bfoosh006

I installed the Criterion barrel today as per Criterions video, used the Loctite 609, lubed the barrel nut with anti seize, torqued it to 50 ft/lbs , Blue Loctited the gas block screws and torqued to SLR spec. I then checked the headspace, with the ejector and extractor removed from the bolt.... closed on a "Go" gage and would not close on a "No Go" gage... even with a little nudge / pressure on the BCG assist......( BTW... the SS PSA upper with the OEM barrel was the same ) With the hammer removed , I hand cycled various .308 and 7.62x51 ( 10 different, 5 of each cal.) brands through it , each brand from a fully loaded 20rd mag, all fed and extracted fine... except the 2016 MEN.. 2 of those 20rds were snug extracting... and the bolt went fully into battery. Are those two rds something to be concerned about ?.... I think I will open another couple of 20rd boxes, hand cycle them and see if it happens again. As per Criterions webpage..." These barrels feature an M4 barrel extension and M118 LR match chamber compatible with both 7.62x51 NATO and .308 Win ammunition. " Here is the explanation on the "M118LR Match Chamber".... https://sierrabulletsblog.com/2017/06/13/the-m118-lr-chamber-the-223-wylde-of-the-308-ar-world/ ...it is similar to a .223 Wylde chamber design.... I feel comfortable with the M118 LR match chamber. I will measure the neck diameter on the MEN ammo and compare it to the other rounds... I would like to test fire it this weekend.

I am no longer a "fan" of NiB bolts... I had never considered the coating aspect. I have numerous other BCG's in NiB, and haven't had any issues, but IMHO.... it does seem like just a bad idea using a coating in such an important area.

hillpitcher2006 ..... this link has some good input as well... http://bulletin.accurateshooter.com/2015/05/what-makes-an-ar-accurate-whitley-offers-answers/ "9. Gas Port Tuning: You want to avoid over-porting the gas port. Being over-gassed makes the gas system pressure up earlier and more aggressively. This causes more impulse, and increases forces and vibration affecting the top end and the barrel. Tune the gas port to give the amount of pressure needed to function properly and adequately but no more."

I am in complete agreement about longer length gas systems.... tapping the gas, further down the barrel will always result in a "softer" shooting AR. If the rifle length version of the PSA had been in stock when I ordered it... I most certainly would have bought that one.

Thank You ! .....I will be checking headspace again after torqueing the barrel ... I was just gettin' antsy !! And as for compatibility ... I e-mailed Criterion weeks ago and they said it should be GTG... I gave them the specific model and make of the rifle.

My main reason for the adjustable gas block was the cyclic action of the PSA... it was needlessly over zealous. I do think the PA10 GenII has a "industry standard" gas port size... but also believe it is slightly bigger ( more gassed ) then needed or wanted... ( at least by me ) USGI weapons are usually overgassed so they will work in the most awful conditions possible.... full of muck, no lube or cleaning for ages.. etc... so they really want the firearm to cyclic "no matter what". My .308 AR will most likely never see severe conditions like that ( I could always increase the gas anyhow.. ). So by using the adjustable gas block, I can limit the available gas volume, and have a fully functioning , softer shooting, easier on the brass and rifle parts, stay on target quicker, more pleasurable .308 AR to shoot. The difference between the OEM non-adjustable and the SLR adjustable gas block configured rifle was "night and day"... The brass cases were not showing signs of violent, still under high pressure extraction after tuning the SLR... ( 5-6 clicks of 12 available ) IMHO, the mere fact that the PA10 GenII will function 100% with , lets just say for the sake of argument, half of the gas of the OEM configuration tells me I did the right thing....remember I am even running a Tubbs .308 Flatwire and a 9.3oz HEAVY rifle buffer with that setting.... Out of all the changes I have done to the firearm... the adjustable gas block was by far the best improvement. To quote someone on another forum... It changed the firing of the rifle from "Linda Blair" in the Exorcist movie to a calm, controllable Winnie the Pooh. I whole heartedly recommend the SLR Adjustable gas block... so much so that I bought 2 more shortly after see how much improvement it does. Much better then just adding weight to the buffer, and or more powerful recoil springs... frankly, if I did it over again... I would skip the KAK 9.3oz buffer completely... and use the adjustable gas block to control the OEM over zealous recoil. On a side note....a lot of people say the recoil isn't bad.... I am 250lbs 6' and can certainly handle the OEM recoil... but have never understood why I should have to ? IE... if I could make your .308 AR recoil like a much smaller caliber, why wouldn't someone want that ?... The benefits of the SLR ( a quality adjustable gas block ) far out weigh the added cost.... you will enjoy every aspect of a adjustable gas block. If anyone orders one from SLR... be sure to consider the 2mm Bondhus wrench they sell and the barrel dimpling jig ( used mine on 4 barrels now ) it took all the guess work out of the install. I hope that answered your question ... if not , feel free to ask more.

BTW.. I have read on numerous different threads around the internet ... that PSA doesn't lube their barrel nuts... this one was 100% lubed.

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.

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

Thank you... I had forgotten about those !!!

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.

Magpul RSA and HK hooks

Like jtallen83 said... make sure to look for possible gas leaks at the gas block, gas tube and gas key interface. One of my completely uppers soaked up the liberal coating of "Go Juice" completely... so be sure to lube a decent amount for the first few times.

I am going to try some more of the BH 168gr Moly after the barrel change. I still have other .308 to test, but the day goes so fast at the range ! Lol I am hoping to amass some of all my .308 and chrono them as well....that will be a long day.

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.

Oops... Nosler 168gr BSB... dismal accuracy

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.

14th Group Photo... CBC / Magtech 2015 Ball 15th Group Photo.... ELD TAP 16th Group Photo... ADI / Aust. Outback 168gr 17th Group Photo... BH 175gr TMK.... MUCH better group then the Nitrated barrel 18th Group Photo... PMC XTAC

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.

5th Photo... Portuguese FN Ball 6th Photo....Atomic 168gr 7th Photo... Malayisan from the .30cal cans... another one that deserves more scrutiny.. quite a few touching shoots. 8th Photo... Hirtenberger '76

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.

What lowers do the PSA uppers fit ? DPMS ? SR25 ? etc.... This is such a common question., across numerous forums.... I am requesting everyone that shoots at a local range, and has a DPMS .308 and / or a PSA PA10 GenII or GenI, and see someone with the other upper / lower ... please go over and ask to see if your uppers will interchange. PSA isn't going to help ( that is their prerogative ) ... so maybe with all of us together we can figure it out. If you do get a chance to try swapping uppers....Please note the specific brand / model lower and upper. And report it here. Thanks ahead of time.

As for someones comment about small primer holes... Guat. and , Hirtenberg 5.56 also have small ( ruin your reloading day flash holes )

Be advised... Independence Ammo is loaded by IMI And some of the first lots produced VERY high velocities.. and with high velocities comes High pressures. Independence 55gr (XM193I).. FC 2,1, 13.................16" Av. 3195, ES 50.................20" Av. 3343, ES 94..........................Same type of headstamp as IMI 77gr , 4 MOA

Oops... and if you want to spend 60 cents per shoot... consider this.. ( cheapest I have EVER seen it. ) https://www.targetsportsusa.com/magtech-cbc-308-win-sniper-ammo-168-gr-hpbt-308d-p-58717.aspx