SS's New Build

[blue109]

Doubt it does anything other than tighten up the fit, but I like it. My Fulton has a tiny wiggle and it bugs the crap out of me. I've honestly considered buying a new upper to swap in.

[survivalshop]

   I only have one receiver set that is tight & that is when I put a flat top Tactical Machining Upper on my Oly. Preban & since it had A2 sights from the day I built it , can't compare it to the scope I put on .

  All my Receiver sets , no matter what Caliber or how they are made ,have a little play & they all soot good , better than me , thats for sure . <dontknow>

[jtallen83]

   Maybe you got a bad one , this one is solid as a metal one , maybe more . We need more reviews .

   I would call or email them with your observations , hell ,maybe its the color  <laughs>

Got a reply to my email already;

 

" Thank You for your purchase. Strike Industries Ultimate Dust Covers have been tested and fits great on almost all the AR-15 Platforms, However when it comes to the AR-10 Platform we have noticed some variances in receiver design and specs making exact fitment hit or miss. Feedback from our customers has varied from quick installation to minor fitting needed such as sanding or shaving of material. Do not be afraid to modify the dust cover as needed but if it doesn't work for you we will gladly refund your purchase. As to the possibility of you receiving a counterfeit Dust cover, The Ebay re seller you purchased from is one of our oldest and best customer so please continue to purchase with confidence. Ebay has been removing alot of our products from there site because of their views on the second amendment and firearm related products.  If you have any more questions or concerns please let us know. 

Thank You, MILLER"

 

Appears to be very good customer service. I'll shave away till I get a good fit.

[survivalshop]

  Appropriate response , we all know how the differences in the 308AR manufactures vary  & I guess we shouldn't be surprised . I've got at least three AR 15 Uppers that need Dust Covers when I get that far . With the Strike Industries  Covers , the DC can wait till the last order for Parts ,because of how they are installed , I like them , we will see how testing goes .

[98Z5V]

  What size is in that Matrix ?

 

I'll pull it tomorrow and post up here.  Does it make a difference in accuracy?  It won't.  All it does it put preload in the rear lug of the upper, and keep the set from wiggling, if the set would wiggle.  It just helps a solid lockup.  Nothing more.  It tensions the upper/lower fitment.

 

If someone should hop in here and say it helps accuracy, I have to ask them "how would it do that?"  It's not fitting the barrel to the receiver any different, not changing headspace, not affecting hammer lock time, not affecting how the BCG rides in the upper receiver, etc.  It won't affect accuracy in any way, either good or bad.  It just makes the receivers lock up tighter when pinned in place.  Better tahn using an AccuWedge - which doesn't affect accuracy, either. 

 

Damn nice to see it in a factory set, though - WAY better than popping something open and finding an AccuWedge.  Also better (IMHO) than a teflon-tipped tension screw through the lower... 

[blue109]

I have a foam ear plug smashed under the rear lug of the 18" gun lol

[survivalshop]

   Got my new Criterion Barrel today & its a nice piece of work , as you would expect , I have to head space the test Bolt I have & its ready to go , mocked it up & I'm impressed .

 

First Barrel I have purchased that came with the dimple for a set screw Gas Block 

 STD AR 15 Rifle gas tube measures 1" past Barrel Extension

 

  I wil order a new bolt from Wilson tomorrow , going with Nitrated.

Edited July 24, 2015 by survivalshop

[unforgiven]

Very nice brother. ^-^

[blue109]

I really dig the exposed gas block look. Kinda sick of seeing the super long rails. Nice build.

[survivalshop]

  My belief is that of two reasons , I believe it runs cooler with it exposed, all three of my 308AR's are exposed  ( heat reflects back off the inside of the Hand Guard ) & its much easier to take off , if need be .

 

  I knew there was a reason I didn't want to go to the range today to try out my new Chronograph . Now I can try my new ( some what new ) rifle out . 

 

  This is also my first Nitrated Barrel , Josh said it may take longer to break in , we shall see . <thumbsup>

Edited July 24, 2015 by survivalshop

[survivalshop]

  I assembled the rifle today & will take some photo's at the range , because they come out so much better . 

