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PA10 Nitrated 18", NB BCG, Gen 2 observations...


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On ‎8‎/‎22‎/‎2017 at 4:58 PM, sketch said:

well you guys say its ok to grind a barrel nut.. barrel nut has no index for gas tube.. gas tube already has bends in it.. ill leave it at that. im sure your fix will work. just not how i fix a problem with a different problem. lets get it down range and worry about that later.. ?

Geez... ya make it sound like we are telling you to do this ! Lol..sooo YMMV !

And, because times have changed ( and no offense to anyone ) ..... I will give a  "beware of what some guy on the internet says to do" warning... and anyone doing what I have done is proceeding at their own risk  !!, ....as I have no way of knowing anyone's level of proficiency with home "gunsmithing" and "do it yourself tasks". IF YOU ARE NOT COMFORTABLE doing what I have chosen to do, then DON'T DO IT !

Me and/or anyone, including the webpage, at  www.308ar.com is responsible for someone else's own decision's and actions.

I am not saying this to be mean spirited, but more as a warning. Make your own decisions, and be responsible for your own choices.

I am saying that is the route I took. I am not sure I could have bent the gas tube enough or correctly.. at least to my liking.

Also, honestly.. had I not ground the barrel nut, I still feel like the edge closest to the receiver would have been pushing on the gas tube.

 

AGAIN no offense to anyone !! I have been quite specific through this thread as to what worked for me... I don't want to feel like I should stop posting based on someone not understanding what I am doing with my property.

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Everything in this thread is GTG brother, don't sweat it. Your approach to things being different from Sketch's doesn't make either approach inferior, it's just a matter of personal preference and that's fine. You've cleared up everything that needs cleared up, and this has been a great write-up of the process. Keep up the good work brother!

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2 hours ago, Matt.Cross said:

Everything in this thread is GTG brother, don't sweat it. Your approach to things being different from Sketch's doesn't make either approach inferior, it's just a matter of personal preference and that's fine. You've cleared up everything that needs cleared up, and this has been a great write-up of the process. Keep up the good work brother!

:thumbup::thumbup:

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8 hours ago, bfoosh006 said:

Mods... at this point I am considering stopping this thread.

At the very least, a huge warning posted at the 1st thread should be added to it, feel free to add  ANY WARNING to any of my posts as desired by the staff.

your good brother just didnt want joeblow to read that modifing a barrel nut is the best way.. like you said its your nut grind it if you want :thumbup:  your thread is a good source of info thanks for posting.

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Thanks guys.. I feel better now... Sketch, you made me realize not everyone would understand what I meant.

Thank You.

Updates...

The D&H 20rd and 10rd mags feel much stronger the Brownells...they latch in better then the Brownells, needing only a normal slap,  but do not drop free currently. I can feel a little feed lip spread when fully loaded, but not enough to hinder seating.

They are not better fitting / sliding then the Magpuls or Lancers...

So if you want some smooth sided fits all USGI M14 type mags... I'd use them.

Hand cycled feeding was perfect....I think after the magwell wears in they will drop free better.

 

The Brownells version of the Geissele reaction rod is "Ok"... I didn't bother to look at the overall length and you need to use a 1/2 drive ratchet to secure it... there is in no way, enough of the rod sticking out the ass end of the receiver to DIY grind vise flats and still engage the barrel extension locking lugs.

And I was expecting a snugger fit into said locking lugs... the rest of the rod fits in the BCG channel perfectly

 

The JP Universal Vise blocks are GTG... I would have preferred the blocks extend the entire length of the receiver, rather then one end or the other.

 

 

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The Criterion Barrel...

I want to make a special notation about the quality of the packaging Criterion did...

Outstanding will sum it up.

Heavy Cardboard tube, bubble wrapped with plenty of spare on both the muzzle end and breach end, PlastiDip type caps on the breach end ( clear over the rim that makes contact with the receiver face ) and on the muzzle and that expandable plastic netting over all of it.

Details count !!!  The care taken in packaging, makes me think they really do take pride in their workmanship.

Thank You Criterion Barrels.

 

I have to say... if I knew which upper was going to be the recipient of the Criterion Barrel... I would probably stay up waaaay to late getting it installed. 

 

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  • 2 weeks later...

Range day 18" SS Upper....

First off... The PSA SS upper run 100%.... no issues at all

The D&H 20 and 10rd mags function perfectly... and by the end of the day, they both were dropping free.

I have some IMI 20rders on order as well as a 20rd C Products.

 

Accuracy results.... all targets are fired at 100yds , solid benched, scoped ( PA 4-14x44 ), bagged front and squeeze bag on the back.... I prefer to shoot mildly rapidly, so, no barrel cooling between shots ( it is a MSR , Lol.. so I shoot it in the manner it was intended to be used )

This barrel demonstrates how different barrels can be.. the result were quite different between this stainless and the nitrated one.

Generally speaking... the SS barrel I have is more accurate, with a greater variety of the tested ammo.... Some of it was dramatically more accurate.

 

The first group of the day was a great start...

First photo

Some of the "sanitized" DAG / MEN ammo SGAmmo was selling ( groove cut around the head of the cartridges rim , removing most of the head stamp ) Great group IMHO, especially considering the ammos cost.

2nd Photo..... Hirtenberger '83

3rd Photo....168gr FGMM ....shot about the same as the Nitrated barrel.

4th Photo.... M118LR... I have hope for this ammo, after the barreled settled into it .. it started shooting those touching rds sub groups.

