Valkyrie undergassed with +2 system and factory ammo?

[dang472]

I just built a 20” Valkyrie with +2 gas system with a Seekins matched billet receiver set. I started with a SLR adjustable gas block and the Federal 60gr varmint ammo. Even with the block wide open (15-16) clicks out, the bolt wouldn’t lock back on an empty mag. The barrel shot decent and I closed off the gas and basically treated it like a single shot. With the block wide open, the brass was ejecting at 3 o’clock and the gun was pretty soft shooting. It just wouldn’t pick up the next round. I grabbed a box of 90gr Sierra MK target ammo from Federal and a few rounds locked the bolt back on an empty mag but most didn’t.

I also took the SLR gas block off and put a standard one on. Same results. This is probably the 20th AR I’ve put together so I’m pretty confident in my block alignment. I’m running a Magpul PRS with standard rifle length buffer. I’ve tried 2 different BCGs and even 2 gas tubes.

I’m just wondering if Federal went a little conservative on their factory ammo because most manufacturers are running rifle gas or even mid length systems. I’m probably going to run the last few rounds I have with the Labradar to see what velocities I’m getting. I’m definitely going to reload once brass is more available.

I’m also going to get in touch with my barrel guy to verify the gas port is big enough. When I started building this gun, I never considered I’d be low on gas which is why I opted for the longer gas system.

 

[RyanScott]

24”? 223 runs without issue from a properly ported 24” barrel with a +2 has system so its not the length of the gas system that’s the problem.

 

[XLR308]

The gas port may be a bit undersized for your set up and everything is still new and tight adding to the issue. The last build I did that was a bit out of the ordinary I used an adjustable gas block with the JP LMOS buffer and carrier to allow maximum flexibility.

 

[dang472]

20in barrel. I originally wanted an 18” barrel because all of my hunting ARs are that length but then I would have to drop down to a normal rifle length gas system. I was told by a few barrel guys that if I wanted to push this cartridge harder, I’d want the +2. Obviously most high end 6/6.5 Creeds are +2 so I figured it would be perfect with an adjustable gas block.

 

[XLR308]

Just out of curiosity it isnt a melonite treated barrel is it?

 

[dang472]

Nope, stainless 7 twist barrel. Wilson Arms blank

 

[XLR308]

Nope, stainless 7 twist barrel. Wilson Arms blank

Ok was just wondering, as you probably allready know if the chamber isnt scrubbed out good on a new nitride barrel it will cause extraction issues that appear like being undergassed and leaves a smoked look on the fired brass. One other thing you could look at is the finish of your chamber a light polish may help.

 

[Niles Coyote]

Agree with XLR308 on a possible small gas port... But I'd bet if you bought a low mass carrier it would run perfect. FWIW, I am using a rock creek 18" with a rifle +1" gas system and my port size is right around .095ish and the gas is more than enough to run my SLR on click 7-8 with factory ammo. All of my handloads to date have also worked well with regard to the gas (H4350, Varget and Reloder 15 using 75-90 grain bullets) the exception has been anything using AR-Comp. AR-Comp will not cycle the action and it also leave a NASTY wet goo behind in my bolt and firing pin that if its not immediately removed after shooting will lock up the BCG like its glued shut. I had to use some penetrating oil to loosen it after it had set a day without being cleaned.

 

[RyanScott]

Rifle +1 is the hook answer for 20” but with a bigger port rifle +2 ought to work.

 

[dang472]

I think you guys might be on to something with the chamber being dirty. I sandblasted and cerakoted the barrel. I thought everything was clean and I ran a few patches down the new barrel before shooting it but maybe there was a little debris that never got out.

Niles, the AR Comp being dirty is really interesting. I’m not sure what Federal is using for their 60gr load but my gun is filthy. This is my first all Flat Dark Earth AR so I kind of assumed the color was showing dirt that normally is on a black gun but it’s pretty bad for about 60 rounds. Also the nickel brass is showing the carbon clouding on the body of the case like you guys we’re saying with a dirty chamber. I noticed that but since I never shoot nickel cases, I chalked that up to something new for me as well.