  I did find out something today testing feeding with different Manufacturers Mags. As those here know this CMMG Lower Receiver will not function properly with PMags & today I actually see why . I did some work to tighten up the Receive set a while ago & redid it a couple of months ago , removing the Bedding for the real Lug of the Upper receiver . It was set up from an article I have on bedding the Rear Lug & using 0.004- 0.007 " of shims to make sure there is room for disassembly . 
 Well I removed the old Bedding & this time I did something else , I found the front Pivot area had about 0.010" of play ( Total ) I got some Revolver Cylinder Shim bearings , made of S.S for single actions , I believe , the Bearings are 0.004 " , After altering the center hole for the Pivot Pin to fit , I placed one on each side & that worked real well for tightening up the play & for better centering of the Upper & Lower Receivers . I then bedded the rear lug again, this time not using any shim stock . I did this because the problem with the PMags was the Bolt passing over the right Cartridge in the Mag. , surprisingly that round has the hump or higher level of the Follower under it , strange . Feeds the left one on the lower side of the Follower , but misses the right one .

  So basically the Mag is sitting too low in the mag well to feed properly , now I will also add here that the rifle functions flawlessly with any Metal Mag . that I put in it , so its just the PMags . I tried a Amalite Mag catch & there was no change in the feeding function , so today with this rifle rebuilt & shimmed up , it functioned with my dummy loads with any Metal mag . I tried , but the Pmag was still a no go , I could get it to feed from the right side if I held up or pushed the rear of the mag up , maybe I need to try the Armalite Mag Catch again .

 What I did today was try one of the Gen.3 25 rd. Pmags & they worked flawlessly . My other Pmags are first Generation & I think they changed something in-between the two .

 Is there a Gen 2 Pmag ? I'm not sure , should be unless they went from 1 to 3 ? <dontknow>

[survivalshop]

 There are differences between the cartridge height of that right Cartridge in the Gen 1 & Gen 3 PMags & there is a difference in height or distance of where the mag Catch indentation is between the two PMags ( Gen 3 is also reinforced compared to the Gen 1 ) . I measured from the top lip of the Catch indentation & the top of the feed lip .

 

Mag Catch indentation :

 

Gen 1 = 1.148" +/-  

 

Gen 3=  1.168 " +/- 

 

 I also measured the distance from the Lower receivers Deck to the top of a loaded mag with two rounds in it to have the round on the right side of the mag.

 

Gen. 1 = 0.393" +/-  

 

Gen.  3 = 0.454" +/-

 

 As you can see the Gen. 3 is set up to have the mag higher in the mag well , in which its set that right cartridge up higher in the path of the Bolt for it to be grabbed & fed into the chamber . These readings are not exact , but as good as I can get with my Digital Caliper & I was going to set up a dial Indicator , but after these initial readings , I see no need to . I have all the other readings I did when I first measured all the mag manufacturers I have . I have a post on it some where around here , but will dig them out & re-post for comparison.

  I found this very interesting , I could see when I was working the charging handle & looking in the Ejection Port , the Bolt was just barely touching that right cartridge with the Gen1 , but would roll over it & miss it .

[jtallen83]

  My belief is that of two reasons , I believe it runs cooler with it exposed, all three of my 308AR's are exposed  ( heat reflects back off the inside of the Hand Guard ) & its much easier to take off , if need be .

 

Just curios if that is a 12 or 12 1/2 inch rail on your latest build here? I'm going with a 16 inch rifle length gas system and want about the same exposure you have on your gas block, I'm thinking a 13.5 inch rail may cover it but I'm not sure. I'm still researching into going with adjustable GB or just a standard low profile but either way I'm thinking I like the advantages to leaving it exposed. I've got short arms so I don't really need all that length anyway. Any rail of GB suggestions will be respectfully contemplated........

[blue109]

13.5 Will cover the gas block. 12 or 12.5 are usually right up to gas block. Sometimes that extra half inch in the description depends on how they measure it. My PRI rails are listed as 12.5 and expose the gas block. Look for it to specify "rifle length"

Edited July 26, 2015 by blue109

[98Z5V]

   Is there a Gen 2 Pmag ? I'm not sure , should be unless they went from 1 to 3 ? <dontknow>

 

No Gen 2 for the 308 mags.  The first series of LR20 Pmags were actually using the 5.56 Gen 2 tech - 5.56 Gen 1 Pmags had some issues in some rifles.  LR20 introduction incorporated what the Gen 2 5.56 mags improved on already.  They just didn't call the LR20 a Gen 2 mag, because it was a brand new introduction.