 

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9th Group Photo... 2016 MEN.. The nitrated barrel did better with this one.

10th Group Photo....Eagle Eye 175gr ... One of the best groups of the day.

11th Group Photo... ZQI Ball... still sucks, I gave up after a 5 shot group over 5" ish, based on the previous results. Why waste the barrels life.. Lol

12th Group Photo... TAP "AR" ...much better in the SS, then the nitrated barrel.

13th Group Photo... Federal 130gr OTM.. pretty good for such a unique bullet design.

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Edited by bfoosh006
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Just because the first group was so good.. ( the sanitized German ammo and a brand new , clean barrel ) , I decided it would be prudent to fire another group with it just to be certain it wasn't a fluke... again mildly rapid fire, shoot, back on target within  1-2 seconds, fire..

20rds.

Sad part is.. that surplus has dried up.

 

 

 

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Well.... so ultimately... the nitrated barrel will be coming off and be replaced with the Criterion Barrel.

I do think the PSA barrels performed at their price point..... but for me ( and YMMV ) I do want better accuracy.

I will try to change them as quickly as possible... I am anxious to see the accuracy improvement.

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Great thread. I really like M118LR in my AR10's. If you really like repeatable accuracy and don't mind a hassle cleaning the barrel, try Moly coated BTHP's sometime. My best accuracy so far have been with Moly coated 168gr BTHP's. I am going to start coating my own, as my over the counter source has dried up. But be warned, cleaning the barrels is a time consuming chore. On the other hand, I have seen some residual accuracy benefits when I switched to some Mil Surp ammo midway through a shooting session, so maybe I should just leave it for a while.

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2 hours ago, Sisco said:

 I am going to start coating my own, as my over the counter source has dried up. But be warned, cleaning the barrels is a time consuming chore. On the other hand, I have seen some residual accuracy benefits when I switched to some Mil Surp ammo midway through a shooting session, so maybe I should just leave it for a while.

Give HBN a try for coating if you do your own, the T site has some very detailed instructions and explains the benefits of HBN vs. Moly. If I understand correctly the moly has a tendency to draw or trap moisture on the bore surface, hence the need to clean it, HBN does not need to be cleaned. I use a HBN treatment during break in, makes cleaning much easier, mix a little HBN with alcohol and run a patch soaked in it just before shooting the next round. You can get the HBN on that auction site pretty cheap, a little goes a long way, and be careful with it, once spilled the location will be forever slick!

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Well.... that was very uneventful !!!

The PSA barrel nut was a breeze to loosen up on the nitrated upper !!

WD-40'd it let it soak for about 5 min. and a reasonable pull was all it took. ( Heck I have turned bolts tighter then this one )

IMHO, it was snug enough... but not Gorilla'd on like I expected !

JP Vise blocks worked perfectly for this upper.

The barrel freely moved out of the upper.

 

So much for worrying about some thing needlessly !!

 

Next, I will true up the receiver face..... most likely "glue / lock tight" the Criterion barrel in place and torque it down.

 

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Checking the headspace w/ PSA Bolt and Criterion barrel.... bolt will close and lock on FGMM .308 , CBC 7.62x51, and Hirtenberger '76 7.62x51 ball....

Bolt will NOT close or lock on a Forster NO GO gage.

 

1st photo....trued the receiver face ..... ignore the haphazard grind marks from the "flattening of the barrel nut"

2nd photo... shows the different barrel profiles... PSA at the top, Criterion SS Nitrated .308 Hybrid Barrel on the bottom

( Criterion Model 1018S-HYM-N...18"... 1-10 RH twist ... 5/8 x 24 threaded muzzle.... .750 gas journal... Mid length Gas system.... Criterion 308 WIN M118 chamber  )

3rd Photo... PSA on top.. Criterion on the bottom

4th Photo ... PSA on top ... Criterion on the bottom

             

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Edited by bfoosh006
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Comparing the fit of the two barrels into the upper receiver.... the PSA barrel shows some slop in the barrel extension to upper receiver....

Using just my hands you can feel a definitive " light thunk" while holding the PSA barrel snuggly into the receiver and shifting the barrel side to side and up and down... interestingly, it is most pronounced up and down..... the Criterion barrel shows MUCH less movement.. in any direction.

I will try to mic both and see what the measurements are.

After hand fitting all the parts together, and slightly snugging the barrel nut on the Criterion barrel ( Not fully torqued ) ... I have hand fed numerous .308 rounds and 7.62x51 rounds... all have fed perfectly... from the Magpul, Lancer ( still the strongest mag spring of all the mags ) , the D&H and even the Brownells.

I will use the Loctite 609 Retaining Compound  ( from the Criterion video #3 ...https://www.youtube.com/watch?v=XHxU8VUAHOY&index=3&list=PLqwwk7tC6Sdanx0b55g2EL8UV5udC2Gwh ) .... when I install the barrel, following their guidelines.

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24 minutes ago, hillpitcher2006 said:

This is a very informative thread. I am picking up a PSA Gen2 complete lower this afternoon and will being building around it, and I've picked up a lot of interesting bits of information from your notes.

Can you reiterate why you installed an adjustable gas block?

Peer pressure mostly. :bitchslap:

 

 

 

 

Seriously though, the .308 has way more gas than it needs. The mid length gas system on the PA-10 compounds it. The adjustable gas blocks allow you to tune it to where it uses just what it needs to operate properly. Makes for lighter felt recoil and it's easier on the moving parts. Or so I've read. 

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