel (~140gr)?  Would it benefit from a heavy buffer, or would an adjustable gas block be sufficient?  

[survivalshop]

  Any for a 308AR should work , you have to start some where , you can always go to a Heavy Buffers, Buffer , if needed , or as you say , start off with one . The 140 gr. load will have less recoil impulse then a 175 gr. 308 , I would think , it would have somewhat the same Chamber pressure ( something that you would need to look up  ) so basically the same  Chamber pressures involved , so go with any 308AR Buffer system , AR 10, DPMS or Heavy Buffers . your call .

https://www.americanrifleman.org/Webcontent/pdf/2009-6/200961145351-hornadycreedmoor.pdf 

 

308 Winchester Reloading Specifications:

Centerfire Rifle Cartridge Reloading: Equipment Procedure Case Primer Powder Bullet Load Testing Run-Out Calculating Kinetic Energy. 308 Winchester Cartridge: Bullet Diameter - .308". Primer Diameter - .210". Primer Type - Large Rifle. Case Neck Diameter - .343". Case Shoulder Diameter - .454". Case Base Diameter - .471". Case Rim Diameter - .473". Min. Case Length - 2.005" / Trimmed. Max. Case Length - 2.015" / Stretched. Min. Cartridge Loaded Length - 2.490". Max. Cartridge Loaded Length - 2.810". Max. Average Pressure - 62,000 PSI.

 

[guruofhotrod]

These guys have one of the better deals going on an Aero Stripped M5 lower:

http://www.schuylerarmsco.com/product.m5-308-stripped-lower-receiver-10-993

[D.R.D.]

Thanks.  I called Falkor again.  Seems they are fresh out of receivers but will probably be making them again for sale as sets and as single lowers too.  We'll see...