 

After the 5.56 was upgraded with the Gen 3 improvements, they moved those improvements over to the LR mags.

[survivalshop]

  Well as far as this old version of the CMMG Lower is concerned , they made it better or should I say more functional . Hasn't been tested on the range yet , but by just cycling it , it should function fine.

 

  All my 308AR Hand Guards are 12" , I can see why some would want the Hand Guard over the Gas Block , some shoot with their hand out that far . It does add a little weight to it , may not be much , but it is weight , some thing the Barrel end of these beasts don't need .

 

  Weight is under 11# ,with out mag on this rifle .

[survivalshop]

Here's the measurements I took from various mags for the 308AR I took a couple of years ago when I got LRPMags & tried them with this CMMG Lower when I had the 16" bbl. with it .

 

Lower Receiver Deck to top of Cartridge case ( Loaded round in the right position of the Mag.)

 

CMMG Lower - Gen. 1 PMag             -  0.396"

CMMG Lower - CProducts Mag ( org)-  0.405" ( note that these CProducts mags are from the original manufacturer )

CMMG Lower - DPMS Mag.               -  0.403"

As you can see it didn't take much for the PMag being lower in the Mag well for it not to function , because the CProducts & DPMS Mags worked fine.

 

Here are the same readings from a DPMS Lower Receive & all Mags work in the Receiver(s) , because I have two.

 

DPMS Lower - Magpul Gen.1Mag      - 0.412"

DPMS Lower - CProducts Mag (org. )-  0.424" ( note that these CProducts mags are from the original manufacturer )

DPMS Lower - DPMS Mag.               -   0.454" ( note this is the same height as the new Gen 3 Pmag in the CMMG Lower Receiver )

 

 With no MilSpec standard on the 308AR"s I can see the differences , The MK 3 CMMG Lower Receiver being off just enough to have a Mag brand not function reliably , we are only talking about a few thousands of an inch, to make it not work . I give Magpul a  <thumbsup>  <thumbsup>  for making the Gen 3 mag sit up higher for it to work in this early CMMG Lower that was made before the 308LR PMag was on the drawing board . This Lower was made before CMMG made complete rifles also .

  There may have been problems with other Manufacturers that we don't know about , but you think we would have heard of something . 

  The Cartridge on the right side is the one FTF , the left one feeds with out a problem , I find that odd & will look into it , I have my suspicions of why . 

[survivalshop]

 Range session today was OK , the Magpul Gen 3 PMag , still gave me fits , it worked for function of FCG testing , but went down hill after that . The right round in the Mag. is being grabbed by the BC instead of the Bolt & it wedges the round in the feed ramp , just like before  , so I can say that because of Tolerance stacking , the Bolt is some times passing over the Base of the Cartridge case , as it has done since I first tried these PMags . What also surprised me is my test CProducts mag . failed to feed in the same way also , this mag has been used a lot , so it doesn't  surprise me . I did have a couple fail to Eject at first , but only had one or two with the first two or three Mags .. I have three or four bent M80 rounds I have to pull the Bullets to re-size the case to straighten them out to shoot them.

  So out came my DPMS test mag, not used as much as the Cproducts , but still has had a lot of use & the rifle functioned with out a problem , note that I had already dumped off about 80 rounds already ,mostly M80 Ball & I did switch to 155gr. Hand Loads & then some 168 gr. SMK's , but had no more Malfunctions. I was popping off two ,three & five shot & sometimes more shot strings . Another thing is I gave this rifle no time to cool off , except once I changed to the CProducts mag., I put a couple of dry patches down the Barrel & lubed the BCG up , but it was load the mag & shoot .

 

  This rifle has not passed my three mag dump test yet , but at the end of my ammo that I brought along with me  ,I think it will . I did have about forty rounds of Barnes 168 gr. Tactical with me ,but didn't want to just dump them .

