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New 20" barrel, now it short strokes


Dracomeister
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6 hours ago, GRA said:

Fulton Armory shows this for their .308 Titan, noting it is .325" longer and also works for Armalite AR10(s):

http://www.fulton-armory.com/gastuberifle-1.aspx 

 They changed their Barrels or the spec's of them a few years ago . I have two Kreiger/Criterion Barrels from them that have AR 15 rifle length Gas Tubes in them & are at the correct position . Both early Barrels before Criterion split from Keiger .

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You're very welcome.  After reading all the issues identified in this thread (which again, I'm glad I caught this thread) from now on when I do a build I'm going to buy the barrel, BCG, gas tube, and most likely the buffer and spring from the same manufacturer (if possible) to at least start with.

I checked Armalite's website and they are out of AR10 rifle length gas tubes however I found some with DSG:

Armalite AR10 rifle length: https://dsgarms.com/arm10007010

Armalite AR10 "carbine": https://dsgarms.com/arm10007005 

Edited by GRA
Corrected links, part numbers
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DPMS BCG ( Actual ) measurements .all photos will follow . I had to hold or apply pressure to the BC to take some measurements & took a Photo after .These measurements are not what I would make a Blue print from , but should be good enough to use for comparison .

BC face to Charging Handle notch   ------ -----------------     0.386"

Bolt Length ( AR 10 & spring loaded FP may be different ) --  2.927"

BC face to Gas Key ( interface with Gas Tube ) --------------  0.304"

BC face to end of Gas Key Base ------------------------------  2.782"

BC face to inner Cam Pin slot ( Locked position ) ------------ 1.155"

BC face to outer Cam Pin Hole ( unlocked breach )----------- 0.475"

Bolt Face to BC face ( locked position , BCG assembled )---- 0.586"

Complete Gas Key Length ( rear base to where Gas Tube enters--2.464"

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Edited by survivalshop
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COOL ... :thumbup:

Maybe I can assist a little bit myself this time.  I just took the following measurements with a tape measure:

BCG Assembly overall lengths (all bolts pushed in):

Factory Armalite AR10: 8 1/2"

DPMS-based .308: 8 1/2 "

Factory Colt AR15: 7 1/8"

Measurements below of the gas tubes inside the upper receivers.  Unfortunately I had to eyeball these with a mic as the mic was too big to fit inside the upper receiver.  This is from the very inside edge of the upper receiver to the very tip of the gas tubes:

DPMS AP4 .308 carbine barrel mounted to a Spikes Tactical forged upper with an AR15 carbine gas tube: .0725"

Armalite model DEF-10 AR10 factory carbine upper (ALL factory parts): 1.1250 "

Armalite model DEF-10 AR10 upper with a factory Armalite 20" rifle barrel mounted with an AR15 rifle-length gas tube: .0725"

 

NOTE: I do not recall which make/model of BCG I'm using in the Spikes/DPMS carbine.  It is a new BCG I bought off of a member selling it via this website way back when I first joined.  If I recall, the seller did indicate that specific information in the as he posted so if a moderator can go back and find this we'll know who's BCG it is.  There is no information at all engraved on this BCG.

I can take other measurements if necessary just give me the specifics on what needs to be measured.

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7 hours ago, survivalshop said:

 They changed their Barrels or the spec's of them a few years ago . I have two Kreiger/Criterion Barrels from them that have AR 15 rifle length Gas Tubes in them & are at the correct position . Both early Barrels before Criterion split from Keiger .

How do you like the Criterion barrels?

I've been eyeballing Criterion .308 16" barrels for a possible Dissipator build.  They currently offer both a mid-length and full rifle length.  I don't know which would work best for the Dissipator since there have been issues with the rifle length gas.  They also offer stainless and nitrided, and stainless-nitrided which costs more.  I don't know if the stainless nitrided would be worth the extra expense.

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1 hour ago, GRA said:

How do you like the Criterion barrels?

I've been eyeballing Criterion .308 16" barrels for a possible Dissipator build.  They currently offer both a mid-length and full rifle length.  I don't know which would work best for the Dissipator since there have been issues with the rifle length gas.  They also offer stainless and nitrided, and stainless-nitrided which costs more.  I don't know if the stainless nitrided would be worth the extra expense.

  I have the two Kreiger/Criterion from Fulton Armory & had a Criterion after they went on their own & all are absolutely better shooters then I will ever be . I had & sold a 308AR with a 18" Criterion Hybrid S/S Nitrated barrel & if you look in the reloading section I have posted quit a bit of Chronograph results & some Target Photo's .

 My 16" has a Rifle Gas system & has not been an issue , the early CMMG lower I had it mated to didn't like the first Gen. LR PMags , but had no issues with Steel Mags or Lancer's . When Magpul came out with the Gen. 3 PMags , they worked in that early CMMG Lower , which was on the 18"  sold & is working fine for the new owner . It only took him a year to talk me out of it .

