6 ARC Upper Build: 18” PVA Osprey (Rifle +2”) + San Tan Tactical Billet Upper + SOLGW M89 Rail

[WeR0206]

I previously had this barrel on a different upper during break in but wanted to switch to a San Tan upper for this build.

Barrel specs:

• Weight: 42.8 oz
• Gas port: 0.093”
• Gas system: rifle +2”

Build notes:

• Zev 7.62 Flash Hider/Compensator ($29)
• CMT .750 JAG Set Screw gas block ($25)
• White Oak Rifle +2” Gas Tube ($17)
• Osprey 18” 6 ARC Rifle +2 barrel ($399) (+$125 with headspaced Rubber City bolt) (Total: $524)
• Rubber City M-16 Blacknitride+ Bolt Carrier ($80)
• San Tan Tactical Billet Upper ($175) (thermofit)
• SOLGW M89 15” Rail ($330)
• SOLGW Ambi Charging Handle ($80)
• Total: $1,260

I already have about 150 rounds through this barrel and shot a sub moa 10 shot group during break in (zero load development)

 

[WeR0206]

Barrel has been mounted in thermofit upper, I used a 1200 watt heat gun on high for 90 seconds to warm the upper threads up before sliding the barrel in. Still need to mount it on a URR & torque the barrel nut but I will be out of town until 8/5. The San Tan billet upper is too tight to fit my URR so instead I will use a magpul bev block

 

[sparky702]

I would be interested to see how this turn's out . I am considering building a 6 arc

 

[Redlion]

I do not yet have a 6mm Arc, but interested in building one at some point. I know nothing about Osprey barrels? They certainly appear to be quality. Where do they rank in the realm of quality? Accuracy?

 

[WeR0206]

I do not yet have a 6mm Arc, but interested in building one at some point. I know nothing about Osprey barrels? They certainly appear to be quality. Where do they rank in the realm of quality? Accuracy?

They are made by Josh (@bohem) at Patriot Valley Arms. I love mine so far and they seem to be near universally loved on this site with many others besides myself getting good results. They come in AR barrels, shouldered prefits, etc.. I don’t own any “premium” cut rifled barrels to compare to (proof, bartlein, etc.) but I do own Geissele, craddock RTR, and criterion AR barrels and the Osprey is probably the nicest of the 3 re: machine work, accuracy, etc..

Here’s some more info on them:

https://patriotvalleyarms.com/osprey-barrel-works/

 

[bohem]

I do not yet have a 6mm Arc, but interested in building one at some point. I know nothing about Osprey barrels? They certainly appear to be quality. Where do they rank in the realm of quality? Accuracy?

The Ospreys are gaining in popularity because the performance, price and availability has been very good. We're not perfect, but I think we're doing a lot more right than wrong.

Here's a thread on the announcement of the AR15 options from PVA last summer. @padom just picked up a 6mm ARC barrel to test out as well, he posted pictures of the 16" 223 Wylde barrel that he got last summer.

PVA now offering AR15 barrels!

Josh @bohem from Patriot Valley Arms posted up on Facebook that he is now offering Osprey match grade AR15 .223 Wylde barrels in 16", 18" and 20" length. Anyone who has used the other Osprey barrels knows that they shoot so I don't expect anything less from these barrels. Worth a look if you are...

www.snipershide.com

 

[Redlion]

I appreciate the information.

 

[Rob01]

Yeah I wouldn’t hesitate to get a PVA Osprey barrel. My 6ARC that I bought as a complete upper before PVA started offering them is past half its life and when the barrel is done it will wear a 20” PVA 6ARC barrel.

 

[black5.3]

Yeah I wouldn’t hesitate to get a PVA Osprey barrel. My 6ARC that I bought as a complete upper before PVA started offering them is past half its life and when the barrel is done it will wear a 20” PVA 6ARC barrel.

What round count are you estimating your current 6ARC barrel will go to?

 

[Rob01]

What round count are you estimating your current 6ARC barrel will go to?

Hoping to get around 3000 or so before swapping out. We will see. I’ve been contemplating doing a completely different upper build with an Osprey though. Started looking at parts and pricing out the other night.

 

[WeR0206]

Hoping to get around 3000 or so before swapping out. We will see. I’ve been contemplating doing a completely different upper build with an Osprey though. Started looking at parts and pricing out the other night.

When you so start your build please share your build list/notes. I love seeing what other people are doing/using for parts etc..

 

[Rob01]

When you so start your build please share your build list/notes. I love seeing what other people are doing/using for parts etc..

Will do.

 

[black5.3]

Hoping to get around 3000 or so before swapping out. We will see. I’ve been contemplating doing a completely different upper build with an Osprey though. Started looking at parts and pricing out the other night.

I was thinking the same neighborhood of round count. Im loading 108gr bergers with 29.0gr of leverevolution so not exactly a light load.

 

[WeR0206]

Barrel has been mounted in thermofit upper, I used a 1200 watt heat gun on high for 90 seconds to warm the upper threads up before sliding the barrel in. Still need to mount it on a URR & torque the barrel nut but I will be out of town until 8/5. The San Tan billet upper is too tight to fit my URR so instead I will use a magpul bev block

View attachment 8737570

Barrel nut has been torqued to 60 ft-lbs per solgw specs, muzzle device torqued to 15 ft-lbs, and upper build is complete. Now I need to load up some handloads, do function check, etc.. I verfied gasport alignment with a borescope so hoping for no issues.

The M89 rail fit perfectly with the San Tan billet upper by utilizing the anti-rotation pin. The black finish doesn’t match but I don’t care bc eventually this upper will likely get spray painted.

If they make one I might actually switch the muzzle device for a CMT one so it matches the CMT gas block (which had a nice tight fit on the barrel).

 

[WeR0206]

Barrel nut has been torqued to 60 ft-lbs per solgw specs, muzzle device torqued to 15 ft-lbs, and upper build is complete. Now I need to load up some handloads, do function check, etc.. I verfied gasport alignment with a borescope so hoping for no issues.

The M89 rail fit perfectly with the San Tan billet upper by utilizing the anti-rotation pin. The black finish doesn’t match but I don’t care bc eventually this upper will likely get spray painted.

If they make one I might actually switch the muzzle device for a CMT one so it matches the CMT gas block (which had a nice tight fit on the barrel).

View attachment 8741724

Handloads are done and heading to the range tomorrow:

Alpha brass, fed 205, N140 (25.6 to 26.4gr), and 109gr berger LRHT @2.260”

This range trip will be rounds 150-200 on the barrel so it should pretty much finish off the break in period.

 

[WeR0206]

Just got back from the range but it was a bit of a bust, only fired 10 shots. The barrel shoots great but I'm still dealing with short stroking (FTE, FTF, FTL) even when I switched to a buffer with 3 aluminum weights (using sprinco white spring) and I'd rather not use a reduced power spring.

I emailed @bohem to see what they recommend....I will likely drill out the gas port a bit from .093" to ~ 0.984" (using a 2.5mm bit), since this is 18" rifle +2 the dwell time is pretty short. I have tried pretty much everything else besides increasing the gas port size (set screw gas block, clamp on gas block, swapped BCG, swapped upper receivers, reduced buffer weights, etc.).

Im also going to clean the barrel and take another peak at the gas port alignment via bore scope.

There is one more thing I can try, the clamp on gas block paired with the new BCG because I think the clamp on was tried with the other BCG but either way it seems to be on the bleeding edge and Id rather have a little wiggle room for colder temps, weak factory ammo, etc..

 

[black5.3]

Interested to see what @bohem says about the issue.