 

   I do think some of this has to do with how tight the gas ring fit is , so when I got back I took some measurements ;

 

   DWilson Bolt Ring Diameter        - 0.662"

   brand new DPMS Ring Diameter - 0.664"

   Test DPMS Bolt ring diameter     - 0.648" ( slightly worn  <laughs>,no wonder they fit easy  )

 

 

   I will put some more ammo through this rifle & break out some new in the wrapper DPMS mags.& a new test CProducts mag.I did notice , as I did before is , the raised part of the DPMS Mag is opposite of the PMag. , PMag is on the right of the Follower & the DPMS is on the Left , wonder if that is why it feeds better  <dontknow>  I have to look at The CProducts mag.

 

  I posted some photo's & measurement differences in the DWilsons Bolt Thread .

[survivalshop]

  I just checked the Gen 3 20 rd. Pmags & found something interesting , the 20 rd. Mags are difficult to insert into all three of my 308AR's , two DPMS Lowers & this CMMG Gen 2 . They will not drop free & have to be pulled out . I tested feeding with a 25 rd. Gen. 3 Pmag  the other day when the DWilson Bolt came & since I already had a 20 rd. Gen 3 in my Bag , I used it at the range yesterday , now I'm wondering if that makes a difference , so , I have a new in the wrapper Gen. 3 , 20 rounder & unwrapped it & it too is hard to get in the mag wells of all three rifles & in no way will drop free . My two 25 rd. PMags fit fine & drop free, WTF?  Some strange stuff going on here, I think Pmags have something against my high $ CMMG Lower Receiver . <laughs>

 I also checked a bunch of the first Gen. 20 rd.  Pmags & have no problem with them & they drop free . I have brought this up before , Magpul is the only one of four manufactures Mags. that have the high side of the Follower on the right , all others are on the left . I ordered four Lancer Mags & we will see how they work & are made .
 

 I'm going to email Magpul & see what they have to say . 

Edited August 1, 2015 by survivalshop

[98Z5V]

SS, check the "over-insertion" tab on the back of the G3 mag - on the 5.56 side of the house, that tab interfered with my Noveske FFL lower, and I had to trim down two of those mags to run in that rifle...

[survivalshop]

   The mags are rubbing on the sides , it seems like they are bowed out in the middle . I'll take a photo , you can see where they are rubbing . I emailed Magpul & asked whats up with these two mags .    

 

  It starts to stick at first insertion into mag well & gets harder as you go , maybe that stop tab is also binding , but its happening from the beginning .

 

  This is what i was talking about with the Followers on all the different mags , the PMag is the only one with the raised portion on the right , I really do not see how that would matter though , as far as feeding ?

[NTXshooter]

Check the width of the Gen 3 mag against a Gen 2.  I think you will find that those ribs make them wider.  My ShadowOps lower will feed Gen 2 just fine but will not feed the Gen 3.  Even after I took a Dremel to the Gen 3, I still have problems with the Mag Catch locking them in place.

[98Z5V]

    This is what i was talking about with the Followers on all the different mags , the PMag is the only one with the raised portion on the right , I really do not see how that would matter though , as far as feeding ?

DSCN2544.JPG

 

It won't matter - militarily, the raised portion was always on the right side, until the military copied MagPuls follower design, directly, with the exception of putting the "new" follower raised portion on the left...

[ChaseFan9]

Have you left the PMags loaded for long periods of time? Maybe the spring tension opened up the top of the mag a little bit. That's what those little "dust cover" thing is really for, right?

[survivalshop]

  Brand new in the wrapper mags , one was just put in my Range bag & the other I opened up to check it out & it too had the same problem . Mags were never loaded before . The two Gen 3 25 rd mags I have , have no such problem .

 

  I could be wrong in my theory , but I believe the Magazine needs some play with in the Mag well for proper function , a little play , if you will . I think if its so tight of a fitment , that in its self can cause misalignment . Check the fitment of all your mags in the mag well , do they have movement or play with the BCG locked back ?  Should have if you expect them to drop free , with the push of the mag release button . <dontknow>

 

  Up until this one CProducts Mag failing once the other day , I have 100% reliability with metal Mags , with this Lower receiver & yes I have tried two complete DPMS uppers on this Lower with the same results , crazy isn't it .

Edited August 3, 2015 by survivalshop