I’ll give the gun a deep clean and shoot a few boxes of brass cased 90gr SMKs and report back.

 

[Niles Coyote]

It was some nasty crap! At first I thought maybe I had left to much lube on my BCG but next time out I was sure to wipe everything down so it was lubed but toweled off... Nope still had the same nasty mess. I've never seen anything like it before in any of my other caliber AR's that I use it in.

 

[dang472]

It’s my first time dealing with an adjustable gas block but these 60gr factory loads are blowing black all over the barrel in front of the block and bcg. I started with a mil spec carrier but switched to my RRA NiB one hoping it was slicker. After 15 rounds it’s got black all over it.

 

[hlee]

It’s my first time dealing with an adjustable gas block but these 60gr factory loads are blowing black all over the barrel in front of the block and bcg. I started with a mil spec carrier but switched to my RRA NiB one hoping it was slicker. After 15 rounds it’s got black all over it.

This sounds like the issue... So, you are seeing black residue on the barrel in front of the gas block? Without removing the gas block? I know you will see some amount of residue UNDER the block, but if you are getting an appreciable amount outside of the block then I would surmise you have enough gas leakage that this is the cause of your short stroking. Getting that sorted out should get your gun running.

 

[dang472]

It was actually residue from the blow off on the adjustable gas block and the adjustment screw. Nothing seems to be leaking from the journal. I just made that comment because it seems this ammo is really dirty.

 

[XLR308]

Agree with XLR308 on a possible small gas port... But I'd bet if you bought a low mass carrier it would run perfect. FWIW, I am using a rock creek 18" with a rifle +1" gas system and my port size is right around .095ish and the gas is more than enough to run my SLR on click 7-8 with factory ammo. All of my handloads to date have also worked well with regard to the gas (H4350, Varget and Reloder 15 using 75-90 grain bullets) the exception has been anything using AR-Comp. AR-Comp will not cycle the action and it also leave a NASTY wet goo behind in my bolt and firing pin that if its not immediately removed after shooting will lock up the BCG like its glued shut. I had to use some penetrating oil to loosen it after it had set a day without being cleaned.

Thats a bit disparaging to hear about AR-COMP I had high hopes for it in the 224V and I have alot of it. When I push the heavies with it in the 68spc (115bthp, 120sst) I get great velocity with no pressure signs and it runs very clean from a 20" barrel. Same with the 223 in a 24" barreled AR and 308 bolt rifle.

 

[Campower]

ARCOMP runs clean in my RLGS 22" Grendel. One of my favorite powders for 123gr.

I want to jump into the Valkyrie badly, but I'm just holding off for starline brass and a reputable rack grade 20-22" 1:6.5 barrel to be available.

 

[XLR308]

ARCOMP runs clean in my RLGS 22" Grendel. One of my favorite powders for 123gr.

I want to jump into the Valkyrie badly, but I'm just holding off for starline brass and a reputable rack grade 20-22" 1:6.5 barrel to be available.

Just watching from the sidelines for now myself, but given the interest in the round and some major players allready invested it wont be long until parts and components will flood the market.

 

[Niles Coyote]

Thats a bit disparaging to hear about AR-COMP I had high hopes for it in the 224V and I have alot of it. When I push the heavies with it in the 68spc (115bthp, 120sst) I get great velocity with no pressure signs and it runs very clean from a 20" barrel. Same with the 223 in a 24" barreled AR and 308 bolt rifle.

It excels in over gassed guns. But try it and see if it will work in your rifle once you have it running. I'm curious if other people will have the same nastiness as I did, or if I have something else going on.

ARCOMP runs clean in my RLGS 22" Grendel. One of my favorite powders for 123gr.

Me too, my most favored and accurate loads have come from this powder in the grendel!

 

[Btillr]

I had similar issues on a 6.8 I built a while back, ordered a wolf reduced power spring and cured everything, ended up closing the Slr down to about 6 clicks out

 

[XLR308]

I had similar issues on a 6.8 I built a while back, ordered a wolf reduced power spring and cured everything, ended up closing the Slr down to about 6 clicks out

Sounds like you had 20" barrel with rifle length gas and .092" port.