 Both my 16" & 20" Kreiger/Criterion Barrels are HB versions , I would not hesitate in purchasing another Criterion Barrel .I believe I may have to order an AR 15 barrel soon , I'm still struggling with what Caliber , 25-45 Sharps or something else , all I need is a Barrel & Handguard . I'm in no hurry , overtime I get extra $$ ,life takes it from my toys .:laffs:

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Thanks gents ... now for the decision :evil:

Currently and for the next few days DVOR is offering the following Criterion .308 barrels:

http://www.dvor.com/criterion-barrels-ar-10-rifle-length-gas-system-barrel.html?promotion=criterion-barrels-54-2017-04-09

Unfortunately, the one SS and nitrided barrel they are NOT offering is this one:

https://msrarms.com/collections/barrels/products/criterion-barrels-nitride-finish-stainless-steel-hybrid-contour-barrel-308-ar

So I am wondering if there is any increased benefit to the SS barrel vs the nitrided SS barrel (or vice-versa), as per the increased cost?

Too bad Fulton isn't offering a 16" Dissipator .308 barrel.  It appears they've come up with a modified profile that appears to save some weight.

I tripped the rule months ago so I'm going to make a purchase sooner or later I just cannot figure out how to win at the price game.

Edited by GRA
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Took some measurements on my AR-10 BCG, I used a cheap chinese digital calipers, measured several times till I got two consistent measurements. This BCG has well over 3,000 rounds on it;

BC face to Charging Handle notch   ------ -----------------     0.376"

Bolt Length ( AR 10 & spring loaded FP may be different ) --  2.925"

BC face to Gas Key ( interface with Gas Tube ) --------------  0.3415"

BC face to end of Gas Key Base ------------------------------  2.824"

BC face to inner Cam Pin slot ----------------------------------- 1.1545"

BC face to outer Cam Pin Hole ----------------------------------- 0.455"

Bolt Face to BC face ( locked position , BCG assembled )---- 0.600"

Complete Gas Key Length ( rear base to where Gas Tube enters--2.468"

We need someone smarter than me to put these on some sort of spreadsheet for easier comparison.

Edited by jtallen83
accuracy
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Measured an unused d. wilson 308AR BCG with the same chinese caliper.

BC face to Charging Handle notch   ------ -----------------     0.379"

Bolt Length ( AR 10 & spring loaded FP may be different ) --  2.93"

BC face to Gas Key ( interface with Gas Tube ) --------------  0.305"

BC face to end of Gas Key Base ------------------------------  2.773"

BC face to inner Cam Pin slot  ------------------------------------ 1.163"

BC face to outer Cam Pin Hole ---------------------------------- 0.462"

Bolt Face to BC face ( locked position , BCG assembled )---- 0.583"

Complete Gas Key Length ( rear base to where Gas Tube enters--2.466"

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3 hours ago, 98Z5V said:

I'm not seeing too big of a difference, besides gas key mounting differences. 

  I see some differences & can say I would not use a AR 10 BCG in a DPMS & or a DPMS in an AR 10 . I'm guessing the Barrels Extensions are a little different also , no matter what works or not . 

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What did you see that would cause issues?  I saw a couple thou here or there, but nothing drastic. Well, besides that gas key placement.  I'll look closer at cam pin cutout dimensions, because I could see that causing a problem, one platform to the other.

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On 4/19/2017 at 2:41 PM, jtallen83 said:

 

                                                                                                AR10        DPMS       DW

BC face to Charging Handle notch   ------ -----------------     0.376"  -  0.386"   -    0.379"

Bolt Length ( AR 10 & spring loaded FP may be different ) --  2.925"  - 2.927"   -   2.93"   

BC face to Gas Key ( interface with Gas Tube ) --------------  0.3415"  - 0.304"    -   0.305" Note : This could cause interference issues with DPMS Upper ?

BC face to end of Gas Key Base ------------------------------  2.824"   -  2.782"  -     2.773"

BC face to inner Cam Pin slot ----------------------------------- 1.1545" - 1.155"    -   1.163"

BC face to outer Cam Pin Hole ----------------------------------- 0.455"  -  0.475"  -    0.462"

Bolt Face to BC face ( locked position , BCG assembled )---- 0.600"  -  0.586"     -   0.583"

Complete Gas Key Length ( rear base to where Gas Tube enters--2.468"  - 2.464" -  2.466"

 

    It doesn't take much to cause an issue , may not show up right away or could cause a fitment issue . The locking of the Bolt & how it engages with the Barrels Extensions Locking Lugs , 0.020" is a lot & may also cause Head Space issues . Just not worth it in my experience to mix this stuff up .

   Some of the measurements between the DPMS & D.Wilson's BCG , could be why some of his BCG's don't work in all DPMS type's , I know I had issues as have others , like I said , it doesn't take much .

Edited by survivalshop
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43 minutes ago, 98Z5V said:

There has to be an OAL difference in the firing pins, if one bolt is longer than the other brand...

I will check that asap, been bugging me that I didn't dig deeper right away. 

We gotta make this stuff a sticky somewhere and get some samples of other brand BCG's. 

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