 

[Btillr]

Sounds like you had 20" barrel with rifle length gas and .092" port.

18” with mid gas believe port was .078

 

[dang472]

Well I gave it a try today with the factory 60gr and 90gr loads. Completely clean and lubed gun went only 2 rounds of 90gr, locking back on an empty mag with the SLR gas block wide open at 16 clicks. None of the 60gr held the bolt open. The 90gr load runs way cleaner than the 60gr. All ejected rounds were about 1.5-2ft away from the rifle at 3:00 position

Average velocity of 3 90gr rounds was 2652
Average velocity of 3 60gr rounds was 3187

I even switched to another one of my lowers that had a carbine length buffer tube. No real change. I’ve got a reduced power spring ordered as well as a JP SCS with optional spring kit.

I’ve got dies and some bullets coming too so I can push the reloads a little harder. 52gr and 75gr ELDs

 

[bkw1911]

Well I gave it a try today with the factory 60gr and 90gr loads. Completely clean and lubed gun went only 2 rounds of 90gr, locking back on an empty mag with the SLR gas block wide open at 16 clicks. None of the 60gr held the bolt open. The 90gr load runs way cleaner than the 60gr. All ejected rounds were about 1.5-2ft away from the rifle at 3:00 position

Average velocity of 3 90gr rounds was 2652
Average velocity of 3 60gr rounds was 3187

I even switched to another one of my lowers that had a carbine length buffer tube. No real change. I’ve got a reduced power spring ordered as well as a JP SCS with optional spring kit.

I’ve got dies and some bullets coming too so I can push the reloads a little harder. 52gr and 75gr ELDs

I bought the 52s as well hoping I can get them smoking. Already got a ton of 75s from my ai. Really hoping those 52 will smoke because the 60gr factory stuff is too slow. I need a reason to ditch my 20 practical, just haven’t achieved that yet.

 

[dang472]

I’d love to see close to 3400 with the 52s not sure if it’s possible but I’m willing to suffer brass life. This will be my primary coyote rig so most of the time I don’t recover brass anyway. Thinking RL15 and Varget. Any other powder choices?

 

[Btillr]

If using the scs the white spring will Be your reduced power spring

 

[dang472]

I appreciate the help. I forgot to mention that I even took the barrel off and put another one on. I ordered 2 of the same spec from the gunsmith. Same result. I have a feeling my reloads will cure my undergassed issue but I’m helping my hunting partner build nearly the same rifle and he will most likely run factory ammo.

This is my first build using a matched billet upper and lower. The Seekins Precision set is awesome. I Cerakoted it like all my builds but I’m wondering if that is contributing to a small drag on the bcg. Am I crazy to think that could be an issue? My buddy’s build will be using an Aero forged upper and lower, so I guess I’ll know the answer if his build runs with a normal spring.

 

[bkw1911]

I appreciate the help. I forgot to mention that I even took the barrel off and put another one on. I ordered 2 of the same spec from the gunsmith. Same result. I have a feeling my reloads will cure my undergassed issue but I’m helping my hunting partner build nearly the same rifle and he will most likely run factory ammo.

This is my first build using a matched billet upper and lower. The Seekins Precision set is awesome. I Cerakoted it like all my builds but I’m wondering if that is contributing to a small drag on the bcg. Am I crazy to think that could be an issue? My buddy’s build will be using an Aero forged upper and lower, so I guess I’ll know the answer if his build runs with a normal spring.View attachment 6891900

Now I know what the problem is. You don’t have a suppressor.

 

[dang472]

Oh how I wish I could run suppressed. Illinois blows. I just noticed you live in Queen Creek, bkw. I lived there for a couple years. That area is way better for long range shooting than where I live now.

 

[bkw1911]

Oh how I wish I could run suppressed. Illinois blows. I just noticed you live in Queen Creek, bkw. I lived there for a couple years. That area is way better for long range shooting than where I live now.

You betcha. Good place to be a redneck and live close to a major metropolitan.

 

[isaacspoon]

i will have a completed 24" valkyrie here in the next few weeks. I will update on any issues I have. I initially will shoot box ammo to build up brass, but I plan to reload most of my rounds.